Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: joesatch on April 25, 2025, 08:57:12 am

Title: cap to ground on mid pot?
Post by: joesatch on April 25, 2025, 08:57:12 am
is this a mistake in the schematic? what's this do?
Title: Re: cap to ground on mid pot?
Post by: Willabe on April 25, 2025, 09:45:54 am
What does what do?

If your asking about the 2 - 220pF caps and switch, flip the switch, puts them in ||, caps add up in ||, so now 440pF feeding the treble pot, a little fatter sound.
Title: Re: cap to ground on mid pot?
Post by: shooter on April 25, 2025, 10:42:22 am
Quote
What does what do?


if it's the .0047 across the 100k, it's a || RC network, sorta like a "tuned tank" to "define" what frequencies get passed down-steam n what gets dumped on the ground.
Title: Re: cap to ground on mid pot?
Post by: tubeswell on April 25, 2025, 11:01:26 am
is this a mistake in the schematic? what's this do?


Not clear on which mistake you’re wondering about.
Title: Re: cap to ground on mid pot?
Post by: joesatch on April 25, 2025, 11:33:42 am
is this a mistake in the schematic? what's this do?


Not clear on which mistake you’re wondering about.

the cap .0047u over the mid pot from input to ground
Title: Re: cap to ground on mid pot?
Post by: tubeswell on April 25, 2025, 01:04:55 pm
I doubt that’s a mistake - rather, it’s more like a ‘mistake’.
Title: Re: cap to ground on mid pot?
Post by: joesatch on April 25, 2025, 01:27:30 pm
wired up this way behaves strangely.  mid pot at 1 has very low mids, then at noon had strong mids, past noon up to 10 the mids progressively disappear pot on 1 or 10 sounds the same
Title: Re: cap to ground on mid pot?
Post by: Willabe on April 25, 2025, 03:54:52 pm
mid pot at 1 has very low mids, ....

It's at 1, no to very low mids. Mids are dialed out.

..... then at noon had strong mids, past noon up to 10 the mids progressively disappear pot on 1 or 10 sounds the same.

How does it sound/work without that cap across the mid pot?

If good, just leave it out.