When humbuckers are wired with a volume and tone, in general they are both 500k pots. My understanding is that two 500k pots equals a resistance of 250k. If that is the case, and you only want a volume to control the humbucker without the tone, should you simply use a 250k pot? Or, is it more complicated? What pot should I use for a volume with no tone on my humbucker?
Single Volume on Humbucker?
- Thread starter Luxu
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freefrog
Well-known member
A single 500k volume pot = roughly 2dB added to the resonant peak of a humbucker. It gives more sizzle, in the EVH fashion.
EDIT- If you want to see the action of resistive loads on resonant peaks, see for instance the fig. 14 in this page: http://buildyourguitar.com/resources/lemme/
There's many other pages of the same kind showing the same thing but this one was among the firsts so I share the link.
A single 250k volume pot gives exactly the same resonant peak than a 500k volume pot + 500k tone control when pots are full up. The differences are...
-harmonics, a tiny wee bit affected by the tone capacitor, even when the tone pot is full up. This difference is minuscule and might even be not really perceptible in some situations but it's there (lab gear and 5Spice sims can detect it);
-the TAPER of the volume pot and its darkening action... a 250k @ half its resistance puts only 125k between hot and output but also only 125k between output and ground so it darkens the sound more when lowered.
If you want to mimic the -2dB rounding action @ resonance of a 500k tone pot full up without loosing the taper of a 500k volume control, put a 470k or 520k resistor in series with a 22nF (0.022µF) then solder the whole from output to ground. I've done that sometimes (and legends tell that EVH had hidden a fixed tone pot in the cavity of his Frankenstrat. If he had used a trim pot or a resistor, it would have been the same).
FWIW: my two worthless cents, not far from the price of a resistor.
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beaubrummels
Well-known member
Yes, it's more complicated. The tone is not in series to hot, the tone is tapped off the volume or switch to ground, so the pickup is not seeing R1 + R2 in the hot signal path. In general, I'd stick with 500k volume for humbuckers and 250k volume for single coils. If you still have problems, you can use other values to help troubleshoot the problem, but that is rarely needed IME.
Thanks, everyone! I dug out two 500k pots and a cap and wired them up as one volume and one tone. It sounds very different from simply one 250k as a volume. It really sounds much better with the two 500k and cap as volume and tone. To my ears, it is warmer and more balanced. I am going back to the traditional wiring. Thanks for sharing your knowledge; it really helped!
freefrog
Well-known member
For the record, 500k volume + 500k tone = 250k resistive load, exactly like a single 250k pot in theory. If you hear a difference, it's most likely because the 250k and 500k pots involved have a lower or higher resistance than mentioned... If you had a "250k" pot measuring actually 271k and have swapped it for a pair of "500k" pots measuring each 440k (and giving 220k once in parallel), it's logical to find the sound warmer with two pots. The filtering of harmonics by the tone cap, even with the tone control full up, might be at play as well but is generally not so obvious than a variation of resistive load.
Anyway, glad for you if it worked. Enjoy!
Ah. That makes sense. One more question: Do you recommend I keep experimenting? Or, is it just smart to stick with the Duncan recommendations? I took the tone out originally because I don't use it and it seems like the simpler the better when I mess around with pickup swapping. Although, in my attempt to keep it simple I seem to have created more work for myself--the curse of the amateur. The 500k volume alone seems a bit harsh to me (it is a Custom SH-5 with an already strong top end).
freefrog
Well-known member
I've nothing against the Duncan recommendations, of course, but a guitar tone depends on many things. So, if you find your SH5 a bit harsh with a 500k volume alone in your guitar, you might be interested by the "fixed tone control emulator" evoked in my 1st answer above: a 470k or 520k resistor in series with a regular tone cap and the whole soldered from hot to ground. It's cheap, easy to do and reversible.
