Experimenting with Pot(s)

smitty_p

smitty_p

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How's THAT for a click-bait thread title!!!

Anyhoo, we've all probably heard the rule of thumb when it comes to potentiometers that we should use 500 K ohm pots for humbuckers and 250 K ohm pots for single coils, right?

Well, sometimes you gotta experiment and ignore the rules.

Way back when I got my Jackson, I soon replaced the pickups with Seymour Duncan JB and Jazz pickups. Basically, I do like the tone of those pickups, but the issue with them in this guitar is that they are very bright...almost harsh.

The thing is, I also had 500 K pots for the volume and tone controls.

So, the idea hit me. Why not try a 250 K ohm pot for the volume and see if that will tame some of the highs?

Well, I swapped just the volume pot for a 250 K ohm pot. Mission accomplished! It still has the essential tonality of the pickups, but with less harshness. I still have enough gain, but it's smoother.
 
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smitty_p said:
How's THAT for a click-bait thread title!!!

Anyhoo, we've all probably heard the rule of thumb when it comes to potentiometers that we should use 500 K ohm pots for humbuckers and 250 K ohm pots for single coils, right?

Well, sometimes you gotta experiment and ignore the rules.

Way back when I got my Jackson, I soon replaced the pickups with Seymour Duncan JB and Jazz pickups. Basically, I do like the tone of those pickups, but the issue with them in this guitar is that they are very bright...almost harsh.

The thing is, I also had 500 K pots for the volume and tone controls.

So, the idea hit me. Why not try a 250 K ohm pot for the volume and see if that will tame some of the highs?

Well, I swapped just the volume pot for a 250 K ohm pot. Mission accomplished! It still has the essential tonality of the pickups, but with less harshness. I still have enough gain, but it's smoother.
Click to expand...

Good experiment!

I do a similar modification by soldering a 220k ohm resistor between the "+" and ground. It basically accomplishes the same thing but I didn't want to change the pot...you can see the resistor in this photo of my SG's control cavity.

IMG_20170307_5510.jpg
 
Robert Herndon said:
Good experiment!

I do a similar modification by soldering a 220k ohm resistor between the "+" and ground. It basically accomplishes the same thing but I didn't want to change the pot...you can see the resistor in this photo of my SG's control cavity.

View attachment 8800
Click to expand...

In one sense it accomplishes the same thing, in another sense it doesn't. It does present a lower impedance to the pickup, but soldering a resistor across the pot can change the taper.

That's not to say that's a bad thing. It all comes down to if you like it!
 
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smitty_p said:
In one sense it accomplishes the same thing, in another sense it doesn't. It does present a lower impedance to the pickup, but soldering a resistor across the pot can change the taper.

That's not to say that's a bad thing. It all comes down to if you like it!
Click to expand...

I got the idea years ago from Bill Lawrence. Thus far, I notice no change whatsoever in taper with audio taper 500k Bourn pots....

Bill Lawrence Modification.jpg
 
Robert Herndon said:
I got the idea years ago from Bill Lawrence. Thus far, I notice no change whatsoever in taper with audio taper 500k Bourn pots....
Click to expand...

Are you sure? Either way, any difference would not be very dramatic, especially if you already started with an audio taper pot.

Nevertheless, I prefer to not to add extra components when using a different pot is what I'm really after.
 
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smitty_p said:
Are you sure? Either way, any difference would not be very dramatic, especially if you already started with an audio taper pot.

Nevertheless, I prefer to not to add extra components when using a different pot is what I'm really after.
Click to expand...

Sure sounds the same...I didn't want to whack up a $110.00 custom 50's cloth harness to change the pot... :-)
 
For years Gibson used 300k volume pots, I suspect for this very reason (I have wired up T-Tops before using 500k pots and not like the sound much, too harsh). My '79 has 300's and they are not getting changed. Many Norlin-era guitars have pots as low as 100k
 
gball said:
For years Gibson used 300k volume pots, I suspect for this very reason (I have wired up T-Tops before using 500k pots and not like the sound much, too harsh). My '79 has 300's and they are not getting changed. Many Norlin-era guitars have pots as low as 100k
Click to expand...

Mom's 1979 LPC has 500k pots....why such variation????
 
I've read many times of people using 250k or 280k pots with the JB for the exact same reason Smitty gives. I did read Seymour Duncan talking about the "Tele-Gib" (there's that scale length thing Robert) that he made the JB for (JB stands for Jazz/Blues, not Jeff Beck) & he used 500k pots though. Speaking of 300k pots for Gibby 'buckers, in my upcoming "Keef Micawber" type build I'll be using a 300k volume pot to match up to the PAF type neck 'bucker & 10k wound bridge single coil. Hopefully it'll work well. Will be wired with the Broadcaster blender circuit. Cheers
 
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smitty_p said:
It’s funny, even the Seymour Duncan Jazz is pretty bright. It makes me wonder if it was designed with 250 K pots in mind.
Click to expand...

I agree...I find that humbuckers, in general, are just too bright to suit my tastes. Passives get a 220kΩ resistor and EMG's get a 10kΩ....
 
smitty_p said:
It’s funny, even the Seymour Duncan Jazz is pretty bright. It makes me wonder if it was designed with 250 K pots in mind.
Click to expand...
I'm really not sure, might have to have a look at his site to see what they recommend. I know the SD Distortions in my Jackson are also pretty bright (500k pot). I just roll the tone controls back, on all my guitars most of the time (& volume). Might have to try gball's 300k pots in the bridge of both my SG & LP that have slightly overwound T top types in them, thanks for the tip gball. Cheers
 
I think that all the pickups that have been mentioned so far, where designed decades ago. Guitar cables of that era had much higher capacitance than what is available now. Especially long guitar cables, or the old coily cables. Cables with high capacitance will dull the high frequencies.
 
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