Pot Resistances

posaydal · Post by **posaydal** » Tue Feb 05, 2008 10:29 am

Hi, first post here (I put this in this section because things like pickups are meant to go here, apologies if this is incorrect)

Does anyone know the effect of the different potentiometer values on the sound of the guitar? I read most places that higher values will make it brighter, but itâ€™s not clear whether the tone pot also has an effect on this.

If it does, will it combine in a series or parallel sort of way? So for two 500K Ohm pots, would it be 500K+500K = 1M or 1/500K + 1/500K = 1/250K (ie 250K), also with guitars with separate tone / volume controls for each pickup would it be the same?

The main implication is that Iâ€™ll probably be converting my Dano DC59 (2007) reissue to the concentric pots which are 1M/100K each pickup, using the 1M for volume. (it has two 500K with 1 master volume / tone for both pickups at the moment).

Does it actually impact the sound that much anyway?

filtercap · Post by **filtercap** » Tue Feb 05, 2008 6:20 pm

Welcome to the boards! No worries -- your topic is fair game for this section, or for "Guitar Projects."

Does anyone know the effect of the different potentiometer values on the sound of the guitar? I read most places that higher values will make it brighter, but itâ€™s not clear whether the tone pot also has an effect on this.

What you read is correct. As for the tone pot, it will have an effect, at least in theory.

Picture a guitar that has all 500K pots, including the tone pot... If you turn the tone knob down until the resistance thru the tone pot is only 250K, you've rolled off a little of your treble. Now if you keep everything the same but replace the tone pot with a 250K pot that's turned up all the way, you've got the same slightly-less-treble sound. So tonewise the all-the-way-up 250K tone pot is the equivalent of a 500K tone pot that's been turned down a little.

(For whatever it's worth, the 250K pot is not the equivalent of the halfway-point on the 500K pot, because the pots don't work in a linear fashion.)

A tone control will combine in parallel, but remember that for all frequencies below a certain threshold, it's as if the tone circuit wasn't there at all. Above the threshold = lower overall resistance to ground; below the threshold = higher overall resistance to ground. You set the threshold frequency by turning your tone control.

Things get a little different with a separate tone control for each pickup. Things are still basically in parallel, but they get disconnected from each other. Take a look at this diagram.

Will · Post by **Will** » Tue Feb 05, 2008 7:50 pm

It's all true! The only other consideration is the "feel" of the control. A higher value pot will have a more sudden dropoff in the first 1/4 of its rotation and then probably be off by around the halfway point, whereas a lower value will give a more even taper.

The usual formula is: resistance of PUP in ohms X 40 (then round to nearest standard value)

a 5k lipstick works out to 200k, which would give the most natural taper (but also lose alot of treble). Tone controls work differently depending on how the capacitor is wired in (between PUP and pot or pot and ground).

filtercap · Post by **filtercap** » Tue Feb 05, 2008 8:13 pm

DuoSonicBoy wrote:The usual formula is: resistance of PUP in ohms X 40 (then round to nearest standard value)

PAUL: Now that indeed is a remarkable piece of information to have at your fingertips.
HOLLY GOLIGHTLY: I keep track of these things.

Post by **Mike** » Tue Feb 05, 2008 8:29 pm

I replaced the pots in my Tele Deluxe with 1megs from the original 250Ks, cue more output and a nice sparkle.

Post by **Doog** » Tue Feb 05, 2008 11:58 pm

I'm gonna do that with my Jazzy I think, there's not quite as much top end as the Strat or Tele. And I likes my sparkle.

Post by **Mike** » Wed Feb 06, 2008 7:53 am

1meg audio pots are your friend

posaydal · Post by **posaydal** » Wed Feb 06, 2008 9:13 am

Okay! hopefully when the dano pots arrive it'll be good times.

It's not often I see them mismatched, especially with a 10:1 ratio like the dano ones though from the schematics on the interwebs.

Post by **Doog** » Wed Feb 06, 2008 10:02 am

Mike wrote:1meg audio pots are your friend

DULY NOTED

The local craft shop only does pots with massive plastic shafts (OOH ERR MISSUZ), so it looks like getting ripped off by a guitar shop is order of the day.

Post by **Mike** » Wed Feb 06, 2008 10:09 am

They might not have 1meg pots, they also might look at you like you're insane. I got mine here, on euan's recommendation. Cheap, and fast shipping even though they're in the US:

http://www.smallbearelec.com/Detail.bok?no=555

"Small Bear Electronics Stock List Items
4 Pot Alpha Single-Gang Audio Taper 16mm (1Meg) @ $1.25 = $5.00

Shipping: $6.25 (USPS)
Sales Tax: $0.00
Small Bear Electronics Stock List Total: $11.25

Store Credit: -$0.00

TOTAL DUE: $11.25"

Do Jazzmaster knobs have grub screws? No? I imagine you'll need the knurled shaft ones:

http://www.smallbearelec.com/Detail.bok?no=688 - Linear (boourns)

Post by **Doog** » Wed Feb 06, 2008 10:13 am

Nah, it has push-on Strato ones. Cheers for the headsup, MIEK

Post by **Mike** » Wed Feb 06, 2008 10:19 am

No worries.

filtercap · Post by **filtercap** » Wed Feb 06, 2008 5:17 pm

posaydal wrote:Okay! hopefully when the dano pots arrive it'll be good times.

It's not often I see them mismatched, especially with a 10:1 ratio like the dano ones though from the schematics on the interwebs.

The 1M/100K vol/tone ratio might be their way of dealing with the low-output lipstick pickups. Get things a little louder (1M volume) but not overwhelmingly top-endy (100K tone).

You can also tailor your tone control by changing the value of the capacitor it uses. So you have that option too.