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Vintage threads from the first ten years

Marshall preamp

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6/21/2000 2:53 AM
Josh	Marshall preamp In the classic marshall style preamp, how would the sound change if I used 1uf cathode bypass caps on the first 2 stages instead of the .68uf caps(I can't find that value cap) also, how would the tone be altered if I bypassed the 3rd stage as well, as opposed to just putting a big resistor on the cathode. thanks, josh

6/21/2000 10:38 AM

quote:
"sound change if I used 1uf cathode bypass caps on the first 2 stages instead of the .68uf caps"

I doubt you'll really hear the difference. .3 pretty small jump. The .68 quite available, unless your in a remote location. I found a 1uF poly cap the other day over a Newark, since somebody bought up all the discounted ones over at AES(Steve I'm guessing). It's a Mallory 150 series, 100V cap. Nice small size capacitor if anybody interested.

quote:
"altered if I bypassed the 3rd stage as well, as opposed to just putting a big resistor on the cathode."

Are talking about the 100K resistor in the CF. Offhand I don't know, but dont' think it will work. a CF has no gain.

bw

6/21/2000 5:50 PM
Josh	No, I didn't mean the cathode follower. usually the first 2 stages are bypassed and the 3rd isn't, instead, it has a big resistor like 10K or somthing. after that stage, it goes to the cathode follower. as far as the caps, I could probabally find some .68 if I tried, but I have some 1uf's laying around Josh

6/22/2000 11:53 PM

Don't sweat the 1uF's. I personally prefer to use slightly larger bypass caps. Try it, you can always change it back if you don't like it.

In the "Classic" circuit, the stage feeding the CF should be 820 ohms...unless when you say CF you're speaking of both stages. I think there's a terminology problem here though.

If we're talking about the 2203/2204 circuit that has a total of 4 stages then the tone/master volume there's a few killer mods to really make these babies hop!

Carl Z

6/23/2000 6:04 PM
Josh	have you ever tried to (cathode)bypass that stage feeding the cathode follower stage? would it give it more gain or just turn it into craptone? Josh

6/21/2000 11:51 AM
Peter S	The 1uf will extend the midband frequencies with a little more gain into the lower mids. The difference is very slight, but definitely audible. Works good for Teles and Strats. Peter S

7/5/2000 6:41 PM
Melanhead	Yup...Soldano uses 1uf caps...

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