Post by ahamm on Feb 25, 2024 2:36:14 GMT -5
I know this seems a bit overkill, but I have an idea for a volume pot with a variable pot value. It would consist of dual concentric pots, where the top is the true volume pot and the bottom serves to effectively control the pot value of volume pot. The principle comes from the idea of putting a resistor to ground, parallel to the volume pot’s connection to ground (sometimes this is done with a switch to change between a 500k and a ~250k pot). The difference here is that the instead of a simple resistor, it would be another potentiometer. Here is a sketch imgur.com/a/ID46fZJ.
I’d like to add for those who don’t know, when you add resistors in parallel, the resistance actually decreases. It follows the equation: Rtotal=(1/R1 + 1/R2 + 1/R3 + …)^-1 (for those who care about math). This makes sense if you think of the fact that even though you are adding another resistor, you are really adding another pathway which allows the electricity to travel through easier.
The biggest reason we care about pot values is that it determines the resistance to ground when the volume knob is 10. The lower the resistance, the more signal leaks through to ground and is lost, especially higher frequencies. A higher pot value will get you a stronger signal with a crisper sound (more highs), but a lower value can give a better tone for some pickups, especially single coils. This would give you control over that at the twist of a knob.
I believe this would be most useful with 1MΩ pots, and bottom pot being modified as a no load pot (https://www.youtube.com/watch?v=fBLp53iNCf4 this video makes the conversion look quite easy, and I would assume it would be just as easy on a concentric pot). The resistive track would be cut at the side of lug 3. This way, you could have a 1M pot, a slightly less than 500K pot, and anything lower than that.
I also know that this wouldn’t completely be like having a different pot value, as you can’t change how much resistance is added along the hot path per amount of rotation of the volume knob, you only can change the resistance to ground. If my theorizing is correct, when the top pot is turned less than 10, along with decreasing the pot value it also makes the audio taper of the volume pot more extreme, ie turning the volume knob down a little will turn the volume down more than normal. I’m not too worried about that really, I don’t think that would be an issue that matters to me.
I’m planning on rewiring a strat soon and I’m thinking about trying this out. There will be a humbucker in the neck (Seymour Duncan JB Jr) and bridge (JB), and I will have a 4pdt on-on-on switch to split them or have them in parallel. These pickups supposedly have good single coil tones, and I think it would be nice to have lower pot values to go along with that, along with higher pot values for humbucking mode. I think I would also make the tone knob a no load, so that the new fancy volume knob is the only pot value that really matters. If you’re wondering about the 3rd knob, I plan on making it a bass cut knob, also no load.
I made a Desmos graph to show the effective pot value as a function of what the knob is turned to (1-10) www.desmos.com/calculator/wxxlhavtei. Blue is the effective pot value while red is resistance of the pot that controls the pot value. The slider for ‘a’ controls the pot’s taper. Keep in mind, a pot value of 250k is like having a 500k tone and volume pot (from what I’ve read, the tone’s capacitor doesn’t do much at these high resistances). 125k is like 2 250k pots. This is assuming the other pots are no load pots (like I plan on).
What do you all think of this? Any suggestions? Should I try it? I know it is definitely overkill, but it seems like a cool idea and it is relatively simple and may turn out to be decently useful. As a disclaimer, I don’t actually have any experience with this stuff, I’ve never messed with guitar wiring, but I’ve been reading quite a bit and it’s something I definitely want to get into.
I’d like to add for those who don’t know, when you add resistors in parallel, the resistance actually decreases. It follows the equation: Rtotal=(1/R1 + 1/R2 + 1/R3 + …)^-1 (for those who care about math). This makes sense if you think of the fact that even though you are adding another resistor, you are really adding another pathway which allows the electricity to travel through easier.
The biggest reason we care about pot values is that it determines the resistance to ground when the volume knob is 10. The lower the resistance, the more signal leaks through to ground and is lost, especially higher frequencies. A higher pot value will get you a stronger signal with a crisper sound (more highs), but a lower value can give a better tone for some pickups, especially single coils. This would give you control over that at the twist of a knob.
I believe this would be most useful with 1MΩ pots, and bottom pot being modified as a no load pot (https://www.youtube.com/watch?v=fBLp53iNCf4 this video makes the conversion look quite easy, and I would assume it would be just as easy on a concentric pot). The resistive track would be cut at the side of lug 3. This way, you could have a 1M pot, a slightly less than 500K pot, and anything lower than that.
I also know that this wouldn’t completely be like having a different pot value, as you can’t change how much resistance is added along the hot path per amount of rotation of the volume knob, you only can change the resistance to ground. If my theorizing is correct, when the top pot is turned less than 10, along with decreasing the pot value it also makes the audio taper of the volume pot more extreme, ie turning the volume knob down a little will turn the volume down more than normal. I’m not too worried about that really, I don’t think that would be an issue that matters to me.
I’m planning on rewiring a strat soon and I’m thinking about trying this out. There will be a humbucker in the neck (Seymour Duncan JB Jr) and bridge (JB), and I will have a 4pdt on-on-on switch to split them or have them in parallel. These pickups supposedly have good single coil tones, and I think it would be nice to have lower pot values to go along with that, along with higher pot values for humbucking mode. I think I would also make the tone knob a no load, so that the new fancy volume knob is the only pot value that really matters. If you’re wondering about the 3rd knob, I plan on making it a bass cut knob, also no load.
I made a Desmos graph to show the effective pot value as a function of what the knob is turned to (1-10) www.desmos.com/calculator/wxxlhavtei. Blue is the effective pot value while red is resistance of the pot that controls the pot value. The slider for ‘a’ controls the pot’s taper. Keep in mind, a pot value of 250k is like having a 500k tone and volume pot (from what I’ve read, the tone’s capacitor doesn’t do much at these high resistances). 125k is like 2 250k pots. This is assuming the other pots are no load pots (like I plan on).
What do you all think of this? Any suggestions? Should I try it? I know it is definitely overkill, but it seems like a cool idea and it is relatively simple and may turn out to be decently useful. As a disclaimer, I don’t actually have any experience with this stuff, I’ve never messed with guitar wiring, but I’ve been reading quite a bit and it’s something I definitely want to get into.
