Stupidly wonderful tone control

[John Lyons]

now how about a switchable nF or half across the outer tonepot lugs?
(variable notch bridged-T).

Well there you go!  Proof positive that:

a) international cooperation is a good thing, and
b) two heads ARE better than one!   

Okay, let's take it a step further.  Let's leave one end of the bridging cap tied to the junction of the two pots, and send the other "free" end to the common of a 3-way SPDT toggle.  The toggle now reroutes the free end to ground, to nowhere, OR to the other end of the tone pot.

This yields the original configuration of a variable lowpass, the tweakable bridged-T you wisely noted, plus a bizarre sort of 2-pole lowpass with a quirky sort of response.  Note that when the tone pot is set at max resistance in this latter setting, the two caps now become parallel caps, increasing the combined capacitance and lowering the rolloff frequency.

Man, that's a whole lotta tonal possibility for a pot, two caps, and a toggle!

If a person wanted to get truly freaky, use the 3-way toggle as described, but have one of the side positions bridge the input and wiper of the volume pot for a treble bypass, and the other side position birdge the T as described.  This could provide crude types of bandpass, notch and lowpass response.  I like it!

Mark
Is this what you were getting at with this one?
Did you end up trying it (I know...it was a while back...)



Thanks

John

[Mark Hammer]

After rereading the post of mine that prompted your drawing, yes that is exactly what I was suggesting.  Have I ever tried it?  No, but once you draw it out, it looks tempting.....

[John Lyons]

Ok, thanks for the confirmation Mark .
I was doing some archive digging and came across some other notch filter notes for the shin-Ei and Superfuzz with similar theories on this theme. I'll have to test these out.
Thanks!!

John

[Gus]

Saw this at the other forum from 1966 look at the tone control
https://www.freestompboxes.org/viewtopic.php?p=289322#p289322

[Mark Hammer]

Yup, not my idea at all.  I just gave it a catchy name.  I forget where I first saw it, but it made me think "Hey, I could do that too!  That could be really useful."

[amz-fx]

Saw this at the other forum from 1966 look at the tone control
https://www.....org/viewtopic.php?p=289322#p289322

Posted 12 years ago: http://www.muzique.com/news/cheap-fuzz-again/

 

Best regards, Jack

[Mark Hammer]

Excellent!  Good catch, Jack! 

[Vivek]

Here is what LTSPICE said re the SWTC values chosen in the Wampler Ecstasy:

[iainpunk]

quite a while ago i worked on a filter that switches from being a lowpass to a notch using a toggle, and a single pot determined the depth of both filters (depth, not frequency) the SWTC circuit reminds me of it. kind of the fuzz 1/2 switch on a super fuzz, but with variable depth. the scoop was at 500-ish Hz and the low pass was at 1500Hz, and they were tuned to deliver similar level drops so that switching over didn't change output volume.

it really needed to be driven by a low impedance source to keep the response the way i wanted it, but worked fantastically. ill look in to my note book if i can find its schematic, maybe even with values of the filters.

cheers

[GibsonGM]

I'd like to see that, Iain...maybe something a little more fun than just 'the usual hi cut'!  Maybe if used in conjunction with something else...bass cut etc.

[iainpunk]

I'd like to see that, Iain...maybe something a little more fun than just 'the usual hi cut'!  Maybe if used in conjunction with something else...bass cut etc.

I originally planned to put a bass cut before the distortion circuit, and that switchblade tone stack behind it.
Right now im looking my notebook in my moving boxes, I think ill be back in like 15 minutes with pictures

Cheers

[iainpunk]

Right now im looking my notebook in my moving boxes, I think ill be back in like 15 minutes with pictures

Cheers

So.... In the meantime, i accidentally burned dinner, had to get new meat and got distracted by starting over.



Here's two versions of the stack, i think i ended up using the top one, as its a bit more elegant.

Cheers