Hello everyone,
I am new to the forum. I have two quick noob questions about modding my Peavey Classic 30:
1. I see in the blue guitar mods that you can put a 22uf capacitor across two legs of the normal volume pot to retain the treble at lower volume. Which two legs specifically? I have no clue how to tell which two are "ungrounded". Also is 22uf the same as 0.22 or code 224?
2. Input cap C10 is currently 39pf. Would changing it to 22pf yield any perceptible treble increase/sparkle? Or don't bother?
Thanks for your time and help in answering my greenhorn questions!
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Blue Guitar Article for bright cap across normal volume pot:
http://blueguitar.org/new/articles/blue_gtr/amps/peavey/c30retro.pdf
Excerpt: "To increase the treble response of the Normal
channel at lower settings of its volume pot you can add in a "bright" cap across the two
ungrounded terminals of the pot. For a subtle treble boost I prefer a very small mica cap
such as 22uF or 47uF (the traditional values used by Fender or Marshall of 120pF,
500pF or even 0.001uF will be way too bright in the Classic 30). The signal from the
Normal volume pot wiper is then routed to the channel switching circuitry."
Schematic:
http://www.bustedgear.com/images/schematics/Peavey_classic-30.pdf
I am new to the forum. I have two quick noob questions about modding my Peavey Classic 30:
1. I see in the blue guitar mods that you can put a 22uf capacitor across two legs of the normal volume pot to retain the treble at lower volume. Which two legs specifically? I have no clue how to tell which two are "ungrounded". Also is 22uf the same as 0.22 or code 224?
2. Input cap C10 is currently 39pf. Would changing it to 22pf yield any perceptible treble increase/sparkle? Or don't bother?
Thanks for your time and help in answering my greenhorn questions!
------------------------------------------------------
Blue Guitar Article for bright cap across normal volume pot:
http://blueguitar.org/new/articles/blue_gtr/amps/peavey/c30retro.pdf
Excerpt: "To increase the treble response of the Normal
channel at lower settings of its volume pot you can add in a "bright" cap across the two
ungrounded terminals of the pot. For a subtle treble boost I prefer a very small mica cap
such as 22uF or 47uF (the traditional values used by Fender or Marshall of 120pF,
500pF or even 0.001uF will be way too bright in the Classic 30). The signal from the
Normal volume pot wiper is then routed to the channel switching circuitry."
Schematic:
http://www.bustedgear.com/images/schematics/Peavey_classic-30.pdf
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Please link here both Peavey Classic 30 schematic and blue guitar mods, otherwise we don´t know what are you talking about.
As of sparkle, Peavey Classic in general is voiced "warm" .
Not saying it does not have any, but they didn´t give it priority.
As of sparkle, Peavey Classic in general is voiced "warm" .
Not saying it does not have any, but they didn´t give it priority.
Thanks. Again, sorry for the noob questions. What would be the 22uf code? I just need to be able to identify purchase the correct cap that the blue guitar article references:
http://blueguitar.org/new/articles/blue_gtr/amps/peavey/c30retro.pdf
Excerpt: "To increase the treble response of the Normal
channel at lower settings of its volume pot you can add in a "bright" cap across the two
ungrounded terminals of the pot. For a subtle treble boost I prefer a very small mica cap
such as 22uF or 47uF (the traditional values used by Fender or Marshall of 120pF,
500pF or even 0.001uF will be way too bright in the Classic 30). The signal from the
Normal volume pot wiper is then routed to the channel switching circuitry."
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I don't know why PV bothered with 39pFd. 22pFd, same thing. There's ~~100pFd in the tube, coming after ~~300pFd in your guitar cable. All of these have effect only above the audio range. (47K+139pFd= 25KHz)
22uFd is so absurd it must be a typo. Especially in context of other values mentioned. 22pFd to 100pFd would be much more likely. Cap code decoders can be found online.
22uFd is so absurd it must be a typo. Especially in context of other values mentioned. 22pFd to 100pFd would be much more likely. Cap code decoders can be found online.
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That is a typo, he means 22pf or 47pf, not uf.
You have three legs on a pot, and you want to know which one is not ground? Get out your ohm meter and measure resistance to ground from each leg. One will be grounded, the others not.
yes, I think reducing C10 from 39pf to 22 pf is a waste of time.
If you order caps, order them by value. Just because a cap has 224 printed on it, doesn't mean you order it that way, I would be ordering 0.22uf caps in that case.
If you want to order 22pf caps, just order 22pf caps.
You have three legs on a pot, and you want to know which one is not ground? Get out your ohm meter and measure resistance to ground from each leg. One will be grounded, the others not.
yes, I think reducing C10 from 39pf to 22 pf is a waste of time.
If you order caps, order them by value. Just because a cap has 224 printed on it, doesn't mean you order it that way, I would be ordering 0.22uf caps in that case.
If you want to order 22pf caps, just order 22pf caps.
The 39pf cap is an anti-RF ploy.
If you look at the board layout, there is also a gimmick cap between the grid and plate of the input triode.
If you look at the board layout, there is also a gimmick cap between the grid and plate of the input triode.
Guitar amps are often intentionally not bright. Distorted electric guitars usually sound better that way, and electric guitars in general often fit into a mix or overall song arrangement better than way too.
There can be a bit of a cognitive trap when listening to an instrument in isolation. The ear tends to like the sound spectrum filled up, and so more bass and more treble often seem like they improve the sound, but when people get together to play it can sound like a muddy mess.
Other than that, I would just say a speaker upgrade is often the best mod.
There can be a bit of a cognitive trap when listening to an instrument in isolation. The ear tends to like the sound spectrum filled up, and so more bass and more treble often seem like they improve the sound, but when people get together to play it can sound like a muddy mess.
Other than that, I would just say a speaker upgrade is often the best mod.
Definitely a typo.
120/220/250pF are traditional Fender values and 470pF the traditional Marshall one.
End up sounding the same because Fender used 120/220pF and 1M volume pots and Marshall 470pF and 470k ones, frequency crossover (and audio result) ends up being the same.
Look at the clean volume pots:they are numbered but Peavey does not follow the most common convention, which is confusing, so Steve Ahola makes it fool proof:
* the pot has 3 legs.
* one of them is grounded, other two are not.
* join 2 not grounded ones with a 120pF (subtle) /220pF (more shimmer) or 470pF (middier, bolder) capacitor.
Ceramic is fine; silver mica won´t hurt but is harder to find so don´t lose sleep over it.
EDIT: C10 (39pF) isn´t even *mentioned* in the Mod, not sure why you add it to the mix 🙂
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Thanks Enzo. My apologies, but I am a novice at this. How exactly do I measure the resistance to ground? I have a multi-meter. Do I just put one one tip on a leg and then one tip on the chassis? I assume I set it to the setting with what looks like a ground icon on the meter?
Thanks for your help!
Thanks so much for the info. I know C10 has nothing to do with the mod, but I have seen on forums that this bleeds treble. I know understand that it is just to block RF so as to not get radio stations playing through the amp.
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