Influence of the resistor on the pot's taper

[CarlosG]

Hi!
Sometimes 500k is to bright and 250/300k is to mellow for me. Sometimes I need something between 1Meg and 500k.
I wonder, does adding a resistor affect the potentiometer taper? If so, will it become more linear or audio?

[Clint 55]

It doesn't affect the taper. You can just as easily put the resistor across the output jack.

[freefrog]

Let's share a 5Spice sim of a Fender style single coil plugged to a 1M amp input through a 370pF cable, with a normal tone control and various volume pots, set from 10/10 to 1/10.

The curve of your solution, with resistor between outer lugs, is pictured on the upper left side. On the upper right, for comparison, is simulated a 250k pot without resistor. Bottom left = 500k volume + resistor from center lug to ground. Bottom right side = the same thing with resistor from center lug to hot. This last option maintains the 500k resistance when the pot is full up but changes its taper...



Not enough time for a longer answer but there's also some food for thought in the page below (scroll down for explanations and screenshots):

http://www.geofex.com/article_folder...s/potscret.htm

FWIW. HTH. :-)

[GuitarDoc]

Hi!
Sometimes 500k is to bright and 250/300k is to mellow for me. Sometimes I need something between 1Meg and 500k.
I wonder, does adding a resistor affect the potentiometer taper? If so, will it become more linear or audio?

I think there is something that I'm not getting. You say 500k is too bright but then you say you need something between 1 meg and 500k. That would be even brighter!

[jeremy]

i think the op is giving two different scenarios where using a resistor with a pot to get an inbetween value would be useful

[beaubrummels]

I would just buy the right pot. They are not that expensive, nor that difficult to install.

[Clint 55]

I've noticed there are now 220, 330, and 550k pots if you use the search bar.

[Teleplayer]

No. The resistor does not affect the taper. However this is an issue with using 1M pots in general - They lose a lot of high end frequencies when the volume is rolled off. For myself I'd stay with a 500k volume control because of that.

If you are they type of player who rides the volume control a lot, you can consider adding a treble bleed if there is not enough brightness with the tone control on max.

[CarlosG]

i think the op is giving two different scenarios where using a resistor with a pot to get an inbetween value would be useful

exactly

[CarlosG]

No. The resistor does not affect the taper. However this is an issue with using 1M pots in general - They lose a lot of high end frequencies when the volume is rolled off. For myself I'd stay with a 500k volume control because of that.

If you are they type of player who rides the volume control a lot, you can consider adding a treble bleed if there is not enough brightness with the tone control on max.

I like 1M pots with my Distortion/59 set. Usually adding an 82-150pF capacitor (depending on the guitar) partially fixes the problem. Resistor and cap in parallel works the best, but changes curve to more linear, so it's not good for hot pickups because it won't clean on high gain.

Adding treble bleed don't change tone when pots are on max

[CarlosG]

I've noticed there are now 220, 330, and 550k pots if you use the search bar.

Not in my country

[Teleplayer]

Adding treble bleed don't change tone when pots are on max

Good point. If max volume gives an overdrive tone, the extra brightness may not be needed anyway. It depends on the player and usage.

[eclecticsynergy]

Adding a resistor-and-cap-in parallel treble bleed seems to change the taper.
I haven't encountered this when adding a 470K jumper to make a 500K pot sound like a 250K..
Not that my personal experience with that has been extensive.

[freefrog]

My screenshots in post 3 were an attempt to suggest without long rambling that a parallel resistor doesn't change significantly the taper until the resonant frequency in 3/4 of cases but modifies the curve beyond this resonant peak.

Now, it's necessarily a variable phenomenon, firstly because the behaviour of a pot with passive PU's depends on the input impedance of the host amp (or pedal) and secondly because the "morphing" of the resonant peak according to how pots are set depends on the inner parasitic capacitance of the pickup (!).

No wonder if personal experiences vary, so... :-)

[eclecticsynergy]

My screenshots in post 3 were an attempt to suggest without long rambling that a parallel resistor doesn't change significantly the taper until the resonant frequency in 3/4 of cases but modifies the curve beyond this resonant peak.

Now, it's necessarily a variable phenomenon, firstly because the behaviour of a pot with passive PU's depends on the input impedance of the host amp (or pedal) and secondly because the "morphing" of the resonant peak according to how pots are set depends on the inner parasitic capacitance of the pickup (!).

No wonder if personal experiences vary, so... :-)

Thanks, freefrog. Your posts are always well-grounded in electronics.
Very helpful for those of us with less understanding of it.

It hadn't occurred to me that the taper would not be consistent at different frequencies.

Adding a parallel cap & resistor treble bleed to a log pot results in a more linear taper, which many don't like.
I think this is primarily what the OP was worried about.
I'm curious - would adding such a treble bleed change the taper of a linear pot also?
Would it become something like reverse-log, or would it just stay linear?