peavey windsor 120 watt head schematic?

[JHJOHNSON]

Hello, I also have a windsor head, and after much research on how to clean it up, I found only 1 blog that made sense, change preamp tube 1 & 2 to 12au7 and 12at7 respectively. I happened to have fisher amp that I was able to rob the tubes from that are at least 50 yrs old (RCA). The amp sounds great with a tube screamer in front now.

[shanx]

Hi there, I am relatively new to the site..just browsed into this forum. I have a clean pdf of the schematic for this amp series, if anyone interested I could send email. I was really interested in getting a windsor too. I noted in the design that the preamp section has a LOT of preamp stages and I am wondering if the low gain input jack could simply be jumpered over to the pregain pot (actually after the decouplng capacitor), effectively dropping the first stage or if there was a way to skip one stage in low gain mode. I have a an old tube amp that is an ongoing rebuild project..it sounds very clean using only 2 stages on the preamp(using both half of 12AX7). If you are interested in modding the resistor/cap values I could post those values too.

[Enzo]

There is more to it than number of stages. This preamp does have four stages. You should also note that between each stage is a large voltage division reducing signal level. The stages are being used for tone shaping, not simply gain.

Yes, you could jump over a stage, not sure you'd want to. But that is only my opinion.

I don't think clean was part of the design spec for this amp. I think it was intended more as a "lead" amp.

[shanx]

Hi Enzo, I absolutely agree with you there. The amp has had a lot of reviews about that, designed to be more of a 60 -70's ''hard rock'' amp. The Windsor series looks like it is being cleared out to make room for Peavey's new series (at more $$). Right now they are going for very low price and I am very tempted to tinker around with the circuit...
Only my opinion, but maybe the tone shaping (other than the tone stack) is great for lead, but for a clean sound I prefer to leave it as close to original signal as possible. Let you know if I pick one up.

[Enzo]

Well, just for science, sometime plug your guitar straight into the PA system. Now you will hear what the "original signal" sounds like. Kinda thin and pale really. When I think of clean, I think of a nice Fender Twin Reverb. It is far from flat or hifi, but it sounds great and darn "clean."

[shanx]

Yes for sure that would be taking it to the extreme, and actually reminds me of back in the day I did try exactly that. I had a little transistor based practice amp (not enough $$ for a Fender when your a 12 year old) , but my dad had built a heathkit (from down your way!) tube based little portable PA/Stereo amp. I cobbled together a cab with some speakers and brought the thing to band practice. With a little electro-harmonix preamp (LPB-1) in between the guitar/amp to boost a bit to line level and take care of impedance...go figure.. it sounded really quite good!
Even a fender twin uses only 2 stages before the PI, with the tone stack right after the input amp stage:you are absolutely right about it sounding 'clean'...I agree when we say clean we are not talking about HiFi etc..

[shanx]

Hi Enzo, I did a bit of checking of what Sloan was going for. Of course you are right about the tone shaping+gain. Sloan's comparison to a JCM-800 front-end is also very accurate, the '76 version is incredibly similar. For the 'clean' input, Marshall however bypasses the input first stage V1 that the lead channel uses exclusively. The clean channel signal goes through the 470K/47pF then into the preamp volume to second stage. The lead channel hits the 1st stage V1, then through 0.022 uF then to the 470K/47pF combo. From what I remember of the JCM 800 the clean input did sound pretty 'clean'.