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1. an audio transformer Radial Engineering 6 JDI User Guide Radial Part 5 Features and Functions The 14 INPUT and THRU connectors The JDI features two 7 jacks on the input panel These are designed to accept normal instrument input levels from basses guitars keyboards drum machines etc The left most input is normally connected to the source instrument The 4 connector to the right of the input is normally used as a thru connector and feeds the instrument signal to the musician s amplifier XLR Lo Z balanced ee CL D SY SIA out to mixer f Using the JDI with a bass guitar with this setup allows both the musician and the engineer to work with the original signal direct from the bass This way the musician can set up his sound on stage with his own EQ while the engineer can EQ the bass to work better in the hall Saga o o COL o o 00008 0000000 J On live stages it is common for instruments such as acoustic guitar to be connected to the DI and then to the snake system using the Lo Z XLR output splitting the signal to feed the stage monitor mixer for foldback just as microphones are In this case the thru jack would not be used instrument to THRU jack to The MERGE switch INPUT amplifier The JDI features an innovative merge function that turns the input and the thru put into a left right to mono mix Depressing the merge switch introduces a r2. The J Rak is an innovative rack shelf chassis that lets you rack mount up to eight Radial JDIs J48s or the other similarly sized Radial DI splitter or isolator products into a high density 2 RU space Each unit can be front or rear mounted allowing the system designer to have the XLRs on the front or rear of the rack depending on the application Radial Engineering 10 JDI User Guide Radial Part 6 Other cool uses for your JDI Use the Radial JDI to re amplify your signal Today a popular studio effect is to record a signal such as guitar voice or keyboard on a track and then run the pre recorded track back through a guitar amplifier or effect pedal This effect is known as reamping or re amplifying and was started by Les Paul in the 1950 s and was widely used on recordings by the Beatles in the 60 s and by Steely Dan in the 1970 s The Radial JDI can be used backwards to convert a low impedance mic level signal back to a high impedance guitar signal Simply connect the output from the recorder to a mixer and the mixer s output to the JDI s XLR output using a female to female XLR turn around adaptor Keep your level down to ensure the signal will not overload the JDI s transformer Connect the input of the JDI to the input of the guitar amplifier and you are set to go To amp using JDI s Hi Z input as output JDI Low Z output used as input JDI Hi Z unbalanced input XLR F to XLR F Us
3. 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 warranty This limited warranty shall not apply if the product has been damaged due to abuse misuse misapplication accident or as a result of service or modification 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 WARRANTIES 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 GIVES YOU SPECIFIC LEGAL RIGHTS AND YOU MAY ALSO HAVE OTHER RIGHTS WHICH MAY VARY FROM STATE TO STATE OR PROVINCE TO PROVINCE Radial Radial Engineering 1638 Kebet Way Port Coquitlam BC V3C 5W9 tel 604 942 1001 fax 604 942 1010 email info radialeng com web www radialeng com Radial Engineering is a division of CeTEC JP CableTek Electronics Ltd JDI amp JDI Duplex manual V1 1 05 19 05 Part R800 9605 00
4. Radial engineering JDD an and DU es User Guide Radial Engineering 1638 Kebet Way Port Coquitlam BC V3C 5W9 tel 604 942 1001 fax 604 942 1010 email info radialeng com web www radialeng com Radial Engineering is a division of CeTEC JP CableTek Electronics Ltd RADIAL JDI amp DUPLEX USER GUIDE TABLE OF CONTENTS PAGE 12 IN FODUCHION sees ii irii aaen O aae Ti RANE aiT 1 2 JDI feature set 2 Si IDI QUICK Staite siaaa EAE EE 3 4 Direct DOX baSiCS i i asicitiiive A iia Bvaencas 4 5 Features and functions Bae A 6 Other cool uses for your JDI ecceeeeeeeeeeeeeeeeeeeeeeseeeteseeeeeaees 11 7 Frequently asked questions ccccccceeeceeeeeeeeeeeeeeseeeeeseaees 12 8 Block diagram and specifications eee Eo Warranty inanir kite ciiiiva priae aiurea aaaeaii Vannai Back cover Radial Radial Engineering 1638 Kebet Way Port Coquitlam BC V3C 5W9 tel 604 942 1001 fax 604 942 1010 email info radialeng com web www radialeng com Radial Engineering Ltd is a division of C TEC JP CableTek Electronics Ltd Features and specifications are subject to change without notice Radial Part 1 Introduction Congratulations on your purchase of the world s finest direct box The Radial JDI Mk3 is the latest version of the highly acclaimed JDI and is without a doubt the finest passive direct box available today The JDI is very unique in that it does not color or alter the so
5. be able to pass every frequency between 20Hz and 20 000Hz flawlessly The transformer must also ensure that all of these frequencies retain their time base relationship or absolute phase In other words whatever you send in should come out at the same time If the bass and mid range are not synchronized in perfect phase it simply will not sound as good A transformer is a simple device It is basically made up of three components 1 the primary or input coil 2 the core material and 3 the output coil The audio signal enters the primary coil and taking full advantage of Faraday s law of electromagnetism the coil converts the electron impulse current into a magnetic field The core acts like a conduit to contain the magnetic field and drives it into the secondary coil A magnetic field when driven into a coil generates electron Radial Engineering 5 JDI User Guide Radial flow Varying the number of windings on the input and the output allows us to control the input and output impedance ratio This is where the specification 10k 150 Ohms comes from The beauty of a transformer is that there is no electrical connection between the primary and the secondary The signal is transformed from electrical energy to magnetic then back to electrical in effect a magnetic bridge This provides two huge benefits with no electrical path ground loops are eliminated and when properly designed a tremendous reduction in c
6. ces in a sound system Proper grounding assures safe use and generally helps reduce system noise As the Radial JDI is an interface it is 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 or may have very different ground reference potentials When connected together these can sometimes cause 60 cycle hum or a loud system buzz This noise is often referred to as a ground loop Radial Engineering 8 JDI User Guide Radial The Radial JDI features an isolation transformer that will generally eliminate most of this type of noise But in severe cases lifting the ground on pin 1 at the XLR by depressing the GROUND switch can help When lifted this assumes the ground will be derived by connection of the THRU through the cable shield to grounded equipment such as an amp Note that when you are going direct by connecting a bass or acoustic guitar to the Radial JDI without using the thru put the ground switch should be set in the out position so that the JDI is grounded at the mixing console If you are using the thru put to your personal amp then your amp and the mixer will have ground paths and lifting the ground would then be considered Parallel speaker connection and the SPEAKER switch IMPORTANT THE JDI IS NOT A LOAD BOX You must ensure that the amplifier is connected to it s speaker load first as the JDI is not designed to handle t
7. d in phase while bad direct boxes vandalize the sound even before it gets to the mix position Q What is the difference between phase and polarity A This is often confused Reversing the polarity means switching the wire with the wire in an electrical connection Reversing the phase has to do with the time domain When a frequency is delayed by 180 and played with the original the out of phase signals cancel each other out Reversing the polarity of one of two speakers has the same audible effect Radial Engineering 13 JDI User Guide Radial Q Is a flat frequency response better than a colored response A This is a good question When buying a large condenser microphone you are most often not getting a flat response mic but a mic colored or flavored to add to your sound palette Most studios boast a selection of mics and the sign of a good engineer is one that knows which mic to use on what in order to get a particular tone With direct boxes this is usually not the case If the sound of the guitar is not right one will usually change the guitar not the direct box therefore we believe the role of the direct box is to transport the original signal as faithfully as possible from the instrument to the destination and allow the engineer and producer to make the artistic choices Here s more food for thought should the direct box change the tone of the instrument If it makes your Strat sound fat will it make your Le
8. dgy and bass and keys sound thin Finally most active direct boxes do not provide electrical isolation Transformers do this naturally and in doing so eliminate hum and buzz caused by ground loops Q What is phantom power and will it harm my JDI A Phantom power is a DC supply that comes from the mixing console that was originally designed to provide power to condenser microphones It is typically 48 volts and about 5mA When phantom is on it will not harm the JDI Q What is phase distortion A Keeping your signal in phase is akin to making sure that when you play guitar the sound coming from the low E string plays at the same time as the G string as they come out of your amp You may take this for granted but the fact is phase distortion can cause an instrument to get lost in the mix and make a bass sound muddy Phase distortion can occur at all frequencies but is most noticeable in the bass or low frequencies Try facing your stereo speakers close together and reverse the wires on one cabinet so that it is wired out of phase and you will immediately become an in phase disciple When we tested several popular direct boxes for phase deviation we found that most were fine at 1000Hz What surprised us is how poorly the other DI s performed at 20Hz One popular direct box was 40 out of phase while another was 20 out The Radial JDI tested at less than 4 We spend thousands of dollars on PA systems to ensure they are time aligne
9. e the Radial JDI for long cable runs High impedance coax cables are susceptible to noise if they exceed 25 feet Balanced lines on the other hand split the signal into two low impedance signals and use phase cancellation to reduce noise Connecting your guitar to one JDI to send the signal and then using another Radial JDI backwards to convert the signal back to high impedance as depicted below is very effective This is a good trick to use when recording the sound from your amplifier at some distance while you play in the control room and listen through studio monitors or headphones Radial Engineering 11 JDI User Guide Radial Part 7 FAQ s or Frequently Asked Questions Q What is the difference between active amp passive A Active Dl s have a built in pre amp that requires battery or 48V phantom power to run while passive DI s use a transformer to convert the signal and do not require any power supply Both transform or convert the instrument s high impedance output to a low impedance balanced microphone level This allows long cable runs without adding unwanted noise Passive boxes have the advantage of providing isolation which can reduce ground hum and noise in systems Q Which is better active or passive A Both have their place just like dynamic and condenser microphones Passive Dls are often easier to use because they do not require power while active DI s tend to have more reach As a rule pa
10. esistive mixer circuit that sums the two channels at the XLR output This function allows two sources such as a stereo keyboard or CD player to merge to mono saving valuable channels on the snake and the mixer when you have more sources than available inputs 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 set to go The internal resistive mixer is set up to do this without introducing any problems such as phase cancellation Radial Engineering 7 JDI User Guide Radial Understanding input distortion and using the 15dB PAD switch Today many acoustic guitars and basses have battery powered active pre amplifiers that boost their pickup output signal These high gain pre amps often generate between 2 volts and 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 sufficient headroom or rail voltage to handle these transients The JDI is designed to handle these signal levels without fear of overloading and is one of the main advantages you will enjoy with your JDI However you may occasionally encounter devices with extremely high output levels such as from CD players a mixer output or even a headphone out that can overdrive the circuit or saturate the transformer For the
11. g the SPEAKER switch also introduces a band pass filter circuit that rolls off the highs and lows in order to better emulate the performance of a typical 12 speaker Mechanical attributes All Radial products display the results of our relentless pursuit of durability Look inside a JDI and you will note that it is literally two boxes in one An internal heavy duty welded steel chassis which houses the circuitry and connectors and an external book end design steel shell designed to protect the switches and jacks from overzealous roadies and other rigors of touring Both boxes are made from 14 gauge steel and protected by a heavy baked epoxy finish that will look great even after years of service Inside the mil spec PC board is two sided which means that all components are soldered twice Further the dual shell enclosure makes it impossible to torque the PC board ensuring years of noise free performance without failure The JDI is also outfitted with a full bottom no slip pad for two important reasons it provides plenty of stay put friction on hectic stages to keep your DI from sliding around or falling when stacked and it also works as an electrical isolator when placed on or around guitar amps many amp heads have handles or hardware which is sometimes connected to the amp s chassis or circuit The isolation pad helps minimize the possibility of shock hazards especially with older amplifiers J Rak 19 rack mount kit
12. he load on its own There are occasions when you may wish to tap the wet signal off the output side of an amplifier as opposed to taking the dry signal directly from the instrument Examples would be capturing the EQ and compression settings from a bass amplifier recording the distorted sound of a guitar amplifier or maybe combining the sound of a mic d amplifier with a direct feed off the speaker Amp must be connected to speaker cabinet peee resoeee LON bo N WE 2 Se 202g o o Q 15dB PAD and lt 7 SPEAKER pad Cabinet thru jack to must be activated JDI Hi Z input Radial Engineering 9 JDI User Guide Radial The JDI s parallel speaker connection feature lets you do this by connecting the JDI directly to the speaker cabinet It is important to note that the JDI is NOT a load box you must have a load such as a speaker connected to the amplifier as connecting the JDI directly without a load could cause severe damage to the equipment Connect your amp as usual then connect a to cable from the second parallel speaker cabinet jack to the JDI Because of the high impedance and low draw from the JDI the amp will only see the speaker cabinet so you do not have to change the amplifier s impedance setting Depressing BOTH the 15dB PAD switch and the SPEAKER switch inserts a special circuit that will protect the JDI from overload and allow the parallel speaker connection to be made safely Depressin
13. ic guitars used piezos Musicians found that connecting the instrument to a direct box then the DI to their amplifier and also to a mixer caused the sound to change Splitting the signal to the instrument amplifier and the mixer added a second load This of course would reduce the level going to the instrument amplifier thinning and colouring the sound Radial Engineering 12 JDI User Guide Radial Q Why is loading no longer a concern A Back in the 1970 s acoustic guitars did not have the sophisticated pickups and built in pre amps that are standard now Today most electric basses incorporate high output pickups or have active electronics built in Acoustic guitar pre amps and keyboards can have equally high output levels These high output levels are so powerful that loading is no longer the concern The fix has in fact caused a new problem input distortion or saturation Q But I have heard that active DI s are better A Active DI s can be good but they can have several disadvantages active direct boxes require power As such they must either run off batteries or 48V phantom power from the console When power is low they distort This means that for the direct box to work well you must have fresh batteries Furthermore today s high output instruments often overload the direct box input as it is unable to handle the dynamic range This causes harsh square wave distortion that makes acoustic guitars sound e
14. o The Radial JDI Duplex is designed as a stand alone device If you are looking for a rackmount solution that takes up even less space than the J Rak the 1 RU Radial JD6 may be your solution with 6 JDI channels in 1 RU space Radial Engineering 14 JDI User Guide Radial Part 7 Block diagram and specifications JDI Block Diagram Type input impedance Output impedance Frequency response Linear performance Total harmonic distortion Phase distortion CMR Maximum input Tevel Size Weight Construction Radial Engineering 15 JDI User Guide RADIAL ENGINEERING 3 YEAR LIMITED WARRANTY RADIAL ENGINEERING a division of J P Cabletek Electronics Ltd warrants this product to be free from defects in material and workmanship to the original owner 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 batteries finish and wear and tear on components under normal use for 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 To make a request or claim under this limited warranty the product must be returned prepaid in the original shipping container or equivalent to Radial or to an authorized Radial repair center and you
15. ommon mode noise is possible In the real world not the test bench signals are never truly balanced leaving the door open for noise to pollute the audio signal Electronically balanced circuits active circuits are ill equipped to manage this common mode noise whereas the JDI provides exceptional noise rejection at 60Hz the crest of hum and buzz An audio laboratory test called The Green Report visit www radialeng com for details pitted the JDI against three other direct boxes commonly used in professional audio The tests showed that the JDI could handle more gain before distortion was more linear throughout the audio frequency range and showed significantly less phase distortion All boxes tested well at 1kHz but as the frequency dropped the ugly truth started to appear One popularly used DI was almost 20 out of phase at 20Hz while another was almost 40 out of phase The JDI tested at less than 4 off the mark making it the most phase accurate DI on the planet With its high signal level handling dynamic response and unmatched phase accuracy the JDI is a significantly better choice for bass keyboard and acoustic guitars with built in pre amps and this can be directly attributed to the quality of the Jensen transformer we use Equipment is Equipment is connected connected through audio through A C cable ground The Problem The Cure Ground loop between Equipment isolated with conneced equipment
16. order We take this very seriously with all our direct boxes and as such have designed them to reproduce the most accurate picture of the source no matter what the instrument Direct boxes perform the important function of impedance matching and signal balancing This means that they take the high impedance output from a guitar or keyboard and transform it to the low impedance signal used in balanced sound systems Balanced signals inherently cancel noise and due to their lower impedance can travel much further without degradation Balanced signals are the norm in professional recording broadcast and live sound By properly matching the impedance you will enjoy better sound less noise and an extended frequency response Typical DI box setup Radial Engineering 4 JDI User Guide Radial Getting to know your Radial JDI Mk3 As a rule all direct boxes follow the same basic procedures when connecting them to a sound system The instrument plugs into the INPUT the musicians instrument amplifier connects to the THRU and the mixer or recorder is connected to the XLR OUTPUT Since the XLR output connection to the mixer taps the signal before it goes to the musician s amplifier this allows the mixing engineer to capture the signal before it is modified by the musician thus resulting in the purest source possible It is important to note that what may sound good on stage may not necessarily sound good in the venue B
17. s Paul muddy We think a properly designed DI should be faithful to the source The Radial JDI direct box gives the engineer and producer a natural and uncolored sound to work with Q What about tube direct boxes A Tube direct boxes are cool and there is a definite place for them in the recording world Tube DI s introduce personality to the sound and should be viewed in the same way as one views a tube microphone Q If my JDI ever fails what do do A In the past 10 years the JDI has been so reliable that it is a rare occurrence when we need to repair one If however something goes bad a switch for example simply call Radial and we will issue a return authorization number for you to send it back to us for repair We do suggest that before you do so visit the dealer where you bought it and have them check it out before sending it away Often times it turns out that bad cables are the actual problem Q What is the warranty on the JDI A The Radial JDI carries a 3 year warranty while the Jensen transformer inside carries a 20 year warranty Repairing the transformer can be done either through Radial or directly with Jensen Transformers Q Can rack mount the Radial JDI A Yes This is easily done with the Radial J Rak The J Rak is a 2RU shelf that holds as many as 8 Radial small format direct boxes like the JDI or J48 which can be front or rear mounted depending on your intended application Q Can I rack mount the Duplex A N
18. s on this application in the Part 5 Features and Functions section of this manual Since the Radial JDI employs an audio transformer you are actually isolating the electrical connections between the input and output This will usually eliminate all buzz and hum caused by so called ground loops The JDI is designed to be grounded at either the input or the output side of the transformer If you encounter 60 cycle hum or noise lift the ground at the XLR output This will assume the JDI is deriving its ground at the input from the instrument or instrument amplifier The JDI also features a polarity reverse This reverses pin 2 and pin 3 at the XLR As the JDI is set following the AES standard with pin 2 hot reversing the polarity is generally not required unless the instrument is being both DI d and mic d The polarity reverse switch would allow both the mic and the JDI to be set in phase should these be reversed You are ready to go Now close your eyes and listen The JDI is without a doubt one of the most musical DI boxes ever manufactured Radial Engineering 3 JDI User Guide Radial Part 4 Direct Box Basics What is a direct box anyway The name direct box comes from direct insertion box This is why these marvelous contraptions are also called Dl s Direct Insertion means exactly that To insert a signal directly or take an audio signal from the source and send it directly to a mix point or rec
19. se rare occasions the Radial JDI is equipped with a 15dB pad to ensure a clean and distortion free signal is obtained The balanced XLR output The JDI features a mic level 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 Connection is made to the mic level input of the mixing console or to a standard mic pre amplifier The JDI is ideally suited for 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 The POLARITY switch A polarity reverse toggles the XLR pin 2 and pin 3 as the hot or positive signal This provides several operational benefits interfacing with older mixing consoles that have pin 3 hot is simply a matter of depressing the polarity reverse and when mic ing and using a direct signal from the same instrument one sometimes encounters phase problems when these are combined Reversing one of the source polarities often alleviates this This same process while recording provides the engineer with another tonal pallet and experimenting with different settings can lead to some very pleasing results The GROUND switch It is common practice to ground all electrical devi
20. se that are familiar with direct boxes and gets right down to action We suggest that you read through the entire manual for a better understanding of your JDI Caution When connecting or disconnecting any audio device always ensure the power is off or all levels are set to zero This practice will reduce the opportunity for any noise such as a capacitor discharge from being sent through the amplifier to the speakers which could cause a big bang in your sound system or even cause a speaker to blow This is especially true with phantom powered equipment The Radial JDI Mk3 is a passive direct box and as such does not require any external power such as phantom or batteries to make it work Just plug in and play To start make sure all switches are in the out position Plug the instrument into the INPUT Connect the THRU to the guitar amplifier or keyboard mixer and the XLR OUTPUT to the PA or mixing console Set the PAD to OdB Slowly turn up the input level at the mixer and listen See the Part 5 Features and functions section about the MERGE function The JDI s Jensen audio transformer should be able to handle most instrument signal levels without distortion At exceptionally high signal levels the 15dB pad should be used to reduce the input level to the transformer If you hear distortion simply depress the 15dB pad button If you intend to use the JDI in parallel with a speaker load it is important that you read the detail
21. ssive direct boxes are preferred for electrically powered devices such as keyboards and electronic drums Q Why do people use passive direct boxes Passive direct boxes are often chosen as they are plug amp play easy to use When equipped with a high quality transformer they can handle exceptionally high signal levels without harmonic distortion and a good one like the JDI will process the signal without introducing artifacts such as phase distortion Best of all passive Dl s eliminate ground loops Q Why do people use active direct boxes A There are two reasons that active DI boxes like the Radial J48 have become popular To get good sound with a passive direct box you need to use a high quality transformer like a Jensen which can be quite expensive This cost dissuades many manufacturers from building passive DI s a basic active direct box can be made much more cheaply The other reason is that back in the 1970 s and 1980 s when Dls first showed up most instruments used passive pickups and these generally had very low output levels Passive DI s with inefficient transformers would load down the pickup and cause the sound to change Active buffered or amplified direct boxes could be made with a high input impedance that would not load down the pickups which solved the loading issue Q Can you explain loading A Years ago most bass guitars used low output pickups such as those found on Fender basses while acoust
22. t the XLR 3 INPUT 1 4 jack 130kOhm instrument input 4 THRU 1 4 jack thru put to send instrument signal through to the instrument amplifier 5 Protective bookend cover overhangs the chassis providing protection for switches and connectors 6 Welded I beam construction for maximum strength and durability and a baked enamel finish offer years of trouble free performance 7 Full bottom no slip pad reduces slipping in use and provides mechanical and electrical isolation 8 Double sided PC board military grade circuit board features a full ground plane for maximum protection against stray magnetic fields and RF noise 9 XLR output connector wired to the AES standard with pin 1 ground and pin 2 hot provides a balanced 150 Ohm mic level signal 10 POLARITY switch 180 polarity reverse toggles the XLR pin 2 and pin 3 to interface with older equipment Also used when combining two sources such as a mic and a DI 11 GROUND switch lifts the XLR pin 1 ground at the output to eliminate hum and noise caused by ground loops 12 SPEAKER switch a pad circuit that allows you to tap the signal from a speaker cabinet Features a band pass filter to emulate a 12 driver Note Only use in parallel with a speaker cabinet or load box Radial Engineering JDI User Guide Radial Part 3 The JDI Quick Start This section is for advanced users it provides a quick set of instructions for tho
23. und in any way This ensures the natural tone and harmonic balance is retained bringing out the very essence of the instrument The JDI Duplex is a two channel stereo version of the JDI with two totally independent and isolated PC boards This allows the Duplex to be used with two sources without causing ground contamination or crosstalk For simplicity this manual will discuss the JDI All features and functions on the Duplex are identical to those of the JDI Both direct boxes employ the Jensen JT DBE transformer for unmatched audio performance exceptional noise rejection and high signal handling This makes them ideal for acoustic guitar bass and keyboards In fact just about any audio signal is transformed gracefully without artifact We advise that you read through this manual before using the JDI so that you can maximize it s potential Please log onto the Radial Engineering website at www radialeng com for further details and updates We invite you to forward any DUPLEX comments questions or suggestions to info radialeng com we d love to hear from you Enjoy Radial Engineering 1 JDI User Guide Radial Part 2 The JDI Feature Set 1 15dB PAD switch a 15dB pad can be introduced to reduce the input voltage and ensure a clean distortion free signal 2 MERGE switch left right merge function turns the input and thru put connectors into a pair of left right inputs with a mono output a
24. y sending an unaltered signal to the front of house mix position FOH the engineer is able to get the sound he is looking for with minimal phase and harmonic distortion This is likely the main reason why Radial direct boxes are so popular with sound engineers Radial Dl s do not alter the sound in any way before it gets to the mixing desk High to low impedance conversion and balancing The Radial JDI features a high 140k Ohm input impedance for the instrument As the signal passes through the JDI to the XLR output it is converted to a balanced 150 Ohm low impedance signal This allows long cable runs without introducing noise into the audio signal path It is important to note that the output of the Radial JDI is a mic level signal This allows the JDI to be used alongside other microphone signals without introducing cross talk or causing transformer saturation when driving the signal through the mic bridging transformers of a splitter The magic of a great transformer The Radial JDI is a passive direct box this means that it employs a transformer to convert the impedance and balance the signal At Radial we believe quality should always be the most important deciding factor in any product design and the best way to make great products is to use the very best parts Many Radial products incorporate Jensen audio transformers which are expensive but to an audiophile these transfrmers are worth their weight in gold A good transformer must
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