Good Morning! I have what I THINK is a basic guitar question, that I can't seem to find a straight answer for on the interwebs. If your guitar volume is turned up full, would there be any noticable tonal difference between a 250k volume pot and a 500k volume pot, or 1M for that matter? It seems to me that if your pot is dimed, regardless of the total resistance of the pot, you're still only sending a few ohms to ground, so it shouldn't make any real difference until you start turning the knob. Am I missing something here?
Ongoing Pot Question...
- Thread starter magillver
- Start date
freefrog
Well-known member
If there were no differences, every guitar would host pots of the same resistance. ;-)
Even full up, a pot puts its resistance between pickup and ground. And yes, it affects the tone. Higher pot resistance = brighter tone.
Here is a video illustrating this, among many others: https://youtu.be/5u-6DHH_EuE?si=pJ3ThpspBqJtK-B0&t=168
FWIW. HTH.
Even full up, a pot puts its resistance between pickup and ground. And yes, it affects the tone. Higher pot resistance = brighter tone.
Here is a video illustrating this, among many others: https://youtu.be/5u-6DHH_EuE?si=pJ3ThpspBqJtK-B0&t=168
FWIW. HTH.
Even one 500k pot (single volume/no tone) makes a difference compared to no pots at all. Depending on the guitar and pickup, it can be enough to make it worth putting in a blower switch. 4 out of my 6 main players either have a blower, or have the bridge wired to the jack (or through a selector switch to the jack) because having a volume knob in the circuit took away the bite and top end I was looking for.
I appreciate the video freefrog, but the information isn't very useful, in that we don't know what his switch is actually doing, whether he's wired through multiple different pots somehow, or just has a bunch of resistors hooked up to it. My main question involves pots that are wide open. I took measurements from the input to the output of 5 wide-open pots, 5M, 1M, 500k, 250k, and 25k. Here are my results in that order:
0.6 ohms
3.4 ohms
10.9 ohms
62.1 ohms
4.1 ohms
When we're talking about that wide of a range of pot values and having a difference of roughly 60 OHMS, I can't understand how that would make any real tonal difference, unless the circuit is somehow getting some sort of transient resistance from the rest of the carbon path? I'm no EE, but that just doesn't make sense to me....
0.6 ohms
3.4 ohms
10.9 ohms
62.1 ohms
4.1 ohms
When we're talking about that wide of a range of pot values and having a difference of roughly 60 OHMS, I can't understand how that would make any real tonal difference, unless the circuit is somehow getting some sort of transient resistance from the rest of the carbon path? I'm no EE, but that just doesn't make sense to me....
freefrog
Well-known member
Once again, even when a pot is wide open / full up (and puts a very low resistance from pickup to output), it remains grounded on the other side, otherwise it wouldn't work. That's why 1M is brighter than 100k: it puts more resistance between pickup and ground (and therefore, it doesn't tame the resonant peak as much as a lower resistance pot would do).
If you prefer pics and graphics to a video, below is a whole topic dedicated to this question.
https://guitarnuts2.proboards.com/thread/7171/pot-values-load-pots
I think you hit the nail in the head for me, freefrog! I'm my mind I was discounting the remainder of the carbon path going to ground, but that's actually the 'transient' resistance I was thinking of previously...I put together a test rig guitar that I can experiment with, so I can just connect the input wire directly to the output wire, and at the junction I can insert various fixed frequency resistors to ground... Cool, thank you!
Chistopher
malapterurus electricus tonewood instigator
Also while we are yapping about pots, a 500k pot turned down to 250k will not sound the same as a 250k pot (obviously a volume 250k pot at 1o doesnt sound like a 500k pot at 5) is because a 250k pot at full has 250k ohm blocking the signal from going to ground and 0 ohm blocking it from going out the guitar, and a 500k pot at 50% has 250k ohm blocking the signal from going to ground and 250k ohm blocking the signal from leaving the guitar
Nothing groundbreaking, just not something thats posted in guitar forums too often
Nothing groundbreaking, just not something thats posted in guitar forums too often
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The math evades my brain today, so why would a 500k pot at full not have 0 ohm blocking the signal from going out the guitar while a 250k pot would?
Chistopher
malapterurus electricus tonewood instigator
Whoops, typing error. Ill fix it
Artie
Peaveyologist
If you hold your meter leads together, you could easily have a few ohms of resistance, through the leads themselves. Same for the wiper-to-pad internal connection. That's why I always do a little squirt of Deoxit or Faderlube an even a new pot. The resistance across the outer lugs is the only one that counts. That's the "load" that the pickup sees. The tone control is an additional load, but frequency dependent depending on the value of the cap. So with both pots on "10", with 500k pots, higher frequencies will "see" 250k, while lower frequencies will "see" 500k.