Radial Engineering JDV-Pre 500 User manual

www.radialeng.com
TruetotheMusic
®
User Guide
JDV-Pre™ 500
500 Series Module
Instrument Preamp and DI
Radial Engineering Ltd.
1588 Kebet Way, Port Coquitlam, British Columbia, Canada, V3C 5M5
Tel: [phone] • Fax: [phone] • Email: [email protected]

Radial®JDV-Pre™500 UserGuide
Table of Contents Page
Overview ........................................................................ 1
Feature Set .................................................................... 2
Connections ................................................................... 3
Using with magnetic pickups.......................................... 4
Using with active pickups ............................................... 5
Using with piezo pickups................................................ 5
Using with a microphone................................................ 6
Using the polarity and high-pass filter ............................ 7
Using the JDV-Pre in the studio ..................................... 8
Specifications ................................................................. 9
Warranty............................................................Back cover
Congratulations… you’ve done it! You have invested
in what we believe is one of the most musical sounding
instrument preamps ever made. The JDV-Pre went
through many design revisions before we finally decided to
release it to market. Why so long? Each time we plugged
it in, we found ourselves asking for extra bits that could
make the JDV that much better.
What this means is that behind what appears to be a simple
control panel are lots of extra cool features that have been
carefully incorporated into the design. And the only way to
take full advantage of them is to read this manual. Once
you have done so, there may be questions that have not
been answered. For these, we kindly ask that you visit the
JDV-Pre FAQ page. This is where we answer questions
from users, like yourself, and post the latest information
that can be helpful when using the JDV-Pre live on-stage
or in the studio. If you cannot find what you are looking for
feel free to send us an email at [email protected] and
we will do our very best to get back to you in short order.
Now close your eyes and listen. You are about to hear your
vintage Fender Jazz bass for the very first time.

TruetotheMusic ®
Radial Engineering Ltd. JDV-Pre™500 Module
1
JDV-PRE OVERVIEW
The JDV-Pre is a preamp dedicated to instruments. In other words, when we designed the
JDV-Pre, our goal was to deliver a device that would be equally effective at amplifying a
guitar, violin, mandolin or a contra-bass. So we started by optimizing the front end for the
most natural tone and widest possible bandwidth. We then added a variable low-cut filter that
would enable the engineer to ‘size’ the preamp so that it would translate the instrument’s true
character while eliminating problem resonance.
As the design advanced, it became abundantly clear that instruments are amplified in many
different ways depending on the transducer. In our audio world, a transducer captures
vibrations and converts them into an electrical impulse. This can be in the form of a magnetic
pickup that captures the vibrations of a string, a piezo element that captures the vibrations
at the bridge or even a microphone capturing the vibrations of sound as it travels through
the air.
Passive Piezo Element
Passive Magnetic Pickups
Condenser Instrument Mic
Multi-track Recorder
PA System
Monitor
Each transducer reacts differently to an electrical circuit. For instance a magnetic pickup
sounds warmest when the impedance is set around the 200k-Ohm mark. A piezo really
works best when the impedance is 4meg-ohms or higher. And with condenser and dynamic
microphones, one has to consider 48V phantom power, the input impedance and of course
how much gain is needed. The more gain, the more opportunity for noise. The more noise
filtering you employ, the more you can affect the instrument’s natural harmonics. Great care
is needed all the way along.
Once you have captured the source, the next goal is to send it along to one or more
destinations. For instance when recording, the JDV-Pre produces a +4dB balanced line
output to feed a digital audio workstation and a thru-put for a musician’s amplifier.
Let’s get started!

Radial Engineering Ltd. JDV-Pre™500 Module
TruetotheMusic
®
2
10
9
8
Rear Panel
7
1
4
3
2
6
5
FEATURE SET
1. GAIN: AccuState™ level control simultaneously
adjusts the gain and input sensitivity to ensure
lowest noise at all gain settings.
2. INVERT: Reverses the polarity on the JDV-Pre
output to reduce feedback on stage or to phase
align two signals for improved stereo imaging.
3. HIGH PASS FILTER: Reduces low frequency
resonance, helps clean up the sound of acoustic
instruments and eliminates run-away feedback.
4. DRAG: Shifts the input impedance from a fixed
3.9meg-Ohms for piezo pickups to a variable load
for magnetic pickups.
5. LED INDICATORS: LED indicators display status
for signal present and peak-overload
6. +48V INDICATOR: LED illuminates when +48V
phantom power is turned on via a small switch near
the card edge connector.
7. INPUT: Used to connect high impedance
instruments to the JDV-Pre. This front switching
jack has priority over the balanced XLR mic input
on the rear panel of a 500 series rack.
8. AUX OUT: Buffered output used to feed a guitar
amplifier. Transformer isolated to eliminate buzz
and hum caused by ground loops.
9. OMNIPORT: The Omniport is assigned as a
balanced line-level output with a fixed gain.
Available when used with a Radial Workhorse™
rack.
10. BALANCED XLR INPUT (on-rear panel of 500
series rack): Microphone input with available
phantom power. Transformer coupled for optimal
signal flow. This input is disabled when a plug is
inserted into the front panel ¼” input.
11. PHANTOM POWER SWITCH: Activates the +48V
phantom power at the rear panel XLR microphone
input. When engaged the front panel LED indicator
will illuminate.
12. FIXED/VARIABLE SWITCH: Sets the XLR output to
a fixed signal level like the Omniport or a variable
level controled by the AccuState gain control.
11
12

TruetotheMusic ®
Radial Engineering Ltd. JDV-Pre™500 Module
3
Installing the module
Before making any connections, start by turning off your audio system and turning all volume levels
down. This helps protect equipment from turn-on transients that could damage loudspeakers and
other sensitive equipment. We recommend using a power bar with an on-off switch as this makes
it easy to turn on and off the 500 series rack, monitors and so on at the same time. There are two
function switches on the rear of the module. The left switch controls how the main XLR output
works. The right switch controls the built-in +48V phantom power. The switches are factory preset
with the main XLR output set to VARIABLE and the phantom power turned OFF. Check that the
switches are in the factory positions before mounting the JDV-Pre in your 500 power rack.
VARIABLE OFF
Carefully insert the JDV-Pre module into your 500 series rack. Slide the module in straight to
avoid putting stress on the card edge connector and press firmly. Use the supplied screws to
secure the module in your 500 series rack and ensure it does not accidentally dislodge. Do
not overtighten as this may damage the screw threads.
Making Connections
The JDV-Pre has two input connections; the front panel ¼” instrument input and the rear
XLR mic input as found on your 500 series power rack. The front panel input is typically
used for high impedance instruments while the rear XLR is optimized for a low impedance
microphones. The JDV-Pre has three outputs; the front panel aux out is used as a thru-put
to the guitar or bass amplifier when recording. The XLR output on your power rack is the
main output. If you are using the JDV-Pre with a Radial Workhorse power rack the ¼” TRS
Omniport is available. This provides a second balanced line-level output that can be used for
monitoring or to feed additional audio systems like a recorder.
Mic
INPUT
OMNIPORT
FEED
LINK
1
OFF
OFF
CARD SLOT 1
OUTPUT
OUTPUT INPUT
-
+
G
-
+
G
-
+
G
1
234
5
Omniport
Out
Recorder
Mixer
Amp
Instrument
JDV-Pre Workhorse I/O
The JDV-Pre is extremely easy to use. You plug in, turn up the input gain, adjust the high-
pass filter and play.

Radial Engineering Ltd. JDV-Pre™500 Module
TruetotheMusic
®
4
Using magnetic pickups
Magnetic pickups such as those found on a typical Fender bass are often recorded direct in
the comfort of the control room. The JDV-Pre’s front mounted ¼” input connector makes this
easy. All you do is plug in, turn up the gain and you are set to go.
INPUT
OMNIPORT
FEED
LINK
1
OFF
OFF
CARD SLOT 1
OUTPUT
OUTPUT INPUT
-
+
G
-
+
G
-
+
G
1
234
5
Line or Mic
Level Out Recorder
JDV-Pre Workhorse I/O
Inst.
Level
Drag™ control brings the natural tone of the instrument to a whole new level by allowing
you to replicate the load on the pickup as if connected to an amplifier. This not only makes
the instrument sound more natural, it changes the response of the instrument so that it feels
right. To activate, you simply depress the Drag control on switch. This changes the input
impedance from 3.9m Ohms (optimized for piezo pickups) to a variable load that ranges from
22k Ohms to 500k Ohms.
Begin by setting the Drag Control to 12 o’clock. Then turn it clockwise.
The sound will become brighter with greater clarity. As you turn it counter-
clockwise the tone will warm up and sound smoother. Setting the Drag
is particularly important if you intend to Reamp the signal down the way
(read more about Reamping later in this manual). By adjusting the load
with the Drag control, guitars, pedals and amps will sound more realistic.
The JDV-pre is equipped with a ¼” Aux output on the front panel. This is used to send the
instrument signal to a guitar amp. This enables the guitarist to hear himself play through a
distorted amp while you capture the instrument’s clean sound via the XLR output. The ¼” Aux
out is transformer isolated to help eliminate hum and buzz caused by ground loops which are
a common problem when interfacing guitar amps with pro-audio equipment.
INPUT
OMNIPORT
FEED
LINK
1
OFF
OFF
CARD SLOT 1
OUTPUT
OUTPUT INPUT
-
+
G
-
+
G
-
+
G
1
234
5
Clean Track
Recorder
JDV-PreAmp Workhorse I/O
Inst.
Level

TruetotheMusic ®
Radial Engineering Ltd. JDV-Pre™500 Module
5
Using an active bass or guitar
Active pickups have been around for years. They have become more popular since the
advent of 5 and 6 string basses. And although these can sound absolutely amazing, more
often than not, these instruments are so loud they overload the input on most devices. This
is because traditional passive basses generally produce around 1 volt while their active
counterparts (powered with 9 volt batteries) can deliver well over 6 volts when played hard!
Unless your preamp or DI has enough headroom, you will get distortion. The JDV-Pre
addresses the problem by providing plenty of clean headroom. Connection is the same as
using a passive bass. However, Drag control will have little or no effect on active pickups as
the signal is already buffered by the bass’s internal electronics.
Using piezo pickups
Musicians usually complain that piezo equipped instruments
sound squawky and harsh. This is not so much the fault of
the piezo element as it is the built-in preamp that normally
accompanies it. Piezo pickups sound best when they ‘see’ a
very high input impedance. But when you increase the input
impedance, you also elevate susceptibility to background
noise and hiss. Therefore most manufacturers compromise
by using a 1meg-ohm input.
But few realize that if you couple the output of a piezo transducer directly to a really good high-
impedance preamp, you can produce sounds that are as good as a condenser microphone.
The JDV-Pre has been carefully crafted with a very high input impedance and ultra low noise
circuitry to get the best possible bandwidth and transient response from piezo elements.
By disengaging the Drag Control, the JDV-Pre’s input impedance elevates to 3.9 meg-ohms,
or about four times higher than the typical input impedance found at the input of most guitar
and bass amplifiers. Careful attention is paid to reducing noise while the class-A feed-forward
circuit assures the most natural tone. For best results, try to bypass the internal preamp in
your instrument and connect the piezo directly to the JDV-Pre’s ¼” input on the front panel.
You will immediately notice a much warmer, natural sounding tone.
Piezo element wired
directly to output jack.
Piezo element wired to
battery powered preamp.
This is not only effective on acoustic guitars, but equally so on difficult to amplify instruments
such as violin, mandolin, banjo, and contrabass. In the studio and live on-stage, piezo
pickups offer consistent results as opposed to microphones where placement can vary the
sound from session to session. Those that simply want to use their guitar’s built-in preamp
with the JDV-Pre will benefit from the JDV-Pre’s extra headroom and lower distortion.

Radial Engineering Ltd. JDV-Pre™500 Module
TruetotheMusic
®
6
Using a microphone
There is no denying that capturing the sound of the instrument with
a high quality condenser microphone is just about as good as it
gets. The real magic lies, not merely with the choice of mic, but the
marriage with the preamp you use. The JDV-Pre’s zero-feedback
front end Class-A circuit sounds nothing short of remarkable. In fact
it sounds so good don’t be surprised if you end up using the JDV-
Pre as your go-to mic preamp for vocal tracks too! It sounds warm,
natural and will captivate your senses as you listen to it.
What truly makes the mic input a marvel is the addition of an old school Hammond broadcast
transformer. Transformers naturally compress the signal to create a sonic effect that folks refer
to as “vintage”. When used on acoustic instruments that are typified with fast transient peaks
such as a banjo, acoustic guitar or mandolin, the transformer gently smooths out the tone.
The connection for your instrument microphone is made using the rear panel XLR input on
your 500 series rack or Workhorse. The JDV-Pre is suited for both dynamic and condenser
microphones. To activate the +48V phantom power, you merely set the phantom switch
adjacent to the card edge connector to ON before inserting the JDV-Pre into your rack. The
+48V LED on the front panel will illuminate when phantom power is active.
INPUT
OMNIPORT
FEED
LINK
1
OFF
OFF
CARD SLOT 1
OUTPUT
OUTPUT INPUT
-
+
G
-
+
G
-
+
G
1
234
5
Line or Mic
Level Out
Mic Level In
Recorder
Instrument
JDV-Pre 500 Rack I/O
Use the gain control on the front panel to set the level you are sending to the PA or recording
system. The high-pass filter can be used to roll off low frequencies below the range of your
instrument or turned off by rotating the control completely counter-clockwise. Drag control
should be turned off when using microphones. Note that if the Drag is turned on, it will affect
the load on the microphone. For fun, try increasing or decreasing the load as you test various
microphones. You may find that the effect can be very pleasing on some instruments.
Normally it would not be possible to connect an
amp with this setup because the mic signal is
to weak to drive an amp. However, an internal
switch can be set to route the mic preamp
output to the ¼” AUX jack and control the level
using the front panel gain knob. You will need
to remove the circuit board cover to access the
switch labeled VARIABLE/UNITY. VARIABLE UNITY
Switch
Location

TruetotheMusic ®
Radial Engineering Ltd. JDV-Pre™500 Module
7
Using the 180º invert switch
This switch reverses the electrical polarity of the signal by 180º, essentially reversing the
phase. The most common application for this function when recording is combining signals
from two mics. Sometimes, flipping the polarity of one mic can bring certain frequencies in
phase with the other mic resulting in better tone.
Another less known application has to do with using the 180º invert switch to eliminate
resonant feedback. This is primarily applied in live performance environments where the
sound from the PA system may be reinforced by sound from your stage amp. This can create
hot spots on stage were certain low frequencies combine in-phase and are amplified causing
resonant feedback.
+=
PA - 0° AMP HOT SPOT
+=
PA - 180° AMP NULL
In-phase frequencies from the floor monitor (A) and the
stage amp (B) combine and create a feedback hot spot.
Inverting the phase of the floor monitor (A) in relation to
the stage amp (B) turns the feedback hot spot into a null.
By inverting the phase, you basically move the hot spot out of the way. On the JDV-Pre this
can be done by pressing the invert switch on the front panel. Try both settings and use the
one that yields the best gain before feedback.
Using the high-pass filter
The JDV-Pre is equipped with a high-pass (low cut) filter that is designed to reduce resonance
and excessive low frequency build up from instruments. In fact, it is always on. You just can’t
hear it. This is because it begins to take effect at 5Hz which of course is well below the human
hearing threshold. As you turn it up (clockwise) it slowly rises to gently remove unwanted
low frequencies up to 800Hz. Mid-range and high frequencies above 1kHz are not affected.
Frequency response of high pass filter at various settings
Using the high-pass filter with acoustic instruments will change your world for the better.
Acoustic instruments are resonating devices with all kinds of harmonics emanating from
the body, top, sound hole and neck. When recording, these resonances many not even be
immediately audible but depending on the playback system, they can turn what could be a
wonderful mix into a low frequency mud-fest. The ‘Nashville Trick’ is eliminating the problem
before it hits the recording system. All you do is dial in the high-pass filter until the bottom end
cleans up. Once you have found what you think is the cut-off frequency, take the time to play
a little longer so that you get use to the effect, and then add some bass back in by dialling
backwards. You will be amazed at how well this can work! Not just on acoustics, but also on
voice, bass guitar and just about any other musical source.

Radial Engineering Ltd. JDV-Pre™500 Module
TruetotheMusic
®
8
Using The JDV-Pre in the studio
Most of the applications detailed in this user guide apply to using the JDV-Pre in the studio
and on a live stage. But for those that are new at recording, we felt it would be good to
discuss a standard recording setup. Generally speaking, if you are recording an acoustic
instrument, the instrument is connected to the JDV-Pre and the output is sent directly to the
recording system. Playback for monitoring is normally done via headphones.
Recorder
Mixer
JDV-Pre Workhorse I/O
Headphones
INPUT
OMNIPORT
FEED
LINK
1
OFF
OFF
CARD SLOT 1
OUTPUT
OUTPUT INPUT
-
+
G
-
+
G
-
+
G
1
234
5
When recording electric instruments like a guitar, the process tends to be a little different as
the guitar signal will have to feed the effects pedals and amp before it is mic’d. Today, most
top studio engineers will record a ‘dry’ track using the JDV-Pre at the same time as they
record the mic’d guitar. This enables them to Reamp the track later to better fit the final mix.
Recorder
Mixer
Headphones
JDV-Pre Workhorse I/O
Amp Mic
Dry
Track
EFX Pedals
INPUT
OMNIPORT
FEED
LINK
1
OFF
OFF
CARD SLOT 1
OUTPUT
OUTPUT INPUT
-
+
G
-
+
G
-
+
G
1
234
5
Reamping in the studio
Once you have recorded a dry track, send the output to a Reamper like the Radial X-Amp
for 500 series racks. From the X-Amp, you can then drive the signal through various pedals
and amplifiers and move the mics around the room to capture the ultimate tone. Best of all,
Reamping lets you do the work without the artist having to perform.
Amp & Mic
Radial X-AMP 500 Module
Recorder EFX Pedals
Reamp Track
Dry Track

TruetotheMusic ®
Radial Engineering Ltd. JDV-Pre™500 Module
BLOCK DIAGRAM*
JDV-PRE 500 MODULE SPECIFICATIONS*
* Subject to change without notice.
9
CONNECTOR WIRING
GROUND
HOT (+)
COLD (-)
GROUND
TRS ¼” Phone Connector
HOT (+)
TS ¼” Phone Connector
12
3
HOT (+)
COLD (-)
XLR Connector
GROUND
Circuit type:....................................................................................................100% discrete, class-A input
Frequency response:............................................................................................. 20Hz ~ 20KHz +0/-4dB
Dynamic range: ................................................................................................................................>93dB
Equivalent input noise: ................................................................................................................... -90dBu
Maximum gain: .................................................................................................................................+46dB
Intermodulation distortion: .....................................................................................................<1% @ +4dB
THD + Noise:....................................................................................................................<0.05% @ +4dB
Input impedance (1/4” input):...................................................................................... 3.9 megΩ(Drag off)
Input impedance (1/4” input) with Drag™:..............................................................................22k ~ 500kΩ
Input impedance (XLR Input):...............................................................................................................7kΩ
Input impedance (XLR Input) with Drag™:............................................................................. 450 ~ 2.7kΩ
High pass filter:................................................................................................. Variable from 5Hz to 2kHz
Omniport:............................................................................................ Balanced output, +20dB fixed gain
Power requirement: ...........................................................................................................................80mA
Phantom power: ........................................................................................................................48V, 10mA
Weight: .................................................................................................................................1.5lbs (0.7Kg)
Size:..............................................................................................................................9 x 6.5 x 2 (inches)
Conditions:................................................................For use in dry locations only between 5°C and 40°C
Warranty: ................................................................................................................... 3 Years, transferable
MIX
BUS
XLR
INPUT
48V
PHANTOM
POWER
DRAG
CONTROL™
FET INPUT
BUFFER
FIXED/
VARIABLE
FRONT PANEL
AUX OUT
FRONT PANEL
AUX OUT
UNITY GAIN
FRONT PANEL
AUX OUT
VARIABLE
GAIN
HIGH PASS
FILTER
ACCUSTATE
VARIABLE GAIN
STAGE
XLR
OUTPUT
MIX BUSS
DRIVER
OMNIPORT
LINE LEVEL
BAL OUTPUT
Peak
LED
FRONT PANEL
INSTRUMENT INPUT
Signal
LED
180°
POLARITY
REVERSE
12
3
1
2
3
+20dB
GAIN

THREE YEAR TRANSFERABLE LIMITED WARRANTY
RADIALENGINEERINGLTD.(“Radial”) warrants this product tobefreefrom defects in material and
workmanshipandwillremedyanysuchdefectsfreeofchargeaccordingtothetermsofthiswarranty.
Radialwillrepairorreplace(atitsoption)anydefectivecomponent(s)ofthisproduct(excludingfinish
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. In the unlikely event that
a defect is uncovered, please call 604-942-1001 or email [email protected] to obtain a RA
number(ReturnAuthorizationnumber)beforethe3yearwarrantyperiodexpires.Theproductmustbe
returnedprepaid intheoriginalshippingcontainer(orequivalent)toRadialortoanauthorizedRadial
repaircentreandyoumustassumetheriskofloss or damage.Acopy of the original invoiceshowing
dateof purchase and the dealer name must accompany any request for work to be performed under
thislimitedandtransferable warranty.Thiswarrantyshall not apply if theproducthasbeen damaged
due to abuse, misuse, misapplication, accident or as a result of service or modification by any other
than an authorized Radial repair centre.
THERE ARE NO EXPRESSED WARRANTIES OTHER THAN THOSE ON THE FACE HEREOF
ANDDESCRIBEDABOVE.NOWARRANTIESWHETHEREXPRESSEDORIMPLIED,INCLUDING
BUT NOTLIMITED 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
YOUMAYALSO HAVEOTHER RIGHTS, WHICHMAYVARYDEPENDING ONWHEREYOU LIVE
AND WHERE THE PRODUCTWAS PURCHASED.
Radial®JDV-Pre™500 Module User Guide - Part #: R870 1254 00
API, Lunchbox, Protools and Neve are registered trademarks of their respective owners.
Reamp, Reamper, Reamping and Workhorse are trademarks of Radial Engineering Ltd.
Copyright 2014 Radial Engineering Ltd.All rights reserved.
Specifications and appearances subject to change without notice.
!This product is intended for professional use only.
The user should be familiar and experienced with
the 500 series rack and module format
To meet the requirements of California Proposition 65, it is our responsibility to inform you of the following:
WARNING: This product contains chemicals known to the State of California to cause
cancer, birth defects or other reproductive harm.
Please take proper care when handling and consult local government regulations before discarding.
®
www.radialeng.com
Radial Engineering Ltd.
1588 Kebet Way, Port Coquitlam BC V3C 5M5
tel: [phone] • fax: [phone]
[email protected] • www.radialeng.com
www.radialeng.com