Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: joesatch on October 25, 2022, 09:20:45 am

Title: unusual results from bright cap
Post by: joesatch on October 25, 2022, 09:20:45 am
Working with this circuit. V1 plate (on the tube) is 115V.  Adding a 470p bright cap (on the gain pot) removes some flubby bass (great) but the highs now lack and i cant get some harmonics that i can get without the bright cap. Also tried a 2200p bright cap but similar results. I thought the bright cap brings in more highs but it seems to be doing the opposite.  Gain is dimed.
Title: Re: unusual results from bright cap
Post by: joesatch on October 25, 2022, 09:30:20 am
what i'm trying to accomplish is to remove the boomy bass. Even with the 2.2n coupling caps still too much bass. I essentially have to run the bass at zero or it's too boomy. I wonder if this mod would help. Where in the circuit do i place this?

Title: Re: unusual results from bright cap
Post by: joesatch on October 25, 2022, 09:50:32 am
cap is placed between pin2 and pin3 of gain pot. it definitely has a big impact on the tone with gain dimed. Hard to explain, it tightens it up but something is lost in feel and overtones, it gets stiffer. i might be able to make a recording of it
Title: Re: unusual results from bright cap
Post by: sluckey on October 25, 2022, 10:12:35 am
cap is placed between pin2 and pin3 of gain pot. it definitely has a big impact on the tone with gain dimed. Hard to explain, it tightens it up but something is lost in feel and overtones, it gets stiffer. i might be able to make a recording of it
Impossible! When the gain pot is dimed (turned max CW), pins 2 and 3 are shorted together and the bright cap is short circuited and can't have any effect. If you hear some effect then your gain pot must be defective.
Title: Re: unusual results from bright cap
Post by: joesatch on October 25, 2022, 10:50:22 am
i will do some more testing. I did remove this cap i had in place which seems to have achieved the results i'm looking for