tone stack module layout

[gaussmarkov]

i'd like to offer a specific follow-up on something that has been floating around in many places in different forms.  acknowledgements to r.g. keen, wampcat1, doug hammond, runoffgroove, martymart, electrictabs.  no doubt others have thought of this sort of thing and maybe even executed this.

after designing a layout for doug hammond's meteor, i started thinking it would be nice to take the tone stack off the main pcb.  it would make the rest of the pcb a lot neater.  also it could be in the spirit of the rog breadboard power module, for experiments.  a lot of folks like to experiment with removing/replacing the tone stack from amp emulation circuits as well as inserting them into various distortion circuits.  so that's pretty simple for a lot of us.  but i doubt that i am going to get all the details right.  so i am offering a draft of a marshall tone stack module in the hope that it's helpful to some and that i'll learn something from feedback.

my goal is to create a narrow perf/pc board layout that fits easily over the lugs of treble, mid, and bass pots (in case i want to box it this way).  as far as i can tell from other schems and something martymart noted, a tone stack module generally needs an input buffer--so i put a j201, as in the dr. boogey q5, at the input.  i did not put anything in front of the j201 but looking at rog's tonemender (as well as many other circuits) i wonder if a pull-down resistor and an input cap to block possible dc (after all this is a module) would be wise?  an output cap too?  the values in the schem are taken from the duncan amps tone stack calculator version of the marshall tone stack.  electrictab's dr. boogey tone stack has similar values.  are there better choices for a starting point?

if this is useful, then it would seem like a good thing to have a library of these:  fender, marshall, bmp, bsiab2, ...

thanks for any help.  you should see 2 images below, a schem and a layout.  in the layout the red is for wires, blue for traces on the board.

[Edit:  OK.  I can see that what I have here is also essentially what is in rog's thunderchief with the tone stack added.  I learned this from Bucksears' recent topic http://www.elixant.com/~stompbox/smfforum/index.php?topic=41314.msg297888#msg297888 and the cite there by RDV.  Bucksears and I have similar questions.]

[b_rogers]

its definitly a good idea...maybe a recovery stage after the stack? is it needed even though there is a buffer in front?

Brent

[gaussmarkov]

its definitly a good idea...maybe a recovery stage after the stack? is it needed even though there is a buffer in front?

Brent

cool.  thanks for your comment.  i wondered about a recovery stage, too.  sometimes it seems unnecessary.  like in the dr. boogey where the tone stack (including the presence control) heads straight into a 1M volume pot.  perhaps you just have to experiment.

my other thought is that once you add a recovery stage, you are on your way to something like the runoffgroove tonemender, a stompbox itself.   i wonder how simple a tone stack module can be and still be useful.

[MartyMart]

I think this is a great idea, in particular for use after these and similar ROG amp sims, you dont
need three or four "eq knobs" for every one do you ? so a generic "Tone module" makes sense
I think that a more standard 5088 recovery tranny, with a 100k out pot, would work fine.
A gain of 4 - 5 will do after this tone stack ... no  ??
It will all fit in a 1590B .... just  !
You could use a large box and include say a "Matchbox" - "Prof tweed" - "Dr boogey" and a JCM800 sim ..
followed by one nice tone stack ....
Or perhaps build one and incorporate the "condor", or the "simple sim" at the end ....

Nice one,

Marty.

[gaussmarkov]

I think this is a great idea, in particular for use after these and similar ROG amp sims, you dont
need three or four "eq knobs" for every one do you ? so a generic "Tone module" makes sense
I think that a more standard 5088 recovery tranny, with a 100k out pot, would work fine.
A gain of 4 - 5 will do after this tone stack ... no  ??
It will all fit in a 1590B .... just  !
You could use a large box and include say a "Matchbox" - "Prof tweed" - "Dr boogey" and a JCM800 sim ..
followed by one nice tone stack ....
Or perhaps build one and incorporate the "condor", or the "simple sim" at the end ....

Nice one,

Marty.

thanks, marty.   if we go all the way to adding a recovery stage, then we might as well consider active filters, too.  i kind of like this idea because of the additional flexibility it allows in filter characteristics.

[nero1985]

I did it to my BSIAB2 but it really lowered the output level, and it has a 5.6k on the source, youur layout has a 10K i would say try a 1K im still waiting from my parts to get this done to mine, i should do it tomorrow.

[stm]

In a sense whats discussed here was one of the motivations for the Tonemender.  It uses a dual opamp for buffering and gain recovery, and a modified Fender tonestack that covers both Fender and Marshall sounds.