From: bold@astroatc.uucp (Jeff Beck)
Newsgroups: rec.music.makers
Subject: Marshall JMP-1 review
Date: 12 Oct 92 19:29:31 GMT
Organization: Astronautics Technology Cntr, Madison, WI

Hi all,

I just bought a Marshall JMP-1 MIDI preamp, and I thought I might post a
review for all of you folks on the net, so here goes:

The Marshall JMP-1 preamp is a single-space rackmount preamp that supposedly
contains the same preamp electronics found in the Marshall 9000 series
amplifiers.  It also contains some digital control circuitry, and of course,
a MIDI interface.  The JMP-1 is mono input and stereo output.  It contains
an effects loop that is mono out to the effects, and stereo return.  The
stereo returns define the stereo output of the preamp itself.  The preamp
also has stereo speaker emulator outputs that can be connected directly to
a mixing board for recording or for live performance, although it is probably
meant more for recording.

I have only played the preamp through a Roland JC-120, going from the preamp
output directly to the JC-120 power amp input, so I cannot comment on how
this preamp would sound if it was driving a tube power amp and a 4x12 cabinet.
However, even with the Roland amp, I think this unit sounds pretty good.
The sound controls are as follows:

There are four basic sounds to choose from:

	1.  OD1 - overdrive one - early "classic" Marshall sounds - bluesy
	2.  OD2 - overdrive two - newer sounds - a more heavily distorted sound
	3.  CLN1 - clean one    - a clean channel - warm and dark
	4.  CLN2 - clean two    - a brighter, jangly sound

I may have reversed CLN1 and CLN2, but the descriptions are correct.

The preamp also has controls for bass, midrange, treble, and presence.
Each of these controls has a range of -6 to +6.  There are also two volume
controls, pregain, and postgain, (each range fromn 0 to 20) along with a
rotary knob on the front that controls the output volume to the power amp.
Note that this rotary knob DOES NOT control the volume output of the speaker
emulator.  I personally think this is a nice feature for live performance
because I can adjust my stage volume without affecting the signal level
going to the mixing board.  There is another feature called "bass shift"
which is supposed to give the sound a more "balsy" sound to it, which I
think it does well.  Basically, all it does is increase the crossover
frequency between the bass and midrange tone controls when turned on.
There is no frequency adjustment, it is either on or off.

As far as the sound, it definitely sounds like a Marshall.  The controls
provide a pretty good range of adjustments, so you can get most every
sound that you would want.  I am extremely impressed with the speaker
emulator output.  I ran the speaker emulator output into a Mackie mixer,
into a Peavey CS400 into a pair of EV speakers, each with a 15" and horn.
I thought the sound was almost as good as that coming out of the Roland amp.
One thing to note is that turning on the bass shift feature improves the
sound through the PA, but is not needed for a guitar amp.  My advice would
be to adjust the sound through the PA first, and then compensate for any
quirks in the stage sound by adjusting the stage guitar amplifier.

As far as controllability, it is pretty good.  It does have about the same
amount of control that a non-rackmount Marshall amplifier would have.
I replaced a Chandler Tube Driver with this Marshall unit, and I believe
that I miss the bias adjustment found on the Chandler.  (BTW, if anyone is
interested in buying the Chandler, send me email.  It basically is a
Marshall preamp, but it is not MIDI, and you only get one setting at a time).

I am somewhat of a MIDI novice, so I can't comment authoritatively on the
MIDI implementation, but here's what I found.  The MIDI section has
built-in MIDI mapping, both input and output.  So, I can send it a command
to change to patch X, it can map that to patch internal Y, and can map the
output patch command to still another patch Z.  I think this will be useful,
because when using the unit with a footpedal that is sending out patch '1',
the JMP-1 changes to patch '0'.  It is always behind by one patch, while my
Korg A3 in the effects loop is on the correct patch.

Summary:

I think this unit was well worth the $750.00 (including tax and (2) cables)
that I paid for it.  A different store in town is selling them for around
$925.00, and they didn't seem to think they would come down, BUT that was
only their estimated price.  I would have liked to see a control for the bias
of the tubes, rather than only having OD1 and OD2, but you don't get those
controls on a Marshall amp anyway.  One really good thing is that there
is absolutely NO delay between patch changes, unlike my Korg A3.  Fortunately,
the patch changes in the Korg shouldn't cause a problem, because the Korg
is in the JMP-1's effects loop, not in series with it.  Programmability
is extremely simple.  All you have to do is push the button of the parameter
you want to edit, and then turn the adjustment knob.  Then just hit the
"store" button twice.  If you want to store to another patch, just hit the
"store" button once, twirl the knob to the right patch, and then hit the
"store" button again.  Oh, BTW, it does have patch protection capabilities.

Considering most places are asking over $1000.00 for the Mesa Boogie Triaxis
preamp, I thought the Marshall was a good deal.  If you are looking for a
Marshall sound, but like the idea of having a MIDI controllable preamp, like
I really do, this might be the unit for you.

Happy jammin' all!


-- 
Jason Bold - Madison, WI:                 +===+   o    +===+  Yeah, but two
bold%astroatc.uucp@spool.cs.wisc.edu      |   |  /|\   |   |  amps can go
                                          |~~~|  Co-"= |~~~|  up to 22.
"With this amazing new "knife"...         |___|  / \   |___|  So there!