madbeanpedals::forum

General => Open Discussion => Topic started by: midwayfair on November 16, 2013, 03:15:31 PM

Title: scratchy guitar pot straight into the amp?
Post by: midwayfair on November 16, 2013, 03:15:31 PM
The DQ Caster was making some static-y noise at practice the other night, so I went back through and checked all the shielding. I improved it a little and I don't,t really hear much static anymore, but the guitar pot is scratchy even right into the amp. Scratchy pot says DC on the pot, but I can't think of what would be producing DC.

Any suggestions, or should I get a new guitar pot in a quickness?
Title: scratchy guitar pot straight into the amp?
Post by: Mike B. on November 16, 2013, 03:27:24 PM
More likely you just need to hit that pot with some contact cleaner.

EDIT: I should qualify that the contact cleaner may be a temporary fix. The scratchiness is usually a result of dust/corrosion built up between the wiper and the resistive wafer. So, you'd be essentially just moving the dirt around. Ultimately, replacing the pot would be the permanent fix. That said, the contact cleaner may buy you a few months or even longer.
Title: Re: scratchy guitar pot straight into the amp?
Post by: jimilee on November 16, 2013, 03:32:34 PM
You're a smart guy and I can't pretend to know more than you, that being said, does it do it on the amp at home? New pot maybe or is it a symptom of something in the amp?
Title: Re: scratchy guitar pot straight into the amp?
Post by: midwayfair on November 16, 2013, 04:05:56 PM
Quote from: jimilee on November 16, 2013, 03:32:34 PM
You're a smart guy and I can't pretend to know more than you, that being said, does it do it on the amp at home? New pot maybe or is it a symptom of something in the amp?

Yeah, I didn't notice it until I got it home and had it plugged into the hot rod deluxe. The amp at practice was solid state. But the HRD has an input cap into a tube at 0V. There shouldn't be any DC in this system.

I'll try the contact cleaner, but I'm wonder if anything else is going on.

Hmm, it occurs to me that static would qualify as DC ... It would produce noise and make static-y noises.

Oh, there's one variable at home I forgot to mention. The amp is plugged into a 3 prong converter.
Title: Re: scratchy guitar pot straight into the amp?
Post by: rullywowr on November 16, 2013, 08:06:34 PM

Quote from: midwayfair on November 16, 2013, 04:05:56 PM
Oh, there's one variable at home I forgot to mention. The amp is plugged into a 3 prong converter.

Hot rod deluxe is a great amp. I had one and still have a blues deluxe.


Sounds like a bad pot. I hope the converter you are using isn't one of those 3 to 2 prong adapters with the ground lifted. This is really dangerous especially on a tube amp. If something goes wrong in the amp you have the potential to be electrocuted seriously if there is no ground connection! 
Title: Re: scratchy guitar pot straight into the amp?
Post by: midwayfair on November 16, 2013, 09:32:26 PM
Quote from: rullywowr on November 16, 2013, 08:06:34 PM

Quote from: midwayfair on November 16, 2013, 04:05:56 PM
Oh, there's one variable at home I forgot to mention. The amp is plugged into a 3 prong converter.

Hot rod deluxe is a great amp. I had one and still have a blues deluxe.


Sounds like a bad pot. I hope the converter you are using isn't one of those 3 to 2 prong adapters with the ground lifted. This is really dangerous especially on a tube amp. If something goes wrong in the amp you have the potential to be electrocuted seriously if there is no ground connection!

Yeah, it's the 3-prong kind that lifts the ground. I know it's dangerous, but it's just my backup amp set up in the work space. I haven't been able to get my regular amp back out of the car trunk (and I can't move this one downstairs) since I hurt my back a few weeks ago, so I'm just using what I have available.

I'm pretty sure there's some contact cleaner around. I'm really hoping this isn't a bad pot; it was pretty expensive. But I've been thinking of changing it out for a linear taper anyway.
Title: Re: scratchy guitar pot straight into the amp?
Post by: rullywowr on November 16, 2013, 09:47:48 PM

Quote from: midwayfairBut I've been thinking of changing it out for a linear taper anyway.

Typical engineer/pedal builder :)
Title: Re: scratchy guitar pot straight into the amp?
Post by: midwayfair on November 16, 2013, 10:02:12 PM
Quote from: rullywowr on November 16, 2013, 09:47:48 PM

Quote from: midwayfairBut I've been thinking of changing it out for a linear taper anyway.

Typical engineer/pedal builder :)

Lol. Sometimes I think that there's no good guitar pot taper. If you use a linear, then buffered signals require large changes in the pot rotation to sound natural; if you use an audio taper, then vintage fuzzes have an "instant cleanup." But I am starting to think that linear is the better choice overall, since all of the usable action in an audio pot is in the top half of the pot, requiring fairly ginger adjustments and a sort of "shelving" at 9-10 that can be very annoying. The Sheraton I got over the summer has linear pots and I would look down every once in a while and be surprised that I had the pot on 3 or something, which is way lower than I'd have my single coil guitars.