Correct Big Muff Potentiometers

[lars]

I've built several different vintage Big Muff clones, and one of the most common mistakes I've seen on almost all schematics is using audio taper pots for volume controls. No version of the Big Muff ever used an audio taper pot in the original designs; they were always linear taper. This is especially critical in the op-amp version Big Muff. Putting an audio taper pot in the volume section kills the gain and shifts the tone stack frequencies so that it will never sound like an original. This common mistake is the main reason people always say the clones don't sound as good as the originals.

[selfdestroyer]

Very cool build and thanks for the information. I will make sure my OpAmp BMP is set up that way. I am curious since I do like the sound of my clone.

[rollo greb]

taper shouldn't affect sound in any way I don't think? Just the ease of dialing in a setting. The resistances between each lug and the wiper will be identical for both linear and log pots, just at different degrees of rotation on the dial. Assuming both pots are the same value.

[lars]

Taper does affect the sound of a pedal because the volume pot in most designs actually acts as a filter for different frequencies. In the case of the triangle knob muff, the volume pot acts as a high pass filter in conjunction with the final coupling capacitor. In an audio taper pot, the resistances are shifted from where they should be at different settings. So the circuit sees different resistances on each side of the pot than what the original design was based around, i.e., in a linear taper pot the resistance is 50/50 when the pot is set at half, whereas an audio taper is uneven. In the Op-amp version, the volume pot is directly connected to the tone pot, so it greatly affects the tone and gain when the resistances aren't correct.

[CRBMoA]

If a particular setting for the Vol - Tone - Sustain pots were to be, let's say, 75K for each pot, what the OP is saying is that the KNOBS will be pointing at approximately 2 O'clock with a Linear taper, whereas  Audio taper pots will be pointing closer to 4 O'clock.

But provided the pots are within spec, meaning that resistance between full CCW = 0K and full CW 100K, you CAN get identical sounds. The knobs won't look the same, but the circuit does not care. 75K = 75K, no matter how you get there.

cb

[bigmufffuzzwizz]

I fully agree with this..I switched over to using a linear pot for the volume as well. I really didn't like how the audio taper dialed in the last 50 percent of its range..especially since my muffs sit at volume max

[midwayfair]

If a particular setting for the Vol - Tone - Sustain pots were to be, let's say, 75K for each pot, what the OP is saying is that the KNOBS will be pointing at approximately 2 O'clock with a Linear taper, whereas  Audio taper pots will be pointing closer to 4 O'clock.

But provided the pots are within spec, meaning that resistance between full CCW = 0K and full CW 100K, you CAN get identical sounds. The knobs won't look the same, but the circuit does not care. 75K = 75K, no matter how you get there.

cb

^this.

[CRBMoA]

I fully agree with this..I switched over to using a linear pot for the volume as well. I really didn't like how the audio taper dialed in the last 50 percent of its range..especially since my muffs sit at volume max

Not to contradict myself, but the Magic Man IS correct in that you will quite probably find a linear taper more forgiving when trying to dial tone, owing to that fact that the resitance changes, well, in a linear fashion as you dial the knob, whereas an audio taper WILL tend to bunch the effacacy of the pot toward the last third of the rotation.

And I do recognize that BMPs were shipped with Linear pots. My point was on to clarify that, notwithstanding ease of use and orientation of the actual knobs, a 100K pot is a 100K pot, regardless of taper.

[bigmufffuzzwizz]

just as a random thought has anyone tried to use a reverse taper (100kc)? If it worked in theory the first half would bunch and then leave a very spread out last 40% for fine tuning max volume..