Mod?

Dax-The-Ax · Post by **Dax-The-Ax** » Wed Jul 28, 2004 10:46 pm

Just wanted to show the people who know alot more than me a picture of some flogging someone did to my amp. This is a 1976 2204 (50 watt Master Volume) head that i have. It has always sounded thin and weak so i use it for clean only. I have the exact same head in 100 watts and it absolutely kills!! Can someone tell me if those nasty looking piggy-backed resistors could be the culprit. It looks like a mod to me. Thanks

Flames1950 · Post by **Flames1950** » Thu Jul 29, 2004 6:52 pm

Both of those should be adjusting the bias circuit for the tubes that your amp is running (originally 6550's now EL34's right?) Looks like nice sloppy work; I've never seen anyone change the 220K value in line with the diode on the right, either. Both of mine have the one on the left piggybacked for the EL34 tubes.
Can you show a pic of the whole board? Early 50watt MV's were just a standard 1987 with only two inputs (a high input for each of the two channels) and a Master added, I've never played one but I've heard other guys say they aren't worth much as a Master Volume amp. No one seems to want to claim to have seen a 100watt like this, they always seems to be the standard MV circuit with only one channel and more gain.

Dax-The-Ax · Post by **Dax-The-Ax** » Thu Jul 29, 2004 8:02 pm

Yeah, im putting in a Metro Super Lead Board, this amp sounds kinda thin, my 100 Watter of the same year smokes! Any suggestions on the Metro board i put in?

Flames1950 · Post by **Flames1950** » Fri Jul 30, 2004 8:11 am

DUDE, STOP RIGHT THERE.

That's the one, the early one that's the high input off each channel of a 1987 Super lead style amp with an MV added. Put in the other two inputs and wire them up like a four-pronger (the holes are already in the chassis, just need to drill the faceplate) take out the MV and wire a volume knob to each channel, and you've GOT a Lead 50watt. That board's already loaded with some nice mustard caps, no need to change the whole thing, just add the missing 68K's for the extra input jacks, wire the volumes up correctly (maybe change the small brown caps to SoZo's) and you're there.
I don't have the schematic in front of me to give more accurate details right now, it's the first 50watt MV schematic in the Doyle "History of Marshall" if you've got that book, but there's plenty of meat to work with right there already. As I noted, guys that have these early 50watt MV's have said the same thing you have; they're not much of an amp as an MV. But you've got a cheaper quicker route ahead of you to simply convert it over with what you've got. Although I would clean up that bias circuit wiring job......

Dax-The-Ax · Post by **Dax-The-Ax** » Fri Jul 30, 2004 10:08 am

Thanks for your help. I have no idea how to remove the Master Volume and wire the volume nobs. I'm pretty sure i could wire in the input jacks, there are 2 open spots on the board right in front of them. I never thought of that but you are right, the board itself can be used either way. So you think the simple conversion would make it sound better, rather than throwing in george's board?

Flames1950 · Post by **Flames1950** » Fri Jul 30, 2004 12:26 pm

I don't know that I'd say it will sound better, after all I did go ahead and use George's board in mine, but the component quality on your board is better than the stuff that was on my '78 (your board has about half mustard caps, the holy grail of Marshall caps that SoZo's are patterned after.) I don't believe that properly modifying your board will sound any less nice either. The old PCB's are pretty straightforward; the real advantage of point-to-point in this situation is for easier component changes.
I just want you to know all the options, and keep you aware of what's in the amp already. I think there are possibilities with the stuff already sitting there that are worth trying before scrapping the original board altogether. But you can't go wrong with George's products if that's the route you choose.

Dax-The-Axx · Post by **Dax-The-Axx** » Fri Jul 30, 2004 1:59 pm

Went ahead and ordered the board today, i just figure i'll need help wiring the input jacks and the volume pots.

Post by **VelvetGeorge** » Fri Jul 30, 2004 4:17 pm

Got your order Dax, thanks. You'll see when you get the CD that there are wiring diagrams for the inputs, pots ect.

George

Dax · Post by **Dax** » Fri Jul 30, 2004 11:25 pm

You are the man, George!!