Adding Tone Controls to 2-Knob Fuzz Pedals

[debrad]

A friend has asked if I could build him an approximation of the Danelectro Eisenhower Fuzz and, from what I can find, it appears to be very similar to a Univox Super Fuzz with extra controls for Bass and Treble.

Over the past few days I have tried to educate myself on how tone controls are implemented on fuzz circuits and read some suggestions from musique.com and amzfx.

What I'm curious to know is whether I could build something close to the Eisenhower by simply adding something like musique.com's bass and treble circuits or the "Stupidly Wonderful Tone Controls" to the SF circuit and, if so, is it most effective at the end of the circuit like the amzfx site shows or would I be better off placing it in another location?

[iainpunk]

warning, the superfuzz is a complex circuit, and really easy to f#ck up. make sure that all transistors are low gain, use the 2 closest matched for the octave part etc...

i really recommend a James tone stack, or a baxandall if you don't mind an extra active element in the circuit.

put the tone control on the end, to shape the tone, put it in the beginning to shape the character. i guess that you'd be better off with putting it in the end.

cheers, Iain

[Vivek]

i really recommend a James tone stack, or a baxandall if you don't mind an extra active element in the circuit.

cheers, Iain

Given the low input impedances of these tone controls,

Maybe we need 2 active elements

With first one being a buffer

[debrad]

Thanks for the quick responses.  I appreciate your input and, as I continue to read similar discussion here in the DIYstompboxes forum and around the web, I also appreciate the relative complexity of what I'm asking (not to mention that the implementation might be a little above my skill level!).

Having said that, I love learning more about this stuff and hope that, with enough feedback, I still might be able to find a way to come up with something workable for this potential project.

Then again, maybe there is a reason why many of the "tone controls" I see on Super Fuzz inspired pedals just employ a potentiometer to access the range of tones in between the two settings of the original switch?

[Vivek]

I would think that almost any tone control can be added to almost any circuit

As long as we take care of

Impedances and loading of stages.
Insertion loss
Undesired clipping in tone control if tone control is active

This might mean active input buffer and/or active gain make up stage

There was a circuit posted here earlier called Bax in a box. That might give decent results in your application.


Alternatively, PCB GUITAR MANIA made many tone control circuits , to be used as add-ons to other circuits. Here's one example :


https://pcbguitarmania.com/product/active-eq/

[debrad]

Thanks for the reassurance Vivek.

Those Pedal_PCB_Mania EQ boards look VERY interesting!

[Vivek]

i entered this circuit in Spice. It appears to have a lot of interaction and loading effects

[GibsonGM]

i entered this circuit in Spice. It appears to have a lot of interaction and loading effects

Did you use a buffer before and gain stage after it in the sim?  Not that it DOESN'T have those issues - it will. Most tone controls will, including FMVs and so on.   

[Gus]

People have posted fuzzes and distortions with tone controls at this forum over the years.
Do a search here and on the web you should find things to read.

Doug H. added a tone control to a Silicon FF the "Hot Silicon" you can find with a search

A lot of fuzz "designs" are cut and paste  find a tone control section and add it the circuit.

here is a link with a one knob tone control. That tone control can be adjusted and it works well for a low parts count circuit.
https://www.diystompboxes.com/smfforum/index.php?topic=112341.msg1036524#msg1036524

[debrad]

I think that it may have been Doug H's implementation that I was reading late last night as I distinctly remember it was for a "Hot Silicon" implementation.

I honestly don't have a clue about the loading on the musique.com image I attached earlier so I'm quite sure it's affected just like you say.  Truth be told, it just caught my eye a) because it had "Bass+Tone" rather than they typical single "Tone" or the amp-like "Bass+Mid+Treb" and b) because I thought the general "in" and "out" points might give me flexibility in terms of placement in the Super Fuzz circuit.

What caught my eye with the "Stupidly Wonderful Tone Controls" was the way amzfx suggested that sticking it just before a volume/level control at the end of a circuit keeps the output resistance "constant so the volume does not vary as the tone control is adjusted" but, not knowing enough about impedance, loading, etc., I figured I should turn to the forum's expertise.

This iteration of the SWTC looks interesting...and relatively simple to implement if it doesn't cause more harm than good:



The description reads:

The next logical question is "How can we combine the two circuits?". After a bit of consideration, I found a way to accomplish this effect.

By adding a single resistor and moving the position of the tone control potentiometer, I have made a tone control circuit that has a response that can be altered from high cut to high boost as the knob is turned. As with the previous "Stupidly Wonderful" circuits, the output resistance is constant so the volume does not vary as the tone control is adjusted.

Suggested values for beginning experimentation are R1=10k, R2=47k, C1=0.022uF and 100k for the tone and volume pots.

[pinkjimiphoton]

Then again, maybe there is a reason why many of the "tone controls" I see on Super Fuzz inspired pedals just employ a potentiometer to access the range of tones in between the two settings of the original switch?

you could do that, a lot of people have. it kinda pans between different parts of the circuit tonally. but you could do it.  just hook up a pot the same way the switch is hooked up i guess. have to look at it, been years... but pretty sure ya could do it easy enough. may need a dual ganged pot, depending on how they'd wired the switch. a bigger pot will give more of an apparent "sweep"... do a search on faking variable caps.

but that's not really a tone control per se. its more like a blend control. adding the tone control at the end may be most useful for you with the least hassle. you can just graft it on the very end, probably, superfuzz has plenty of output as i recall.

[iainpunk]

the circuit you posted last, the SWTC cuts and boosts trebble. for a super fuzz, i think boosting treble can become harsh and un-useful, except if you want to sound like the Jesus and Mary Chain.

i guess that a Big Muff Pi tone control is more useful for a superfuzz type circuit, especially because it gives a little bit of mid scoop, which complements the superfuzz a lot.
if you want some vintage superfuzz tone, you could make a variable mid scoop circuit to go from ''fuzz1'' to ''fuzz2'' with a single knob just like this schematic:

(the mid-control is the part after the fuzz pot and before the volume pot.)

i think the above mid scoop is more useful than pink's sweep control, since his control always diminishes volume, and this only does that when the mids are scooped, not when its flat.

cheers, Iain

[pinkjimiphoton]

works for me, homie!

[debrad]

Thanks guys,

Those last two posts make me feel a little better about potentially grafting one of these onto the tail end of a Super Fuzz.

I haven't seen schematics of the Dano "Eisenhower Fuzz" but it seems like it's Super Fuzz with the Super Fuzz 2-position "Tone" switch (labelled "Flat/Scoop") AND controls for "Bass" and "Treble".  To that end, my plan was to build a Super Fuzz circuit WITH the 2-position switch AND some kind of tone control(s).  But maybe there isn't a lot of benefit to the additional tone controls...perhaps it makes more sense just to move the 2-position switch to a potentiometer or something more like Iain's "mid scoop" or a BMP tone circuit.

If the SWTC version I just posted doesn't make sense because of the option to boost treble, maybe one of the other SWTC variants would make more sense.

This one supposedly maintains output levels but always attenuates some of the highs:



While this SWTC-esque circuit supposedly has some pro's and cons (amzfx suggests "A simple change to the values of the capacitors will yield a response with more high end, which is a better response for modern rock styles (3n3 rather than 47n and 22n rather than 100n):

[pinkjimiphoton]

ya know, one of them great ideas i just now had and will probably never bother with doing myself, would be to take a couple hunks-0-veroboard or perf, and build a big muff pi tone control, maybe with a midrange option. i think the superfuzz would sound great like that, but i like disturbingly disgusting sounds others may find ludicrously revolting and potentially reverse peristalsis inducing in "normal" people unfamiliar with such disgusting stench emanating from my amplification. but do i care?

but seriously, a bunch of tone stacks on mini little daughterboards would probably be a great diy thing for someone smarter than me to pick up the ball and run with; simple pcbs for this stuff would be handy, and then ya can try them in any dang circuit you come across to see if it adds any tumescent factor to the circuit presently under mole station.


SWTC,BMP, bax, whatever... modularity may be worthy of consideration. try 'em all. if its a commercial project, ya kinda gotta KISS. after maybe 4 knobs peeps eyes tend to glaze over, and fear of too many unfamiliar options can make their drawers uncomfortably full, and many reviewers can't seem to grok them, either.
but for us demented freaks, unafraid of societal norms and sonic deviance?

hell... it may sound better with a tone control of some sort at both ends. a super fuzz should have more than enough nardzinal fortitude to work with, even tho there will  be some inevitable loss.

just tequila thoughts and psilly visions....

[debrad]

You have me searching for something stronger than the "like" button pinkjimiphoton...the sentiment (and the language in particular) put a big smile on my face!

Interestingly enough, Vivek's link to PCB GUITAR MANIA opened my eyes to a number of relatively modular tone stack PCBs available on that site and I suspect there might be other places with similar options.

For me, the bottom line of your message (or a least what I took to be the bottom line of your message) is that I should really stop theorizing on the "possibilities" and simply put solder to circuit.  Now that I know there is at least a chance that some of this might work, I won't really know if they add the right "tumescent factor" until I actually try them out!

Inspiring post my friend!

[pinkjimiphoton]

You have me searching for something stronger than the "like" button pinkjimiphoton...the sentiment (and the language in particular) put a big smile on my face!

Interestingly enough, Vivek's link to PCB GUITAR MANIA opened my eyes to a number of relatively modular tone stack PCBs available on that site and I suspect there might be other places with similar options.

For me, the bottom line of your message (or a least what I took to be the bottom line of your message) is that I should really stop theorizing on the "possibilities" and simply put solder to circuit.  Now that I know there is at least a chance that some of this might work, I won't really know if they add the right "tumescent factor" until I actually try them out!

Inspiring post my friend!

<3

yes, put iron to solder.... create! never fear the magick smoke leaking out, if it does, it just means innovation is around the corner.

damn. these shrooms are GOOD.

[Vivek]

the circuit you posted last, the SWTC cuts and boosts trebble.


cheers, Iain

I feel that the standard SWTC only cuts treble.

[Vivek]

For me, the bottom line of your message (or a least what I took to be the bottom line of your message) is that I should really stop theorizing on the "possibilities" and simply put solder to circuit.  Now that I know there is at least a chance that some of this might work, I won't really know if they add the right "tumescent factor" until I actually try them out!

While it is nice to keep theory aside sometimes, especially when fine tuning by ear a circuit that a technical due diligence has already confirmed should work,

I would not just add another stage to a circuit without first having an idea about impedances, signal levels and insertion loss.

I would put solder to circuit after first doing some math

[11-90-an]

well yes, basic theory is essential and all but... when you think about it... sometimes you can get so winded on the numbers and sims that you don't end up building anything... you can also spend all your time testing and building and not know the exact numbers but... this stompbox building... is about building, right?