OT: Marshall MG15DFX Schematic

[Alpha579]

Hi all,
Ive got a tiny Marshall MG15, and i want to mod the distortion channel for a smoother sound, but i cant find the schematic anywhere, can anyone help me?
Thanx,
Alex

[sir_modulus]

Hey, I got a MG15DFX too. The schematic is complex (I know you only want the easy bit of it, but it's tedious for a DIYer to sketch it out since it has a DFX module. You can try requesting a factory schematic...

A suggestion: Try mellowing out the disortion by adding caps to the switch. Have you installed a footswitch instead of the little puny one?

BTW: I'm having some trouble opening the speaker backboard to this, do you know how to remove it?

[ED]

Alpha, sorry this isnt helpful at all, but generally modern amps like marshall MG series are very complicated, don't sound anygood, and use specialised parts that are next to impossible to get.

Therefore no-one could be bothered drawing a schematic.

I just seached every place i thought might have one but no luck.


sorry mate,
ED

[Alpha579]

Hey, I got a MG15DFX too. The schematic is complex (I know you only want the easy bit of it, but it's tedious for a DIYer to sketch it out since it has a DFX module. You can try requesting a factory schematic...

A suggestion: Try mellowing out the disortion by adding caps to the switch. Have you installed a footswitch instead of the little puny one?

BTW: I'm having some trouble opening the speaker backboard to this, do you know how to remove it?

nah, I havent added a switch because i only use this amp at home, so i dont really need it. On mine, the speaker board is just fixed in with screws, just pop them out, and then ease it out (its very tightly fitted, so it might not budge at first...)

Ed,
well, looking at the pcb, it looks like a basic opamp feedback loop clipper with 1n914's(i think), then followed by head to toe LED's to ground. I might just try removing the LED's to get a smoother sound, and replace the 1n914's with 1n60a's...Doesnt look to complex....

[petemoore]

Actually I'm just wondering, partly because I don't have a transistor amp, and would like to know if a tube front end added to a little solid state job like my buddies [under warranty needs fixed] Fender Frontman 15.
 It too has 'yer basic little SS amp distortion sound, I threw many circuits I use with my tube amp at it, he says the Fender by itself beats them all [well partly true], and I said these boxes don't help it out much...theorizing the amp is already hot as can be on the distortion channel, and the clean channel is already brightened so as to not benefit from further voiceing, distortions sound ill defined, noiisey, garbled etc the basic sound. Phazer worked great.
 I know some SS amps run an input tube [I had a legend 30], and purport to the tubes warming and dynamics characteristics etc...
 Putting a tube in front would certainly alter the character of the Dist and amp.
 I started building with tubes, the hardest part is the PS, I sidestepped and used two power supplies, a 9Vdc [measured 11.2 loaded by the heater] and a printer Psupply 30VDC...second build was even easier, I lucked/cajoled into some Power Supplies [these printers die/ask, wait and ye shall recieve] . I'm using them between the guitar, in the effects chain positions with great results, Id say "Warms things right up".
 Works real neat driving a Dist.

[sir_modulus]

For Petemoore: Yah, Putting tubes in is possible, infact Marshall has the AVT series that has 12AX7a's in the preamp. The MG amps are pretty good sounding, and have some FDD (freq. dependant dampening) to make it sound pretty good for a S/S combo.

For Alpha: Try what I do, and put caps, replace the diodes, and have low guitar volume, low gain, high distortion volume, and put contour to max.

[Johnny G]

I have an MGDFX15 as well, havnt opened it up since its the only amp i have atm lol.

when i first got it i thought that the distortion on it was great, untill i got a jackhammer and now i almost never use it except when im messing about. amusinglly, if you put a booster like the AMZ mosfet boost infront of it and cracnk the gain up, when you play you can look through the gaps next to the little channel button and see the LED's glowing lol