250k or 500k for JB and PG-esque humbuckers?

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daveyisgreat

New member
I've got some pickups on the way, supposed to be based on the JB and Pearly Gates. They will be going into a superstrat type parts guitar with an alder body and maple neck (supertele, actually). So I'm gathering some of the electrics and I'm trying to decide if I want to use 250k pots or 500k pots. I've had excellent results with both, but I'm leaning towards the 250k because my other guitar has the same setup, alder body with maple neck, stock JB and PG, 250k pots, and I do really love how it sounds. Any advice or suggestions?
 
Re: 250k or 500k for JB and PG-esque humbuckers?

The added load of the 250k over the 500k pot lowers the treble by dropping the Q factor. The tone control also lowers the Q factor in the top portion of the sweep, and doesn't really move the resonant peak until you reach the bottom of the weep. IOW, turning down the tone control with 500k will be similar to, if not the same as, using a 250k pot.


Here's what increase load does to the peak. When the sharpness of that peak drops, it means the Q factor is decreased.
pick-up-frequency-response-with-load.gif


and here's what turning down the tone knob does to the peak:
ToneControlGraph.jpg


As you can, the tone knob does essentially the same thing between 5 and 10 as the increased load of a lower value pot, so get a 500k pot and just rest the tone at 8 or 9, and allow yourself the added bite should you ever need it.
 
Re: 250k or 500k for JB and PG-esque humbuckers?

Awesome info! Does the tone pot value matter, or must it be a no-load pot? I never realized there was so much to it!
 
Re: 250k or 500k for JB and PG-esque humbuckers?

A "no load" pot isn't necessary. The volume and tone pots combine to represent an overall load, so if both are 500k then it will be brighter than if you have one 500k and the other 250k (doesn't matter which).
 
Re: 250k or 500k for JB and PG-esque humbuckers?

Nice chart drex, but the Psycho-acoustic experience of turning a pot down is NOT the same as using a 250/500k pot.

I agree - you get an approximation, but a real 250 will sound better than a 500k turned down to most people, and many dogs.
 
Re: 250k or 500k for JB and PG-esque humbuckers?

Aceman said:
... a real 250 will sound better than a 500k turned down to most people, and many dogs.
Click to expand...

I do love the sound I get with the 250k. It was a wiring kit set up for a tele, so it had a .047uf cap with it and I just went with it. I'd think I'd be more comfortable sticking with what I know I like and am familiar with.
 
Re: 250k or 500k for JB and PG-esque humbuckers?

Aceman said:
Nice chart drex, but the Psycho-acoustic experience of turning a pot down is NOT the same as using a 250/500k pot.

I agree - you get an approximation, but a real 250 will sound better than a 500k turned down to most people, and many dogs.
Click to expand...


+1. Over the years, several knowledgeable members have detailed why turning down a tone pot on 500K does not, and cannot, sound the same as using a 250K. I think one of them may have been RayBarbee a couple years ago. I much prefer the sound of 250K's on most of my bridge PU's; not thrilled with the sound of 500K's with the tone pot turned down. Takes off some treble, but it's a different sound.

I 'get away with' 250's because I use 9's in standard tuning and use beveled edge picks (which add bite). For guys with thicker strings and/or down-tune, 250K's may be too dark. There's no right or wrong in what pot values anyone uses or whether or not they adjust their tone pots. Audiences don't know and don't care. The final sound is all that matters.
 
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Re: 250k or 500k for JB and PG-esque humbuckers?

Keep in mind that when people talk about 250k versus 500k and "turning down a knob", they usually mean "turning down the volume knob", not the tone knob, which is very much not the same thing. When you turn down the volume knob you're not just increases the load, you're putting resistance between the positive lead and the pickups, which increases the overall resistance / impedance of the circuit, but when you turn down the tone knob the load drops but there is no added resistance in series with the pickup, same as if you switch between 250k and 500k pots.

You can see from the frequency charts that the tone knob load increase is doing the same thing as a pot value load increase, and so I'd be skeptical of claims that anyone can hear that difference. The reason you might like a 250k pot better than a turned down tone knob is because when you plug a 250k pot guitar into an amp, you tweak the EQ kbobs on the amp so that it sounds good with all the guitar's knobs at 10. When you plug in a guitar with 500k pots, again, you set the amp to sound good with all the knobs at 10, which probably means less treble since you don't need as much of it with 500ks, so now when you turn down the tone know, your amp is still set up for the knobs to be at 10 with 500k, where you had set the treble lower, so now the tone is darker than what you'd have expected with 250k pots. And that's probably where the "psycho acoustic" business comes from, where you know something is different, but you can't put your finger on what. Does that make sense?
 
Re: 250k or 500k for JB and PG-esque humbuckers?

blueman335 said:
+1. Over the years, several knowledgeable members have detailed why turning down a tone pot on 500K does not, and cannot, sound the same as using a 250K..
Click to expand...

They were talking about volume knobs.
 
Re: 250k or 500k for JB and PG-esque humbuckers?

DreX said:
Keep in mind that when people talk about 250k versus 500k and "turning down a knob", they usually mean "turning down the volume knob", not the tone knob,
Click to expand...

The advice routinely given here is turning down the tone knob, same with the guys who said 500K's cannot replicate the sound of 250K's.

What good would it do to turn down the volume knob for a solo? You want to be heard over the other instruments and because your bridge PU is too bright you have to turn down the volume to get a warmer tone? That's a solution?
 
Re: 250k or 500k for JB and PG-esque humbuckers?

blueman335 said:
The advice routinely given here is turning down the tone knob, same with the guys who said 500K's cannot replicate the sound of 250K's.
Click to expand...

If ever there were a time to heed the argumentum ad populum fallacy, it's on guitar forums, where folklore is routinely peddled as fact, so if a rolled back tone knob doesn't have a substantially similar effect of using a 250k pot, explain why, to the best of your knowledge, and don't say "some guy said here once that..."

blueman335 said:
What good would it do to turn down the volume knob for a solo? You want to be heard over the other instruments and because your bridge PU is too bright you have to turn down the volume to get a warmer tone? That's a solution?
Click to expand...

Again, take your mind off the volume knob, it's not being discussed here.
 
Re: 250k or 500k for JB and PG-esque humbuckers?

250k works great for JB but might not sound so good with PG. sometimes just rolling back the volume really sweetens the sound of the JB. I use 500k pots in my Strat. It has a JB in the bridge.


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Re: 250k or 500k for JB and PG-esque humbuckers?

Personally I would put 500k pots in with those pickups in a strat. Unless I only had 250k on hand then I would use those...
 
Re: 250k or 500k for JB and PG-esque humbuckers?

Rolling down the volume can attenuate some high frequencies as well, unless a high-pass filter is used, correct?
 
Re: 250k or 500k for JB and PG-esque humbuckers?

I'm saying don't turn down the volume at all. You're correct in saying that turning down the volume is not the same as using a 250k pot, so leave the volume at 10 and turn down the tone control slightly instead. That is substantially similar to using a 250k pot, which is to say, I bet you couldn't hear the difference in a blind test.

The intuitive thing is to believe the fact that a tone control has a cap in series with it makes it meaningfully different than a resistance change in the volume pot by itself, but somewhat surprisingly, as the second graphs shows, between 7 and 10 on the tone dial, the resonant peak heads in a south-south-west direction, the same thing is seen in the first graph, which shows how the resonant peak changes as load is increased (which is what you're causing when you use a lower resistance pot). The tone pot doesn't really act like a tone pot until you get down to zero on the tone dial. Above that point, it's basically a "load increasing" dial.
 
Re: 250k or 500k for JB and PG-esque humbuckers?

daveyisgreat said:
Rolling down the volume can attenuate some high frequencies as well, unless a high-pass filter is used, correct?
Click to expand...

Yes, but it also impedes the pickups since as you turn down the volume there's added resistance between the psotive lead and the pickups, which leads to a different end result, makes the pickups sound a bit weaker in addition to darker, IMO. When you operate the tone dial, there is no added resistance between the positive lead and the pickups.
 
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