Marshall 9000 Series MGP9004 Guitar Preamp

Old Friend Number 15 - Marshall MGP9004 Guitar Preamp has left home.
This device is simplicity itself. A very compact 1U rack-mounting device intended for use in recording studios in lieu of an actual Marshall guitar amplifier.
This example is in good cosmetic condition, although all its front panel pots are very rustly, and need to be cleaned or replaced. In fact, rustling can also be due to leaky electrolytic signal-coupling capacitors, meaning that they may also need replacement. Life is much too short for me to fix that sort of problem!
The Lead channel very quickly gets to heavy distortion as the Gain pot is turned up.
Of course, it's nice to think that this allows a genuine Marshall sound to be put down on a recording without upsetting the neighbours. However, the aim for current guitar processors (20 years on from when this was produced) is to simulate the whole guitar amplifier and its speaker cabinet, while throwing in a range of digital effects for good measure - and all for very little money.
And in practice, the magical effect of real, loud sound waves causing a guitar's body and strings to resonate can't be readily simulated: even if a reasonable facsimile can be produced, there still isn't the visceral sensation of a guitar 'coming alive' in the player's hands when played loud.
This unit made sense to me when I bought it second-hand in 1993 (even though I have seldom used it), but nowadays, players would buy a comprehensive guitar FX unit, and studios would either bite the bullet and record a real guitar cabinet, or use one of the many guitar FX plugins available for their digital audio workstation of choice.
To me, 20 years doesn't seem vary long, but for music technology, it's several lifetimes!

[@kellyjackson7889]

How about tuning the guitar for the "sake of amusement?"

[@FarewellOldFriends]

Kelly Jackson Ha Ha!

[@wodenoftheangles3339]

+Kelly Jackson - best comment I read in ages. lol

[@mnbluestube]

clean sound at: 4:00 distortion sound: 5:31

[@delano1901]

Aeee man, THX.

[@guzzis3]

Thank you very much for this. I am looking for one to pair with my 8008 as a practice amp, into a Kustom 4x12 which has cheap but acceptable celestions. I know that's a weird practice rig but combos and little speakers annoy me. Everyone else who demos the 9004 focuses on the chainsaw which doesn't interest me.

[@greatvanzini]

These seem to be quite inexpensive these days. Looking for something like this as I am putting together my 1st ever rack mount for the fun of it.

[@greatvanzini]

+greatvanzinni Oh forgot my point,,,,,, Thanks!

[@JRP3music]

A Red Box Hughes and Kettner would have been useful for this demo. It is a speaker sim that would sound great with this preamp. The Red Box works better with a cab, but you can run it in line for a preamp like this to get a speaker sound.

[@FarewellOldFriends]

Hmm.. thought I'd already replied to to your comment ages ago, but maybe KZbin lost it - that sort of thing happens sometimes :-( The point of this video was to demonstrate the sound made by the unit itself. In its day (20 years ago), people in their home studios were using this for plugging directly between their guitars and recorders - probably because their moms didn't approve of loud guitar amps in their kids' bedrooms! It's thoroughly superseded now, and I'm sure if a gigging guitarist were to use one these days, he or she would be adding speaker sims and all sorts of other FX (looks like you have a serious collection of pedals and amps yourself!), but that was outside my remit here. It sold a couple of years ago, so I can't do any further testing on it. Cheers!

[@page29]

@@FarewellOldFriends That's not entirely true. More often than not, they were used as preamps into a poweramp into a speaker as part of an integrated rack system. Just as you would the JMP-1, ADA MP-1, TriAxis or any other preamp.

[@LeeKirkman88]

Sexual Chocolate everybody, Put your hands together for Sexual Chocolate !!

[@FarewellOldFriends]

5 over S9!

[@LeeKirkman88]

FarewellOldFriends thanks for the video i looked it up as theres one forsale locally for £60

[@BLACKSNAKEGUITAR]

Thanks for the review, it is very concise but I think this unit really works well through a good amp, it sounds great through my old Twin reverb. I have recorded it through my Mustang II with an SG copy and got great results and as far as I am concerned it sounds better that the Marshall presets on the Mustang II. Have a listen and see what you think I am obviously selling the guitar but just listen to that old HMetal sound. "kzbin.info/www/bejne/nnerlp94n6iInpI" I actually did the same thing and bought the unit second hand in the early 90's and have had it ever since but I do think when used properly it can really sound great.

[@FarewellOldFriends]

Thanks for the compliment, and thanks for the pointer to your video. Great sound, nice guitar, and I wish I had your fretboard skills to have made my demo sound more interesting! It's all about finding the right sound for each individual instrument, and simply dialling up a preset on a modelling FX box doesn't always come up with the goods. Cheers!

[@danieldemayo6209]

So basically your saying this thing is useless? Lol guess Il be saving for a jmp-1....

[@FarewellOldFriends]

I'm happy for everyone to draw their own conclusions!

[@greg4272]

Man, youre talking way tooooo much and not playing this preamp! Dont you think we are interested HEARING THE SOUND of the preamp? When you finally strum a chord, it turns out, you did not even use a speaker, or a speaker emulator, but just recording the raw output sound???? Did you come from Mars?

[@FarewellOldFriends]

Don't knock Mars, dude...

[@fredriksvard2603]

sounds absolutely awful, that's my opinion of most marshall stuff

[@user-ju6dz4sx3l]

Jmp1