Footswitch-able FET Boost

[martin manning]

Nice compact board. I'll be interested to hear how you bias the FET, and whether you prefer a clean boost or added distortion from the FET. The FET bias document has updated info, if you haven seen it yet.

[didit]

Hello --

Nice compact board. I'll be interested to hear how you bias the FET, and whether you prefer a clean boost or added distortion. The FET bias document has updated info, if you haven seen it yet.

First application will be in a 6G2 derived design. Goals are mixed: first off a clean boost to fatten up Fender single-coils; however firmer push into distortion also an inspiration aspiration. Absolute plans to make use of your fine biasing guidance. For the moment bench time is scarce. I can listen to Zoom calls while also drawing schematics and PCB layouts. Stuffing and soldering work is in a space with no screens. If all proves in will share more details, including any surplus PCBs if there's interest. Perhaps you'd noted, layout is arranged for easy installation with either PCB trimmer or faceplate mounted pot+switch for level adjustment.

Best .. Ian

[dorrisant]

Looks nice Ian.

[didit]

Hello --

Thanks Tony. And belated thanks to Martin too. You are a bit too kind as it's still WiP, requiring at least a few more revs (hopefully only in eCAD) to be called OK.

Best .. Ian

[captaincoconut]

Martin, could you please give me some input on how I would wire this when using seperate input jacks for "Normal" and "FET" plus the relay? Would I simply wire a switching jack in line with the "FET Input"?

[GAStan]

Captaincoconut, to me one of the big benefits of putting the FET on a relay is that I'm able to replace the FET jack with a B10k pot to replace the trimmer on the FET board, allowing a front panel level adjustment of the FET output.

Is it that you do not want this front panel adjustment or do you have another plan? I'm just curious, always open to new ideas.

[martin manning]

I'm also wondering what the reasoning is for doing this. I'd rather just pull the knob out or step on the foot switch, and bonus, you have a gain control for the boost.

[captaincoconut]

Captaincoconut, to me one of the big benefits of putting the FET on a relay is that I'm able to replace the FET jack with a B10k pot to replace the trimmer on the FET board, allowing a front panel level adjustment of the FET output.

Is it that you do not want this front panel adjustment or do you have another plan? I'm just curious, always open to new ideas.

I'm also wondering what the reasoning is for doing this. I'd rather just pull the knob out or step on the foot switch, and bonus, you have a gain control for the boost.

Steel String Singer: seperate inputs for FET and Normal, frontpanel mounted "FET Drive" potentiometer and footswitchable relay...I'm working on a SSS #005 build using the same frontpanel layout. So after some thinking just putting a switched jack in line with the FET input would be the simplest solution.

[GAStan]

Interesting, I hadn't looked at #005. Your reasoning makes sense but now I'm curious what HAD's reasoning was. Something we may never know...

How exactly would you want it to work? Both FET and Normal inputs selected by footswitch or only Normal Selected with FET as FET only or ???

[martin manning]

I'm wondering if the foot switched FET was a retrofit and the FET jack was just left in place. A gain pot with a pull switch in the FET jack hole makes more sense to me.

[captaincoconut]

A gain pot with a pull switch in the FET jack hole makes more sense to me.

Why an additional gain pot in the FET jack hole? The gain pot was already there from the beginning.

[martin manning]

A gain pot with a pull switch in the FET jack hole makes more sense to me.

Why an additional gain pot in the FET jack hole? The gain pot is already there.

It brings the FET gain adjustment outside the chassis, moving it from the FET board to the front panel.

[captaincoconut]

A gain pot with a pull switch in the FET jack hole makes more sense to me.

Why an additional gain pot in the FET jack hole? The gain pot is already there.

It brings the FET gain adjustment outside the chassis.

Sorry, but are we talking about different things? There is one already labeled "FET Drive".

[GAStan]

What I find interesting on #005 is the fact it already has a front panel FET level adjustment.

Here is my #004 SSS where I put the pot in the input hole. This is a common method on ODS amps.

20250319_071950.jpg

[captaincoconut]

What I find interesting on #005 is the fact it already has a front panel FET level adjustment.

Here is my #004 SSS where I put the pot in the input hole.

20250319_071950.jpg

It's not only #005. #004 has it too and both of SRV's amps as well. The 'Mid Accent' switch on the far right was also replaced by an actual presence potentiometer on #005 and at least on one of SRV's amps, too: