RNDMA User Guide Iss 2.
Contents
1. Priere de lire dangereuses pouvant dangereuses pouvant avant utilisation r sulter en des r sulter en blessures blessures graves ou personnelles mineures causant la mort l g res ou en dommages la propri t premi re fois Suivre les instructions de s curit Lire et comprendre ces intructions avant l utilisation de l appareil ou avant d pannage essai ajustement ou r paration Ne pas se conformer aux instructions de s curit peut provoquer de graves blessures AVIS RISQUE DE CHOC ELECTRIQUE NE PAS OUVRIR Avis Terre Cet appareil DOIT tre branch la terre En aucun cas devoir la terre principale est d branch e du plomb principal Avis Changer le Fusible Afin d viter un risque de feu remplacer seulement avec fusible de la meme valeur et type 200mA T 230V ou 400mA T 1 15V Les fusibles sont de type IEC 20mm protection surtension pour fusibles Avant de changer le fusible teindre l appareil et enlever la prise d alimentation Utiliser un tourne vis t te plate appuyer sur le capuchon du fusible doucement vers l interieur et tourner dans le sens contraire des aiguilles d une montre pour d gager le capuchon Mettre le nouveau fusible dans le capuchon et remettre en place en faisant la proc dure inverse 5 Important Ce manuel est lire attentivement avant de brancher cet appareil pour la INSTRUCTIONS DE S CURIT IMPORTANTES Cable de Secteur Le cable de secteur IEC2. Screen Pin 2 Hot Pin 3 Cold The inputs are electronically balanced using Rupert s TLA transformer like amplifier design The outputs are transformer balanced coupled using Rupert Neves tertiary feedback output stage design 11 Audio Connections Block Diagram NE IX 9 9 ules days 9 99 0 H Rem Me 8 d O indu YIL LN H V d O v1 0 71 0 r Bi 3y 3ndu YIL A8 c NO SW UIPIM ul SW Operational Guide ell om ol aT o7 ow un e ecc mA or eo gc o Overview The System 9098 Dual Mic Amplifier contains two identical high quality signal paths that can be used as a stereo pair or two individual paths as required When used with a stereo microphone or a stereo pair of microphones the central WIDTH and 5 controls enhance the functionality and manipulation of the stereo image Gain The DMA is capable of high output levels in excess of 25dBu The switched gain control provides a range of 0 66dB in 6dB steps so when using the minimum gain setting of OdB only the most extreme sources are likely to produce an overload Certain types of capacitor microphones are capable of producing output levels well in excess of OdBu when placed close to very loud sound sources so care should be taken
3. _ System 9098 Microphone Amplifier by Rupert Neve the designer User Guide Serial No A IMPORTANT For convenience write your serial number in the box above and keep this guide in a safe place The number can be found on the rear of the product and also on the Authentification Certificate This number MUST be quoted in all communications in order to obtain technical support and spare parts from either the factory or your dealer Harman International Industries Ltd 1997 All rights reserved Parts of the design of this product may be protected by worldwide patents is a trading division of Harman International Industries Ltd Information contained in this manual is subject to change without notice and does not represent a commitment on the part of the vendor AMEK shall not be liable for any loss or damage whatsoever arising from the use of information or any error contained in this manual or through any mis operation or fault in hardware or software contained in the product No part of this manual may be reproduced stored in a retrieval system transmitted in any form or by any means electronic electrical mechanical optical chemical including photocopying and recording for any purpose whatsoever without the express written permission of AMEK It is recommended that all maintenance and service on the product should be carried out by AMEK or it s authorised agents AMEK cannot ac
4. as the phase of the difference component is manipulated In this position the A and B outputs remain a stereo pair At points in between the degree of image width can be selectively controlled however care should be taken because the degree of out of phase information 15 being increased and is actually doubled at the Wide position Note The Width control is integrated within the Output M S circuitry and is intended for use with L R output format If both are selected at the same time the difference signal of the M S pair can still be manipulated but the results may be undesirable E M S Operation by Rupert Neve Two channel stereo is most often conveyed as left and right channels carrying two independent signals These channels can create a stereo image because they do not carry exactly the same signal and any elements which are identical on both left and right will produce a central mono image This can be illustrated by considering an image created using mono sources and pan pots Anything panned to the centre will be identical on both left and right signal paths Signals positioned anywhere other than absolute centre will have differing levels on the left and right outputs The same stereo image can therefore be conveyed either by sending a left and right signal or by sending the centre mono signal together with the left right difference information Deriving M and S signals In hardware terms the mono signal is d
5. in the selection and placement of microphones to obtain the best results Trim The variable trim control has a range of 6dB allowing fine gain adjustment between the 6dB switched gain steps It also allows the gain to be extended by 6dB at either end giving an overall gain range of 6dB to 2dB DI The DI switch changes the channel input from the rear XLR to the front panel jack socket In DI mode the input impedance is greater than O0kOhm and suitable for use with guitars and synthesisers plus the gain control is restricted 30dB max 48V A phantom power switch is fitted for use with capacitor microphones and applies phantom power to the rear panel mic input XLR only The DI jacksocket is NOT affected 15 Operational Guide ell om ol aT o7 ow un e ecc mA or eo oar Phase A phase invert button is fitted to easily correct any phase anomalies caused by difficult microphone placement or mis wired cables Filter The high pass filter attenuates signals below 20 2 8dB Octave Mute The mute switch cuts the DMA output but does not affect the meter signal Meter An eight segment lightmeter is fitted to indicate output level Although the top segment is marked O L it indicates peak signal level activity not necessarily overload conditions The threshold is factory preset to 22dBu but alternative levels can be set via internal jumpers Image The image section ope
6. the apparatus has been exposed to rain or moisture the apparatus does not operate normally the apparatus has been dropped Unplug the unit under these circumstances e Adjust only those controls that are covered by the operating instructions Use only the mains lead provided with the equipment Other leads may not have sufficient current rating Do not operate this unit with the cover removed IMPORTANT SAFETY INSTRUCTIONS Mains Cable The supplied IEC mains cable must be terminated correctly to the AC mains supply before use Use only an approved AC plug or power distribution device The three cores are colour coded as follows Green Yellow Safety Earth The Green Yellow core in the mains Brown Live cable is a safety ground and must be Blue Neutral connected at all times 115V 230V Operation Before adjusting the operating voltage always switch off the unit and remove the AC power cable To adjust the operating voltage use a flat blade screwdriver to click the voltage selector across the required position until the legend 15V 230V appears in the window and fit the appropriate fuse supplied in the fixings pack S curit Pr caution Pour votre s curit et afin de ne pas interrompre la garantie il est important de lire attentivement les paragraphes marqu s d un symbole Conserver ce document Importante Avis Avertissement information Dangers ou pratiques Dangers ou pratiques
7. unsafe Hazards or unsafe Read this before practices which can practices which can proceeding result in severe result in minor personal personal injury or injury or product or death property damage Important Please read this manual carefully before connecting this apparatus to the mains for the first time Obey the following safety instructions Read and understand these instructions before operating the apparatus or doing troubleshooting testing adjustments or repairs Failure to comply with the safety instructions may result in personal injury CAUTION RISK OF ELECTRIC SHOCK DO NOT OPEN Caution Earthing This apparatus MUST be earthed Under no circumstances should the mains earth be disconnected from the mains lead Caution Changing the Fuse To avoid the risk of fire replace only with same value and type of fuse as marked on the unit 200mA T 230V or 400mA T I 15V Fuses are 20mm anti surge type Before changing the fuse always switch off the unit and remove the AC power cable Using a suitable flat blade screwdriver press the fuse cap inwards gently and twist anti clockwise to release the cap Fit the new fuse to the cap and replace it in the fuseholder by reversing the procedure gt Safety WARNING For your own safety and to avoid invalidation of the warranty please read this section carefully e Do not place the apparatus on an unstable surface Do not insert objects throug
8. air techniques with either a 90 degree pair of figure of eight microphones or a 10 degree pair of cardioid microphones produce reliable results but can make aiming difficult when used on booms and fishpoles Instant mono Mono feeds are often convenient for monitoring purposes but must be specifically derived if only L R audio is in use 5 audio means a mono signal is always available with no issues of compatibility Mono compatibility If not all systems are receiving in stereo it is important the signal sounds good in mono 5 signals can easily be adjusted to increase mono compatibility I e made more mono by reducing the 5 signal to any required degree The two extremes are to have no 5 at all which gives central mono All S is out of phase mono of the difference signal and is therefore completely incompatible with mono listening as it will produce silence M S robustness Signals in M S form have the advantage that they can make some recording and transmission faults sound less objectionable If a L R pair of channels have different gains or phase shift a disturbing image movement will occur to the left or right Any mismatch in a pair of M S channels results in a change of image width which is subjectively less of a problem For example if the 5 channel has a narrower bandwidth the stereo separation will reduce as the S response rolls off but the image remains central 19 Jumpers O L indicator All jump
9. aler within 14 days of the defect appearing and C No persons other than the authorised representatives of Amek or the Dealer have effected any replacement of parts maintenance adjustments or repairs to the Equipment and d The End User has used the Equipment only for such purposes as Amek recommends with only such operating supplies as meet Amek s specifications and otherwise in all respects in accordance with Amek s recommendations 5 Defects arising as a result of the following are not covered by this Warranty Faulty or negligent handling chemical or electro chemical or electrical influences accidental damage Acts of God neglect deficiency in electrical power air conditioning or humidity control 6 The benefit of this Warranty may not be assigned by the End User 7 End Users who are consumers should note their rights under this Warranty are in addition to and do not affect any other rights to which they may be entitled against the seller of the Equipment 22
10. cept any liability whatsoever for any loss or damage caused by service maintenance or repair by unauthorised personnel Part No Issue 2 Harman International Industries Ltd Langley House Third Avenue Trafford Park Manchester MI7 Ap United Kingdom Tel 44 0 161 868 2400 AM EK Fax 44 0 161 873 8010 E mail amek amek com Web www amek com 4 Unpacking 4 Safety Safety symbols 5 Earthing Changing the fuse Mains Cable 15V 230V operation Installation Location 10 Rack mounting Power up and clicks Cleaning Audio Connections Block Diagram 12 Operational Guide DMA Controls 13 5 Operation by Rupert Neve l6 Specifications 21 Warranty 27 3 Unpacking Check List The following items are included with the product It is recommended that packaging materials are retained until all expected items are accounted for and found to be operating correctly Carton Packet containing 4 off M6 mounting screws Moulded 4 off plastic washers IEC off fuse for 10 operation mains lead Quality Certificate ideas Dual Mic Amp Guide p Protective foam materials A IMPORTANT SAFETY INSTRUCTIONS Safety Caution For your own safety and to avoid invalidation of warranty all text marked with these Safety Symbols should be read carefully Please keep this information Important Caution Warning information Hazards or
11. el The facia graphic layer is under surface printed to provide a robust hard wearing surface designed to last the life of the product in virtually any operating environment Failure to use the supplied fixings may result in damage to the facia surface which can invalidate the warranty It is recommended that additional rack mount side supports are used in conjunction with the facia panel fixings particularly when the unit is mounted in a flite case or vehicle where vibration and transit shocks can be expected Powering up and Clicks Clicks may be heard from in out switches when the product is powered up these will dissipate after approximately 10 minutes This is perfectly normal Cleaning The product should be cleaned with a soft brush around the controls If the facia becomes dirty use a damp cloth with a little household soap to remove the dirt DO NOT use solvent cleaners under any circumstances or the facia may be permanently damaged and warranty invalidated Earth Link The CHASSIS GROUND post is internally connected to both the case and the safety earth If the link is removed for technical reasons such as earth loops then the ANALOGUE GROUND post must be wired separately to the installation technical earth point Audio Connections Two identical sets of 3 pin XLR connectors are provided for each mic amp channel A and B Inputs are female outputs are male All connectors follow the European wiring convention Pin
12. er link information is printed on the PCB The threshold for the O L indicator 15 marked next to jumper P3 Limiter insert The optional limiter inserts P and P2 must both always have jumpers fitted across pins 3 4 and 5 6 The limiter is not available as an option the jumpers provide for future development Trimmers Trimmers are provided to optimise the Mid Band and HF common mode rejection ratio CMRR These are factory calibrated and should not be adjusted without special test equipment 20 Noise 200R source Figures measured with RMS rectifier 22Hz 22kHz filter Equivalent input noise 66dB gain RMS 28dBu Output noise floor OdB gain RMS O0dBu Frequency Response measured from a 50R source driving an open circuit load OdB Gain 20Hz 20kHz 0 dB lt OHz and gt 10 2 5dB 66dB Gain 20Hz 1246 20kHz 0 5dB OHz and gt 65kHz 3dB THD Noise measured with 66dB gain when driving 5dBu into a Ok load OdB gain 66dB gain 20Hz lt 0 01 0 0396 lOkHz 0 00596 0 0496 Crosstalk CH A to CH B channel A set to OdB gain and driven with 20dBu Signal level w r t 20dBu measured at output better than OOdB at 20Hz kHz and 20kHz Mechanical Dimensions and Weight Size 19 JU rack unit 482 x 44 5mm Specifications Depth including connectors 330mm Weight 3 94kg Power Consumption SW typical Notes specifications are subject to change without
13. erived by adding together the left and right signals in a mixing amplifier The following maths example should help to explain what happens in an M S matrix M the mono signal L R The difference information is obtained by subtracting one signal from the other To ensure consistency between different types of equipment the right signal is subtracted from the left 5 the difference signal L R 16 Phase inverted signals are normally represented by placing minus sign in front so R represents the right hand signal with phase inversion We can therefore use a second summing amplifier to produce the 5 signal by adding both signals together but inverting the right hand signal in the process As many stereo signals have a lot of energy in the central parts of the image the M signal will usually be greater than the 5 signal If the 5 signal has more energy than the M the image Is a very wide one and contains a lot of out of phase information This should be handled with care as it will often be an indication that something is wrong in the mix If the same OdBu signal is applied to both left and right inputs of a unity gain matrix an output of 6dBu would be produced To prevent risk of overload the summing amplifiers have a gain of 6dB With OdBu applied to both inputs the output is still only OdBu not the 6 that would otherwise have occurred This reduces this risk of overloads M S microphones In the maths it was sh
14. fourni doit tre correctement au cable d alimentation avant l utilisation Prot ger le cordon d alimentation afin d viter quil soit pi tin cras ou pinc en particulier au niveau des prises de courant des fiches femelles et des points de sorties de l appareil Utiliser seulement une prise de courant conforme Les 3 cables l int rieur du cable d alimentation sont de couleurs suivantes Le cable vert jaune l int rieur du cable d alimentation est la s curit terre et doit tre toujours connect Vert Jaune Prise de Terre Marron Phase Bleu Neutre 115V 230V Fonctionnement Avant le r glage du voltage toujours teindre et d brancher l appareil Pour le r glage du voltage utiliser un tourne vis t te plate afin de d clancher le voltage sur la position choisie jusqu ce que 5V ou 230V apparaisse dans la fen tre et mettre le fusible appropri qui se trouve dans le kit fourni Installation 10 Location This product 15 designed and screened to minimise Internal electromagnetic emissions and provide immunity to external electromagnetic fields To reduce the risk of performance degradation due to external interference do not site this unit close to sources of strong magnetic fields such as power supplies power amplifiers loudspeakers etc Rack Mounting This product is designed to be rack mounted using the screws and washers supplied to help preserve the finish of the facia pan
15. h any apertures Do not use this apparatus near water e Unplug the unit before cleaning Clean only with a damp cloth not block any of the ventilation openings Install in accordance with the manufacturer s instructions e Do not install near any heat sources such as radiators heat registers stoves or other apparatus including amplifiers or power supplies that produce heat Do not defeat the safety purpose of the polarised or grounding type plug A polarised plug has two blades with one wider than the other A grounding type plug has two blades and a third grounding prong The wider blade or the third prong are provided for your safety When the plug provided does not fit into your outlet consult an electrician for replacement of the obsolete outlet e Protect the power cord from being walked on or pinched particularly at plugs convenience receptacles and the point where they exit from the apparatus e Avoid using mains outlets on the same circuits as air control systems or other equipment that regularly switches on and off e Only use attachments accessories specified by the manufacturer e Unplug this apparatus during lightning storms or when unused for long periods of time e Refer all servicing to qualified service personnel Servicing is required when the apparatus has been damaged in any way such as the power supply cord or plug is damaged liquid has been spilled or objects have fallen into the apparatus
16. notice 2 Figures quoted are measured on a normal production sample and typical of performance normally achieved however they do not constitute a guaranteed 21 e Warranty Amek is a trading division of Harman International Industries Ltd End User means the person who first puts the equipment into regular operation Dealer means the person other than Amek if any from whom the End User purchased the equipment provided such a person is authorised for this purpose by Amek or it s accredited Distributor Equipment means the equipment supplied with this manual 2 If within the period of twelve months from the date of delivery of the Equipment to the End User it shall prove defective by reason only of faulty materials and or workmanship to such an extent that the effectiveness and or usability thereof is materially affected the Equipment or the defective component should be returned to the Dealer or to Amek and subject to the following conditions the Dealer or Amek will repair or replace the defective components Any components replaced will become the property of Amek 3 Any Equipment or component returned will be at the risk of the End User whilst in transit both to and from the Dealer or Amek and postage shipping must be prepaid 4 This warranty shall only be available if a The Equipment has been properly installed in accordance with instructions contained in Amek s manual and b The End User has notified Amek or the De
17. own how adding and subtracting left and right pm electrical signals could produce 5 signals but these can also be produced acoustically by choosing suitable types of microphones A forward facing cardioid microphone will produce a mono output with a fairly consistent level for all signals which are in front of it and within a certain angle either side of centre Cardioid polar diagram A microphone with a figure of eight response has a dead zone at right angles to the main axis Signals arriving at the front of the microphone are in phase shaded area but the rear produces a phase inversion AXIS Figure of eight polar diagram If both microphones are placed very dose together they produce outputs which are of the same type as the M 5 signals derived electrically AXIS Let s assume we have a coincident pair connected to the DMA with the cardioid mic in the left channel A and the figure of eight mic in the right channel B Coincident cardioid figure of eight polar diagram 4h wy 5 Operation Consider both signals arriving from the front left area These arrive at both the cardioid and figure of eight capsules and are in phase with each other Adding them together will produce a signal level increase Now consider both signals arriving from the front right area These also arrive at both the cardioid and figure of eight capsules but are out of phase with each other Adding them together will produce a
18. rates on the A and B channels to provide alternative input and output formats together with variable image width Input M S The Input 5 matrix operates immediately after the input gain stage If 5 sum and difference microphone signals are connected to the inputs the DMA can be used to amplify them directly before sending them on to the mixer or tape recorder If any DMA signal processing is required e g high pass filter or image width controls then the Input 5 switch must be used to convert the signals to conventional L R format first When M S signals are required to be sent on the Output M S matrix can be used to convert the post processed signals back into M S format again 1 4 Output M S The Output 5 matrix operates immediately before the output driver stages The Output M S switch converts conventional L R signals into 5 format Used in conjunction with the Input M S matrix 5 encoded output signals can be generated no matter which input format is used L R or 5 Width When the DMA is used with a stereo signals the Width control can be used to modify the nature of the stereo image When central stereo the normal image is unaffected When fully clockwise mono both signals are merged together into mono and fed to both A and B outputs equally At points in between the degree of mono compatibility can be selectively controlled When fully anti clockwise wide the stereo image appears much wider
19. signal level decrease However if we subtract the two signals anything arriving from the front right will be enhanced and signals from the front left reduced The two outputs after 5 decoding can therefore be considered similar to what an angled pair of coincident cardioid microphones would produce facing front left and front right respectively The output from the front facing cardioid microphone can therefore be seen as being an M signal and that from the figure of eight an S signal Commercially made 5 microphones have output levels designed so that equal mic amp gain applied to the IM and 5 paths produce correct left right decoding Converting M S to L R M S signals were obtained by adding and subtracting left and right signals Let s do some more maths M sum L and 5 difference L R By adding them together we get M S L L R R In audio terms the L signal comes out at Increased level and the right signal is cancelled Subtracting the two equations gives M S L L R R In audio terms the R signal comes out at increased level and the left signal is cancelled 1S Uses of M S signals M S signals have been in use for a long time though not always thought of as such by audio engineers For example FM radio broadcasting transmits an M signal with a separate 5 signal which is ignored in mono receivers 5 audio can offer a number of advantages to sound engineers Aiming Traditional coincident p
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