From mncamero–(at)–orldnet.att.xxnet Tue Mar 10 23:07:15 CST 1998
Article: 90070 of alt.guitar.amps
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From: “Michael”
Newsgroups: alt.guitar.amps
Subject: Re: Champ/Filter cap question
Date: Tue, 10 Mar 1998 08:42:59 -0800
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Henry, I spent some time learning what effect cap values have on an amps
sound when I built my first amp. I used the 5E1 and 5F1 Champ circuit,
homebuilt . The stock 5E1 used a choke between the first two caps and the
5F1 uses 10K 1watt resistor. Basically I found that the Champs with only
3X8uf caps could not afford to have fewer caps because of the need to
decouple different sections of the circuit. Trying to take the B+for the
power tube and preamp tube from the same location would be a disaster. 3
caps are required for this circuit IMO.

In terms of capacity going to 3X4uf made the sound even spongier but the
noise and hum went up. Changing to 3x16uf got rid of the hum dramatically
and the sound tightened up just a little. I then tried 16uf, 47uf, 47uf
goin down the line and the single ended hum nearly vanished. The amp lost
a little bit of its lively flavor though. Even though it is hard on the 5Y3
rectifier tube I tried 100uf, 100uf,100uf. Hum now all but gone and so was
a lot of the springy, spongy Champ character.

My favorite combination was in the 5E1 layout using a 5h choke with 3X16uf
caps. this combined with using a false center tap heater arrangement for
the low hum gave me the tone and the low hum I was lookin for. Basically I
found more capacitance lowered hum but compromised the sound . 3X16uf seemed
like the best compromise.

Using a choke instead of a resistor seemed to give the amp a little more
headroom before breakin up. I also tried using oil caps instead of
electrolytics. Love that oil cap sound in power supplies, but there is no
room for them on a factory built amp chassis. My feeling after fooling
around with this for several days was that the low capacitance of the
orignal tweed champs was an integral part of their sound. Change the caps
dramatically, and the sound does also, and not for the better IMO.
Michael remove x’s to respond direct
Henry Mabry wrote in message <3504bd1f.3558937--(at)--ews.mindspring.com>…
>What would adding or removing filter capacitors do to a Tweed Champ?
>i.e. How does it affect clean vs. crunch? How does a choke’s
>function compare with the capacitor’s?
>Thanks.
>

 

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