Marshall Amplification JVM 2 - Manual (Page 6)

8
E
N
G
L
I
S
H
E
N
G
L
I
S
H
Rear Panel Operation
SERIAL / PARALLEL FX LOOP (12)
The JVM is equipped with a series / parallel FX
loop. Connect your external FX equipment input
to the JVM SEND jack, and the FX output to the
JVM RETURN jack. As described previously,
this effects loop can be bypassed from the front
panel and the amount of effect can be dialed in
with the MIX control.
The +4dBu/-10dBV switch allows you to
configure the loop for its use with either
professional equipment (+4dBu setting) or with
guitar level effects like effects pedals (-10dBV
setting).
When MIX is set to WET all the signal goes
through the external loop, adding more direct
(unprocessed) signal as you turn it towards
DRY. This allows you to mix any amount of the
external effect without loosing or degrading the
direct signal quality.
When mixing the WET and DRY signals the
external effects processor’s output should be
configured to remove the direct (unprocessed)
signal or unpleasant phasing effects may occur
when mixing it again in the amplifier. If the
amplifier sounds thin after connecting an
external effect check that no direct signal is
being returned from the processor’s output.
Note that if the FX loop is ON and the MIX
control is set to WET without an external
processor connected, the amplifier will be
muted.
POWER AMP INSERT / SERIAL LOOP (13)
This is a passive loop connected right before the
master controls. It is a line level loop so it is
recommended to only use high headroom
devices to avoid signal degradation. Plugging
only into the return jack allows the use of the
JVM’s power section overriding the preamp.
Master controls and the emulated line out are
located after the serial loop so it is still possible
to take advantage of those features when using
an external preamplifier. The loop can be taken
off the circuit by pressing the BYPASS switch,
but as opposed to the Series / Parallel loop this
switch cannot be programmed.
EMULATED LINE OUT (14)
The pre master volume signal, processed
through a 4x12 speaker cabinet emulator and
electronically balanced is made available at this
connector.
FOOTSWITCH (15)
Connect the supplied footswitch using any
standard 1/4" jack mono lead. Using any other
type of footswitch rather than the supplied will
have no effect and will be ignored by the
amplifier.
MIDI In / Through (16)
Connect any external MIDI equipment to the
MIDI In DIN socket. A copy of the signal in this
connector will be available on the MIDI thru
socket to allow daisy chaining of MIDI
equipment. Note that the JVM only accepts
incoming data and it is not able to send any
MIDI commands.
SPEAKER Outputs (11)
There are 5 speaker outputs available on the
rear panel. They are labelled according to the
intended impedances:
16 Ohm: connect any 16 Ohms guitar cabinet to
this jack.
8 Ohm: connect a single 8 Ohms guitar cabinet
or two 16 Ohms guitar cabinets.
4 Ohm: connect a single 4 Ohms guitar cabinet
or two 8 Ohms guitar cabinets.
WARNING: Although the JVM amplifier has 5
speaker outputs, never attempt to connect more
speakers than rated. The safe combinations are
1x16 Ohm, 1x8 Ohm, 1x4 Ohm, 2x16 Ohm or
2x8 Ohm. Any other speaker configuration may
stress the power amplifier section and in
extreme cases may lead to valve and/or output
transformer failure.
HINTS & TIPS
Factory Reset
This will erase all the MIDI presets and set MIDI
reception channel to #1. Please note that once
the memory is erased it cannot be recovered.
Switch the amplifier off (power switch off, not
standby switch).
Press and hold CLEAN/CRUNCH CHANNEL
switch.
Switch the amplifier on (power switch on, not
standby switch).
The 2 channel LEDs will glow red.
Release the switch.
To confirm the factory reset press OVERDRIVE
MODE switch.
If you want to abort, press any other switch.
Footswitch Reset:
It is possible to reset the footswitch to the
factory default status. This is achieved as
follows:
Unplug the footswitch at any of the cable sides.
Press and hold the switch #4 (right switch).
Plug in the footswitch cord.
Release the switch and the FX led will start
blinking.
If you want to erase the footswitch memory
press the switch #3. To keep the memory press
either the #1 or #2 switch. Please note that once
the memory is erased it cannot be recovered.
Release the switch and the footswitch will
synchronise with the amplifier.
The factory default is as follows:
FSW #1: Clean/Crunch Mode
FSW #2: Overdrive Mode
FSW #3: Master
FSW #4: Reverb
Hints
Hint 1: It is possible to use different modes in
the same channel with different volumes to
avoid imbalance between mode levels. To do
this simply create 2 presets in the footswitch
assigning MASTER 1 or MASTER 2 to any of
the modes.
If you do not connect any effect to the
SERIAL / PARALLEL FX LOOP the MIX control
can be used to act like an extra volume control
in any of the channels.
Hint 2: To have a tuner output muting the
amplifier, connect the tuner to the FX send and
select the Clean channel. Turn the MIX control
to WET and switch the FX loop on. Store this
preset as described before and label it for
example as ‘tuner’. Obviously in this
configuration it is not possible to connect any
other effect to the loop.
Hint 3: To use a different preamplifier and
combine it with the JVM channels, connect the
external preamplifier output to the parallel loop
return and turn the MIX to WET. Connect the
external preamp input with a splitter to the
amplifiers input (it might be necessary to use an
active splitter to keep a high impedance and/or
an isolated one to avoid ground loops).
Switching the effects loop ON and OFF will
alternate between the external preamp and the
JVM preamp.
As the JVM reverb circuitry is connected after
the parallel loop it is also possible to create a
preset to add reverb to the external preamp. To
do this, simply switch the reverb ON and create
a preset in any channel with the reverb ON and
FX ON and assign it to the footswitch. That
would be external preamp + reverb.
You can also go further and assign a different
Master level to both external and internal
preamplifiers in the same way as you assigned
reverb.
Hint 4: Notes about using 2 heads
simultaneously. The suggested procedure is
connect the ‘master’ head PREAMP OUT to the
‘slave’ head POWER AMP IN and switch the
POWER AMP INSERT to ACTIVE in the ‘slave’
amplifier.
In order to track the master volume settings in
both heads (as the master volume circuitry is
wired after the loop) it is suggested to use MIDI
control with both amplifiers programmed in the
same way. Connect the MIDI IN of one of the
amplifiers to the MIDI THROUGH of the other
and the pedalboard or MIDI equipment to the
remaining MIDI IN.
9