New metalmod - Marshall JMP

[emaushenric]

I've come up with a new metalmod. Built it in a Marshall 1992 from 1983.

Here are some clips:
http://www.youtube.com/watch?v=Afw8ZpxB9Xs
http://soundcloud.com/emaushenric/marshall-jmp-modded-with-some
http://soundcloud.com/emaushenric/modded-marshall-jmp-both#

Here are some pictures from the buidling process:

















Almost done, need to clean it up.

[DoomBuggi]

can you do these kind of mods to a Marshall 2203?

[gwEm]

wiring looks neat

[HTH AMPS]

what kind of circuit topology are you using? - Fender or Marshall (i.e. tonestack after first gain stage, or after 2-3 stages as per many Marshall-type designs).

[darkbluemurder]

can you do these kind of mods to a Marshall 2203?

I guess you could - except that you have to drill another hole in the chassis front since the 2203 has only two input jacks. You probably would want to use a custom front panel in order to save the original front panel.

Cheers Stephan

[emaushenric]

can you do these kind of mods to a Marshall 2203?

Of course I can!  :D

[emaushenric]

what kind of circuit topology are you using? - Fender or Marshall (i.e. tonestack after first gain stage, or after 2-3 stages as per many Marshall-type designs).

Tonestack after fifth gain stage  8)

[DoomBuggi]

can you do these kind of mods to a Marshall 2203?

Of course I can!  :D

Man I wish that I had the experience to do that to my 89' 2203.  I could tell that the sound you got from the amp was super tight and crunchy.  I wanted to get the Hulk Mod done by Mr. Fortin, but he is a bit busy these days.  Super nice guy though.

Now I am on the fence about selling my amp to get something more geared for what I am doing.

[HTH AMPS]

what kind of circuit topology are you using? - Fender or Marshall (i.e. tonestack after first gain stage, or after 2-3 stages as per many Marshall-type designs).

Tonestack after fifth gain stage  8)

so its not intended for playing jangle pop then  :lol:

some serious gain in five stages, well done on getting that stable and low hum/hiss.

[darkbluemurder]

I have seen on 5 gain stage design on the Metroamp forum. The guy who designed it used an ECC82/12AU7 in one preamp tube location. This gives a lot less gain compared to an ECC83/12AX7 which may be what the doctor ordered to keep it from being over the top compressed.

Cheers Stephan

[HTH AMPS]

I suppose the best way of keeping the noise low and stopping the amp from being so compressed (but heavily distorted) is probably to build up the gain conservatively in multiple stages - some of the really high gain amps do this like the 5153 which has six gain stages, then a CF stage driving the tonestack, then another CF stage driving the FX loop, plus a further gain stage as the effects return.  I'd guess that even on 2/3 gain it'd be way to saturated for my own use.  I've heard the 'rhythm' channel (2) on this amp which has four gain stages prior to the CF driven tonestack, and that is already lots of gain and well into hotrodded JCM800 territory.

[emaushenric]

I have just 12ax7 in this amps, no 12au7 or 12at7. As you can hear there is no hum and no hiss. It's a bit tricky as I nearly don't cut any treble in the preamp, if you look at a 5 stages high gain/metal schematic there is always a lot of treble cut in the preamp to turn down the hiss and make it stable, but that kind of amp do not often sound good if you roll back the volume on the guitar.  :)