Chuck D. Bones
Circuit Wizard
So how do know which taper to use? It really comes down to how the circuit responds when we turn the knob. For the most part, A-taper is good for GAIN and VOLUME knobs where we want to be able to easily access settings over the full range of rotation. Examples: The maximum output from a TS is around 825mVp-p. The pickups on my Tele output around 150mVp-p. Unity is around 4 on the VOLUME knob. B-taper is fine here. Vintage Fuzz Faces can barely get to unity with VOLUME dimed, so B-taper is good there too. A Skreddy Hybrid Fuzz Driver outputs 2.5Vp-p with all knobs at 5 except VOLUME at 10. Unity with my Tele is around 2.5 on the A-taper VOLUME knob. If it was B-taper, unity would be below 1, not good. Now maybe you don't want to set your OD pedal to unity. You want to overdrive your amp, so you set the VOLUME knob waaaaay above unity. B-taper might be good for that too.
Tone stacks use a variety of tapers, depending on the tone stack and its tuning.
The FMV tone stack is typically B-taper for TREBLE & MID, A-taper for BASS. I have also seen A-taper used for TREBLE. Play with the Tone Stack Calculator and see how the different tapers respond.
Baxandall tone stacks are almost always B-taper and that provides a smooth sweep from min to max with flat freq response in the middle.
The passive James tone stack, like the one found in the Orange amps and the Viceroy pedal, use A-taper. It works well up to around 8, then a lot happens between 8 and 10. The freq response is flat when both knobs are at 5. B-taper works well above 5, but is very touchy below 2 and the freq response has a mid scoop when both knobs are at 5.
Graphic EQs normally use B-taper, but the impedances have to be carefully matched, otherwise the knobs (or sliders) get very touch at the ends. This is why TS typically uses W-taper for the TONE knob. It smooths out the ends of rotation. With the right impedances, B-taper works well in the TS.
The variable-freq treble cut in the Rat uses an A-taper pot, but it's wired backwards (max treble cut at 10). If we wire it for "normal" rotation (max treble cut at 0), then we need C-taper.
The GAIN knob on a BluesBreaker is B-taper and the circuit is specifically designed to work with that taper. If you start fiddling resistors values to increase the gain, then C-taper might work better for you.
FuzzFaces have historically used both B and C-taper for the FUZZ knob. If you're just going to dime the FUZZ knob, then the taper doesn't matter. But as soon as you start backing off from 10, there is a HUGE difference between B and C-taper. C-taper is much smoother from 8 to 10.
The Carcosa uses B-taper for the BEFORE knob, C-taper for the AFTER knob and A-taper for HICUT and OUTPUT. The result is every knob has a smooth sweep across its entire range of rotation.
Very often, pot taper is subjective and it depends on individual preferences. If we never turn the knob below 2 or above 8, then our choices may be different from someone who wants to go from 0 to 10.
W-taper is like A-taper from 0% to 50% rotation and C-taper from 50% to 100% rotation. The taper at the two ends is more extreme than 15% A- or C-taper because the A- and C-taper sections each have to fit into half of the total rotation. The main use for W-taper is in balanced EQ circuits like we see in the TS or graphic EQ pedals. It might also be useful in some circuits as a BLEND pot.
Tone stacks use a variety of tapers, depending on the tone stack and its tuning.
The FMV tone stack is typically B-taper for TREBLE & MID, A-taper for BASS. I have also seen A-taper used for TREBLE. Play with the Tone Stack Calculator and see how the different tapers respond.
Baxandall tone stacks are almost always B-taper and that provides a smooth sweep from min to max with flat freq response in the middle.
The passive James tone stack, like the one found in the Orange amps and the Viceroy pedal, use A-taper. It works well up to around 8, then a lot happens between 8 and 10. The freq response is flat when both knobs are at 5. B-taper works well above 5, but is very touchy below 2 and the freq response has a mid scoop when both knobs are at 5.
Graphic EQs normally use B-taper, but the impedances have to be carefully matched, otherwise the knobs (or sliders) get very touch at the ends. This is why TS typically uses W-taper for the TONE knob. It smooths out the ends of rotation. With the right impedances, B-taper works well in the TS.
The variable-freq treble cut in the Rat uses an A-taper pot, but it's wired backwards (max treble cut at 10). If we wire it for "normal" rotation (max treble cut at 0), then we need C-taper.
The GAIN knob on a BluesBreaker is B-taper and the circuit is specifically designed to work with that taper. If you start fiddling resistors values to increase the gain, then C-taper might work better for you.
FuzzFaces have historically used both B and C-taper for the FUZZ knob. If you're just going to dime the FUZZ knob, then the taper doesn't matter. But as soon as you start backing off from 10, there is a HUGE difference between B and C-taper. C-taper is much smoother from 8 to 10.
The Carcosa uses B-taper for the BEFORE knob, C-taper for the AFTER knob and A-taper for HICUT and OUTPUT. The result is every knob has a smooth sweep across its entire range of rotation.
Very often, pot taper is subjective and it depends on individual preferences. If we never turn the knob below 2 or above 8, then our choices may be different from someone who wants to go from 0 to 10.
W-taper is like A-taper from 0% to 50% rotation and C-taper from 50% to 100% rotation. The taper at the two ends is more extreme than 15% A- or C-taper because the A- and C-taper sections each have to fit into half of the total rotation. The main use for W-taper is in balanced EQ circuits like we see in the TS or graphic EQ pedals. It might also be useful in some circuits as a BLEND pot.
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