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1. making it the most phase accurate DI on the planet Less phase shift equals tighter and more coherient low frequency response as well as an indicator of overall quality RADIAL JDI PHASE RESPONSE omo Radial Engineering Ltd JDI Duplex mk4 User Guide Radial The 14 INPUT and THRU Connectors The Duplex features two 1 4 jacks per channel These are designed to accept instrument inputs from basses guitars keyboards drum machines etc The source instrumentis normally connected to the 1 4 input jack The 4 thru jack is normally used as a parallel connection to drive the instrument signal to the musician s on stage amplifer Using the thru jack with an on stage amplifer allows both the musi cian and the engineer to work with the original signal direct from the instrument This way the musician can set up his stage sound with his own EQ while the audio engineer can process the instrument to sound good in the venue through the PA system Some instruments do not use on stage amplifration Itis common for instruments such as acoustic guitars to be connected directly to the PA system through the Duplex This allows the signal to feed the stage snakes monitor mixer for foldback and main PA just like microphone signals do In this case the thru jack would not be used Hi C ut Filter The high impedance 1 4 and RCA inputs for each channel can be routed through the high frequency fiter by depressing the HI CUT
2. Radial engineering JDI e DUPLEX m STEREO PASSIVE DIRECT BOX USER GUIDE Radial Engineering Ltd 1588 Kebet Way Port Coquitlam BC V3C 5M5 Tel 604 942 1001 Fax 604 942 1010 email info radialeng com www radialeng com JDI DUPLEX A STEREO PASSIVE DIRECT BOX USER GUIDE TABLE OF CONTENTS heels ie ee ee E Iddie UE MS Ee COC E E EEE E E Kee EO AN E AIT IG BAG EE ZIP es ana CUE EE Merge 180 leese Block ele TEE ae ele EE Mee Thank you and congratulations on your purchase of the world s fnest direct box The Radial J DI Duplex is the stereo version of the highly acclaimed J DI and is without a doubt the fnest passive direct box available today The J DI Duplex is very unique in that it does not color or alter the sound in any way This ensures that natural tone and harmonic balance is retained bringing out the very essence of the instrument The Duplex employs two Eclipse transformers for unmatched audio performance exceptional noise rejection and high signal handling This makes it ideal for acoustic guitar bass and keyboards In fact just about any audio signal is transformed gracefully without artifact We suggest that you read this manual before using the J DI so that you can maximize its potential Please log onto the Radial Engineering website at www radialeng com for further details and FAQ updates We invite you to forward any comments questions or suggestions to info 9 radiale
3. S YOU SPECIFIC LEGAL RIGHTS AND YOU MAY ALSO HAVE OTHER RIGHTS WHICH MAY VARY DEPENDING ON WHERE YOU LIVE AND WHERE THE PRODUCT WAS PURCHASED Radial Radial Engineering Ltd 1588 Kebet Way Port Coquitlam BC V3C 5M5 v tel 604 942 1001 fax 604 942 1010 RoHS CC email info radialeng com web www radialeng com JDI Duplex MK4 User Guide Part R870 1210 10 Copyright 2012 all rights reserved Features and specif cations subject to change without notice Made in Canada W
4. Switch This fiter can also be called a low pass fiter because it gently attenuates frequencies above 10k Hz while letting lower frequencies pass through unaffected The fiter is designed to help remove high frequency noise or hiss from older or consumer audio devices Many of these types of audio devices may sound just fne connected to a typical home playback system but when connected to a 50 000 watt PA or high resolution 24bit recording system the high frequency hiss can become an issue If you hear a lot of hiss try depressing the fiter switch 15dB PAD Today many acoustic guitars and basses have battery powered ac tive pre amplifers that boost their pickup output signal These high gain pre amps often generate between 2 to 7 volts at their outputs This high voltage can saturate the input of most direct boxes causing a harsh square wave distortion This is most prevalent with active phantom powered direct boxes that simply do not have sufftient headroom or rail voltage to handle these transients The Duplex is designed to handle these signal levels without fear of overloading and is one of its main advantages However you may occasionally encounter devices with extremely high output levels such as CD players and DJ mixers that can overdrive the circuit or saturate the transformer F or these rare occasions the Radial Duplex is equipped with a 15dB pad to ensure a clean and distortion free signal is obtained If you hear distorti
5. UT 15dB CH 2 XLR PAD OUTPUT CH 2 THRU Radial Engineering Ltd Specifrations Audio circuit type Frequency response Phase deviation Maximum input Total harmonic distortion Common mode rejection Input impedance Output impedance Features Input pad 180 polarity reverse Ground lift Merge High cut XLR input XLR confguration General Construction Size Weight Power Warranty Passive transformer isolated 20Hz 20KHz 0 2dB 0 3 100Hz 5 20Hz 21dB 20Hz 0 006 1kHz 100dB 60Hz unbalanced source 140k Ohms unbalanced 600 Ohms balanced 15dB Inverts signal polarity Disconnects pin 1 at XLR outputs Input summing mixer Low pass fiter 3dB 9 15kHz Switchable balanced XLR input AES standard pin 2 hot 14 gauge steel baked enamel fnish 6 25 w x 5 0 d x 1 875 h 159 x 127 x 48mm 2 9 Ib 1 32 kg Passive no power required Radial 3 year transferable Specifrations are subject to change without notice JDI Duplex mk4 User Guide RADIAL ENGINEERING 3 YEAR TRANSFERABLE LIMITED WARRANTY RADIAL ENGINEERING LTD Radial warrants this product to be free from defects in material and workmanship and will remedy any such defects free of charge according to the terms of this warranty Radial will repair or replace at its option any defective component s of this product excluding fnish and wear and tear on components under normal use f
6. acks 6 BOOK END DESIGN Creates a protective zone around the jacks and switches 7 4dB XLR INPUT For balanced line level sources like mixing consoles and pro VTRs 8 180 POLARITY REVERSE Inverts signal polarity at the XLR output to help align phase when mixing with mics 9 XLR OUTPUT 600 Ohms balanced mic level output for runs to 1000 300m without noise 10 GROUND LIFT Helps reduce noise caused by ground loops lifts pin 1 on both channels 11 FULL BOTTOM PAD Improves electrical insulation and mechanical isolation 12 I BEAM REINFORCED 14 guage steel enclosure with extra Stiff i beam shape makes it impossible to torque the P C board and eliminates cold solder joints Durable baked enamel fish Radial Engineering Ltd 2 JDI Duplex mk4 User Guide Radial The J DI DUPLEX Quick Start This section is for advanced users it provides a quick set of instruc tions for those that are familiar with direct boxes and gets right down To Start 1 Make sure all switches are in the outward position to action We suggest that you read through the entire manual for a 2 Plug the instrument into the INPUT better understanding of your J DI Caution When connecting or disconnecting any audio device 3 Connectthe 4 THRU jack to the instrument amplifer or keyboard mixer always ensure the power is off or all levels are set to zero This 4 Connect the XLR OUTPUT to the PA or mixing console practi
7. ce will reduce the opportunity for any noise such as a 5 Slowly turn up the input level at the mixer and listen capacitor discharge from being sent through the amplifer to the 6 If you hear distortion depress the 15dB PAD switch speakers which could cause a big bang in your sound system or even cause a speaker to blow This is especially true with 7 If you hear buzz and hum caused by ground loops depress the phantom powered equipment GROUND switch The Radial Duplex is a passive direct box and does not require any See the Features and Functions section for information about using external power such as phantom or batteries to make it work J ust the merge hi cut fiter and line level inputs plug in and play You are ready to go Now close your eyes and listen The Duplex is withouta doubt one ofthe mostmusical DI boxes ever manufactured a CHANEL C m SR FL um eur Near L el T NH e wart Radial Engineering Ltd 3 JDI Duplex mk4 User Guide Radial Direct Box Basics The name direct box comes from direct insertion box This is why these marvelous contraptions are also called Die Direct Insertion means exactly that to insert an eletronic signal directly into a mix point or recorder This is opposed to a microphone which transduces acoustic vibrations into an electronic signal Because the signal from an instrument like a synthesiser is already electronic we can skip the tran
8. f channels from balanced line level devices like broadcast video DAW tracks and satellite feeds The balanced XLR IN feature is designed to directly interface balanced line level devices with the mic snakes and preamps allowing line sources to be treated like other mic and DI signals on stage Atthe same time balanced devices are isolated from hum and buzz caused by ground loops and troublesome noise from less than ideal consumer electronic sources 1802 Polarity A polarity reverse switch toggles the XLR pin 2 and pin 3 as the hot or positive signal This provides operational benefts First interfacing with older audio equipment that use the pin 3 as hotis simply a matter of depressing the polarity reverse switch Secondly when combining mic and Duplex signals from the same instrument one sometimes encounters phase problems because of the time delay between the direct signal and the mic signal Reversing one of the signal polarities can correct phase or lessen its effects This same process can be used while recording microphone and direct box signals to one track to provide the engineer with another tonal palette to experiment with In a live performace situation the polarity reverse can sometimes reduce feedback from acoustic instruments Radial Engineering Ltd JDI Duplex mk4 User Guide Radial Block Diagram CH 1 XLR OUTPUT CH 1XLR Line ln GND LIFT CH 2 XLR Line In INP
9. med from electrical energy to magnetic then back to electrical in effect a magnetic bridge betweein the input and the output The beneft is that only alternating current audio signal can cross this bridge Noise like hum and buzz mainifest as DC or direct current and are blocked by the transformer Thus 60 cycle hum caused by ground loops are eliminated The left diagram below shows the ground loop through the power cable and the signal cable that connects the keyboard to the mixer The right diagram shows how an isolation transformer like the one found in the Duplex DI breaks the loop and keeps DC noise from passing into the audio signal Transformer inserted into the loop path audio path breaks the loop Dotted line shows ground The transformer will isolate noise caused by ground loops when the ground switch is depressed This disconnects pin 1 atthe XLR output If you hear hum or buzz try depressing the GROUND switch Low Frequency Phase Shift An audio laboratory test called The Green Report visit www radialeng com for details pitted the J DI single channel version of the Duplex against three other direct boxes commonly used in professional audio All the direct boxes tested well for phase shift at 1kHz butas the frequency dropped the ugly truth started to appear One popular DI was almost 202 out of phase at 20Hz while another was almost 40 out of phase The Duplex tested at less than 49 off the mark
10. ng com We d love to hear from you Enjoy Radial Introduction The Radial DI Duplex is a full feature stereo passive direct box de Signed to enhance connectivity reduce noise and simplify the hectic life of the touring professional broadcast engineer or AV integrator It is plug and play easy to use while delivering the utmost sonic quality Like the Radial J DI the Duplex employs two high performance Eclipse audio transformers and the same pristine audio signal path that has made the J DI the industry standard It features exceptional Signal handling with virtually zero phase shift or harmonic distor tion while remaining linear across the entire audio spectrum When driven to extremes the natural transformer saturation and resulting warm Bessel curve makes the Radial Duplex the perfect choice for Smoothing out highly dynamic instruments such as digital pianos and electronic drums that can sound harsh when pushed Transformer isolation provides the additional beneft of eliminating troublesome ground loops that can cause hum and buzz in the audio system This Swiss Army knife DI is equipped with 14 connectors for instru ments RCA connectors for unbalanced 10dB consumer electron ics and XLR inputs for 4dB professional line sources Radial s innovative book end design provides protective zones on the front and rear to keep connectors and switches out of harm s way The 14 gauge I beam inner frame adds tremendous rigidity t
11. o eliminate outside stresses that could torque the PC board and cause prema ture solder joint and trace failure The steel outer shell couples with the transformer s mu metal shield to protect against stray magnetic felds from power transformers or lighting systems that could cause interference F inally a full bottom no slip pad works double duty by providing both mechanical and electrical isolation The Radial DI Duplex delivers outstanding connectivity superlative audio and quiet dependable performance Radial Engineering Ltd p s w eq ued Jo niu ui eJe Syoel Et Fz Ki NS i 8 i H ah A di j J T Sf b See Sf D O gt 7 t ki 3 3 c Q 3 kel 2 s 2 So o D bieu eq UEI Jo Niy 9 ui eJe Sy26f Si XIN 8PSL 2ZH OL XIN 8PSI ZHMOL 39yd3W Qvd JInD H EP E MEO LND IH L 13NNVHO J c IANNVHO JDI Duplex mk4 User Guide Radial Features amp Functions 1 HI CUT FILTER Works when the PAD is engaged to reduce hiss and noise 2 15dB PAD Allows loud signals from keyboards to be con CHANNEL 77 oi d SE nected without distortion mor we ume m EE won mo wwe LE s 3 MERGE Turns the input and thru jacks into a passive mixer E e bd uL A ee SELECT to sum stereo signals to mono 4 V PHONE amp RCA JACKS For instruments and line level sources like CD players 5 XLR IN Activates the dB XLR input and disconnects the 4 amp RCA j
12. on when working with one of these high output devices simply depress the PAD switch and adjust the mixing console input gain to suit Merge The Duplex features an innovative merge function that turns the V4 input and thru jacks into a passive summing mixer Depressing the merge switch introduces a resistive mixer circuit that sums or combines the signals appearing at these jacks and sends a mono signal to the XLR output The merge function allows two sources to connectto each Duplex channel This can be used for stereo sources such as keyboards or CD players to save valuable channels on the snake and the mixing console It can also be used to connect two mono keyboards to one Duplex channel To merge simply connect two instruments with similar output levels into the IN and THRU jacks depress the MERGE switch to the ON position and you are setto go The internal resistive mixer is setup to do this without introducing any problems such as phase cancellation Radial Engineering Ltd JDI Duplex mk4 User Guide Radial Balanced XLR Output Each Duplex channel features a mic level low impedance balanced output jack that uses a standard XLR male connector This jack is wired to the AES Audio Engineering Society standard with pin 1 ground pin 2 hot and pin 3 cold Today pretty much all equipment is manufactured using this standard Connections are made from the XLR output to the input of the mixing console or to a standard mic
13. or a period of three 3 years from the original date of purchase In the event that a particular product is no longer available Radial reserves the right to replace the product with a similar product of equal or greater value In the unlikely event that a defect is uncovered please call 604 942 1001 or email service radialeng com to obtain an RA number Return Authorization number before the 3 year warranty period expires The product must be returned prepaid in the original shipping container or equivalent to Radial or to an authorized Radial repair center and you must assume the risk of loss or damage A copy of the original invoice showing date of purchase and the dealer name must accompany any request for work to be performed under this limited and transferable warranty This warranty shall not apply if the product has been damaged due to abuse misuse misapplication accident or as a result of service or modiftation by any other than an authorized Radial repair center THERE ARE NO EXPRESSED WARRANTIES OTHER THAN THOSE ON THE FACE HEREOF AND DESCRIBED ABOVE NO WARRANTIES WHETHER EXPRESSED OR IMPLIED INCLUDING BUT NOT LIMITED TO ANY IMPLIED WARRAN TIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE SHALL EXTEND BEYOND THE RESPECTIVE WARRANTY PERIOD DESCRIBED ABOVE OF THREE YEARS RADIAL SHALL NOT BE RESPONSIBLE OR LIABLE FOR ANY SPECIAL INCIDENTAL OR CONSEQUENTIAL DAMAGES OR LOSS ARISING FROM THE USE OF THIS PRODUCT THIS WARRANTY GIVE
14. pre amplifer The Duplex is well suited to interface with concert Snake systems and splitters where mic and direct box signals are directed to several destinations at the same time such as recording monitor broadcast and front of house mix positions Ground Lift Itis common practice to ground all electrical devices in a sound sys tem Proper grounding assures safe use and generally helps reduce system noise As the Radial Duplex is an interface itis often placed between two grounded AC powered devices such as a keyboard and a mixer Often these two devices will be connected to different AC outlets that may have very different ground reference potentials In this commom situation an audio device has two paths to ground One path is through it s power cable the other path follows the audio signal cable to the second device and fnally to ground through the second devices power cable This creates what is commonly known as a ground loop This is a problem because some stray DC current may exist inside an audio device especially one with a poorly designed grounding scheme This current should fbw to ground through the power cable but some of it will find its way onto the audio cable s ground where it bleeds into the sound as 60 cycle hum or buzz This noise is often referred to as a ground loop noise XLR In Select The live mixing console is no longer limited to mixing mics and instru ment signals Todays live mixers see a signifrant amount o
15. sducing part and inject it directly into the audio system using a DI Direct boxes allow direct insertion by performing the important functions of impedance matching level convertion and signal balancing This means that they take the high impedance unbalanced output from a guitar or keyboard and transform it to the low impedance mic level Signal used in a balanced sound system By their design balanced Signals inherently cancel noise and due to the lower impedance signals can travel much further without degradation like high frequency loss High impedance unbalanced signals are the norm in electronic musical instruments and consumer audio devices The direct box interfaces the two and allows the best sound least noise and fullest frequency response This is why low impedance balanced signals are the standard in professional recording broadcast and live sound There are a couple of important things to understand about the XLR output This output taps the instrument signal before it goes to the musi clan s effects and amplifer This allows the mix engineer to capture the signal before itis modifed by the musician This is important because what may sound good on stage to the musician may not necessarily sound good in the venue Another important fact is that the level of the XLR output is mic level signal This allows the Duplex to be used along side other microphone signals without introducing cross talk or overdriving the mixing con
16. soles input The Magic of a Great Transformer The Radial Duplex is a passive direct box This means thatitemploys a transformer to convertthe impedance and balance the signal Many Radial products incorporate Eclipse audio transformers which are expensive but to an audiophile these transformers are worth their weight in gold To understand how a passive DI works we have to understand DI transformers A transformer is a simple device It is basically made up of three com ponents the primary or input coil the core material and the secondary or output coil The audio signal enters the primary coil and according to Faraday s law of electromagnetism the current is converted into a pulsing magnetic feld The metal core acts like a conduit to contain the magnetic feld and concentrate it into the secondary coil The secondary coil bathed in modulating lines of magnetic flix converts the magnetism back into an audio signal through induction Varying the number of windings on the primary and secondary coils allows us to control the input and output impedance ratio This is where the specifration 10k 150 Ohms for transformers comes from LAMINATED MAGNETIC CORE BRIDGE PRIMARY SECONDARY WINDING WINDING Radial Engineering Ltd JDI Duplex mk4 User Guide Radial Magnetic Bridge The beauty of a transformer is that there is no hard electrical con nection between the primary and the secondary coils The signal is transfor

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