Body control pot

[uki]

What this body control does (see video) ? Couldn't find any schematics.

[tubenit]

Kevin O'Connor has a "body control" idea using a pot to turn a push/pull amp into a pseudo single ended amp.

Having said that, it will not surprise me if other builders use/d the term "body control" and mean something totally different.

With respect, Tubenit

[d95err]

There's a gutshot of the amp on their site: http://bcaudio.com/bel-air.html

Most likely (haven't analyzed the gutshot), the pot gradually fades in a second coupling capacitor in parallell with the first coupling cap. I.e. it's a variable highpass filter, most likely before the volume pot.

[uki]

There's a gutshot of the amp on their site: http://bcaudio.com/bel-air.html

Most likely (haven't analyzed the gutshot), the pot gradually fades in a second coupling capacitor in parallell with the first coupling cap. I.e. it's a variable highpass filter, most likely before the volume pot.

I did got the pic already been looking at that but can't figure out what is going on there, very interesting feature !

[shooter]

best guess from your snippit, you guess values 


updated, connect the dots version 

[uki]

best guess from your snippit, you guess values 

There is a bright control switch there behind the body pot. I think you missed that.

[d95err]

This is what it looks like to me. Interesting non-traditional bright-switch arrangement.

EDIT: Oups - mistake! The switch should go to the volume pot wiper, not the input.

[uki]

Yeah I think we got it !

Check it out !

Where is the tone stack connected?

[VMS]

Where is the tone stack connected?

My guess is that tone stack is between second gain stage and phase inverter.

[tubeswell]

Or it could be resonance control in the NFB loop, or a mid-hump/mid-scoop control in the TS? or something else? 


(Edit: Oops - I see uki has a picture. Cool sales video too)

[uki]

Any guesses for the components values on the body control schem guys ?

I got a few

[VMS]

the cap on the pot looks smaller than .022


KOC uses in his soma 84 amp values 22nf and 1nf


body control works so that in one end of pot coupling cap is the .1 cap and on the other end .1 cap in series with the smaller cap.
so effectively the value of the smaller cap, which means thinner sound