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JDI

™

Duplex MK4 S T E R E O PA S S I V E D I

Features

• Linear response from 10Hz ~ 40kHz

• Jensen transformer equipped for great sound

• Enhanced connectivity: ¼”, RCA, and XLR inputs

• Merge function sums stereo sources to mono

• Built tough to survive the road

Applications

• High output keyboards and drum machines

• Ideal for active acoustic guitars and basses

• Great for rentals and AV staging

• Converts +4dB line-level to mic-level

Cool Factors

• ‘Plug & play’ easy-to-use!

• Transformer isolation eliminates hum & buzz

• Virtually impossible to overload

• Ultra-low phase distortion

• 3 year transferable warranty

-15dB PAD allows

super-hot signals

to be connected

without distortion.

MERGE FUNCTION turns the input

and thru jacks into a passive mixer

to sum stereo signals to mono.

INPUT and THRU

jacks for ¼” and

RCA sources.

OUTPUT 600Ω balanced mic-

level output for runs to 1000

feet without appreciable noise.

180° POLARITY REVERSE

ﬂ ips the polarity from pin-2

to pin-3 on the XLR output.

GROUND LIFT disconnects

the transformer ground from

pin-1 on the XLR outputs.

R ad i a l E n g i n e e r i n g - D i v i s i o n o f J P C a b l e Te k E l e c t r o n i c s L t d . · Te l : 6 0 4 - 9 4 2 - 1 0 0 1 · F a x : 6 0 4 - 9 4 2 - 1 0 1 0 · w w w.r a d i a l e n g . c o m · e m a i l i n f o @ r a d i a l e n g . c o m

T h i s d o c u m e n t i s t h e p r o p e r t y o f J P C a b l e Te k E l e c t r o n i c s L t d . S u b j e c t t o c h a n g e w i t h o u t n o t i c e .

Two independent DIs. Bass

guitar uses THRU jack to

connect to stage amp.

Stereo summed

to mono using

MERGE function.

XLR line input for

+4dB balanced

sources like mixers.

HI-CUT FILTER works

when the PAD is engaged

to reduce hiss and noise.

XLR INPUT balanced +4dB

input for line-level sources

like pro VTRs and mixers.

XLR INPUT SELECT activates

the +4dB XLR input (on back

panel) and disconnects the ¼”

and RCA jacks.

True stereo DI. Connections for

¼” instruments, -10dB (RCA),

and +4dB (XLR) sources.

U s e r G u i d e A d d e n d u m

Congratulations on your purchase of the Radial JDI Duplex MK4 direct box. The Duplex has

been redesigned for 2006 with several new features. Like all Radial DIs in the JDI series, the

Duplex features excellent sonic performance, low phase and harmonic distortion, authen-

tic Jensen transformers and rugged steel construction. Your Duplex features two identical

channels and an enhanced connectivity panel making it the most ﬂ exible stereo direct box

available. Best of all, the new Duplex can interface virtually any audio source from musical

instruments to consumer electronics to balanced +4dB pro-audio devices.

This addendum contains information about features speciﬁ c to the Duplex MK4. However,

we encourage you to read through the standard JDI manual before using your Duplex so

that you can maximize its features to your advantage.

14 GAUGE STEEL

bookend shell creates

a protective zone

around the switches.

Summary of content (19 pages)

PAGE 1
User Guide Addendum JDI ™ Duplex MK4 S T E R E O PA S S I V E D I Congratulations on your purchase of the Radial JDI Duplex MK4 direct box. The Duplex has been redesigned for 2006 with several new features. Like all Radial DIs in the JDI series, the Duplex features excellent sonic performance, low phase and harmonic distortion, authentic Jensen transformers and rugged steel construction.
PAGE 2
www.radialeng.com JDI and Mk3 DUPLEX 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 C•TEC (JP CableTek Electronics Ltd.
PAGE 3
RADIAL JDI & DUPLEX USER GUIDE TABLE OF CONTENTS PAGE 1. Introduction .................................................................................1 2. JDI feature set ............................................................................2 3. JDI quick start ...........................................................................3 4. Direct box basics .........................................................................4 5. Features and functions ............................................
PAGE 4
True to the Music 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 sound in any way. This ensures the natural tone and harmonic balance is retained, bringing out the very essence of the instrument.
PAGE 5
True to the Music 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, distortionfree signal. (8) Double sided PC board - military grade circuit board features a full ground plane for maximum protection against stray magnetic ﬁelds and RF noise. (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 at the XLR.
PAGE 6
True to the Music Part 3 – The JDI Quick Start This section is for advanced users — it provides a quick set of instructions for those 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.
PAGE 7
True to the Music 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 DI’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 recorder.
PAGE 8
True to the Music 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’.
PAGE 9
True to the Music 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’.
PAGE 10
True to the Music Part 5 – Features and Functions The ¼” INPUT and THRU connectors The JDI features two ¼” jacks on the input panel. These are designed to accept normal instrument input levels from basses, guitars, keyboards, drum machines, etc. The left-most ¼” input is normally connected to the source instrument. The ¼” connector to the right of the input is normally used as a ‘thru’ connector and feeds the instrument signal to the musician’s ampliﬁer.
PAGE 11
True to the Music 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.
PAGE 12
True to the Music 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.
PAGE 13
True to the Music 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 ¼” to ¼” cable from the second (parallel) speaker cabinet jack to the JDI.
PAGE 14
True to the Music 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.
PAGE 15
True to the Music Part 7 - FAQ’s or Frequently Asked Questions Q: What is the difference between active & passive? A: Active DI’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.
PAGE 16
True to the Music 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.
PAGE 17
True to the Music 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.
PAGE 18
True to the Music Part 7 – Block diagram and speciﬁcations JDI Block Diagram 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.
PAGE 19
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.