capacitor list or kit for session 400
Moderator: Dave Mudgett
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Bob Cox
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capacitor list or kit for session 400
Does any one have a list of the capacitors needed to replace in a session 400? Or do you have a set you did not use for sale.
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Todd Brown
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Bob Cox
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Marty Nemanick
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Brad Sarno
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Guys,
Just so you know, I built that web page about 10 years ago and it hasn't been updated at all. Basically it all still stands, but a number of the parts numbers at Mouser have changed. But it's pretty straightforward stuff. Replace ALL electrolytic capacitors in the amp because it's time. Then the "upgrades" are basically to replace all of those little 2.2uF audio coupling/interstage capacitors with either a film type capacitor or now I can also recommend the Nichicon MUSE capacitors or the ELNA RFS (Silmic II) capacitors as well. This greatly cleans up and clarifies the audio signal quality.
Then the other upgrades are to replace the ceramic disc capacitors that are used in the tone control circuit sections and upgrade to either mylar or polypropylene film types.
There really aren't any circuit design mods at all, just component quality upgrades. And also that little trick of adding the high quality film caps across the terminals of the big main power supply filter cap's, that's a subtle but nice way to help improve the performance of the filtering in the power supply, helps keep high frequency crap from getting into the amp. They kind of take over where the big electrolytics begin to lack high frequency performance.
Overall, the mod really takes that great amp design to its real potential, really opens up the transparency and clarity and smoothness beyond where Peavey ever did at the factory due to the nature of bean counters and component costs.
Brad
Just so you know, I built that web page about 10 years ago and it hasn't been updated at all. Basically it all still stands, but a number of the parts numbers at Mouser have changed. But it's pretty straightforward stuff. Replace ALL electrolytic capacitors in the amp because it's time. Then the "upgrades" are basically to replace all of those little 2.2uF audio coupling/interstage capacitors with either a film type capacitor or now I can also recommend the Nichicon MUSE capacitors or the ELNA RFS (Silmic II) capacitors as well. This greatly cleans up and clarifies the audio signal quality.
Then the other upgrades are to replace the ceramic disc capacitors that are used in the tone control circuit sections and upgrade to either mylar or polypropylene film types.
There really aren't any circuit design mods at all, just component quality upgrades. And also that little trick of adding the high quality film caps across the terminals of the big main power supply filter cap's, that's a subtle but nice way to help improve the performance of the filtering in the power supply, helps keep high frequency crap from getting into the amp. They kind of take over where the big electrolytics begin to lack high frequency performance.
Overall, the mod really takes that great amp design to its real potential, really opens up the transparency and clarity and smoothness beyond where Peavey ever did at the factory due to the nature of bean counters and component costs.
Brad