Radial Engineering JDX User manual

www.radialeng.com
UserGuide
JDX
AmplifierDirectBox
CAUTION: Please read safety disclosure
statement on the inside cover before
connecting your Radial JDX.
Radial Engineering Ltd.
1588 Kebet Way, Port Coquitlam BC V3C 5M5
Tel: [phone] Fax: [phone]
email: [email protected]
®TruetotheMusic

THE JDX IS NOT A LOAD BOX
It is mandatory that your amplifier be connected to a
loudspeakeror loadbox atall times.TheJDX doesnot
provide a significant resistive load for an amplifier to
safely operate. Damage may occur to your amp if the
JDX is used without a proper loudspeaker load.
ALWAYS TURN YOUR AMPLIFIER OFF BEFORE
CONNECTING OR DISCONNECTING THE JDX.
Itis yourresponsibility toconfirmthe JDXis connected
properly before operating your amplifier. If you are
unsureabout connectingor operatingtheJDXconsult
a qualified technician or see your dealer. Damage
causedby improperoperationisnotcovered underthe
warranty. See the back cover for warranty details.
SAFETY DISCLOSURE STATEMENT
CAUTION:
Please read before
connecting your Radial JDX
www.radialeng.com

TruetotheMusic
Radial Engineering JDX User Guide
1
RadialJDXAmplifierDirectBox
UsersGuide
Table of Contents Page
Introduction...................................................................1
Design Concept............................................................2
Applications..................................................................5
Feature Set...................................................................6
Input Panel...................................................................7
Output Panel ................................................................7
Making Connections.....................................................8
FAQ..............................................................................8
Specifications...............................................................9
Warranty................................................................Back Cover
Congratulations on your purchase of the Radial JDX guitar amp
direct box, a unique tool for recording and performing with ampli-
fiedelectric guitar.The JDXis anactive speaker-levelDI that taps
thenatural toneof youramplifierand interfacesit withprofessional
recording and PA systems.
TheRadial JDXis easytouse,howeverit differs significantlyfrom
standard direct boxes. Like any tool, the best way to get the most
out of your JDX is by understanding the design, functions and
safety features. We recommend you take a few minutes to read
this manual before operating your JDX.
Shouldyou haveany questionsregarding theJDXorit’s functions
check our FAQ at www.radialeng.com. If you would like to share
your experience with Radial products we invite you to contact us
at [email protected].
The JDX, one small step for mankind, one huge leap for tone
fanatics!

TruetotheMusic
JDX User Guide
Radial Engineering
2
DESIGN CONCEPT
The JDX differs from a standard DI like the Radial J48. A stan-
dard DI taps the output of the guitar before it is connected to an
amplifier. The JDX taps the output of your amplifier yielding a
completely different sound.
The JDX is placed between the amplifier and loudspeaker.Apro-
prietaryreactive circuitfollows theconstantly changinginteraction
between amp and speaker to capture the dynamic response of
youramp. Thenan activemulti-stage filterprocesses thesignal to
emulate the frequency response of a loudspeaker and finally, the
JDX uses a Class-Abuffering amplifier to output a signal suitable
for pro-recording and and PA systems.
JDX Amplifier Direct Box vs. Standard Direct Box
Bass and acoustic guitars often use a standard DI to capture the
clean sound of the instrument. This works because these instru-
ments almost always use an unprocessed sound and the PA
system merely amplifies the levels of the direct signal.
Electricguitars generally don’tuse standardDIs becausetheam-
plifierand loudspeaker playan importantpart in aplayer’ssound.
Typically a microphone is used to capture the amplified guitar
sound. This raises several other variables such as bleed, place-
ment and acoustics that come along with using microphones.
The Radial JDX offers an easy solution by eliminating the mi-
crophone and delivering the sound of a player’s amp directly
to the recording or PA console. By removing the variables of a
microphone the consistency of the sound from night to night is
improved. This is a boon to in-ear monitor users. When listening
through in-ear monitors subtle differences in mic placement and
roomacoustics can translateinto hugechanges in tone.TheJDX
provides great sound while eliminating bleed from other instru-
ments, like drums, from leaking into the guitar mix.
JDX Amplifier DI J48 Standard DI
Mixing Console

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Radial Engineering JDX User Guide
3
TYPICAL APPLICATIONS
Replace a Microphone with JDX.
The most basic use of the JDX is to eliminate the need to use an
open microphone to capture the sound from the guitarist’s amp.
The diagram shows the typical connection of the JDX.
Using the JDX with a Microphone
Mixingthe signalfrom theJDX witha microphoneis agreat wayto
createnew sounds.TheJDX canalso bemixed witha cleandirect
boxsignal fora cooleffect.TryrecordingtheJDXandmicrophone
to separate tracks that are panned hard left and right.
Using the JDX with the Radial Phazer
When the signal from the JDX and a microphone combine there
will inevitably be a small time delay between the signals. The
Radial Phazer can be used to time-align the JDX signal with the
microphonefor perfectphase response.TheRadial Phazersaves
you editing time because it works in real-time while recording.
Radial Phazer inserted
on JDX channel
JDX
AMPLITUDE
TIME
Microphone
Phase off-set
JDX and Microphone in
perfect time-alignment.
AMPLITUDE
TIME

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JDX User Guide
Radial Engineering
4
BLOCK DIAGRAM
To help you understand how the JDX works take a few moments
to trace the signal flow through the block diagram.
CAUTION, THE JDX IS NOT A LOAD BOX
Please read the saftey disclosure statement on the
inside cover of this manual before connecting or
operating the JDX.
FROMAMP
TO SPEAKER
ACTIVE
BANDPASS
FILTER
ACTIVE
BALANCED
DRIVER POLARITY
REVERSE
BALANCED
XLR OUTPUT
TRANSFORMER
REACTIVE LOAD
GROUND
LIFT
Parallel Amplifier Input and Speaker Thru-put
The FROM AMP input and TO SPEAKER thru-put jacks are
paralleled together and provides the means to patch the JDX
in-between the amp output and loudspeaker.
Transformer
The transformer is the front end of the JDX reactive circuit and
is used as a reactive load that responds into the various electri-
cal phenomena that dictate how a particular amplifier and loud-
speaker sound together.
This is what makes the JDX unique when compared to the “load
box” approach. A load box simply burns off the excess energy
into heat and completely ignores the amp and loudspeaker in-
teraction. By capturing the reactive effect between the amp and
loudspeaker the JDX comes closer to the original tone than any
other interface system.
The transformer also pulls double duty by electrically isolating
thesignal passing throughit, effectivelyblocking noisecaused by
groundloops.This isimportant becausetheJDXconnectsa guitar
amplifier to a recording or PA system that may be powered from
adifferentACmain circuit. Withoutthe transformer aground loop
may form that can cause buzz and hum in sound systems.

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Radial Engineering JDX User Guide
5
Ground Lift
A ground lift switch is provided to further reduce noise caused
by ground loops.
Active Bandpass Filter
The analog filter section is the back-end of the reactive circuit
and its job is to emulate the typical response curve of a speaker
cabinet. The Class-A active filter in the JDX produces superior
sound over passive filter circuits.
Active Balanced Driver
Theoutput driverin theJDX convertsthe outputto abalanced600
ohm mic-level signal for driving long cables without signal loss or
noise. This JDX output can be patched into typical microphone
snakes and be processed along with other microphone signals.
The active balanced driver uses a discrete Class-A design for
excellent headroom and low distortion.
180° Polarity Reverse
The polarity of the JDX output can be inverted with the 180°
switch. Depressing the switch will reverse the signal on pin-2
and pin-3 at the XLR output. The polarity reverse may be used
to interface older "pin-3 hot" equipment that does not follow the
AES standard for XLR pin-out, or to correct a polarity reversal
upstream in the signal chain.
Balanced XLR Output
TheJDX outputs abalanced mic-levelsignal.Themale XLRcon-
nector pin-out is wired to the AES (Audio Engineering Society)
standard with pin-1 ground, pin-2 hot and pin-3 cold.

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JDX User Guide
Radial Engineering
6
FEATURES AND FUNCTIONS
FROM AMP connection
for amplifier output, max
300 watts.
TO SPEAKER connects your amp
to the speaker through the JDX.
Connection to a loudspeaker is
mandatory. Please read the safety
disclosure statement before con-
necting the JDX.
GROUND LIFT switch
eliminates hum and buzz
caused by ground loops.
PSU JACK connection
for the included 15 volt
DC power supply.
POWERLEDlights to indi-
cate the JDX is connected
to its power supply.
XLR OUTPUT mic-level,
600 Ohms balanced XLR
output connects to your
mixing console.
POLARITY RREVERSE
for pin-2 and pin-3 at
the XLR output. Used
to correct signal polarity
problems.
BOOKEND DESIGN
creates a protective zone
for the jacks switches.
FULL BOTTOM PAD Neoprene
keeps it from sliding around and
provides isolation from electrified
amplifier frames and handles.

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Radial Engineering JDX User Guide
7
CONNECTING THE JDX
The JDX will typically be located on or near the guitar amplifier to
facilitateshort speakercables. Werecommendspeaker cablesbe
6 feet or less in length with a minimum of 16AWG two conductor
cable. Longer cables should use heavier gauges to maintain the
best power transfer. The balanced XLR connection from the JDX
tothemixing consolemay be madethrough severalhundredfeet
of balanced cable without signal loss.
Before you begin, ensure your amplifier and PA or record-
ing system are turned off. Lower all the volume controls to
minimum to avoid loud transients.
1. Connect your amplifier’s speaker output to the FROM AMP
¼” jack on the JDX.
2. Connect the SPEAKER ¼” jack on the JDX to your speaker
cabinet.
3. Connect the XLR output to a mic preamp input on your mixing
console using a standard XLR microphone cable.
4. Connect the JDX power supply and check the LED power
indicator to confirm power is present.
5. Turn on your amp and bring up the volume to a low level for
testing. Always test at low volume before cranking it up.
6. If all is well, set the amp volume to an appropriate level. Keep
in mind that the level at the balanced XLR output will follow
the amp so it’s best to set the level of the amp before setting
levels at the mixing console.

TruetotheMusic
JDX User Guide
Radial Engineering
8
FREQUENTLY ASKED QUESTIONS
Q: Can Imount the JDXon the backor inside myamp/speaker
cabinet?
A: Yes, the Radial J-Clamp allows you securely mount the JDX
to almost anything.
Q: Does the JDX provide a load for the amp to drive.
A:No.The JDXis notaload box.For safeoperationaloudspeaker
must be connected to the SPEAKER OUT jack.
Q: Can I use the JDX with a load box or power attenuator?
A: Yes. The load box takes the place of a loudspeaker and pro-
vides a load for the amp to drive.
Q: Can I leave the JDX connected to my amp when I’m not
using it?
A: Yes, as long as a loudspeaker is connected the amps output
will flow thru the JDX to your speaker even when the JDX power
supply is disconnected.
Q: Can I use the JDX with a bass amp?
A: Yes. Keep in mind the JDX has a max power input of 300
watts. Bass amps that exceed this rating can damage the JDX.
Try combiningthe signals fromthe JDXand a standarddirect box
to record bass guitar for a new sound.
Q: My combo amp doesn't have amp and speaker jacks on
the back. Can I still use the JDX.
A: Yes. Solder a 1/4" plug onto your amps speaker cable to con-
nect to the FROM AMPLIFIER jack. Then make a short jumper
cableto connect theTOSPEAKER jackto the speakerterminals.
Or contact a qualified amp tech to make these changes.
Q: Can I also use the JDX like a standard direct box.
A: No. The JDX is an amp DI exclusively.
Q: What does the speaker emulation sound like?
A:Theactive analogspeakerfilter circuitisa compromisebetween
a closed-back 4x12 and an open-back 2x12 speaker cabinet.
Q: Will the JDX sound exactly like my amp?
A: Nothing is 100% transparent. We feel the JDX comes closer
than anything else and sounds terrific.

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Radial Engineering JDX User Guide
9
JDX Specifications
Circuit type: Class-A 100% discreet
Speaker emulation Reactive load sensing with
proprietary band pass filtering
Total harmonic distortion 0.005 % @ 1KHz
Amp input 1/4", 300 watts max
Speaker thru-put 1/4", paralleled to amp input
Balanced outputs XLR 600, -60dB mic-level
XLR pin configuration AES standard: pin 1 ground
pin 2 hot (+)
pin 3 cold (-)
Power supply (included) 15VDC, 400mA current draw
Size (W x D x H) 3.25”x 5”x1.75” (83x126x45mm)
Weight 1.5 lbs. (.7 kg)
Warranty 3 Years, transferable

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RADIAL ENGINEERING
3 YEAR 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)ofthisproduct(excludingfinishandwearandtearon
componentsundernormal use)for aperiodof three(3) years from
theoriginaldateofpurchase.Intheeventthataparticularproductis
nolongeravailable,Radialreservestherighttoreplacetheproduct
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 must assume the
risk of loss or damage.Acopy 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 oras aresult ofservice or
modification by any other than an authorized Radial repair center.
THERE ARE NO EXPRESSED WARRANTIES OTHER THAN
THOSEONTHE FACEHEREOFAND DESCRIBEDABOVE. NO
WARRANTIES WHETHER EXPRESSED OR IMPLIED, INCLUD-
ING BUT NOT LIMITED TO, ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PUR-
POSESHALLEXTENDBEYONDTHERESPECTIVEWARRANTY
PERIODDESCRIBEDABOVEOFTHREEYEARS.RADIALSHALL
NOT BE RESPONSIBLE OR LIABLE FOR ANY SPECIAL, INCI-
DENTAL OR CONSEQUENTIAL DAMAGES OR LOSSARISING
FROM THE USE OF THIS PRODUCT. THIS WARRANTY GIVES
YOU SPECIFIC LEGAL RIGHTS, AND YOU MAY ALSO HAVE
OTHER RIGHTS, WHICH MAY VARY DEPENDING ON WHERE
YOU LIVEAND WHERE THE PRODUCT WAS PURCHASED.
®
Radial Engineering Ltd.
1588 Kebet Way, Port Coquitlam BC V3C 5M5
Tel: [phone] Fax: [phone]
email: [email protected]
Radial JDX user guide - Part #: R870 1200 00 - Rev1.1 - Oct. 2009
Apperances and specifications subject to change without notice.
Copyright © 2009 Radial Engineering Ltd. all rights reserved.
www.radialeng.com