advice on volume pot/ pickup problem

[ggunn]

ggun, find one piece of information that indicates that guitar electronics are AC, alternatiing current and I will apologize. This I gotta see.

Acorec, thank you for your explanation, that is exactly what I was indicating but did not explain out as eloquent as you.

What he said had nothing to do with what you said. He said...

...using higher value pots (500K) will give the guitar a brighter sound and lower value pots (250K) will give the guitar a slightly warmer sound. This is because higher value pots put less of a load on the pickups which prevents treble frequencies from "bleeding" to ground through the pot and being lost.

...which makes sense because the extra loading on the pickup from a smaller pot lowers the frequency response of the first order LC circuit made up by the inductance of the pickup and the resistance of the pot, producing a darker sound. In fact, he said exactly the opposite of what you initially said; you said that a lower value pot gives you a brighter sound. Here, I'll quote you:

As mention before the 1k pots are passing a lot of highs. I used these for years with solid state amps but when I went back to a tube amp, I went back to 250 and 500 pots on my guitars...I got tired of the super treble thing.

Beyond that, ANY audio signal is, by definition, AC (DC is an AC signal of 0 Hz). Capacitors and inductors are AC circuit components; to DC, inductors are shorts and capacitors are opens. The only DC in guitar electronics are the power supply nodes in active circuits, and most guitars don't have them. If there's no battery, there's no DC.

There's lots of different flavors of AC; I didn't say that you have to plug your guitar into a wall socket, fer chrissakes! ;^)

Look, I apologize if I've said anything that offended you. I'm an engineer (I have studied this stuff, although it's been a while), and I enjoy getting into technical discussions and getting to the bottom of things. I've been told that I can be a bit abrasive at times, and I guess that's true.

Peace,

 

[Light]

*except for a tiny amount of signal bleed to ground through the pot resistor. A lower value pot loses more signal to this effect, not less.

You just answered your own question, but you are forgetting one of the basic truths of audio. High frequencies are much more delicate than low frequencies, which means when a lower value pot bleeds off signal, it is taking more high frequency information than low, which is why a high value pot is brighter than a lower value pot.


Light

"Cowards can never be moral."
M.K. Gandhi

 

[ggunn]

You just answered your own question, but you are forgetting one of the basic truths of audio. High frequencies are much more delicate than low frequencies, which means when a lower value pot bleeds off signal, it is taking more high frequency information than low, which is why a high value pot is brighter than a lower value pot.

It's grand when we all agree, ain't it? Can we agree that it's about time to go grab a beer?

 

[ggunn]

BTW, when you guys said "1 k" (1000 ohms) did you really mean "1 M" (1,000,000 ohms)? This whole discussion would have made a lot more sense to me if that were the case.

At any rate, we all ran off talking about frequency response, but the OP was asking about his too-hot signal. I think (given what I've learned today) that changing from a 1 M ohm (if that's what he meant) pot to a 500 k would make his guitar sound a little darker, but wouldn't have much effect on amplitude or distortion.

 

[Light]

As far as volume affecting tone, it happens not from the volume pot, but the tone control and associated cap(s). For sure if you back the volume off on a Strat, you can get treble loss. But only because the tone pot and cap are still in the circuit.

Yes...and no.

That is certainly an issue, but there is a tone difference between different value volume pots as well. And that is before we even get into the whole high frequency loss as you turn the volume pot down. There is a whole other mod for that, which involves soldering a very low value cap (usually a .001mf or a 670 Pico fared) between the input and output on the volume pot. I don't like this at all, as it makes the overall guitar a bit brighter, which is not what I am looking for, myself.

I have seen (and done) a tone pot mod, opening it up and scraping the carbon off the track at the full up position, so the pot and cap are totally out of the circuit when the tone control is full up. No more treble loss when rolling off the volume.

Some Fender guitars have had this or a similar mod stock from the factory, where the goal is to bypass the tone circuit.

Fender sells a "True Bypass" pot, but again, I don't really see the need, personally. If I played country, then I would see it, but of course, I don't play country.


Light

"Cowards can never be moral."
M.K. Gandhi

 

[Light]

BTW, when you guys said "1 k" (1000 ohms) did you really mean "1 M" (1,000,000 ohms)? This whole discussion would have made a lot more sense to me if that were the case.

I am pretty sure I said that in my first post to this guy:

Even if it does have a 1meg pot (I assume that is what you meant), that should just make it a bit brighter than a 500K pot.

I've never seen anyone use a 1K pot for, well, anything in a guitar.


Light

"Cowards can never be moral."
M.K. Gandhi

 

[boingoman]

Yes...and no.

That is certainly an issue, but there is a tone difference between different value volume pots as well.
Light

"Cowards can never be moral."
M.K. Gandhi

Yeah, something I never really though about till now.

 

[Middleman]

Yeah that was my bad. I was thinking K and applied that to the 1M. From now on I'm just going to let Acorec be my publicist because he knows what I'm thinking even when I state it wrong. A little eery actually.

 

[ggunn]

Couldn't the OP do a Q&D check of what changing from a 1 M pot to a 500 k pot would do for/to his sound (at least in the full up position) by soldering a 1 M resistor from the hot pin of his volume pot to ground?