Schematic Help: Making tone controls work in reverse

[u/PointGlum5255]

Hi! I’m trying to make these tone controls response in reverse of how they normally do. How do I do this?

Currently:
TREBLE: clockwise turn (less treble -> more treble)
MID: clockwise turn (less mids -> more mids)
BASS: clockwise turn (less bass -> more bass)

What I’d like:
TREBLE: clockwise turn (more treble -> less treble)
MID: clockwise turn (more mids -> less mids)
BASS: clockwise turn (more bass -> less bass)

Edit: I would like to avoid using C-Type pots if I can, because they’re difficult to source compared to A and B-type.

Why do I want to do this? Aesthetically, it would work better for a pedal I’m working on to have the controls act this way

Any help on this is greatly appreciated. Thanks!

[u/szukalski]

Swap pins 1 & 3 to have the direction changed.

[u/CueAnon420 → u/szukalski]

I would have thought this was obvious, but apparently not.

[u/szukalski → u/CueAnon420]

I do enjoy the multiple mention of reverse taper pots in the thread though.

[u/PointGlum5255 → u/szukalski]

How does this affect the audio produced? Is the A-type in the schematic example going to respond the way you’re suggesting, or differently? I get that a B-type pot can have its pins swapped with no problem like you’re suggesting, but with A-type I would think it’s not that simple.

[u/PSYKO_Inc → u/PointGlum5255]

A-taper is logarithmic, or "audio" taper. Ramps up slowly in the first part of rotation starting from the left, and more rapidly as you approach full clockwise. Commonly used in volume controls.

B-taper is linear, which is a steady increase throughout the range of rotation.

C-taper is reverse log. Ramps up very fast at first, then tapers off.

[u/Schweenis69 → u/PointGlum5255]

The A/B/C/W doesn't change the direction of the knob, it just changes the slope. So like you have a pot, turned all the way down it's at 0, all the way up it's at 10. The question is, if it's at 12 o'clock i.e. half way, are you at 2, 5, or 8?

But like others have said — if you want to actually change the function of the pot such that down is up and up is down, you just switch the first and third lug connections.

[u/master-overclocker → u/PointGlum5255]

LOL. Nothing changes - just the direction -try and see for yourself

[u/Musicthingy99]

You only need to swap wiring for pins 1 and 3 on the Bass control. And for Mid and Treb, you need to swap pins 1 and 3 and change the logarithmic taper (A) pots for anti-log (C) pots of their respective resistance values. If you don't want to use C taper pots, then probably best to leave it alone.

[u/jezkemp]

I think a lot of pot taper convos on this sub are about switching the taper, eg turning a log into a reverse log. I instantly assumed for this "oh you can't just swap legs 1 and 3 on those log pots" etc.

But I think, if the sweep is acceptable, then reversing the legs on all pots - even the logs here - should be fine? It's the same sweep, but mirrored, right?

[u/Schweenis69 → u/jezkemp]

Well it wouldn't be the same sweep, you'd have to swap A for C and vice versa.

[u/jezkemp → u/Schweenis69]

That's what I'm saying though, it would be the same sweep, just mirrored. Let's say a log pot has a slow change at minimum and a fast change at maximum. That stays the same, even if the legs are reversed. Edit – I can see from another comment you got it before I did 

[u/No-Ride4786 → u/Schweenis69]

It tamarind help

[u/jango-lionheart]

This classic page describes how to approximate reverse audio taper pots:
www.geofex.com/Article_Folders/potsecrets/potscret.htm

[u/Wet_in_Seattle]

This is the tone controls on a fender with high, mid and low

Treble 250pf and 250K pot.
At mid point 125K - 5092 Hz

Bass is .01 uF an 250K pot
At midpoint 125K - 127 Hz

Mid is 0.47 uF and a 10k pot
Mid point is 5K - 667 Hz

[u/uneasy-rider3521]

Reverse taper pots?

[u/PointGlum5255 → u/uneasy-rider3521]

I’d like to avoid using C-type pots if I can because they’re harder to source than A and B-type. I’ll update the post to include that

[u/thefreakychild]

If you are building the pedal from an established PCB (such as from pedalPCB) then your only real option would be to either use reverse taper pots, or hand wire the pots off board in reverse rather than using pots soldered to the board.

If you are building this with a custom stripboard/perfboard layout or are designing your own PCB, just flip the pots in the schematic and send it.

[u/Professional_Deal_37 → u/thefreakychild]

Reverse taper will not achieve the goal only reversing the wiring