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1. 4 Cause permanent hearing loss Do not operate for a long period of time at a high volume level or at a level that is uncomfortable If you experience any hearing loss or ringing in the ears you should consult an audiologist Do not expose the apparatus to dripping or splashing Do not place objects filled with liquids flower vases softdrink cans coffee cups on the apparatus WARNING To reduce the risk of fire or electric shock do not expose this apparatus to rain or moisture 5 N utilisez pas cet allareil proximit de l eau 6 Ne nettoyez qu avec un chiffon humide est potentiellement dangereux d utiliser des pulv risateurs ou nettoyants liquides sur cet appareil 7 Installez selon les recommandations du constructeur 8 Ne pas installer proximil de sources de chaleur comme radiateurs cuisini re ou autre appareils don t les amplificateurs produisant de la chaleur 9 Ne pas enlever la prise de terre du cordon secteur Une prise murale avec terre deux broches et une troisi rme reli e la terre Cette derni re est pr sente pour votre s curit Si le cordon secteur ne rentre pas dans la prise de courant demandez un lectricien qualifi de remplacer la prise 10 Evitez de marcher sur le cordon secteur de le pincer en particulier au niveau de la prise et aux endroits o il sor de l appareil Vipre Reference Manual 17 18 14 Refer all se
2. 15 Connecting 18 Connecting Instruments 18 Connecting Line 18 ABOUT VIDEO sa 19 Why is the microphone preamplifier so important vix Lu I n MEN EE 19 The Input SECTION ei sete Poco eR rhet be 20 About the Input Transformer 20 Introduction Safety Instructions o8 Welcome How to Use This Manual This manual is divided into the following sections describing the various functions and applications for the Vipre While its a good idea to read through the entire manual once carefully those having general knowledge about microphone preamplifiers should use the table of contents to look up specific functions Thank you for making Groove Tubes Vipre part of your studio This is a truly unique product so to take full advantage of the Vipre s functions and enjoy long and trouble free use please read this users manual carefully Chapter 1 Quick Start This will get you started using the Vipre right away It s a short guide to the essential elements of hooking it up and using it for the first time Chapter 2 Connection This chapter gives detailed instructions for connecting the Vipre to a variety of typical audio systems Chapter 3 About the Vipre This section gives detai
3. Microphone Self Noise Acoustic 401856 uses Troubleshooting Troubleshooting Index Care and Maintenance Refer All Servicing to Groove Tubes Obtaining Repair Service Specifications Instructions de S curit Importantes French 4 Beim Benutzen dieses Produktes beachten Sie bitte die folgenden Sicherheitshinweise German P 6 CE Declaration of Conformity 7 QUICK Start Guide 8 OOK AT BID ES 8 Step 2 Set the Controls 8 8 o RON 8 VU Meter 8 Mute 8 Gain Coarse 5 dB and Fine 1 dB 8 simo Hc 10 Impedance Selector 10 HEP ASS tT 10 10 About the Instrument Input 11 Step 3 Experiment 11 GONNECHONS inne 12 Unpacking and Inspection 12 EE e ER 12 mo prn c E 13 Avoiding ground loop noise 14 Basic 02 2 15 Output To a Mixing Console
4. 11 Puisque son fonctionement normale genere de la chaleur placez cet appareil au moins 15cm des equipments p ripheriques et assurez que l emplacement permet la circulation de Ce produit utilis avec un amplificateur et un casque ou des enceintes est capable de produite des niveaux sonores pouvant engendrer une perte permanente de Ne l utilisez pas pendant longtemps un niveau sonore lev ou un niveau non confortable Si vous remarquez une perte de l ouie ou un bourdonnement dans les oreilles consultez un sp cialiste 15 16 N utilisez que des accessoires specifies par le constructeur N utilisez qu avec un stand ou table con us pour l utilisation d audio professionnel ou instruments de musique Dans toute installation veillez de ne rien endommager cause de c bles qui tirent sur des appareils et leur support D branchez l appareil lors d un orage ou lorsqu il n est pas utilis pendant longtemps Faites r parer par un personnel qualifi Une r paration est n cessaire lorsque l appareil a t endommag de quelque sorte que ce soit par exemple losrque le cordon secteur ou la prise sont endommag s si du liquide a coul ou des objets se sont introduits dans l appareil si celui ci a t expos la pluie ou l humidit ne fonctionne pas normalement ou est tomb Vipre Reference Manual 12 13 14 Introduction Safety Instructions
5. 5 50 as to optimize it for a given application This is not just another first class mic pre this box a UT can help you get sounds out of your mic s that have eluded you up until now 77 Walter Becker March 2002 Steely Dan Vi The Groove Tubes Ad The Vipre offers the engineer 8 Whole new world of tube sound choices in a single well made great sounding unit The culmination of over three years of work by Aspen Pittman and Groove Tube s engineering staff Vipre is the epitome of vintage tube amplification perfected for these digital times 7 Barry Rudolph August 2001 66 this Vipre is just too good to send back Mix Magazine gotta have it Here s the check 77 PRODUCER ENGINEER Pat Benatar George Petersen Mr Mix Mix Magazine L4 44 Vipre mic preamp with it s variable impedance highly recommend this unit to anyone with vintage mics The Vipre made all the difference about any other preamp I ve worked with I ve used it on when it was compared to others made available to me voice Sultan and Bass all win stunning results for the review can t say enough about this unit and variable slew rate gives me more tonal control than just encourage all to check it out 79 Frank Filipetti NYC Audio Media PRODUCER ENGINEER James Taylor Carly Simon Elton John Barbara Streisand Pavarotti Celine Dion Kenny G Michael Crawford a
6. back off the GAIN If not you may raise the mixer s Overload characteristic The soft clipping characteristic of an all Class A tube design leads to a much gentler transition to clipping than that of a solid state circuit The onset of clipping is slow and its characteristics are soft Low feedback amp stages keep clipping recovery times short as there is very little loss of feedback overdrive induced by soft clipping at any given stage Furthermore the clipping maintains its moderate behavior due to the fact that all gain stages operate in push pull Class A mode The sum of the bias and audio currents that flow through each push pull stage is held constant at all times None of the audio currents can escape meaning the balanced design is free from undesirable bilateral interaction with other stages or the power supply Vipre Reference Manual input gain to get the desired recording level in most cases with the channel fader and output faders set to the nominal 0 dB position the Vipre s output is too loud In cases where the mixer or signal processor s input doesn t have enough attenuation to handle the Vipre s output at maximum you may try the following e Insert a passive attenuator between the Vipre and the input of the device or e Use the lower level 10dBv balanced 1 4 LINE OUT of the Vipre instead of the XLR output This output has approximately 12 dB less level 26 chapter 3 about the Vip
7. How to replace tubes While tubes will rarely if ever need replacement it is possible to replace them in the field if necessary Remove the cover INSERT STEP BY STEP INSTRUCTIONS HERE Test the tubes Familiarize yourself with the location of the tubes on the circuit card suspended in the center of the Vipre Then carefully remove the tubes noting which tube type goes to which socket Tube types are written on the circuit board but it is possible that the designation on the tube itself may have burned off Note one tube the miniature 6205 is soldered in place it should only be replaced if the INSTRUMENT INPUT is noticeably noisy or inoperative Test the tubes on a standard testing device setting the parameters carefully before applying voltage If a defective tube is found replace it and its pair if applicable with a new military specification replacement Contact Groove Tubes for hand selected and tested equivalents Reassemble the unit Replace the tubes in their sockets and carefully reassemble the unit Make sure nothing has fallen into the unit which could cause a short Vipre Reference Manual troubleshooting chapter 5 ng CONTROLS Spray onto a cloth then use cloth to clean the unit Refer All Servicing to Groove Tubes We believe that the Vipre is one of the best microphone preamplifiers that can be made using current technology and should provide years of trouble free use However sho
8. Beim Benutzen dieses Produktes beachten Sie bitte die folgenden Sicherheitshinweise German N 1 Lesen Sie die Hinweise 2 Halten Sie sich an die Anleitung 12 Ziehen Sie wahrend eines Gewitters oder wenn Sie das Gerat Uber einen Beachten Sie alle Warnungen l ngeren Zeitraum nicht benutzen den 4 Beachten Sie alle Hinweise Netzstecher aus der Steckdose 5 Bringen Sie das Ger t nie mit Wasser in 13 Die Wartung sollte nur durch Ber hrung qualifiziertes Fachpersonal erfolgen Die Wartung wird notwendig wenn das 6 ene en Ger t besch digt wurde oder aber das gt 21 eee E x Stromkabel oder der Stecker D ESRA ETAC NE Gegenst nde oder Fl ssigkeit in das gelangt sind das Ger t dem 7 Halten Sie sich beim Aufbau des Ger tes an die Regen oder Feuchtigkeit ausgesetzt war Angaben des Herstellers Je nn normal arbeitet oder heruntergefallen ist 8 Stellen Sie das Ger t nich in der Nahe von aa Heizk rpern Heizungsklappen oder anderen 14 Dieses Gerat produziert auch W rmequellen einschlieBlich Verstarkern auf PA nn cen 5 9 Verlegen Sie das Netzkabel des Gerates 55222 2 bel Adr niemals so da man dar ber stolpern kann Ger ten oder da es gequetscht wird 15 Dieses Produkt kann Verbindung mit empfohlene Zubehor Lautsprechern Lautst rkepegel 11 Verwenden Sie ausschlieBlich Wagen Stander erzeugen die anhaltende
9. Gehorschaden verursachen Betreiben Sie es nicht Uber langere Zeit mit hoher Lautstarke oder einem Pegel der Ihnen unangenehm is Wenn Sie ein Nachlassen des Gehors oder ein Klingeln in den Ohren feststellen sollten Sie einen Ohrenarzt aufsuchen Vipre Reference Manual oder Tische die speziell fur professionelle Audio und Musikinstrumente geeignet sind Achten Sie immer darauf da die jeweiligen Ger te sicher installiert sind um Sch den und Verletzungen zu vermeiden Wenn Sie einen Rollwagen benutzen achten Sie darauf das dieser nicht umkippt um Verletzungen auszuschlieBen Introduction Safety Instructions CE Declaration of Conformity 4 Manufacturer s Name Groove Tubes llc Manufacturer s Address 1543 Truman Street San Fernando CA 91340 USA declares that the product Product Name Vipre Model Type Microphone preamplifier conforms to the Standards for Safety and EMC for this product listed on the Internet site www groovetubes com Vipre Reference Manual 7 chapter 1 Quick Start Guide Step 2 Set the Controls Phantom lf the mic requires phantom power 48 volt turn the PHANTOM switch on WARNING DO NOT use Phantom Power with a Ribbon Microphone Serious Damage may occur Input Since we re using a microphone in this example set the INPUT switch to BALANCED XFMR If you want to bypass the input transformer and use an electronically balanced input set the switch to BALANCED BR
10. or when miking opposite sides of a diaphragm above and below a piano soundboard a snare drum etc The Vipre is wired according the modern standard of Pin 2 Hot Some older microphones were wired with Pin 3 hot i e a positive pressure on the diaphragm leads to a positive voltage on Pin 3 if you re using one of these set the POLARITY switch to REV Vipre Reference Manual quick start guide chapter 1 Rise Time There is no right setting for the RISE TIME control just your artistic judgement But generally speaking settings toward the FAST side will sound more modern while settings towards SLOW will bring out the more vintage aspects of the preamp See page 27 for more Impedance Selector This switch is only active when the INPUT switch is in the BALANCED XFMR position When it is you can experiment with any of the four impedance selections from 300 to 2400 ohms W How this affects the sound of a mic will vary upon the microphone s actual impedance and other characteristics but again generally speaking lower impedances are more suited to older microphones The most modern or neutral setting of the Vipre is to set the INPUT to Balanced Bridge which bypasses the IMPEDANCE SELECTOR entirely and the RISE TIME to FAST This is the setting tha
11. GAIN STAGE FIRST DIFFERENTIAL GAIN STAGE ATTENUATOR POLARITY HI PASS SWITCH FILTER 5 db STEPS 6922 METER RANGE SWITCH POLE Ovu 10 20 ie a 3 db LED l cu CLIP LED 1 db STEPS Vu METER METER DRIVER OUTPUT TRANSFORMER ET mon BALANCED XLR STANDBY REAR OUTPUT SWITCH MUTE PANEL DENVER CIRCUIT 4 dbM OUT VI p R E BALANCED TRS 6201 CAD PANEL MICROPHONE I wr leu PREAMP Tea Te BLOCK DIAGRAM Groove Tubes FEEDBACK 10 dBV OUT XS BALANCED TRS REAR MUTE SWITCH PANEL Rac CAM aley ICG AT 0 rs E Mg 5 552 SAL QU NU VAR VA RAN N 4 N INN N N NN Len 6 AR AW Me RARE TEST RETAIN 0 NN e NN ae N NS AN ds AS QS NN NUR vi Ms 1 NES B N Na NN hi WS CHA VARIABLE IMPEDANCE INPUT Custom wound transformers load mics at 300 600 1200 or 2400 ohms multiplying the performance potential of every microphone Additional transformerless balanced bridged line and instrument inputs VARIABLE RISE TIME Select between five amplification styles ranging from Smooth and Classic Slow to Bright and Modern Fast Stop dreaming These first two exclusive Vipre features alone provide 25 W ake up your mics unique tone shaping combinations from any
12. goes well beyond the appearance of the front panel Most importantly unlike other tube preamps that feature a single vacuum tube in a largely transistorized circuit 19 about the Vipre chapter The Input Section induced noise from the environment or nearby circuitry Impedance Matching vs bridging In early audio devices circuits were designed to maximize power transfer between units This meant that input and output impedances should be matched e g a 150 ohm source would be terminated by a 150 ohm load This impedance matching maximized the current in the load at a time when every bit of current was necessary due to primitive amplification methods One obvious down side to impedance matching was that a single source couldn t easily feed several inputs at once After the advent of high impedance solid state circuitry the era of maximum power transfer was over and the focus shifted to conveying signals through voltage not current The microphone or other source generates a varying voltage but very little current is drawn in the circuit because the load it sees is so high that it may as well be connected to nothing at all Most modern audio equipment is designed to present a very high impedance load to the source The typical input impedance of a load is designed to be 10 to 20 times the output impedance of a typical source This is
13. line input of the console 2 3 N 1 SHIELD However the line input of most modern consoles is a three conductor TRS 1 4 phone jack as shown below T D S SHIELD To maintain the benefit of fully balanced operation you will need to get an XLR female to 1 4 male TRS adapter or cable like this Sleeve Ground Tip Pin 1 Ground Pin 2 Ring Important tip Many XLR to 1 4 adapters sold at electronics stores are NOT adapters but transformers and very low quality transformers at that Don t use these on the output of the Vipre they re unnecessary and generally sound awful because they don t have the headroom handle the Vipre s output Get a hard wired adapter or cable from your professional audio dealer or make one yourself from components Vipre Reference Manual 15 connections chapter 2 _ you must connect to a MIC IN jack Connecting directly to a 4 dBu recorder Tip For the cleanest possible recording connect the Vipre directly to the inputs of the recorder and avoid going through a mixing console entirely while tracking Professional recorders typically feature balanced 3 pin XLR line level balanced inputs This allows you to connect the LINE OUT of the Vipre direct
14. stage is powered by a Groove Tubes 6205 The output section uses a single Groove Tubes selected 12AT7 to drive a Matched Pair of GT6005 s A K A 6AQ5 The 6922 6008 tubes in your Vipre can be replaced with the consumer grade 6DJ8 but it is possible that sonic performance will be slightly degraded and tube life will not be as long Field replacement of tubes should only be performed by qualified electronic service technicians For more information see page 34 23 Care and feeding of vacuum tubes Unlike the tubes found in guitar amplifiers the tubes in the Vipre should not burn out very often in normal use Nor will their sonic characteristics change dramatically over time This is because the tubes are not being operated at the extremely high plate voltages and currents typical of that required for a 100 watt amplifier connected to a loudspeaker When they do fail in normal use it is usually a gradual process rather than a sudden stop The gain will be noticeably lower or the noise floor will rise is also possible for tubes to experience filament failure Vacuum tubes have small glowing heating filaments inside them similar to those in light bulbs except their job is to make heat instead of light When they are hot they are more susceptible to physical stress Avoid shaking the Vipre when power is turned on even in standby mode If you re going to move the Vipre let the unit cool of
15. variable input impedance and adjustable rise time It can be set for over 20 different tonal variations all without ever requiring EQ or other signal degrading devices to achieve them ALL TUBE FULLY DIFFERENTIAL CLASS A DESIGN Class A means that the same amplification device in this case tubes are doing the entire waveform both the maxima and minima of the wave Class AB and Class B use separate amp devices to do the maxima or top side and minima low side of the wave Those are more efficient but not nearly as accurate or true Fully differential means that the signal remains balanced throughout never becoming unbalanced or single ended Almost all amp circuits break the balance In a console the signal is single ended from the time it comes into the preamp until bridged at the output Vipre s balanced signal path is accomplished by using identical mirror image signal paths throughout Therefore twice the components are required at every stage and why we use expensive ceramic deck attenuators instead of potentiometers for gain adjustments This approach literally doubles the component and labor cost but distortion is lowered and common mode rejection ratios are significantly improved as are signal to noise ratios PRECISION GAIN AND GENUINE VU In order to maintain a fully floated and balanced signal path throughout the entire circuit there are no potentiometers on the front panel Instead gain controls
16. CED BRIDGE 8 BALANCED XFMR 8 Block Diagram 30 Class A 23 27 Clip LEDs 25 clipping 9 Connections 15 direct box 18 EIN 33 ELCO 16 filament 24 fuse 34 GAIN 8 18 Gain Controls 26 Ground Loops 14 grounding 3 13 headroom 26 Hi Pass 10 impedance 22 32 of tubes 23 source and load definition 32 Impedance Selector 10 INSTRUMENT INPUT 11 18 Instruments 18 LINE IN jack 18 Maintenance 35 MIC IN connecting Vipre output to 16 microphone ribbon low impedance 22 Microphones 18 mixer gain setting with 26 Mute 8 29 noise 14 33 PHANTOM 8 18 phantom power 28 Polarity 10 potentiometer 26 Power 13 Power cable 3 rack mounting 12 Rise Time 10 28 Safety 3 shock 3 slew rate 28 Specifications 37 STANDBY 29 Transformer input 21 38 Groove Tubes Limited Warranty GROOVE TUBES llc GROOVE TUBES warrants this product to be free of defects in material and workmanship for a period of one 1 year for parts and for a period of one 1 year for labor from the date of original retail purchase This warranty is enforceable only by the original retail purchaser and cannot be transferred or assigned The purchaser should complete and return the enclosed warranty card within 14 days of purchase During the warranty period GROOVE TUBES shall at its sole and absolute option either repair or replace free of charge any product that proves to be defective on inspection by GROOVE TUBES or i
17. Groove Tubes ie american Tube Company since 1979 1543 Truman Street San Fernando CA91340 818 361 4500 fax 818 365 9884 PRESS RELEASE The 12 time Grammy winning engineer producer with more on the way for this years Grammy nomination for Natalie Cole s latest Mr Al Schmitt talks about his ViPRE and he is all smiles Many thanks for the kind words Al ee This box brings out the best from all my mics When want a tube pre go to my Vipre wish I had a stereo version bought one for myself after trying it on several sessions it s variable impedance allows me to match the mic with the performer and the slow rise time feature can really sweeten up a shrill vocal highly recommend this tube pre amp Al Schmitt Jan 2003 Vipre Variable Impedance Preamp Stop dreaming Only Vipre does what no other preamp can Visit our website or call us at 818 361 4500 for complete specs and a list of Groove Tubes Vipre dealerships 5 CUSTOM SHOP PRODUCTS 2001 Groove Tubes LLC All rights reserved Groove Tubes the GT in a circle logomark Groove Tubes Custom Shop Products and Vipre are trademarks of Groove Tubes LLC Groove Tubes U n VARIABLE IMPEDANCE Custom wound transformers 300 600 1200 2400 performance potential of every 1e Additional transformerless balanced
18. IDGE VU Meter Range For now set this to 0 dB You can experiment with other settings after you ve set the initial gain Mute Switch After 60 seconds of warm up switch this to NORMAL Use this feature when changing microphones Gain Coarse 5 dB and Fine 1 dB These are the most important controls to set in any microphone preamp The Vipre uses two rotary step switches to set the gain with laboratory precision The left control goes from 20 dB to 70 dB of gain in 5 dB steps the right control allows you to change it in single dB increments 5 dB Typical gain settings on lead vocals range from 30 to 50 dB but that of course depends upon the microphone and source and the input sensitivity of the mixer or recorder connected to the 5 output There are two different methods commonly used to set the gain of any mic preamp The nominal level method maximizes headroom the peak method maximizes the dynamic range of the system by using up much headroom as desired Vipre Reference The Groove Tubes Vipre is a unique product but its basic hookup and operation is similar to other outboard microphone preamplifiers in most respects This chapter is a shorthand guide for those who want to start using the Vipre right away If you have questions about any of the features don t worry later chapters will unveil the mysteries of the Vipre s special features Step 1 Hook it up 1 Pull the Vipre out of t
19. Tubes check over all your connections and make sure you ve read the manual Customers in the USA and Canada If the problem persists call Groove Tubes 818 361 4500 and request the Customer Service department Make sure you have the unit s serial number with you Talk the problem over with one of our technicians if necessary you will be given a return order RO number and instructions on how to return the unit All units must be shipped prepaid and COD shipments will not be accepted For prompt service indicate the RO number on the shipping label Units without an RO will not be accepted If you do not have the original packing ship the unit in a sturdy carton with shock absorbing materials such as Styrofoam pellets the kind without CFCs please or bubble pack surrounding the unit Shipping damage caused by inadequate packing is not covered by the Groove Tubes warranty Tape a note to the top of the unit describing the problem include your name and a phone number where Groove Tubes can contact you if necessary as well as instructions on where you want the product returned Groove Tubes will pay for standard one way shipping back to you on any repair covered under the terms of this warranty Next day service is available for a surcharge Field repairs are not authorized during the warranty period and repair attempts by unqualified personnel may invalidate the warranty Service address for customers in the USA Groove T
20. Tubes Warranty card e Rack mounting hardware two pieces plus parts to attach them to the Vipre when rack mounting It is important to register your purchase if you have not already filled out your warranty card and mailed it back to Groove Tubes please take the time to do so now 12 chapter 2 connections Power Voltage conversion If you need to use the Vipre in a country with a N Make sure you read the initial Important Safety 7 2 2 Instructions chapter at the front of this manual 7 gt IgINg 9 requires internal adjustment on circuit boards that operate at dangerous voltage levels Again refer to a Groove Tubes service center for adjustment The Vipre works with a single standard line voltage and comes with a detachable AC line cord suitable for the destination to which the preamplifier is shipped Units sold in the United States are designed for use with 110 to 120 volt AC power nominal 60 Hz but N there is a plug in voltage selector in the power entry NEVER OPERATE THE VIPRE AT A module in the rear panel switch allowing voltage DIFFERENT VOLTAGE THAN THAT conversion to 100V or 220V 240V operation MARKED ON THE UNIT This will damage the unit The line cable is an IEC spec AC power cable designed to be connected to a grounded 3 pin outlet with the third round pin connected to ground Do not substitute any other type of AC cord IEC spec cables of vari
21. ained in proper studio grounding techniques In some cases a star grounding scheme must be used with the mixer at the center of the star providing the shield ground on telescoping shields which do NOT connect to the chassis ground of other equipment in the system Vipre Reference Manual connections chapter 2 kh Avoiding ground loop noise In today s studio where it seems every piece of equipment has its own computer chip inside there are many opportunities for ground loop problems to occur These show up as hums buzzes or sometimes radio reception and can occur if a piece of equipment sees two or more different paths to ground While there are methods to virtually eliminate ground loops and stray radio frequency interference most of the professional methods are expensive and involve installing a separate power source just for the sound system Alternatively here are some helpful hints that professional studio installers use to keep those stray hums and buzzes to a minimum KEEP ALL ELECTRONICS OF THE SOUND SYSTEM ON THE SAME AC ELECTRICAL CIRCUIT Most stray hums and buzzes happen as a result of different parts of the sound system being plugged into outlets of different AC circuits If any noise generating devices such as air conditioners refrigerators neon lights etc are already plugged into one of these circuits you then have a perfect condition for stray buzzes Since mo
22. ake up the true noise floor of a typical live recording Even in recording studios very few facilities are soundproofed well enough to have ambient sound pressure levels much below 40 dB SPL Audio control rooms now with computer cooling fans hard drives and other motorized equipment often have an ambient SPL sound pressure level of 50 dB or higher For this reason the most effective way to improve the signal to noise ratio of a recording is to move the microphone closer to the source A loud singer can generate 100 dB at 3 which in a 40 dB SPL environment gives a dynamic range of 60 dB still notably less than the range of 16 bit digital recording but a vast improvement over what happens if the singer is ten feet from the microphone Since classical music is usually recorded using microphones placed at a distance from the source careful attention has to be paid to minimizing noise from all parts of the system Setting gain to optimize the performance of the preamp selecting a microphone with low self noise and recording in a room that has been carefully soundproofed should all be considered Only with all three will you get the quietest recording possible Vipre Reference Manual mic preamp theory chapter 4 designers usually although not always manufactured and tested their micropho
23. al recorder that peaks at 19 dBu for example the VU meter will be pegged most of the time The Vipre overcomes this by a separate meter driver circuit and the VU METER RANGE switch This changes the voltage reference of the meter as follows VU 0 VU 4 dBm output range 20 to 3 dB 16 dBm to 7 EXPAND 0 VU 4 dBm range 60 to 9 dB 10 dB 0 VU 10 dBm range 10 to 13 dBm 20 dB 0 VU 20 dBm range 0 to 23 dBM 30 dB VU 30 dBm range 10 to 33 dBM Note that these are still average values however If the VU RANGE switch is set to 20 and the meter is reading around 0 there still may be peaks of 10 12 dB that will not be shown on the meter Those will be caught by the SIGNAL LEDs 24 Vipre Reference Manual chapter 3 about the Vipre Oo sss Gain Controls GAIN Setting Procedures The best method for setting the gain will vary depending on what the output of the Vipre is connected to but here are some general guidelines See page 8 for the basic gain setting procedure Start low and work up The Vipre has an incredible amount of potential output gain much more than most mic preamps For this reason use caution with the GAIN control Start with the 5 dB control at its minimum setting and increase it Step by step until the level is correct as shown on the meter of the receiving device mixer recorder etc Check the sensitivity of the receiving device Digital recor
24. and the last example of a source that s entirely shorted out you can see the simple but crucial way the load and source interact In the case of the Vipre which is the load that the microphone or other input source sees a great deal of care was taken to allow for the many subtle variations between different sources by allowing the user to set a specific load impedance that the mic will see As explained earlier in this manual the need for different impedances is a result of the history of the development of the audio industry as the circuitry and capabilities of preamplifiers and consoles changed Microphone Vipre Reference About Impedance The importance of impedance Understanding what we mean by variable impedance preamp is crucial to getting the most from your Vipre A quick review of some basic electronic theory often taken for granted in today s studio may help A microphone is essentially a small electrical generator trying to push voltage to its output The input impedance of the microphone preamp is what it s pushing against When you think of it this way it s clear that the input impedance of a preamp can have significant effect on the sonic characteristics of a microphone Let s look at three different situations between the source and its load When sound strikes the diaphragm of a microphone it translates that mechanical energy into electrical energy In a dynamic microphone a coil of fine wire is p
25. avoid clipping the input section of the mixer For maximum dynamic range set the mixer s input trim to its lowest level and increase the GAIN controls of the Vipre until the Vipre s 3 dB and or CLIP LEDs barely flash on the loudest peaks Check to see if the mixer s input meter is clipping if so you ll have to 25 Proper setting of microphone gain is one of the most crucial aspects of recording If there s not enough gain at the preamp and you try to make up for it later by adding gain at the console you will be amplifying noise If there s too much gain the sudden transients common to many types of music will drive the system into distortion The dynamic range and clarity of the entire recording are determined at this critical stage Yet most mixing consoles relegate this important task to a single carbon track potentiometer covering a 40 to 60 dB range Worse still in most cases the taper of the control puts most of the gain in a few degrees of rotation at the very top of the control On many consoles the difference between 40 dB and 50 dB of gain the most common range for many applications may be covered in as little as 1 8 of a turn This makes setting the gain correctly almost impossible And if you want to recreate the exact gain structure at a later time after the control has been moved you re out of luck The Vipre s GAIN controls prominently located at the center of the front panel surrounding the VU meter and si
26. ay be simply set on a table or installed in a standard 19 audio equipment rack While the rack mounting holes are integral to the front panel the Vipre is unusually deep and heavy so extra support must be provided for the rear of the unit Before the Vipre is installed in a rack we recommend that you attach the reinforcing rack kit to handle the weight of the unit and provide ventilation room The rail kit requires one free rack space above the Vipre J Since the vacuum tubes in the Vipre generate a certain amount of heat make sure adequate ventilation is provided in the rack the rack kit The reinforcing rails should be attached to the sides of the unit They are screwed to the sides of the preamp and extend to above the front panel Standard rack screws are then used to fasten both the Front Panel and the Rack Kit to the Rack Rails panels SIDE VIEW TYPICAL OF EACH SIDE 4 SINN gt gt FRONT VIEW 0 Y Y io io 2 Y 0 Reference Your Groove Tubes Vipre was carefully packed at the factory and the shipping carton was designed to protect the unit during shipping Please retain this container in the unlikely event that you need to return your Vipre for servicing The shipping carton should contain the following items e Variable Impedance Preamp e This instruction manual e Power cable e Groove
27. b ui E 7 30 Vu SLOW vo J 1 dE INSTRUMENT INPUT 5 5 VU 4 dem e o T SIGNAL B 1 div PHANTOM 225 e o kea Oe a G o Ga 2 gt E 4 e 1 3 4 a5 Variable Impedance Proamp ER 1 nu Au AU AR AAT EEE Nu po TI OT d PORE DRE Gas aa ul es INPUT IMPEDANCE SELECTOR BALANCED INSTRUMENT BRIDGE INSTRUMENT dg A 3 INSTRUMENT INPUT MUTE STANDBY Preamp POLARITY HI PASS NORM OFF pe a Variable jmpedeac gt zz iu LLL EEE amp oc cue gt en m LR LOT En DE EZ SUN EZ ED 1 1 wir Bat i E 2 Eh haha ana 44 heard the Vipre demo at the NY AES show New York and bought one right W t away Since I ve had it I ve used it in many different applications and gotten great Ot h rs results would not have been able to obtain otherwise This is a beautiful piece of equipment well designed lovingly crafted a state of the art a re expression of Aspen Pittman s thinking on vacuum tube microphone preamplification As such it offers a number of unique options for shaping the output of a favorite mic 5
28. bridged line and instrument inputs VARIABLE RISE TIME Select between five amplification styles ranging from Smooth and Classic Slow to Bright and Modern Fast These two features alone provide 25 unique tone shaping combinations from any single microphone ALL TUBE BALANCED CLASS A DESIGN Eight Groove Tubes in a fully differential signal path dramatically lowers noise and distortion while expanding bandwidth 7 Hz to over 10077 PRECISION GAIN Custom built ceramic deck attenuators control 75 of gain in 5dB and 1dB stepped increments AUTHENTIC VU METERING With five switchable viewing ranges GROOVE TUBES sil g IMFEDANCE vedi POWER SWITCH TRANSFORM SELECTOR ER POWER SUPPLY INPUT SWITCH 600 m FIRST SECTION INPUT BALANCED 6 2 CS 48 oe gt IE poa XLR REAR BALANCED PANEL XFMR BALANCED INSTRUMENT BRIDGE INPUT mi BALANCED F 9 2 REAR INSTRUMENT BALANCED BRIDGE ONLY PANEL BALANCED BRIDGE ED INPUT SWITCH SECOND SECTION INSTRUMENT 6205 TUBE INPUT BUFFER INSTRUMENT UNBALANCED INPUT 69 TO BALANCED UNBALANCED FRONT PANEL RISETIME SWITCH 10 db gt ATTENUATOR POWER SWITCH POWER SUPPLY 100 110 130 210 230 VAC 50 SECOND DIFFERENTIAL
29. called a bridging input For a more in depth explanation of the importance of impedance see page 31 But what is the actual impedance of the microphone you re plugging in And what kind of circuit was that microphone designed to see for optimum performance Particularly in the case of vintage condenser and ribbon microphones the original design usually were set up for impedance matching not bridging When these microphones are plugged into the MIC IN jacks of today s solid state mic preamps or consoles they re seeing a very different load than they were designed for When they re plugged into the input of the Vipre and the impedance is set to lower values they exhibit the more open sound heard on classic recordings Yet other microphones may need to see a higher bridging load for best performance In any case altering the load against which the microphone has to push fundamentally alters the tone and character of the output signal The Vipre gives you the best of both worlds A key to this flexibility is the input transformer which is the first component the microphone sees when the INPUT SELECT switch is in the XFMR positions What s the best input impedance There is no best one Like EQ or effects the right setting is the one that sounds best in a particular situation However it might help you to choose a Vipre Reference Manual About the Input Transformer The Vipre features an exclusive input transformer cu
30. ch as the Groove Tubes microphone systems feature outboard power supply boxes that connect directly to the microphone using a multipin cable The power supply usually has a standard 3 pin XLR output which should be connected to the XLR input of the Vipre using a shielded microphone cable This type of microphone doesn t require phantom power from the Vipre so leave the 48V PHANTOM switch on the front panel OFF 18 chapter 3 About the Vipre Why is the microphone preamplifier so important the Vipre has NO semiconductors transistors integrated circuit chips or electrolytic capacitors anywhere in the signal path Vipre Reference In today s era of high resolution digital recording the sonic characteristics of the microphone preamplifier have become crucial in determining the overall sound quality Most of the gain in the recording signal path is provided by the mic preamp and accordingly the dynamic range of the recording is set by the noise floor of the preamp The wider availability of large diaphragm condenser microphones coupled with the scarcity of vintage equipment properly designed for use with those microphones has been another trend that focused attention on the preamp Many recording studios own large assortments of mics and preamps in order to be better prepared for the needs of various artists and groups And for good reason the more tonal variations a facility can provide the more diverse and desirable
31. chever lights first flashes briefly on peaks Back off either or both of the controls to dial in exactly the headroom you want for example one click back of the COARSE control and one click back of the FINE control would be 6 dB below clipping If the Vipre s VU meter is pegging change the VU METER RANGE to the 20 or 30 position Unlike solid state microphone preamplifiers the Vipre exhibits a very gentle clipping characteristic which is to say that it s OK to drive it into clipping if that s what the artistic situation calls for Note however that the Vipre is capable of extremely high output which may clip the following device if the recorder or mixer has its own input level control make sure it s set low enough to avoid clipping in that unit In some situations a passive attenuator may need to be inserted between the Vipre and the recorder mixer or the 10 dBV BALANCED OUT may need to be used instead of the LINE OUT 1 Make sure the VU METER RANGE switch is set to 0 2 With the source playing into the microphone raise the 5 dB GAIN control until the VU meter of the Vipre is peaking at 0 or just barely going into the red Raise or lower the 1 dB GAIN control as necessary The average level of the output will be nominal 4 dBu at the balanced line out 10 dBV at the unbalanced line out with peaks typically 8 10 dB above that The Vipre s green and red SIGNAL lamps should never flash with thi
32. consist of ceramic deck rotary switch assemblies arranged for discrete step attenuation providing repeatability ultra wide control range and superior accuracy To watch over all this signal manipulation capability the Vipre is fitted with a genuine VU meter for signal observation complete with five separate types of VU response through an amplified VU meter driver circuit that allows for an expanded view of 20dB to 4dB up to a 60dB to 9dB response BOTTOM LINE ONLY VIPRE DOES WHAT NO OTHER PREAMP CAN Hear the Vipre along with our full line of mics and other signal processors at your Groove VARIABLE IMPEDANCE INPUTS Altering the input impedance changes the load against which the mic has to push This dramatically alters the performance of any mic from classic ribbons to vintage and modern condensers even dynamics All mics will respond similarly in that the apparent proximity gets closer when the impedance is lowered but since you re changing the load on the mic you re altering the performance of the mic not the preamp Some vintage mic preamps like Neve modules can be internally hard wired to one of two different impedances Avalon s 2022 and Joe Meek s VC 1 both have an impedance matching circuit consisting of a resistor network placed AFTER the load is already terminated But this isn t the same as what the Groove Tubes Vipre offers This is the only preamp we know of with a fr
33. d lowers distortion The result is a preamplifier with a 7 Hz to 100 kHz frequency range and the ability to convey great detail while remaining nearly free of unwanted sonic imprints The Vipre employs eight different tubes seven of those tubes are rubber shock mounted on the main PCB to avoid transmission of mechanical noise to the circuit e 6922 6DJ8 4 preamplification rise time circuitry e 12AT7 1 output driver 276205 1 Instrument Input preamp tube e 6AQ5 2 Class A push pull output About Class A circuitry The Vipre uses fully differential push pull Class A topology throughout The term Class A refers to a particular method of utilizing amplification devices tubes or transistors in an amplifier Class A designs are the most linear i e the lowest distortion because 22 chapter 3 about the Vipre o Tube Replacements The tubes used in the Vipre are special he cream of the crop They have each been individually tested by Groove Tubes before being used in your Vipre and further burned in for many hours before we shipped it to you While replacements are available from electronics supply stores for the highest quality replacement tubes please contact Groove Tubes This will assure you of receiving a premium selected tube that will give you the same performance as the original There are four Groove Tubes 6922 aka 6DJ8or ECC88 in the first two stages of Vipre instrument input Gains
34. d to 6 V usecond 20 20 000Hz 1 5 dB any input to any output Vipre Reference Input impedance LINE IN INSTRUMENT IN Outputs Output impedance Maximum Output Level MAX Available Gain Equivalent Input Noise EIN THD N Slew rate Frequency Response 36 Specifications EE a total range 4 2 20 1 5 dB 100 kHz BALANCED XFMR position 472 206 1 5dB 9 100kHz BALANCED BRIDGE position 20Hz 20K 1 5 db 100K INSTRUMENT INPUT PASS filter Switchable 4 dB per octave below 100 Hz Power consumption 90 watts Max Size 5 25 H 19 W x 14 75 D without rack kit Rack spaces 3 spaces without rack reinforcing kit 4 spaces with rack reinforcing kit Weight 28 lbs w rack kit All measurements done over a 20Hz 20 000Hz range with a nominal 1KHz sine wave Impedances are measured at 1 kHz Dimensional drawing Allow 4 additional FRONT 5 25 H by 19 W TOP 14 75 D by 19 W clearance for rear connectors Allow extra kk 1 7 8 height for rack reinforcement kit Note rack holes are in middle of top and bottom space U S style spacing Vipre Reference Manual 3 Reference index output 28 Tubes 23 replacing 24 35 unbalanced output 17 ventilation 12 voltage 34 Voltage conversion 13 VU Meter 25 XLR 16 input 18 to TRS adapter 15 XLR output feeding unbalanced device 17 AC power and noise 14 ADAT 16 26 BALAN
35. ders Since most professional digital recorders don t have input level controls if you re plugging the output of the Vipre directly into them the GAIN settings must be set while watching the recorder s meter not the Vipre s For example some popular digital recorders are calibrated for 15 dB of headroom over a nominal 4 dBu input which means the maximum signal the recorder can accept at its balanced input connector without clipping is 19 dBu about 11 dB less than the maximum output of the Vipre Most other digital recording systems have similar amounts of headroom from 12 to 18 dB In this case the CLIP and 3 dB SIGNAL LEDs of the Vipre should obviously never come on Set the Vipre s GAIN controls while watching the digital recorder s meter adjusting to get the hottest level possible while never exceeding O dBFS MAX perhaps allowing several dB of extra headroom to allow for unexpected transients When using digital recorders with 10dBv O reference use the 10dBv Referenced Output 1 4 TRS jack on the Vipre Mixer signal processor If the output of the Vipre is feeding a mixer or other signal processor your options are more varied A mixer with its own input trim controls or attenuator switches may be set up in different ways depending on the effect desired For the best signal to noise ratio or to intentionally overdrive the Vipre for a particular effect you will need to decrease the input sensitivity of the mixer to
36. e cumulative effect over the whole spectrum is unmistakable This kind of variation would be almost impossible to recreate with any kind of EQ unless the principle of a simple uncluttered signal path is abandoned altogether Moreover a balanced bridged or transformerless input is provided bypassing the variable impedance input transformer altogether for a completely different sonic character An instrument input is also provided on the front panel of the Vipre for easy access and can be padded by 20dB to accommodate the stronger output signals from active instrument electronics He IN THE ANNALS OF PRO AUDIO Contents Frequently Asked Questions About Vacuum Tubes BRAS IN RE Impedance of tubes About Class A circuitry Care and feeding of vacuum tubes Tube Replacements The VU esed VU Meter Range Control Gain 620017058 GAIN Setting Procedures Overload characteristic RSE MING ET The Output Transformer Mute Switch Standby ae ae Block Microphone amp Preamp Theory About Impedance The importance of impedance ABOUT NOISE eub Thermal Noise
37. e the B voltage is applied across the tube the cathodes will not be stripped of molecules before the cathode is fully charged 2 It lowers the unit s power consumption when it s temporarily not being used and 3 It saves you from having to wait for the tubes to warm up when you want to use the Vipre again y Turn STANDBY ON e before turning the POWER switch on leave the unit in STANDBY for at least 30 seconds after power has been turned on e afew seconds before turning the POWER switch off this is less important than during power up but it s still a good practice e whenever the Vipre is not going to be used for a short period up to an hour or two N Do not leave the Vipre unattended for long periods of time with the POWER switch on even in STANDBY mode Turn off the POWER switch whenever you leave the studio at the end of the day Vipre Reference Manual The MUTE switch is designed to cut off all output signal from the Vipre when you re changing microphones making connections or drastically changing settings The output is muted off when the yellow light is ON Use MUTE to avoid potentially damaging pops and clicks in the system y Turn MUTE ON when e youre plugging in a microphone e the unit is in STANDBY mode e youre switching to a different input source INSTRUMENT INPUT and aren t sure of the level e you need to set the GAIN before the recorder or mixer is ready e when the drummer tr
38. f for five minutes before moving it A hot tube filament that is shaken is more likely to fail Vipre Reference Manual about the Vipre chapter The VU Meter VU for Volume Unit meters one of the oldest and perhaps still the best tools for displaying the level of an audio signal The meter for the Vipre was custom built to match the characteristics of classic meters right down to the ivory color of the background Compared to less expensive LED meters the VU meter by its nature averages out the peaks to display the RMS root mean square value of a signal which is what most people perceive as loudness A VU meter s ballistics are intentionally designed to respond to a newly applied signal within 3 10ths of a second Clip LEDs However while the VU meter accurately models what the human ear perceives as level it does not respond quickly enough to show very short peaks which can distort the signal particularly on digital devices For this reason the Vipre supplements the VU meter with two SIGNAL LEDs 3 dB and CLIP located under the meter These respond instantly to any audio signal approaching the maximum output level of the Vipre VU Meter Range Control Another limitation of the classic VU meter is its 23 dB range If you re recording audio with a very low level the meter won t move at all at its standard setting Similarly if you re sending very high level signals to a digit
39. former but directly to the BALANCED BRIDGE position of the INPUT switch Set the INPUT SWITCH to that position to hear signal at the LINE IN jack Disconnect any connection to the MIC IN jack when using the LINE IN jack Vipre Reference Manual The balanced female XLR connector on the rear panel is intended for use by low impedance microphones needing preamplification It is wired in the standard configuration Pin 1 shield Pin 2 hot Pin 3 cold and will receive 48 volt phantom power when the 48V PHANTOM switch is on WARNING DO NOT USE PHANTOM POWER WITH RIBBON MICROPHONES SERIOUS DAMAGE MAY RESULT When the GAIN switches are both set to maximum the signal at the XLR jack will be amplified 75 dB When both GAINs are at minimum it will be amplified 15 dB Warning about connecting line level sources to the XLR input Though the XLR IN may be used with a balanced line level source such as the output of a VCR headroom will be limited even with the GAIN at minimum the input will clip when the input level rises above 10 dBu For this reason it s better to connect balanced line sources to the 1 4 LINE IN jack on the rear panel using an XLR to 1 4 TRS adapter or cable A Never connect an electronic line input to the XLR IN jack if phantom power will be turned on Doing this could damage the equipment and the Vipre Connecting microphones with outboard power supplies Many high quality microphones su
40. gnal LEDs are a vast improvement on potentiometer gain controls They are ceramic deck rotary switches attached to individual precision resistors This discrete step attenuation provides repeatability economy ultra wide control range and superior accuracy The 5 dB control sets the gain from 20 to 70 dB in 5 dB steps and the 1 dB control sets the gain 5 dB in 1 dB steps If you see on the meter of a digital recorder that you have exactly 4 dB of headroom left you can add exactly 4 dB of gain at the Vipre before the next take if you wish Besides their usefulness in operation the GAIN controls add to the sonic integrity of the Vipre Continuous potentiometers in a balanced circuit must be of the double pot type and precisely matching resistances between the two carbon tracks is impossible The Vipre s step attenuators are built to have greater than 1 interstage matching at any and all chosen settings maintaining a fully floated and balanced signal path throughout the entire circuit Extra effort has been expended to frequency compensate the 5 dB coarse gain attenuator eliminating the typical bandwidth robbing effects of parasitic circuit and wiring capacitance While most consoles have 60 dB of mic preamp gain at best the Vipre boasts an impressive 75 dB of available gain This extra 15 dB of gain is particularly valuable when miking classical instruments from a distance Vipre Reference Manual about the Vipre chapter
41. he package and plug it into a grounded AC power source with the supplied power cable 2 Connect the output of a microphone to the MIC INPUT on the back of the Vipre 3 Connect the LINE OUT of the Vipre to a line input not a microphone input of a mixing console or recording device 4 For now set the 5 dB GAIN control to minimum 20 full counter clockwise 5 Turn the STANDBY switch to the right STBY position the red light will light 6 Turn the MUTE switch to the right MUTE position for now The yellow light will light 7 Turn the Vipre s POWER switch ON J Remember that the Vipre has an all tube signal path and it will take about 20 seconds for the tubes to warm up before you would be able to hear audio Tube life will be prolonged if you leave the unit in STANDBY mode for at least 30 seconds before turning STANDBY to the B ON position 8 After 30 seconds or so turn the STANDBY switch to the left B ON position the red light will turn off chapter 1 quick start guide To set the gain using the peak method To set the gain at nominal level set the Vipres VU METER RANGE switch to 10 Vu With the source playing into the microphone raise the 5 dB GAIN control until the meter of the receiving unit the mixer or recorder the Vipre is feeding is nearing its maximum level Carefully raise the 1 dB GAIN control until the receiver s CLIP LED or the Vipre s SIGNAL CLIP LED whi
42. how long an implied warranty lasts so the above limitation may not apply to you INNO EVENT WILL GROOVE TUBES BE LIABLE FOR INCIDENTAL CONSEQUENTIAL INDIRECT OR OTHER DAMAGES RESULTING FROM THE BREACH OF ANY EXPRESS OR IMPLIED WARRANTY INCLUDING AMONG OTHER THINGS DAMAGE TO PROPERTY DAMAGE BASED ON INCONVENIENCE OR ON LOSS OF USE OF THE PRODUCT AND TO THE EXTENT PERMITTED BY LAW DAMAGES FOR PERSONAL INJURY Some states do not allow the exclusion or limitation of incidental or consequential damages so the above limitation or exclusion may not apply to you THIS CONTRACT SHALL BE GOVERNED BY THE INTERNAL LAWS OF THE STATE OF CALIFORNIA WITHOUT REFERENCE TO CONFLICTS OF LAWS This warranty gives you specific legal rights and you may also have other rights required by law which vary from state to state This warranty only applies to products sold to purchasers in the United States of America or Canada The terms of this warranty and any obligations of Groove Tubes under this warranty shall apply only within the country of sale Without limiting the foregoing repairs under this warranty shall be made only by a duly authorized Groove Tubes service representative in the country of sale For warranty information in all other countries please refer to your local distributor GROOVE TUBES llc 1543 Truman Street San Fernando CA91340 818 361 4500 www groovetubes com PLEASE SEND IN YOUR WARRANTY CARD for more effective service and product upda
43. ips over a mic cable sending your best overhead drum mics crashing into the cymbols and beyond e when in doubt NOTE The MUTE switch is connected to a sealed multipole double throw mechanical relay that switches the signal on and off between the output transformer and the LINE OUT jacks 28 chapter 3 about the Vipre sss Block Diagram Vipre Reference Manual 29 about the Vipre chapter 30 Reference Manual chapter 4 Microphone amp Preamp Theory R where R is t load in ohms But remember those coils of wire inside the generator microphone They also have an impedance This source impedance is a crucial factor in the design of the circuit As current flows in a circle from the source to the load and back again it expends power some in the load and some in the source The symbol R above represents the source impedance in ohms And if the goal is to get maximum transfer of power R should equal R Consider what would happen if instead of loading the generator microphone with a resistor we simply placed a straight wire across the outputs shorting it out When the load impedance is zero all the power has to be expended in the source itself If it was a generator this would obviously cause overheating and failure The consequences of shorting out a microphone aren t so drastic but between the first example of an unterminated source
44. iverse The only way to get equipment that has no thermal noise is to freeze the circuit to absolute zero 459 F an expensive proposition The Equivalent Input Noise EIN spec of a microphone preamp is determined by plugging in a pure resistive load or in some cases shorting out the input cranking up the gain to its maximum measuring the noise voltage and subtracting the gain The EIN of the Vipre is 129 dBu which is only 3 88 dB above the theoretical minimum However even this small figure when you amplify it by the 75 dB gain available in the Vipre becomes a signal of 54 dBu which may be audible in the control room depending on masking by other factors 32 chapter 5 Troubleshooting you experience problems while operating your Vipre please use the following table to locate possible causes and solutions before contacting Groove Tubes Product Support for assistance DO NOT SPRAY THE Solution Test with a known good input Replace the cables Check the connections and the level of the mixer or amp that the Vipre is connected to Turn the switch on Time for a coffee break Make sure that the Vipre and its audio cables are kept away from power cables other power transformers and wall warts Replace the cable with new high quality cable Try bypassing the Vipre by connecting the input cables to the output cables or using another preamp and see if the problem remains Correc
45. k on the front panel labeled INSTRUMENT INPUT This is intended for inputs that ike extremely high impedances such as electric guitars and basses Simply plug an unbalanced 1 4 cable into the jack and set the INPUT switch to INSTRUMENT This jack has a nominal impedance of 470 kohms more than twice that of a typical line input on a console This keeps the pickups of the instrument from being loaded down and improves high frequency response For that reason it is not necessary to use a direct either passive or active between a guitar and the Vipre The Vipre is itself an extremely high quality direct box If the CLIP light goes on when the instrument is played even though the gains are turned down to minimum set the INPUT switch to INSTRUMENT 20 dB You may need to increase the GAIN controls of the Vipre to compensate a little for this attenuation Connecting Line Inputs On the rear panel is a 1 4 jack labeled BALANCED LINE INPUT This jack is in parallel with the XLR microphone input but has a 20 dB lower sensitivity When the front panel gain controls are at 30 5 dB Gain Switch and 1 1 dB Gain Switch a 4 dBm input to the LINE IN jack will be equivalent to unity gain 4 dBm output If you need to connect the output of a line level device such as a signal processor synthesizer or recording device through the Vipre connect it here The 1 4 BALANCED LINE IN jack does NOT connect to the input trans
46. led information on the unique technology of the Vipre and how to use it Chapter 4 Microphone and Preamp Theory covers deep background information that will help you use your Vipre and all microphones to their greatest capability Chapter 5 Troubleshooting This chapter contains troubleshooting tips and service information should problems occur Helpful tips and advice are highlighted in a shaded box like this J When something important appears in the manual an icon like the one on the left will appear in the left margin This symbol indicates that this information is vital when operating the Vipre 2 Vipre Reference Manual Important Safety Instructions Safety symbols used in this product 8 Do not install near any heat sources such as N radiators heat registers stoves or other This symbol alerts the user that there are apparatus including amplifiers that produce important operating and maintenance instructions in heat the literature accompanying this unit This symbol warns the user of uninsulated AN 9 Do not defeat the safety purpose of voltage within the unit that can cause dangerous the polarized or grounding type plug A electric shocks polarized plug has two blades with one wider than the other A grounding type plug has n two blades and a third grounding prong The This symbol warns the user that output wide blade or the third prong are provided for connectors contain voltages that ca
47. loom in a way most people have never heard The equalization changes slightly as well with the entire spectrum from about 100 Hz to 15 kHz taking on a very slight tilt typically around 1 dB at the low end and around 1 dB at the upper registers This is very slight when looking at individual frequencies but the cumulative effect over the whole spectrum is unmistakable This kind of variation would be almost impossible to recreate with any kind of equalizer unless the principle of an simple uncluttered signal path is abandoned altogether Tip Try matching the era with the impedance Generally speaking the older the microphone the lower the impedance Microphones from the 1940s and 50s can handle 300W quite well Mics from the 60s tend to like 1200W while those from the 70s and 80s prefer 2400W New mics since they were designed in an era when almost all consoles have high impedance bridging inputs will sound the way the designers intended when the Vipre s INPUT is in BALANCED BRIDGE mode But this is just a starting point The IMPEDANCE SELECTOR switch is an audio time machine and can make new mics sound like vintage mics Remember you can t hurt a microphone by setting the input impedance incorrectly Vipre Reference Manual the entire swing of the signal positive and negative goes through a single device By comparison other types of amplifiers such as Class B and Class AB switch the positive and negative halve
48. ly to the input of the track you plan to record on The nominal signal level of these units is 4 dBu 1 23 volts Balanced cables between the recorder and the Vipre can be very long if necessary without adding noise Digital Recorders Many Digital multitrack Recorders feature a multipin ELCO or EDAC connector that features 8 balanced inputs and 8 balanced outputs on a single connector To connect the Recorder directly to the Vipre obtain an ELCO to TRS multipair cable This will connect from the ELCO type connector on the Recorder on one end fanning out to sixteen connectors labeled INPUT 1 OUTPUT 1 and so on on the other end Simply plug the 1 4 TRS Input on the desired track of the Digital Recorder into the Vipre s XLR output Using a cable assembly with 1 4 TRS plugs allows a choice of the 4dBm level referenced output jack on the Vipre or the 10 dBV output jack Because the Vipre uses balanced transformer outputs an unbalanced plug may be used with either 1 4 output jack and will automatically convert the jack from balanced to unbalanced operation with no loss of signal level Note that some recorders with XLRs may not be truly balanced with pin 2 or 3 depending on vintage tied to ground which may cause a ground loop Also depending on the characteristics of the deck metering levels may not match between the deck and the Vipre Some multitracks have high low level input switches follow the manufacturer s instructi
49. med for having an edgy sound when in fact all they are doing is accurately recording a very fast rising preamp The Vipre features special tube circuitry that allows the user to adjust the rise time from slow to fast in five steps The FAST setting corresponds to the slew rates of modern preamplifiers 6 volts per microsecond while the SLOW setting is more typical of vintage equipment 75 volts per microsecond The effect especially on a large diaphragm vocal microphone is like that of a time machine the slower the rise time the more it will sound like 1950 Another way of looking at it is that FAST preserves the full percussive and forward qualities of the source while SLOW helps tame overly aggressive sound qualities and rounds out or smoothes the material As with the IMPEDANCE SELECTOR switch there is no best setting for the RISE TIME control You simply experiment to find the right setting for a particular sound Rise Time is a very subtle effect but with critical material the settings can significantly affect the tonal characteristics of the recording Vipre Reference Manual about the Vipre chapter Mute Switch Standby The STANDBY switch turns off the plate voltage also called B to the amplifier tubes but leaves the tube filaments on There are several reasons for a standby switch in tube gear 1 It extends tube life If you allow the filaments to warm up the tube cathodes befor
50. n cause your safety When the provided plug does dangerous electrical shock not fit into your outlet consult an electrician for replacement of the obsolete outlet Please follow these precautions when using this product 10 Protect the power cord from being walked on or pinched particularly at plugs convenience receptacles and the point where they exit from the apparatus MN 1 Read these instructions 11 Use only attachments or accessories specified by the manufacturer 2 Keep these instructions 12 Use only with a cart stand bracket or table 3 Heed all warnings designed for use with professional audio or music equipment In any installation make sure that injury or 4 Follow all instructions damage will not result from cables pulling on the apparatus and its mounting If a cart is used use Do not use this apparatus near water caution when moving the cart apparatus combination to avoid injury from tip over 6 Clean only with a damp cloth Do not spray any liquid cleaner onto the faceplate as this may damage the front panel controls or 13 Unplug this apparatus during lightning storms cause a dangerous condition or when unused for long periods of time 7 Install in accordance with the manufacturer s AN instructions 3 Vipre Reference Introduction Safety Instructions _
51. nd oh so many others was unaware of the difference variable impedance could make a microphone preamplifier Now am a believer And now that have had the occasion to have variable impedance in an all tube audio path with the ability to adjust the circuit s rise time am in hog heaven The Groove Tubes Vipre is a good as it gets Russ Long April 2001 Pro Audio Review heard about the Vipre from a colleague After extensive listening tests comparing it to all other mic preamps at my studio EN ER iSi the Vipre came out CAST 3 ET 1 1 If fee way on top in terms of BT RI sound clarity and SS SMS eee depth The variable impedance gives you the ability to fine tune every microphone for it s optimum performance A real killer 1 aueh deu d RESP The Groove Tubes Michael Wagener PRODUCER ENGINEER Dokken Current users Janet Jackson Stryper Alice Cooper and others WALTER BECKER THE VILLAGE RECORDER FRANK FILIPETTI HYPROBOLIC STUDIOS West Los Angeles California CONWAY STUDIOS Maui Hawaii Bush and others Hollywood California Steely Dan Korn GREG LADANYI ALEX LEIFSON TIDAL WAVE ENTERTAINMENT VIRGIN RECORDS LERXST STUDIO West Hollywood California ARROWHEAD STUDIOS Toronto Canada Jo Davidson Leiper s Fork Tennessee Rush Clay Davidson 44 The studio does have a couple of bo
52. nes using the circuitry of the period Most people thought that a higher load impedance than an original design would have no effect or even improve performance But the slight tilt in frequency response when a microphone sees different impedances coupled with other factors like distortion and small damping effects can have subtle effects that no other device in the studio can truly replicate About Noise One of the primary questions people have about a mic preamp is how quiet it is Any noise that s generated in the preamp will persist through the rest of the chain and can t be eliminated But when you crank up the gain of any mic preamp and hear hiss it s usually a mistake to think that the noise is coming from the preamp In most cases the preamp is merely amplifying noise that s already there And frankly since the Vipre has 15 to 25 dB more gain than other preamps you may have used this noise will be louder when you crank the gain up Simply setting two competing preamps side by side will lead to misleading results unless you control the test very carefully So where does the noise come from Thermal Noise Thermal noise is always present in audio circuitry Molecules rubbing against each other in any piece of wire produce random electronic signals In a resistor of 150 ohms at 70 degrees Fahrenheit these random voltages are equivalent to 132 88 dBu This for all practical purposes is the noise floor of the audio un
53. oad into an input about 10 times the impedance roughly 2000 3000 ohms Altering the load against which the mic has to push fundamentally alters the tone and character of the output signal At the core of the Groove Tubes Vipre is a multi tap high performance input transformer with four distinct positions 300 600 1200 and 2400 ohms This changes the working impedance or loading of a given microphone and can strongly influence the sound qualities by the cumulative effects of small differences These differences vary from microphone to microphone but all mics respond quite audibly when the preamp input impedance is altered This control feature opens a much larger sonic window to each mic and provides the ability to magnify certain attractive tonal shifts in the way it responds to impedance changes Vintage microphones are especially sensitive to load terminations as impedance matching was the norm in early broadcast and recording facilities Ribbon mics for example are sought after for their smooth tonal properties When properly terminated or loaded with 300 ohms the tonal characteristics change and the sound seems to bloom in a way most people have never heard The equalization changes slightly as well with the entire spectrum from about 100Hz to 15kHz taking on a very slight tilt typically around 1dB at the low end and around 1dB at the upper registers Very slight when looking at individual frequencies but th
54. ons on setting these properly Vipre Reference Manual Whenever possible the output of the Vipre should be connected to a balanced line input of a console designed for a nominal input of 4 dBu 1 23 volts However in some situations you may have no other choice than to connect to the XLR MIC IN of a console or sound system If this is the case to avoid clipping of the console s input e Set the console s input gain which may be labeled TRIM ATT GAIN or MIC to its lowest setting N Turn off any phantom power coming from the console if possible e lf there is an input pad switch labeled PAD 20 DB etc turn it on e With the Vipre s gain set for optimum as described in the first chapter see if the console s input is clipping lf it is you can either turn down the Vipre s GAIN controls or insert a line attenuator between the Vipre and the console e Instead of using the Vipre s XLR LINE OUT jack connect the Vipre s Lower Balanced 1 4 TRS output to the unit This cuts the output level of the Vipre by 11 8 dB the difference between a 4 dBu and 10 dBV nominal level 16 chapter 2 connections Connecting to an unbalanced device Although it s not ideal the Vipre may feed an unbalanced input of a console or recorder and still provide excellent results particularly if the cable lengths are short and the AC power system is not complicated The 10dBV 1 4 jack output of the Vip
55. ont panel selectable truly variable impedance transformer In short You haven t heard your mics until you ve heard them loaded at different impedances With all the control functions available on this unit anyone with even a modest selection of mics can dramatically increase their tonal options by using a Vipre VARIABLE RISE TIMES Hise time is very much the same as slew rate the rate of speed at which the amplification circuit can amplify the signal You can t go from zero to five volts in no time and how fast a circuit can amplify is part of what imparts its sound Vintage circuits were much slower than are today s and in theory faster is better Faster amplification circuits retain the leading edge of the transient signal especially apparent on the higher frequencies But slowing the rise time down can mellow or smooth out the signal often rounding out harsh sibilants from vocals or edgy tones of instruments In a way you can think of rise times as a time machine for preamps the slower the rate the more vintage the sound No other preamp but the Vipre has this special feature GROOVE TUBES LLC www groovetubes com sales groovetubes com 1 800 459 5687 mics and mic preamps were often made by the same company and the output and input impedance between the mic and preamp were matched to provide the best possible audio quality Those days are long gone now and most condenser mics send a 200 250 ohm l
56. ous lengths may be purchased from electronics stores or your Groove Tubes dealer The ground connection is an important safety feature designed to keep the chassis of electronic devices such as the Vipre at ground potential Unfortunately the presence of a third pin does not always indicate that an outlet is properly grounded You may use an AC line tester to determine this If the outlet is not grounded consult with a licensed electrician When AC currents are suspected of being highly unstable in VAC and Hz a professional power conditioner should be used To connect power to the Vipre attach the female end of the AC power cord to the Vipre s back panel and the male end to a good quality noise free AC power source of the proper rating Do not operate any electrical equipment with ungrounded outlets Plugging the Vipre into an ungrounded outlet or lifting the unit off ground with a three to two wire adapter can create a hazardous condition Groove Tubes cannot be responsible for problems caused by using the Vipre or any associated equipment with improper AC wiring Vipre Reference Manual 13 Make sure that all of the audio cables in good working order Cables with a detached ground wire will cause a very loud hum D Keep all cables as short possible especially in unbalanced circuits the basic experiments don t uncover the source of the problem consult your dealer or technician tr
57. re Oo sss Rise Time The Output Transformer Even though the Vipre is a line level device 1 watt maximum output its output transformer is comparable in size to those used in 30 watt guitar amplifiers This overcapacity ensures that the nonlinearities that plague less expensive transformers are diminished while the classic sound and other benefits of transformer coupling already covered on page 20 are gained the output sees phantom power The transformer output by nature is balanced so a common 48 volt phantom voltage received on each side pin 2 and 3 will not harm the Vipre However avoid plugging the LINE OUT of the Vipre into a MIC IN whose phantom power is on The output should be plugged into a line level input in any case 27 A voltage cannot instantly change from nothing to something or from 0 volts to 2 volts There is always some transition time Technically this is called the slew rate measured in volts per microsecond This is often shown by how square a square wave is on an oscilloscope Since slew rate or rise time has a relationship to extended high frequency response and transient response the faster a circuit can go from one voltage to another one the better or so the logic has been In fact classic circuitry used to process audio in decades past often did not have the fast rise times of modern integrated circuits and that was part of its sound Digital recorders are sometimes bla
58. re can be used for this purpose If the receiving device has 1 4 input jack obtain an 1 4 to 1 4 mono cable or adapter The nominal output of this output is 10 dBV 316 volts at the same time that the balanced outputs on the XLR and upper 1 4 connectors are putting out 4 dBu 1 23 volts If you want to use the 1 4 or XLR outputs It is possible to use the 4 dBm balanced 1 4 or XLR output of the Vipre to feed an unbalanced device Note however that besides being balanced these devices put out a hotter level that may overload the input of the receiving device Use an adapter similar to the one shown on page 15 The adapter may be an XLR to TRS or XLR to 1 4 mono jack in either case pin 3 must be connected to the shield preferably at the input to the device Alternatively if there are noise problems you may try isolating the device by building or purchasing a special cable that uses the balanced output on pins 2 and 3 of the Vipre to feed the and connectors of the unbalanced receiver leaving the ground floating disconnected at the receiver s end The shield must still be connected at the Vipre to provide some path to ground for interference Vipre Reference Manual 17 connections chapter 2 _ _ _ Connecting Microphones Connecting Instruments The Vipre has a 1 4 jac
59. rvicing to qualified service personnel Servicing is required when the apparatus has been damaged in any way such as when the power supply cord or plug is damaged liquid has been spilled or objects have fallen into the apparatus the apparatus has been exposed to rain or moisture does not operate normally or has been dropped 15 This unit produces heat when operated normally Operate in a well ventilated area with at least six inches of clearance from peripheral equipment 16 This product in combination with an amplifier and headphones or speakers may be capable of producing sound levels that could Instructions de S curit Importantes French Symboles utilis s dans ce produit N Ce symbole alerte l utilisateur qu il existe des instructions de fonctionnement et de maintenance dans la documentation jointe avec ce produit symbole avertit l utilisateur de la pr sence d une tension non isol e l int rieur de l appareil pouvant engendrer des chocs lectriques T Ce symbole pr vient l utilisateur de la pr sence de tensions sur les raccordements de sorties repr sentant un risque d lectrocution Veuillez suivre ces pr cautions lors de l utilisation de l appareil N 1 Lisez ces instructions 2 Gardez ces instructions Tenez compte de tous les avertissements 4 Suivez toutes les instructions Introduction Safety Instructions
60. s method NOTE Preparing the Vipre rotary switches for silent operation Vipre uses special ceramic rotary switches to maintain a fully balanced signal path Low noise resistors and high grade capacitors are hand soldered onto these rotary switch decks These caps can become charged during the period and this can cause a loud popping sound in some positions the first time they are activated To eliminate this from happening we recommend 1 Engage the mute switch to silence the Vipre 2 Exercise all positions of the front panel rotary switches switch them from full left to right 3 Restore the Mute switch to Normal position 4 This will insure silent operation This step will need to be repeated each time the Vipre is turned off for any period of time Leaving the Vipre in Standby operation B off will keep the capacitors charged and so this step will not need to be repeated when resuming operation Vipre Reference Manual Polarity This reverses the and of the input Most of the time you ll leave this set to NORM It may not make an obvious difference but ideally the polarity should be set so that a positive pressure on the microphone generates a positive pressure from the speaker In other words if you re miking a drum the first transient of a drum hit should make the loudspeaker move forward not back Polarity also makes a difference in multi microphone situations
61. s of the waveform between different drivers in other words one tube goes only positive and one tube goes only negative Class B designs are more efficient at using power but they are inherently less linear Since the Vipre s main requirement is to amplify the signal as accurately as possible Class A was the only way to go This led to the requirement for a massive high tension power supply with over 60 Joules of energy storage For a device that only needs to put out 1 watt of power this may seem high but it guarantees that the Vipre can follow the input waveform wherever it may lead The term fully differential may need some explanation as well In essence it means that from input to output there are two identical signal paths each of opposite polarity from the other While most engineers understand the benefits of balanced connections between separate pieces of equipment some may not be aware that in most devices especially mixing consoles the signal becomes unbalanced right after the input circuit and stays unbalanced until just before the output circuit In contrast the Vipre is balanced all through its signal path providing common mode rejection of noise in internal circuitry as well as externally Vipre Reference Manual about the Vipre chapter 3 About Vacuum Tubes Theory Tubes are the original devices for amplifying signals Although
62. setting can only be determined by your ears However knowledge is power There is considerable information about the Vipre in the following chapters that will help you understand the art and science of why the Vipre affects your microphones the way it does Read on 11 The 1 4 input on the front panel labeled INSTRUMENT INPUT is specially designed for guitar and bass pickups Instruments such as basses and guitars sound best if they see an extremely high input impedance 1 2 megohm or greater This input feeds a special high impedance circuit with its own tube a GT 6205 making the Vipre not only a great mic preamp but an incredible direct box for recording basses and guitars the instrument has active electronics internally it may be so loud that it clips even at low settings of the GAIN controls turn the INPUT switch to INSTRUMENT 20 dB you be able to tell from looking at the INPUT switch the front panel INSTRUMENT INPUT jack does not use the input transformer so the IMPEDANCE SELECTOR has no effect on it However RISE TIME and all the other controls do affect the Instrument Input Alternatively instruments may be plugged into the LINE IN jack on the back panel for a slightly different sound The impedance and the first preamp tubes are different in that input Vipre Reference Manual chapter 2 Connections Unpacking and Inspection Installing in a Rack The Vipre m
63. single mic ALL TUBE BALANCED CLASS A 2 Eight Groove Tubes in a fully differential Only Vipre does what signal path dramatically lowers noise and NO other preamp can distortion while expanding bandwidth flat from 7Hz to over 10OkHz PRECISION GAIN CONTROL No pots Custom built ceramic deck attenuators control Vipre s incredible 75dB of total gain in SdB and 1dB Visit our website or call us at 818 361 4500 stepped increments for precision gain while maintaining for complete specs and a list of Groove Tubes the integrity of Vipre s fully balanced signal path Vipre dealerships AUTHENTIC VU METERING Custom built back lighted VU meter with GROOVE TL five switchable viewing ranges CUSTOM SHOP PRODUCTS D GROOVE 2001 Groove Tubes LLC All rights reserved Groove Tubes the GT in a circle logomark TUBES Groove Tubes Custom Shop Products Vipre are trademarks of Groove Tubes LLC 74 ERREKI EH j Er i LLELLLLLIELEMOUET LELIT 4 LM um LHL tt BEBE BE 1 j masa INSTRUMENT BRIDGE VU METER RANGE INSTRUMENT 20B RISE TIME 0 Vu M
64. solid state transistor semiconductor circuitry has replaced them in general use there are still applications where vacuum tubes or valves in the UK demonstrate their superior characteristics Only a few of the mic preamplifiers on the market today are truly all tube from input to output most of them also tube circuits with significant parts of the signal path consisting of semiconductors Cost constraints almost invariably lead to hybridized designs and sonic compromise The engineers at Groove Tubes drawing on their years of experience as providers of high quality vacuum tubes set out to build a state of the art true tube preamp The result is both uncomplicated and uncompromising utilizing a symmetrically arranged mirror image circuit configuration that is a fully differential Class A push pull design balanced and floated throughout the entire signal path Impedance of tubes An important fact about tube circuitry is that its impedance can be much lower than most solid state circuitry In the business of amplifying a microphone this is a distinct advantage While the input transformer provides the load impedance seen by the microphone if switched to that position the low impedance of the following stages helps maintain the Vipre s inherently simple circuit philosophy and performance while significantly increasing signal to noise ratio and dynamic range This approach both reduces power supply induced noise an
65. st electronic devices of a sound system don t require a lot of current except for power amplifiers it s usually safe to run a multi outlet box or two from a SINGLE wall outlet and plug in all of the components of your system there KEEP AUDIO WIRING 5 FAR AWAY FROM WIRING AS POSSIBLE Many hums come from audio cabling being too near AC wiring If a hum occurs try moving the audio wiring around to see if the hum ceases or diminishes If its not possible to separate the audio and AC wiring in some instances make sure that the audio wires don t run parallel to any AC wire they should only cross at right angles if possible TOELIMINATE HUM IF THE ABOVE HAS FAILED A Disconnect the power from all outboard devices and tape machines except for the Vipre the mixer and control room monitor power amp B Plug in each tape machine and outboard effects device one at a time If possible flip the polarity of the plug of each device turn it around in the socket until the quietest position is found 14 chapter 2 connections Basic Connections Output To a Mixing Console Since the Vipre is a high output preamplifier its LINE OUT 1 4 TRS Balanced 4dB should be connected to a balanced line input of a console not to the microphone input whenever possible If the console s line input has XLR input you re in luck simply connect a standard XLR to XLR cable from the Vipre s output to the
66. stom made in California to the highest industry standards key feature is that its a multitap transformer allowing a selection from four different load impedances for a microphone Some other variable impedance products on the market simply switch in additional resistors which actually makes them variable resistance a subtle but potentially audible difference because of the insertion losses that resistors cause Benefits of transformers generally While modern solid state input circuitry can deliver excellent results at very low cost input transformers deliver several significant advantages e Greater CMRR common mode rejection ratio this means that noise from the cable that appears on both the and leads simultaneously is more likely to be rejected Solid state differentially balanced circuits may have a good CMRR spec at 1 kHz but often aren t as good at other frequencies e More resistance to HF radio frequency interference the windings of a transformer being naturally inductive reject ultra high radio frequencies without requiring a capacitor in the audio path as electronically balanced circuits do e Lower impedance it is easier to build a low impedance input transformer than a low impedance transistor input which is one of the reasons the industry went to bridging impedances in the last few decades e transformer is fully floating isolating the circuit from DC offsets and to a certain exten
67. t any problem that may have caused the fuse to blow and replace the fuse with the proper type Turn off unit and reset the voltage switch to 120 volts Turn off unit replace the fuse reset the voltage switch to 240 V Replace the tubes with high quality selected pairs from Groove Tubes Use only balanced connections in the studio Place all equipment in the studi on a common ground see p 14 409 or Fantastik CLEANER DIRECTLY ONTO THE FRONT OF IT MAY DESTROY THE THE UNIT AS LUBRICANTS USED IN THE SWITCHES AND Vipre Reference Cause No input audio Bad cables Destination is turned down MUTE switch Or STANDBY switch is on Power is not connected Cables are crossing a power cable Bad cables Problem with the source Blown fuse Voltage set to 240 V on rear panel when AC is 120 volt Voltage set to 120 V on rear panel where AC is 240 volt Tubes are wearing out typically after several years of use Ground loop Troubleshooting Index Symptom No audio from outputs Buzz from outputs Power LED won t go on Lights are low erratic operation Fuse blows immediately on power up Unit is becoming noisy or gain is less AC hum Care and Maintenance Cleaning Disconnect the AC cord then use a damp cloth to clean the Vipre s metal and plastic surfaces For heavy dirt use a non abrasive household cleaner such as Formula 33
68. t from surges and stray signals You could think of it as a magnetic link that keeps the circuits free from mutual contamination For these and other reasons the highest level audio consoles especially those used by touring sound companies have always used input transformers But good quality input transformers are expensive and cheap input transformers used in affordable consoles several decades ago gave transformers a bad name with some engineers due to their irregular frequency response and distortion The input transformer used in the Vipre is a totally different story Special care is taken to shield the transformer windings from noise high quality double Mu metal can surrounds the transformer The transformer itself is a humbucking type with specially wound oppositional coils that cancel out 20 chapter 3 about the Vipre onn Frequently Asked Questions set the impedance too low will it hurt the microphone No Even microphones with their own power supplies are protected against a dead short Is there a special setting for ribbon microphones Vintage ribbon mics like the RCA 77 were designed in an era when impedances were supposed to be matched to give maximum power transfer These mics are particularly suited for the Vipre s 300 setting Note DO NOT USE PHANTOM POWER WITH RIBBON MICROPHONES SERIOUS DAMAGE CAN RESULT But modern ribbon mics like those from Beyer and Royer tend
69. t is most similar to contemporary solid state console preamps but with a more pleasing warmth But the fun really starts when you start to experiment with the fifty or so combinations that use the different transformer impedances and different rise times Hi Pass This switch is another optional control it rolls off the bass below 100 Hz at a gentle rate of 4 dB per octave Its designed to get rid of undesirable low frequency rumbles and noises Note however that many microphones also feature high pass filters of their own make sure the mic s filter is out if you want to hear the effect of the Vipre s Hi Pass filter only 10 chapter 1 quick start guide EE About the Instrument Input Step 3 Experiment Once you have experienced the difference that the Vipre makes on one microphone you ll want to try every other mic in your possession with it You ll find that each mic reacts differently to the settings and a whole new sonic palette will open up Finding the right setting The Vipre s fundamental concept is different from other kinds of studio equipment Settings for impedance and rise time will change the flavor of the sound but will vary from case to case The changes of each interact in very subtle ways it s not nearly as obvious as changing the settings on an equalizer or compressor limiter So this manual doesn t provide a chart that lists the right settings for a particular microphone because the right
70. te notices Groove Tubes llc 1543 Truman Street San Fernando CA91340 Vipre Reference 39 Warranty 2001 Groove Tubes Specifications Subject To Change Without Notice 40 Vipre Reference Manual
71. their clientele The choice of microphone and preamp are primarily responsible for these variations The 20 bit and 24 bit digital recorders now commonly available allow engineers to capture subtleties that used to be lost in tape noise or covered up by irregular frequency response Early complaints about the harshness of digital have been recognized for what they are complaints about inferior microphone preamps that are only now being revealed by the accuracy of digital recording The engineers at Groove set out to build an authentic no compromise mic preamp that utilizes the best of vintage technology to fulfill the potential of today s digital technology They have achieved that goal with the Vipre Variable Impedance Preamp an all tube variable impedance microphone preamplifier with selectable rise time and VU meter range It s a premium single channel device designed for critical recording applications demanding the ultimate in mic preamplification It features extremely wide frequency response low inter stage feedback very high gain enormous dynamic range and graceful overload characteristics Each component in the signal path was carefully chosen for its sonic purity When components were not available off the shelf they were custom manufactured to Groove Tubes exacting specifications Even the phenolic knobs on the front panel were custom molded But as you will read in the rest of this chapter the attention to detail
72. to be designed for higher impedances although you can try them at any setting How come it sounds so different in bridged mode Because it s bypassing the transformer with its many complex impedance and inductance characteristics and using a purely electronic input with a much higher impedance Aren t electronic inputs cleaner than transformer inputs Input transformers got a bum rap several decades ago mostly because of the sound of the cheap versions used in popular consoles But a high quality custom wound transformer such as that used in the Vipre doesn t have that kind of degradation In addition the common mode rejection of noise of a transformer especially at high frequencies is superior to that of an electronic circuit Having said that a transformer does have certain nonlinearities that may not be suited to certain applications That s why the Vipre gives you a choice BALANCED BRIDGE position the input transformer is bypassed giving you a modern electronically balanced 12 KW impedance input 21 setting if you understand whats going on electronically The choice of impedance between 300W 600W 1200W and 2400W on the front panel will make slight variations in equalization and residual distortion depending upon the individual mic For example an early broadcast microphone like the RCA 77 will sound smoother when terminated at 300W The tonal characteristics change and the sound seems to b
73. ts authorized service representative In all cases disputes concerning this warranty shall be resolved as prescribed by law To obtain warranty service the purchaser must first call or write GROOVE TUBES at the address and telephone number printed below to obtain a Return Authorization Number and instructions concerning where to return the unit for service All inquiries must be accompanied by a description of the problem All authorized returns must be sent to GROOVE TUBES or an authorized GROOVE TUBES repair facility postage prepaid insured and properly packaged Proof of purchase must be presented in the form of a bill of sale canceled check or some other positive proof that the product is within the warranty period GROOVE TUBES reserves the right to update any unit returned for repair GROOVE TUBES reserves the right to change or improve design of the product at any time without prior notice This warranty does not cover claims for damage due to abuse neglect alteration or attempted repair by unauthorized personnel and is limited to failures arising during normal use that are due to defects in material or workmanship in the product THE ABOVE WARRANTIES ARE IN LIEU OF ANY OTHER WARRANTIES OR REPRESENTATIONS WHETHER EXPRESS OR IMPLIED OR OTHERWISE WITH RESPECT TO THE PRODUCT AND SPECIFICALLY EXCLUDE ANY IMPLIED WARRANTIES OF FITNESS FOR A PARTICULAR PURPOSE OR MERCHANTABILITY OR OTHER IMPLIED WARRANTIES Some states do not allow limitations on
74. ubes Service Department 1543 Truman Street San Fernando CA 91340 Vipre Reference Manual Specifications Subject to change without notice MIC IN balanced XLR Pin 2 Hot LINE IN balanced 1 4 INSTRUMENT IN front panel unbalanced 1 4 MIC IN XFMR 41 dBm MIC IN BRIDGED 30 dBm LINE IN 10 dBm INSTRUMENT INPUT 12 dBm INSTRUMENT INPUT 20 dB pad 8dBm Inputs Nominal Input Voltage to obtain 4 dBm out with 45 dB of Gain Maximum Input Level both GAIN switches set to minimum IN Balanced Transformer 10 dBm MIC IN Balanced Bridged _ 14dBm LINE IN 30 dBm INSTRUMENT INPUT 26 dBm Both Instrument positions Switchable from 300 600 1200 2400 ohms BALANCED XFMR position 2 4K ohms BALANCED BRIDGE position 24K ohms 470K ohms LINE OUT XLR amp 1 4 TRS 4 dBm nominal LINE OUT 1 4 TRS 10 dBV nominal 600 ohms LINE OUT XLR amp 1 4 TRS 4dBm referenced 10 000 ohms LINE OUT 1 4 TRS 10 referenced 30 dBu 24 4 rms volts at XLR LINE OUT 18 dBm 6 13 vrms volts at balanced LINE OUT 75 dB MIC IN XFMRto XLR LINE OUT 64 dB MIC IN BRIDGED to XLR LINE OUT 44 dB LINE IN to XLR LINE OUT 46 dB INSTRUMENT IN to XLR LINE OUT 26 dB INSTRUMENT IN 20 dB to XLR LINE OUT 129 dBu 600W source A Weighted lt 0 06 RISE TIME at FAST BALANCED XFMR INPUT 600 ohms 45 dBm input Varies according to setting of RISE TIME control from 0 75 V usecon
75. uld problems occur DO NOT attempt to service the unit yourself unless you have training and experience Service on this product should be performed only by qualified technicians NO USER SERVICEABLE PARTS INSIDE The unit must be totally disconnected from all sources of AC power before the unit is opened HAZARDOUS VOLTAGES EXIST WITHIN THE CHASSIS THAT MAY BE FATAL The following instructions are intended only for professionals with experience and training in servicing electronic equipment IF YOU DON T KNOW WHAT YOU RE DOING DO NOT ATTEMPT TO REPLACE TUBES YOURSELF HAVE THE UNIT PROFESSIONALLY SERVICED 34 chapter 4 troubleshooting Customers outside the USA and Canada Contact your local Groove Tubes distributor for any warranty assistance The Groove Tubes Limited Warranty applies only to products sold to users in the USA and Canada Customers outside of the USA and Canada are not covered by this Limited Warranty and may or may not be covered by an independent distributor warranty in the country of sale Do not return products to the factory unless you have been given specific instructions to do so Internet Address Important information and advice is available on our web site WEB SITE http www groovetubes com Email may be addressed to SALES sales groovetubes com TECHNICAL lab groovetubes com 35 Obtaining Repair Service Before contacting Groove
76. ushed back and forth in a magnetic field Similarly in an AC generator several coils of wire are rotated around through magnetic fields and the result is also a voltage potential across the output In a schematic diagram the symbol for a generator and its outputs is this This is a source of voltage but it is not yet a circuit In audio terms this unplugged microphone is unterminated Note that even an unplugged dynamic microphone still generates a voltage when it hears audio But since it s not in a circuit it s not generating a current To be useful a voltage source must be terminated in a load which is symbolized by the signal for a resistor like this 31 Microphone Self Noise Beyond this thermal input noise the picture changes dramatically when you plug in an actual microphone Even the best microphones generate noise signals considerably above this theoretical thermal minimum called self noise Since the microphone has to be tested in an absolutely silent space for this with 0 dB SPL or better the measurement is very difficult to make Typical figures are in the 9 to 14 dB range above the thermal noise floor which means that in most cases the microphone generates more noise than the preamp does Acoustic Noise On top of all of this the room the microphone is placed in is almost always noisier than either the or the preamp Air conditioning fans traffic rumbling nearby and audience noises usually m
77. xes that aren t TC a Tube Tech MEC LA which was used on Jo Davidson s vocals electric guitar and bass along with another favorite Ladanyi weapon Groove Tube s Vipre tube mic preamp It s got eight tubes in there and you can control the impedance he enthuses You can raise the highs and bring the mic closer to you or smooth it out and make it rounder There s a rise time control that will push the mic away or bring it closer somebody has hard esses you can slow it down and they become softer without having to go into a de esser It s a classic 77 Interview with eg Ladanyi Mix Magazine May 2001 GROOVE TUBES CUSTOM SHOP PRODUCTS Vi The Groove Tubes 44 combination of the Groove Tubes Vipre pre with an AM 40 was stellar used it the cellos for my new main title for the CBS series Survivor and they ve never sounded so good Rich pure yet punchy with a velvet sheen best describes the sound Dialing in varied impedance on the Vipre actually change the sonic placement of the signal like it in my face 77 Russ Landau Film score composer On using a Vipre on the theme music for the TV show Survivor WHITE PAPER SERIES OHM MAZING DISCOVERIES SECRETS OF THE GROOVE TUBES VIPRE PREAMP m min The Groove Tubes Vipre is a mono block fully differential Class all tube preamp with

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Vipre - aspen & associates