500K Pots: Adding a Resistor Inline to Emulate 250K Pots in Bill Lawrence Wilde-Gate Forum

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500K Pots: Adding a Resistor Inline to Emulate 250K Pots

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SeizeTheDave

500K Pots: Adding a Resistor Inline to Emulate 250K Pots

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Posts: 386

Feb 9 11 1:46 PM

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Hopefully this is a quick one:

I have a 45/45/L904H Strat with 500k pots. It's too hot for me so I want emulate having 250k pots in there. If I am not mistaken, I can place a resistor inline with the schematics in order to refrain from changing out the pots. Where do I place said resistor? Can I do it between the hot and ground lugs of the input jack? Do I need to put it inline with the hot lug on the input jack and the hot lead from the volume pot? Should it be between the hot lug to the middle lug of the volume pot?

...or should I just suck it up and replace the pots?

Thanks in advance!

Ibanez S1625FB - L-500 R/XL, Ibanez RGA-321 - L-90 4H/6H, Warmoth Tele - Minicoils, Fender Strat American Deluxe - L-45/L-45/L-90 4H, The Heritage H150 - L-80s, Fender Strat MIJ - Keystones, Ibanez Pro Series MIJ - L-200 / L-298 / L-610XL

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markanini

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Posts: 514

Feb 9 11 9:39 PM

I think the simplest way is adding a resistor between the outer lugs of the volume pot. This is outlined here: http://www.projectguitar.com/tut/potm.htm
You could add it between hot and ground at the jack as well. Or across the leads of idividual pickups. I believe adding to the pots is the most fool-proof way but will have a slight change on the taper of the pot.
No need to change the pots, Bill recommends starting 500k and adding resistors as needed.

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t42tae

#2

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Posts: 44

Feb 9 11 10:20 PM

+ 165 posts
Contrib. Gold Charter Member
Wilde Tech
(aka fuzzy beard (2117 posts))

What Mark said

For what it's worth, I use 250k or 300 k pots for all my BL pickups except the XL-models.
I even have a switchable 50k tone pot in one of my guitars for a very sweet and soft tone.

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SeizeTheDave

#3

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Posts: 386

Feb 10 11 2:29 AM

Great link. Thanks!

I presently have a resistor between the hot and ground of the input jack. It's too muffled, though. I have too little resistance, though, so that could explain it. It's a 220K resistor (highest I have). I need at least a 250, I believe, but I think a higher one would be preferable

Ibanez S1625FB - L-500 R/XL, Ibanez RGA-321 - L-90 4H/6H, Warmoth Tele - Minicoils, Fender Strat American Deluxe - L-45/L-45/L-90 4H, The Heritage H150 - L-80s, Fender Strat MIJ - Keystones, Ibanez Pro Series MIJ - L-200 / L-298 / L-610XL

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handsplayingbutterfly

#4

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Posts: 1182

Feb 10 11 3:45 PM

Bronze Member

Are you trying to drop the pot to 250k? You would need a 500k resistor.

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PeteMK1

#5

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Posts: 475

Feb 10 11 5:37 PM

Contributing Palladium Member
Resident Electronics Guru

I don't mean to spoil the enthusiasm about this mod, but it has one big disadvantage: You lose more treble when you turn down a higher value pot, no matter how many parallel resistors are added. That's why I believe it's generally preferrable to use 250k pots for all pickups. Many BL humbuckers work great with 250k pots. The old rule 250k for single coils and 500k for buckers is just coming from historic guitar models, and these choices were probably pure coicidence at the time.

FWIW, putting the resistor across the jack (output side of the volume pot) is not the same as having it across the input side. I think it can be a useful option, but I never tried it.

Eat. Work. Eat, work, and sleep.

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darkbluemurder

#6

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Posts: 76

Feb 11 11 4:54 PM

handsplayingbutterfly wrote:
Are you trying to drop the pot to 250k? You would need a 500k resistor.

That is correct. 470k or 510k would be the nearest standard resistor values. If you want exactly 500k, you can put two 1 Meg in parallel.

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darkbluemurder

#7

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Posts: 76

Feb 11 11 4:59 PM

PeteMK1 wrote:
I don't mean to spoil the enthusiasm about this mod, but it has one big disadvantage: You lose more treble when you turn down a higher value pot, no matter how many parallel resistors are added. That's why I believe it's generally preferrable to use 250k pots for all pickups.

I agree because when you turn down the volume pot you are putting series resistance in the signal path. This series resistance will interact with the miller capacitance of the first tube gain stage in the amplifier which will form a low pass filter. The higher the gain of that first stage the worse the effect will be. A 500k log pot turned down to 5 will put about 450k resistance in the path compared to about 220k for a 250k log pot. This can make a substantial difference.

Cheers Stephan

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SeizeTheDave

#8

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Posts: 386

Feb 12 11 2:39 AM

Okay, is there any way that I can add extra resistance just to the bridge pup to soften it up a little?

Ibanez S1625FB - L-500 R/XL, Ibanez RGA-321 - L-90 4H/6H, Warmoth Tele - Minicoils, Fender Strat American Deluxe - L-45/L-45/L-90 4H, The Heritage H150 - L-80s, Fender Strat MIJ - Keystones, Ibanez Pro Series MIJ - L-200 / L-298 / L-610XL

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PeteMK1

#9

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Posts: 475

Feb 12 11 2:26 PM

Contributing Palladium Member
Resident Electronics Guru

You can always put a resistor between hot and ground of the bridge pickup, e.g. where the hot wire meets the 5-way switch. Or, if you have a dedicated bridge pickup tone pot, you can solder the resistor across the tone circuit.

The resistor of course affects all pickup combinations in which the bridge pickup is involved.

Eat. Work. Eat, work, and sleep.

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