Radial Engineering JDV MK3 Owner's Manual - page 6
-30dB Parallel Speaker Pad
Sometimes, it may be desirable to tap the signal from the speaker cabinet to
get the sound of the instrument after the amplifier (post effect). The JDV is
equipped to do so by inserting a -30dB input pad into the circuit..
Using a speaker-tapped signal can be fun however it should be noted that
the signal from the guitar amp is designed to drive 12” and 15” instrument
speakers which mask high frequencies (no tweeters). Because of the extreme
fidelity of the JDV, it is possible that residual noise content from the amp
and the speaker 'hang-over' effect will be audible. Try using the JDV’s high-
frequency roll-off (
HI-CUT
filter) or adjust EQ to suit.
To activate the -30dB pad, depress the recessed ‘PAD-30dB’ switch using a
pen or small screwdriver, then connect the signal from the speaker cabinet or
the amplifier’s second speaker output using a regular speaker cable. Failure
to connect a speaker or load box in parallel to the JDV may cause
severe damage to the JDV and/or the amplifier which would not be
covered under warranty.
Balanced Output Panel
BALANCED OUTPUT
600 Ohm mic level XLR-M output connector wired to the AES (pin -2 hot)
standard connects to mixer or mic pre-amp input.
POLARITY 180º
Reverse
Switches XLR pin-2 (normally hot) with pin-3, useful when interfacing with
older equipment wired with pin-3 hot. Also a useful creative tool in the
studio. When mic'ing an amplifier and recording a direct signal, reversing
the polarity can lead to some very interesting and fun effects - try it!
GROUND Lift
Switch lifts the ground path from the JDV to the mixer. When depressed,
the JDV ground is solely connected to the guitar amp and/or aux outputs.
-15dB Pad
As the JDV is a unity-gain device with an exceptionally high internal rail
voltage, a powerful input signal will produce a powerful output level. As
the JDV’s output can often exceed the input capacity of many mixing
consoles, a -15dB output pad is provided to ensure it does not overload the
input.
BALANCED OUTPUT provides
to mixing desk
600 Ohm signal
POLARITY180
everse
flips pin-2 and pin-3
º R
GROUND switch lifts ground at
the XLR from JDV to mixer
PAD -15dB Output pad reduces
level to prevent mixer overload
POWER 30V-DC
connection jack for
the JDV’s special
power supply
Made in Canada
by fanatics
IMPORTANT: The Radial JDV is NOT a load box and can not handle the
power coming out of an amplifier head on its own. A speaker or properly
matched load box must be connected to the amp before connecting the JDV.
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JDV Mk3 Owner’s Manual
In this set-up, if ground hum is encountered, lift the ground to the mixer with the
ground lift switch. The JDV will now derive its safety ground from the amp. For
safety, make sure you only use amplifiers with proper 3-pin U-grounds!
Reversing polarity can have dramatic effects on stage if the bass is also in the
stage monitors. Polarity reverse only affects the XLR output. Try in-phase first,
then reversing polarity. It may sound better or widen the players sweet spot.
Activating the
LO-CUT
(High-Pass) filter can help reduce low-end rumble and
help clean up the mud which often is difficult to manage in large PA systems.
Acoustic guitar set-up
One of the most important features of the JDV is its ability to handle extreme
transients without overloading. Guitar players often drive the pre-amps on their
acoustic guitars above the nominal 0dB level and then push it further by
increasing treble or bass. What few realize is that a mere 3dB increase is actually
increasing the headroom demand by twice the power at that frequency. The
JDV's 30Volt internal rail system is able to handle these demands without a
whimper making it a great choice for acoustic guitars on live stages.
Use the bass guitar set-up described previously. Use of the
LO-CUT
(Hi-Pass) is
recommended to reduce rumble. Test for best polarity setting as above.
Keyboards
The JDV is perfectly fine for use with electronic keyboards. In fact, the JDV's
sonic performance is superior to what most of these are able to generate. Where
the JDV will shine will be on very dynamic sounds such as grand-piano
samplers where the frequency response is very wide, harmonics are rich and
amplitude variations extreme. Use the same setup as described in Set-up 1 or 2,
depending on whether or not an instrument amp is used.
Driving more than one amp
One of the more exciting aspects of the JDV Mk3 is its ability to drive
several amplifiers or devices at the same time. This expanded functionality
provides freedom to build new sounds that spur the creative process.
The Radial JDV makes this possible and easy by providing two active outputs
designated Aux-A and Aux-B. These are transformerless Class-A feed-forward
outputs that have been designed to reproduce the instrument without adding
artifact. At this stage, it is important to understand how Drag™ control works
and when it would be appropriate to use it (see ‘Drag Control’ on page 5).
The most common application would be driving a stereo amplifier rig.
Important Note: 3-pin U-ground plugs did not exist in the ‘50’s and early ‘60’s
and, as great as they sound, the amplifiers of those days were never designed to
be combined together as we often do now. You may find using un-grounded
equipment a problem because of noise from hum and buzz. For more advanced
or difficult set-ups, check out the Radial JD7 Injector. It is equipped with
isolation transformers as a means to solve some of these electrical challenges.
Connect the JDV's two auxiliary outputs to the stereo rig or two amps. As these
outputs are not transformer isolated, both amps should have grounded A/C cords
in electrical phase and be connected to the same power bar as the JDV. This will
reduce possibility of electrical shocks and noise caused by ground loops. For
safety, please observe correct grounding, check for shock potential with a
voltmeter and/or consult with a trained technician.
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JDV Mk3 Owner’s Manual
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