No taper on Vol pot, just drops like rock

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jeff0633

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Hi folks. I wired my Gibson sG for one volume pot following the Sd
site diagram. I went with one volume and no tone controls. It works
fine, but now my volume pot has no taper, it is the same volume almost
all the way down, then right before I turn it all the way off, it
drops like a rock and loses a ton of high end.

I know players sometimes put a cap on the volume to stop the loss of
high end, what cap should this be for the 500K pots on a Gibson?

Is there something I can do about this taper problem?

Thanks

Jeff
 
Is it an audio taper or linear taper pot? Theres also a chance you fried the wafer if you soldered it and kept heat on it too long, too. You can overheat and ruin a pot fairly easy.

H2H
 
Hi. Well, someone else just said the same thing on another forum. He said I need an audio taper pot. I just used the vol pot that came with my SG. Isn't that a taper pot? The damn thing tapered before I wired it for one volume. Here is the diagram I used for wiring. My friend is a very good solderer, and the joints are clean and perfect, so I don't think the pot is messed up. I am getting the feeling that I should have purchased another pot, because now I look at it on the diagram, here
http://seymourduncan.com/website/support/schematics/schematicspdf/2hb_1vol_3way.PDF

And it does say audio taper pots are to be used. I just used the pot that came on the SG.

I am gettingt he feeling I know what's wrong. I bet the SG pot is not an audio taper. Damn!!

If I run down to radio shack, I should have enough time before my gig to change it.

Can someone tell me the proper cap to get so that it will not lose high end when backing off the volume? I know it goes from middle lug to ground, but I am not sure what cap to use on a 500K "audio taper" pot.

Thanks for any help guys.

Jeff

Hard2Hear said:
Is it an audio taper or linear taper pot? Theres also a chance you fried the wafer if you soldered it and kept heat on it too long, too. You can overheat and ruin a pot fairly easy.

H2H
Click to expand...
 
Even a linear taper pot shouldn't be doing what you describe. It sounds to me like you've somehow got the wiper (center lug) shorted to the hot (right) lug. It could be internal to the pot where you'd never see it.

Get a voltmeter and check the pot. With all the wires off the pot, you should see the rated resistance between the outer lugs, and resistance that runs from very low or zero ohms to very near the rated value between the center lug and both of the outer lugs as the shaft is turned (one at a time, of course; as the resistance between the center lug and one of the other lugs goes up, the resistance between the center lug and the third lug goes down). If you see anything else, the pot is whacked.

You asked about a capacitor. In the diagram you referenced, there is no cap; if the diagram is complete, then this is a "hot wired" configuration with no tone control. It doesn't matter, though; a capacitor to ground can only subtract highs, not add them. Passive (non DC powered) components are always cut only, no boost.


Hope this helps.

PS: Just out of curiosity, why are you changing it? The stock 4 pot control of an SG works pretty well as is.
 
Get a new pot and give it a try, they are cheap after all. It sounds very much like there is something wrong with the pot.

As to the high pass cap, the most common value is .001 mf, but I find they make the signal too bright even when the volume is at 10.


Light

"Cowards can never be moral."
M.K. Gandhi
 
Light said:
As to the high pass cap, the most common value is .001 mf, but I find they make the signal too bright even when the volume is at 10.
Click to expand...

The cap in a guitar is part of a low pass filter. It passes the highs to ground, I guess, if you want to look at it that way... ;6)

I thought that .047 mfd was the most commonly used value.
http://www.guitarnuts.com/wiring/stockgibson.php
 
ggunn said:
The cap in a guitar is part of a low pass filter. It passes the highs to ground, I guess, if you want to look at it that way... ;6)

I thought that .047 mfd was the most commonly used value.
http://www.guitarnuts.com/wiring/stockgibson.php
Click to expand...


Nope. The one he is talking about is a very low value cap between the input and the output of the volume pot, in parallel to the pot. It passes high to the output, with the intention that it gets rid of the loss of high end as you turn your guitar down. The cap on a TONE knob bleeds highs to ground, but this is a different use of a much smaller sized cap.

For a TONE control, yes a .047 mf is the most common for humbucking pickups with 500k pots, but of course on a strat with single coils and 250k pots, the most common is a .022 mf cap.



Light

"Cowards can never be moral."
M.K. Gandhi
 
Light said:
Nope. The one he is talking about is a very low value cap between the input and the output of the volume pot, in parallel to the pot. It passes high to the output, with the intention that it gets rid of the loss of high end as you turn your guitar down. The cap on a TONE knob bleeds highs to ground, but this is a different use of a much smaller sized cap.

For a TONE control, yes a .047 mf is the most common for humbucking pickups with 500k pots, but of course on a strat with single coils and 250k pots, the most common is a .022 mf cap.

Light
Click to expand...

D'oh! I see, said the blind man when the dead horse kicked him.... I maybe should read posts more carefully before I reply, huh?

BTW, his prob sounds like the wiper is shorted to the hot side; as he turns it down both the input and output are at the same point in the voltage divider, so there's no change in volume until he gets near the bottom of the pot where hot, ground, and wiper all approach a short.
 
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