Radial Engineering JDI Mk3 User Manual Download

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Part 7 – Block diagram and speciﬁcations

True to the Music

Radial Engineering

JDI User Guide

JDI Mk3 (and JDI Duplex) Speciﬁcations

Type

Passive Jensen Transformer equipped

Input impedance

Unbalanced 140k-Ohms typical

Output impedance

Balanced 150 Ohms typical

Frequency response

10Hz to 40kHz

Linear performance

< -0.22 dBr deviation @20kHz

Total harmonic distortion

0.05% @ 20Hz, 0.005% @ 1kHz

Phase distortion

< 4º at 20Hz, 0.3º at 1kHz

CMR

100dB @ 60Hz

Maximum input level

+22dBu

Size

3.5" wide, 2" high, 5.5" deep

Weight

1kg / 2.2lbs

Construction

Welded 14-gauge steel

Finish

Baked enamel ﬁnish

JDI Block Diagram

Summary of Contents for JDI Mk3

Page 1: ...g 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 C TEC JP CableTek Electronics Ltd JDI and www radialeng com DUPLEX Mk3 ...

Page 2: ... your JDI 11 7 Frequently asked questions 12 8 Block diagram and speciﬁcations 15 Warranty Back cover 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 ...

Page 3: ...on 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 gracefull...

Page 4: ...formance 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 ...

Page 5: ...dio 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 details on this application in the Part 5 Featur...

Page 6: ...eproduce 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 tr...

Page 7: ...s 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 w...

Page 8: ...nd 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 dr...

Page 9: ...ruments 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 The MERGE switch 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 ...

Page 10: ...d 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 an...

Page 11: ... 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 the load on its own There are ...

Page 12: ...ctors 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 enclos...

Page 13: ...put 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 Use 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 i...

Page 14: ...s such as phase distortion Best of all passive DI 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 ba...

Page 15: ... 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 mi...

Page 16: ...duce 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 I 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...

Page 17: ...ced 140k Ohms typical Output impedance Balanced 150 Ohms typical Frequency response 10Hz to 40kHz Linear performance 0 22 dBr deviation 20kHz Total harmonic distortion 0 05 20Hz 0 005 1kHz Phase distortion 4º at 20Hz 0 3º at 1kHz CMR 100dB 60Hz Maximum input level 22dBu Size 3 5 wide 2 high 5 5 deep Weight 1kg 2 2lbs Construction Welded 14 gauge steel Finish Baked enamel ﬁnish JDI Block Diagram ...

Page 18: ...laim 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 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...

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