300k or 500k volume pots for P90 and HB?

[josesrv]

Recently I found that Gibson used a 300k linear pot as volume on the Appetite Slash Les Paul. It comes with Seymour Duncan Alnico II, this is a vintage value Hb with around 8k ohms. What is the purpose for it when they usually use 500k?
Also, I have been checking 1954 Les Paul circuit and they draw it with 500k volume pots, does this applies for P90 pickups? What if we use 300k for a vintage oriented P90 values (8k) with Alnico II or V magnets?

[StarryNight]

the pot reading will have the same effect on the pickup regardless of the magnet. 300k pot should produce less low end and accent the mids more perhaps giving the P90 a more focused sound. using a lower resistance pot may also cut the high end as well.

[David Schwab]

using a lower resistance pot may also cut the high end as well.

Yes, the 300K won't be as bright as a 500K. 250K would be even warmer.

[Mark Hammer]

While I wouldn't go so far as to say they would do so in all respects, much of that "warmth" can be emulated using a conventional 500k pot by simply placing a suitably-chosen cap between the two outside lugs of the volume pot. "Suitable" values will likely be in the range of 680pf-3300pf, depending on your taste, strings, pickup height, and amp.

And as I am fond of reminding people, virtually all of the audible differences between volume pots of different values occur when the volume is maxed. Once you turn down and some of that 250k, 300k, 500k, or 1M is now no longer simply a resistance to ground, but rather a resistance placed in series with the pickup, all bets are off.

[David Schwab]

And as I am fond of reminding people, virtually all of the audible differences between volume pots of different values occur when the volume is maxed. Once you turn down and some of that 250k, 300k, 500k, or 1M is now no longer simply a resistance to ground, but rather a resistance placed in series with the pickup, all bets are off.

Right, so when you use something like a 1M pot for maximum brightness from an over would pickup, it really gets muddy when you turn it down half way! You end up with 500K in series with the pickup.

Sounds like a job for a buffer.

[Mark Hammer]

Or a bypass cap, which is the usually-adopted solution.

[MistaT]

An interesting thing I found on a guy's Tele I was fixing the other day, after I put it all back together, I noticed that the tone knob did VERY funky things to the volume!

As in as you rotated the tone knob, the volume would go loud, then very quiet, then loud, then quiet, the loud!!

I measured the tone pot, and found out that it was a 500k pot.

No big deal if this were a Gibson that also used 500k pots for the volume, but being a Tele, I knew the volume pot was a 250K.

So I swapped out the 500K tone pot with a 250K to match the volume control, and all was well!

Sorry, I know this is a bit off topic, but I thought I would throw this out there just in case someone else ever runs into this problem.

-- Mike

[bbsailor]

Recently I found that Gibson used a 300k linear pot as volume on the Appetite Slash Les Paul. It comes with Seymour Duncan Alnico II, this is a vintage value Hb with around 8k ohms. What is the purpose for it when they usually use 500k?
Also, I have been checking 1954 Les Paul circuit and they draw it with 500k volume pots, does this applies for P90 pickups? What if we use 300k for a vintage oriented P90 values (8k) with Alnico II or V magnets?

josesrv,

The rule of thumb for scaling pot control values to pickup resistance is to multiply the pickup resistance by 40. Thus, a 300K pot is designed to work best with a 7,500 ohm pickup.

As pickups have been getting hotter with more turns over the years, the pot value have been increased to 500K ohms to accomodate pickups in the resistance range of about 12.5K ohms.

Pickup pot loading is a subjective evaluation. If you want less high end, use a lower value pot by putting a 750K resistor in parallel with the 500K pot to bring it back down to 300K. This is a quick and cheap way to see if you would like a little warmer sound.

Guitar pots have pretty much standardized on 250K for single coil pickups, 500K for humbuckers and 1 meg for Telecaster players who want a little more bite in the top end. Active pickups typically use about 25K pots.

Joseph Rogowski

[josesrv]

An interesting thing I found on a guy's Tele I was fixing the other day, after I put it all back together, I noticed that the tone knob did VERY funky things to the volume!

As in as you rotated the tone knob, the volume would go loud, then very quiet, then loud, then quiet, the loud!!

I measured the tone pot, and found out that it was a 500k pot.

No big deal if this were a Gibson that also used 500k pots for the volume, but being a Tele, I knew the volume pot was a 250K.

So I swapped out the 500K tone pot with a 250K to match the volume control, and all was well!

Sorry, I know this is a bit off topic, but I thought I would throw this out there just in case someone else ever runs into this problem.

-- Mike

Many thanks Mike, I appreciate this note. It is very useful.