50 watt Questions!

[vanhalen5150]

Does it look like a bright cap was removed?

[motrock]

Was never there to begin with. I don't see any signs of one ever being there!

[Strat78]

The 220k resistors going to v3 is to stifle cymbal crash or distortion blocking, take that off and see if it improves things. No bright cap with a 330uf fat cap plus a 2.2k v1b resistor and who knows what the screens are (probably too high), no wonder it sounds dark. Looks like it has been partially converted to a 2204 or did it come with a master(?), I can't see what is going on with the inputs, need more pics, cant tell if channel 3 and 4 are hooked up. -whats that funky little v1b cap, that position can be very sensitive to the brand of cap. What's that miserable little cap doing on v1, who ever did the work on this thing must have had allot of left over parts from his effects pedals projects. MM tranny's are a little modern sounding for what you are going for here, is the PT an MM as well? Once you get the pre amp board dialed in along with the proper PI, screens and mains caps, the 4ohm tap and 100k nfb might be a little too fizzy and loose for other tones besides vh. Ralle swears by the 16ohm tap and a 27k nfb. My 73 marshall 50w came stock with the 4ohm tap and 100k nfb and it sounds great, but it makes up for the stiff filtering typical for 50w'rs of the time. Like Neil says, each amp will need individual fine tuning to make it sound right to you. You just need to get to the proper jumping off point, and that would be a non master plexi circuit with the right components.

[vanhalen5150]

Those Variplex's never had master volumes. That little upright black cap on v1 is original.

[motrock]

Oh I agree, the amp will needs its own fine tuning. I have a good friend thats going to help me out with it. Right now he's working on my Mojave Peacemaker. Had it converted in to a 2203. Getting SoZo's installed in a few days. Can't wait to hear it at JMP specs.

The VariPlex is non-master. The amp does sound great, but it needs more work to nail the EVH thing. Its always been too dark. And I agree with the MM OT. I have heard that those are way to modern. I won't worry about that till we get the rest of the amp back to specs. Thanks for the info Strat78. Gonna forward this info on to my friend. I am sure it will help.

[vanhalen5150]

Remember that amp was originally with a 3rd tranny for the heater supply. Therefore it may have had few tweaks designed for that very low voltage seen throughout the amp as the variac was reduced giving you just a few watts of output. That's why I think they have the MM's. Older style OT's may have not been able to produce a good sound at the lower volumes. Setting it up as a none master stock plexi may need an OT change but adding that bright cap will do wonders if its dark sounding. Also simple changes in the tone stack makes a difference.

[jnew]

.68 on V2? Yes I have. Punchy in the mids/hi mids but for me, I like some lows for that EVH tone.

[vanhalen5150]

And the Xicon caps are there to reduce noise from what I understand.

[motrock]

Remember that amp was originally with a 3rd tranny for the heater supply. Therefore it may have had few tweaks designed for that very low voltage seen throughout the amp as the variac was reduced giving you just a few watts of output. That's why I think they have the MM's. Older style OT's may have not been able to produce a good sound at the lower volumes. Setting it up as a none master stock plexi may need an OT change but adding that bright cap will do wonders if its dark sounding. Also simple changes in the tone stack makes a difference.

Oh wow, thats a great point. Almost forgot about the 3rd tranny. Yeah, I will do all the other stuff first, then go from there. I may swap out the OT. Classic Tones are like $55 or something like that. Marstran was $150. Georges OT were the same price. Not sure which one would be the best? I guess its a matter of preference!