Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: joesatch on October 03, 2025, 10:13:40 am

Title: add mid pot to tonestack
Post by: joesatch on October 03, 2025, 10:13:40 am

i think this is a bassman tonestack. unsure. where would i add a mid pot to it?

Title: Re: add mid pot to tonestack
Post by: shooter on October 03, 2025, 10:40:29 am

personally I'd add it to the guitar and leave that TS alone.  2nd option is to use the Treble/Bass pots to "bring out mids" by attenuating the highs n lows

Title: Re: add mid pot to tonestack
Post by: joesatch on October 03, 2025, 11:25:47 am

Quote from: shooter on October 03, 2025, 10:40:29 am

personally I'd add it to the guitar and leave that TS alone.  2nd option is to use the Treble/Bass pots to "bring out mids" by attenuating the highs n lows

i think i'll scrap this TS and just run a normal cathode driven TMB tonestack. All kinds of voltage dividers and weird things going on with this

Title: Re: add mid pot to tonestack
Post by: shooter on October 03, 2025, 12:36:59 pm

 :laugh:


now ask guitarists if that makes any difference when they play. sometime what makes sense electronically make NO sense to musicians.

Title: Re: add mid pot to tonestack
Post by: astronomicum on October 03, 2025, 01:15:16 pm

Quote from: joesatch on October 03, 2025, 11:25:47 am

i think i'll scrap this TS and just run a normal cathode driven TMB tonestack. All kinds of voltage dividers and weird things going on with this

Would’nt it be a good idea to understand how this tone stack is affecting the gain profile before replacing it with something else?

Title: Re: add mid pot to tonestack
Post by: tubeswell on October 03, 2025, 03:48:11 pm

Quote from: astronomicum on October 03, 2025, 01:15:16 pm

Quote from: joesatch on October 03, 2025, 11:25:47 am

i think i'll scrap this TS and just run a normal cathode driven TMB tonestack. All kinds of voltage dividers and weird things going on with this

Would’nt it be a good idea to understand how this tone stack is affecting the gain profile before replacing it with something else?

I’m not 100% certain that joesatch’s  tone-stack is in an amp he has built at this stage - I’m 95% confident this is an idea he is batting with.

Title: Re: add mid pot to tonestack
Post by: tubeswell on October 03, 2025, 10:36:01 pm

Hey Joe - this is where you might be goin', or not. I redrew that tone stack a couple of different ways to help you see where to look for a 'mid pot' position.

I vote for swapping out the 220k resistor in red ('R 13') with a 250k pot wired as a variable resistor. It's more of a 'slope' control idea but it might have the funky effect you're looking for

Title: Re: add mid pot to tonestack
Post by: tubeswell on October 04, 2025, 12:51:40 am

Or this

Title: Re: add mid pot to tonestack
Post by: jjasilli on October 04, 2025, 07:32:03 pm

I agree that the tone circuit looks like that of a Bassman 5e6. This is not a tonestack.  It's a treble bleed circuit plus a bass bleed circuit, which are interactive.


There is no filtering for a mid control.  The 5e6 is reputed to have great mids.  Do you want more mids, or less???


Theoretically, you get more mids by decreasing treble & bass; then turn up the volume to make up for signal loss.  Reverse this for less mids.


For more info google Bassman 5e6 mid control.

Title: Re: add mid pot to tonestack
Post by: Willabe on October 04, 2025, 08:21:43 pm

That's the Bassman Rory Gallagher used, a 5E6. With a Range Master treble boost in front. 

Irish Tour live album rig/sound.