Remind me again... how do I turn a 500K pot into 250K with resistors?

[RockStarNick]

I know there's a way to turn a 500K pot into a 250K using a resistor across the tabs or something.

And I know I saw a thread on here about it, but I've been searching and can't find the right one...

can anyone help?

 

[idsnowdog]

Re: Remind me again... how do I turn a 500K pot into 250K with resistors?

A 500k pot + a 500k resistor across the 1 & 3 terminals.

 

[STRATDELUXER97]

Re: Remind me again... how do I turn a 500K pot into 250K with resistors?

Doing that will decrease your pot down to 250k,but you may not like the taper? Why not just get yourself the 250k pot..???

 

[dr. ad]

Re: Remind me again... how do I turn a 500K pot into 250K with resistors?

what are the differences in the taper?
i'm not cheap, i just don't like paying 20 bucks and waiting a month for a 5 buck part to arrive ; ]

 

[STRATDELUXER97]

Re: Remind me again... how do I turn a 500K pot into 250K with resistors?

what are the differences in the taper?
i'm not cheap, i just don't like paying 20 bucks and waiting a month for a 5 buck part to arrive ; ]

You'd have to see how it works for ya.....I remember just not liking the way the taper was....It works,but it's kind of cheating... ;o) Try it though. No harm in that.

 

[dr. ad]

Re: Remind me again... how do I turn a 500K pot into 250K with resistors?

You'd have to see how it works for ya.....I remember just not liking the way the taper was....It works,but it's kind of cheating... ;o) Try it though. No harm in that.

fair enough, will do. considering this as a quick and easy way to test bright bridge humbuckers with <cough> 250K pots...

thanks for that SDLX97

 

[STRATDELUXER97]

Re: Remind me again... how do I turn a 500K pot into 250K with resistors?

fair enough, will do. considering this as a quick and easy way to test bright bridge humbuckers with <cough> 250K pots...

thanks for that SDLX97

Let us know how it works out for ya,so others will know also!

 

[STRATDELUXER97]

Re: Remind me again... how do I turn a 500K pot into 250K with resistors?

Sometimes you have no other chance. I had to buy quality 500K pull/pushes when needing 330K ones but... did someone see a 330K pull/push?.

So, to have that 330K pull/push, I need to tweak it with a 970K resistor (976K is the closer real available value out there).

Yep sometimes we do have to make compromises! The resistance change works,but it changes the taper...It bothered me,but it might not bother someone else...


I've never seen a 330k push/pull pot,but I have seen 250K pots that read over 300k...

One of my how tos on the subject...

http://www.projectguitar.com/tut/pots.htm

 

[idsnowdog]

Re: Remind me again... how do I turn a 500K pot into 250K with resistors?

I have tried it to come up with in between values. While I like the tone at 100% volume, rolled back they just didn't feel right. The biggest problem was the curve was shifted, so the sweep was no longer graceful. Instead it was all or nothing.

 

[STRATDELUXER97]

Re: Remind me again... how do I turn a 500K pot into 250K with resistors?

I have tried it to come up with in between values. While I like the tone at 100% volume, rolled back they just didn't feel right. The biggest problem was the curve was shifted, so the sweep was no longer graceful. Instead it was all or nothing.

Yes I agree with what you say....That's what my findings were..

 

[uOpt]

Re: Remind me again... how do I turn a 500K pot into 250K with resistors?

Parallel 500 Kohm resistor.

Note that this only makes it behave like 250 Kohm. It will behave like a 500 Kohm pot the closer you get to fully closed. I posted the math some time ago.

 

[mariosyjp]

Re: Remind me again... how do I turn a 500K pot into 250K with resistors?

this information is all over the forums that if you put a 500k resistor across the outter lugs of a 500k pot then when the pot when turned to 10 is like having a 250k volume pot

I just want to report how I wasted my time soldering the resistor to a push pull pot so that I could have both options
it simply does NOT sound the same as having a 250k pot, it is more like turning down a bit your tone pot

the tone difference switching from a 500k to 250k (or 300k) volume pot is very big, not only it is less bright but also adds a big amount of low mids, lowers the resonance peak a lot

in my LP I ended up having a master tone pot, a dedicated 500k vol for the neck pickup and a 2 switchable vol pots for the bridge 500k and 300k
night and day difference switching between them as expected.
instead when I was switching between having the resistor connected and off the difference was minimal and useless, it can be accomplished by rolling down a bit the tone pot

 

[Artie]

Re: Remind me again... how do I turn a 500K pot into 250K with resistors?

The difference between 500k and 250k would, indeed, be a very subtle affect. However, if the resistor is placed properly between the outside two terminals, it should have no affect on the taper. Not sure what's going on there.

 

[mariosyjp]

Re: Remind me again... how do I turn a 500K pot into 250K with resistors?

The difference between 500k and 250k would, indeed, be a very subtle affect. However, if the resistor is placed properly between the outside two terminals, it should have no affect on the taper. Not sure what's going on there.

I had no issues with the taper I'm just pointing out that the result is nothing like using an actual 250k pot

 

[trevorus]

Re: Remind me again... how do I turn a 500K pot into 250K with resistors?

http://www.geofex.com/article_folders/potsecrets/potscret.htm

 

[Teleplayer]

Re: Remind me again... how do I turn a 500K pot into 250K with resistors?

I have done this quite often. I used a 510k resistor in between lug 1 & 3 of a 500k volume pot. There are no issues with taper.

The problem is the output resistance is not the same as using a 250k, so you lose more high frequencies due to cable capacitance. If using an actual 250k pot, the treble loss would only be half as much.

If you want to make the 500k pot sound more like a 250k, then you need to use 510k resistor in parallel (between lugs 1 & 3), and also use a "treble bleed" capacitor + series resistor combination between input and output of the volume control. My treble bleed is a small 0.00022uF (220pF) capacitor in series with a 150k resistor. I use a low capacitance 10' cable as well. With a 20' cable you should probably use a 0.00033uF (330pF) value capacitor instead.

 

[Artie]

Re: Remind me again... how do I turn a 500K pot into 250K with resistors?

However, if the resistor is placed properly between the outside two terminals, it should have no affect on the taper.

This is weird. I have to back-pedal on my own statement. It's a position I've held based on theory. At work tonight, I measured some different linear-pot/resistor combinations, and plotted the result in Excel. The resistor absolutely "bends" the taper. Different ways depending on where you put it and the value relative to the pot. But a bend all the same.

 

[beaubrummels]

Re: Remind me again... how do I turn a 500K pot into 250K with resistors?

When I did this, it didn't work as expected because when the pot was full up at ten, half the signal was still always bleed to ground through the resistor.

 

[freefrog]

Re: Remind me again... how do I turn a 500K pot into 250K with resistors?

As Bill Lawrence used and recommended pots & resistors in parallel, there's other discussions about it here:

http://guitarsbyfender.yuku.com/reply/55827/500K-Pots-Adding-a-Resistor-Inline-to-Emulate-250K-Pots

I personally use this trick as well but yes, of course, it can change the taper of the pots as explained in the link posted by trevorus... If we use linear pots, we must expect them to work as log or anti log controls as long as we select the lugs 1-2 or 2-3 to connect the resistor...

... Anyway, the goal has never been to emulate exactly a 250k pot with a modified 500k one : pot + resistor in parallel = interesting recipe when we want a "preset variable" tone network, so to speak - IOW: a wiring working like a 250k vol + tone network in position 1, like a 125k network in position 2 and so on. It avoids to lower the tone pot each time the pickup selector is toggled and I don't find that useless at all when I'm on stage. YMMV.

EDIT - below a simplified emulation of the taper obtained from 100% to 10% with a linear 250k volume control vs a 500k one in parallel with a 500k resistor (soldered to the outer lugs).

This simplified model doesn't take in account the specific interaction of the amp with the guitar wiring (cf. for example the answer 7 in the link that I mention above).



BTW, and IMHO, it's necessary to keep in mind that a guitar wiring behaves in a way partly defined by to the "host" in which we plug it... Another instructive link about it (see the last part and last pics): http://www.moore.org.au/pick/04/04_lgen.htm

 

[Artie]

Re: Remind me again... how do I turn a 500K pot into 250K with resistors?

Interesting. What kind charting software is that?