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Bypass cap question
Posted: Tue Dec 14, 2004 10:54 am
by puretube
On the '68 100 watt SuperLead board, what is the value of the electrolytic bypass cap on the cathode of the first stage of valve 2 (pin 3)? Most amps I see have a .68uF cap here.
Posted: Tue Dec 14, 2004 2:22 pm
by VelvetGeorge
.68uf is correct.
George
Posted: Tue Dec 14, 2004 2:24 pm
by Billy Batz
The only other common (not that common though) Marshall value I know of there is 330uF. Thats the supposed value in the EVH Holy Grail amp. Ive always had the stage 2 Ck on a switch to take it in and out. I mostly used .68 but I tried the 330u and its a interesting sound in its own right. Its inspired me to use an on/off/on minitoggle in my newest 100W project to switch between no bypass and those 2 values though Ive read posts were people do things like put a 5 way rotary switch in there and go through more values. Usually .68uF wouldnt be an e-cap.
Posted: Tue Dec 14, 2004 3:55 pm
by puretube
Thanks for the help.
The picture I saw was George's '68 100-watt SuperLead board. I will have to try out the 330uF on one of mine.
Posted: Sat Jan 15, 2005 12:21 am
by puretube
Just an update............
I tried the 330uF cap and I am very pleased with the tone. The cap has brought a little more focus to the midrange (but not making it over pronounced). The amp still has a great open growl, but I feel that it now sits better in the mix of a full group. Its similar to adding light compression to the channel at the mixing desk, but I get it onstage (without relying on monitors).
For reference sake, this is a split cathode design with the channels bridged (50-watt).