Adding Tone Control Help

[Jallenfuzz]

Hey everyone, I wanted to add a tone control on to a Mark2 Tonebender. I don't want to build the 3 knob sola sound because I like the sound of the Mark2 better.  I was thinking about doing a simple one I found on BeavisAudio and putting it last in the circuit.  Anyone had any experience adding tone stacks to fuzz pedals? Any advice?

[midwayfair]

I find that the most useful tone controls in a simple fuzz are bass rolloff controls. A treble rolloff will usually mean a lackluster sound and exacerbate getting lost in the mix. There are two good ways to go about this:

1. Pregain bass rolloff - input cap blend or switch: Use a small input capacitor and put a larger cap and variable resistor (pot) in parallel with the smaller cap. As you turn up the pot, you decrease how much signal the larger input cap sends into the circuit, cutting the bass from the circuit. A variation of this is commonly used in Rangemaster treble boosters and sometimes in Fuzz Faces.

Here's an example (sorry for the ascii schematic):
      -----||-------    (100nF)
in --                    -- to Q1
      -||+--100KA--    (4.7uF) (500KA also works but could be overkill)

Less bass also means less signal overall, and therefore less distortion. This is particularly useful for dialing in similar levels of distortion and brightness between humbuckers and single coils, because typically driving the circuit really hard will cause the bass to overwhelm the treble. This is one reason humbuckers seem to get lost in the mix more easily when using Fuzz Faces or Tone Benders, and also why the 3-knob bender is considered a better bucker buzzer.

2. Post-gain bass blend. There are a couple ways to do this. You could do it just like above, but using different cap values, or you can take a look at the three knob Tone Bender, or the Buzzaround. Both of these fuzzes use a pot to pan between two output cap values, one really tiny for a thin sound, and one very big for a full sound. The difference between this and the input cap blend is that it will allow you to alter the tonality without affecting the gain structure.

Both 1 and 2 keep the output and overall tonality of the pedal relatively stable.

Other useful tone controls:

3. You can also use the Big Muff Pi tone stack, as long as your circuit has enough drive that the volume loss is acceptable. The Big Muff tone stack eats up a LOT of volume. It's more complicated, too, and requires more parts. The benefit is that it can give you a treble rolloff OR bass rolloff, and it can also be tailored to have no mid scoop (and hence a little less volume will be destroyed). AMZ has a good article on the BMP tone stack that might be worth a look

4. Stupidly Wonderful Tone Control. AMZ's version 2 works as a treble cut counterclockwise from noon and a treble bleed clockwise. (It sounds like a treble "boost" but really it's cutting a little signal overall and simply allowing more treble to pass without being cut. You don't hear it as a bass cut because when things are at neutral it's almost the same tonal response as the signal was before the tone control was added, just with a little less output.) I think this works great in overdrives, but it's lackluster in most fuzzes. There are some fuzzes that have enough high end content that cutting it post clipping can result in a smoother overall sound without getting lost. This is worth considering if you also do the input cap blend bass control and have a lot of drive volume, because then you can create a mid-hump and voice your fuzz more like an OD.

[selfdestroyer]

If you want to go the route of the Big Muff tone stack you can try these transfers I made and have tested. I use them to quickly test in circuits to see if they play nicely or not.

http://music.codydeschenes.com/wp-content/uploads/2013/05/BMP-Tone-Stack-TRANSFER.pdf
http://music.codydeschenes.com/wp-content/uploads/2013/05/BMP-Tone-Stack-Beavis-Tone-Mod-TRANSFER.pdf

Hope this helps.