Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Captain chunkulus on January 24, 2019, 10:53:50 am

Title: Preamp filter cap values
Post by: Captain chunkulus on January 24, 2019, 10:53:50 am

So I currently have 22uf caps in the preamp stages. How much would it benefit by upping those to 47uf in regards  to noise and hum if any? Thanks.

Title: Re: Preamp filter cap values
Post by: jjasilli on January 24, 2019, 01:03:09 pm

Probably not at all. Filtering is progressive from one node to the next.  Excessive filtering in preamp stages can adversely affect tone.  E.g., some amps use 8uF in the last filter stage > 1st preamp stage.  OTOH, some amps use 30uF throughout, like Marshals, but are not known for good clean tone. 


If there is excessive hum & noise the problem is elsewhere.

Title: Re: Preamp filter cap values
Post by: derekiseric on January 25, 2019, 08:20:08 am

What kind of hum and noise are you getting? 
Does it increase or decrease with the volume controls?