Hoffman Amplifiers Tube Amplifier Forum

Other Stuff => Guitars => Topic started by: tubenit on October 19, 2011, 11:47:15 am

Title: bad vol pot?
Post by: tubenit on October 19, 2011, 11:47:15 am
Help, please.

I need to do something to resolve this dilemma. Both of my guitars when the volume pots are dialed to "8" have a noticeable hum thru the amp. Pickups are DiMarzio humbuckers and it doesn't matter how I have the 5 way switches set.

There is not hum at "7" or above "9.5" ........... but between those there is a obnoxious hum that sounds like a grounding issue.

In other words, I can dial the volume to "10" and it's dead quiet at idle. Dial it down to "8" and I get a hum. It is the noisiest on "8".

Are there some really good potentiometers that would eliminate that as a problem?

Both guitars do the same thing with all 3 amps.

With respect, Tubenit
Title: Re: bad vol pot?
Post by: jjasilli on October 19, 2011, 12:00:15 pm
Checkout:
http://www.tdpri.com/forum/tele-technical/281392-hum-goes-up-volume-pot-goes-down.html (http://www.tdpri.com/forum/tele-technical/281392-hum-goes-up-volume-pot-goes-down.html)

http://www.strat-talk.com/forum/squier-strat-forum/33886-cv60-strange-hum.html (http://www.strat-talk.com/forum/squier-strat-forum/33886-cv60-strange-hum.html)
Title: Re: bad vol pot?
Post by: Willabe on October 19, 2011, 12:31:14 pm
Huh. That's interesting what their talking about. Thanks for posting that jjasilli.

Wonder what tubenit will find?


                     Brad         :think1:
Title: Re: bad vol pot?
Post by: tubenit on October 19, 2011, 01:37:47 pm
Wow! That first link describes what's happening right on the mark!  UGH!!!!

Not sure about the idea of going from 500k to 250k pots?

I may experiment with paralleled resistors and see what happens?

I was hoping it was a "bad" pot and replacing would resolve the issue.

Thanks, Tubenit
Title: Re: bad vol pot?
Post by: jjasilli on October 19, 2011, 03:02:53 pm
This has me wondering about possible solutions:

1.  A series resistor to the signal out jack inside the guitar -- might decouple capacitances, and attenuate hum.  Anything from maybe 1K up to 1/10th the value of the pot might work.

You say you have a 5-way SW with humbuckers;  usual gibson wiring has the resistance of the vol pots isolating the PU's from ea other.  Fender wiring lacks this, so the PU's load one another.  Maybe this affects your hum problem?  It may help to put a series resistor between ea PU and its SW lug.

2.  Balanced line:  Balanced line phono plug @ guitar jack > balanced line cable > Balanced line phono plug into amp

3.  Buffer between guitar & amp; any effects pedal might work.
Title: Re: bad vol pot?
Post by: G._Hoffman on October 19, 2011, 03:21:06 pm
It maybe that, but I would try cleaning the pot first.  You'd be amazed at what cleaning a pot can do.


Gabriel
Title: Re: bad vol pot?
Post by: Ritchie200 on October 20, 2011, 04:23:27 pm
Ummm, helloooo...  All you have to do is look at the shape of the body.  It is wrong in so many ways, I'm surprised they play at all - oh wait....

Yer pal,
Jim
Title: Re: bad vol pot?
Post by: tubenit on October 20, 2011, 07:22:11 pm
Quote
Ummm, helloooo...  All you have to do is look at the shape of the body.  It is wrong in so many ways, I'm surprised they play at all - oh wait....

....................... they're strat pickups!!  :l2:

'Nit
Title: Re: bad vol pot?
Post by: Ritchie200 on October 20, 2011, 10:18:26 pm
It's hard to fly like an eagle when you are surrounded by a turkey.

Thought for the day...
Jim
Title: Re: bad vol pot?
Post by: tubenit on October 22, 2011, 05:33:54 am
Quote
It's hard to fly like an eagle when you are surrounded by a turkey.



:l2: :l2:
Title: Re: bad vol pot?
Post by: John on October 22, 2011, 12:24:07 pm
That must be some turkey!