Master Volume Static

[Charlie Wilson]

Hello, I notice with my amp that when I hit a note on my guitar and turn the master volume I get some static noise. It does it more on low notes. The pot is quiet when I rotate it with no signal. I know that is a very sensitive spot in the amp and it may be normal. I am using a vintage Fender 1meg there that I am concerned that the track may be a little worn and yes I rather carefully cleaned the pot.
CW

[groovtubin]

Hello, I notice with my amp that when I hit a note on my guitar and turn the master volume I get some static noise. It does it more on low notes. The pot is quiet when I rotate it with no signal. I know that is a very sensitive spot in the amp and it may be normal. I am using a vintage Fender 1meg there that I am concerned that the track may be a little worn and yes I rather carefully cleaned the pot.
CW

i`d try V1 change first..

[Charlie Wilson]

Groovtubin, are you saying try a different V1 tube? I am talking about the master not the preamp volume. I have been rolling through different tubes and it still does it. I am thinking that may be the one spot to use a fresh pot rather that a vintage one.
CW

[lovetone]

I've not come across that before, when the pots dirty in normally is noisy when its rotated. It might be that its just on the edge of trouble so thats why you can only hear a problem with signal.

Try turning you preamp level quite low down and see if the problem is there all across the master or just in one place. Easy way is just change it and it the problem persists then we can look for the fault.

Cheers

[groovtubin]

Hello, I notice with my amp that when I hit a note on my guitar and turn the master volume I get some static noise. It does it more on low notes. The pot is quiet when I rotate it with no signal. I know that is a very sensitive spot in the amp and it may be normal. I am using a vintage Fender 1meg there that I am concerned that the track may be a little worn and yes I rather carefully cleaned the pot.
CW

i`d try V1 change first..

Heard u first time loud n clear, try that first..

repaired pro since 91, i`ve seen it ok?? Either that or a leaky cap,or a cold solder joint

jim

[erwin_ve]

Hello, I notice with my amp that when I hit a note on my guitar and turn the master volume I get some static noise. It does it more on low notes. The pot is quiet when I rotate it with no signal. I know that is a very sensitive spot in the amp and it may be normal. I am using a vintage Fender 1meg there that I am concerned that the track may be a little worn and yes I rather carefully cleaned the pot.
CW

i`d try V1 change first..

Heard u first time loud n clear, try that first..

repaired pro since 91, i`ve seen it ok?? Either that or a leaky cap,or a cold solder joint

jim

Or a bad pot in my case...

[Charlie Wilson]

Thanks guys for the responses. Groovtubin, sorry if I sounded a little short in my response, I appreciate your ideas. I should maybe expand on this master volume issue in my amp. I have been working on this Low Plate Classic for close to a year. For awhile it was sounding inconsistent, sometimes bright(overly) and sometimes dark. I finally figured out it was the vintage 1 meg pot I used for the master volume. I then took the pot apart and carefully cleaned the the metal track with Brasso and the carbon track with isopropyl alcohol and replaced the damping grease. After I reinstalled it the amp sounded great and sounded the same every time I turned it on. Up to this point I was using a Strat and there did not seem to be this static issue. Recently I borrowed a Les Paul type guitar and noticed that when I hit low notes I hear this static when rotating the pot and it only does it between 1 and 2 on the control. There is no static when a signal is not going through the amp and the pot is rotated. Nor is there any static at all when I am playing through the amp and the pot is not being rotated. I acquired a couple more Fender vintage 1 meg pots and swapped them out and they do the same thing at the same place on the pot. As you guys know, these 30% Fender 1meg pots are hard as heck to come by but if that spot in the amp is so sensitive that the only fix is a new fresh pot, so be it.
CW

[groovtubin]

Thanks guys for the responses. Groovtubin, sorry if I sounded a little short in my response, I appreciate your ideas. I should maybe expand on this master volume issue in my amp. I have been working on this Low Plate Classic for close to a year. For awhile it was sounding inconsistent, sometimes bright(overly) and sometimes dark. I finally figured out it was the vintage 1 meg pot I used for the master volume. I then took the pot apart and carefully cleaned the the metal track with Brasso and the carbon track with isopropyl alcohol and replaced the damping grease. After I reinstalled it the amp sounded great and sounded the same every time I turned it on. Up to this point I was using a Strat and there did not seem to be this static issue. Recently I borrowed a Les Paul type guitar and noticed that when I hit low notes I hear this static when rotating the pot and it only does it between 1 and 2 on the control. There is no static when a signal is not going through the amp and the pot is rotated. Nor is there any static at all when I am playing through the amp and the pot is not being rotated. I acquired a couple more Fender vintage 1 meg pots and swapped them out and they do the same thing at the same place on the pot. As you guys know, these 30% Fender 1meg pots are hard as heck to come by but if that spot in the amp is so sensitive that the only fix is a new fresh pot, so be it.
CW

ALL good my frioend, really trying to help, even if i`m wrong, i love helping! I know, these amps do have a sweet spot, i`ve got amillion pounds of great highs in my HRM/70`s hybrid, ( yes weird!) but it snds ridiculous, n dialing it in is a job, i find the guitar vol n tone really come n handy! lol! My best, jim shoot me yer postal addy, i`l send you one of my 1meg fender originals!

[Charlie Wilson]

Well, I auditioned a few new 1 meg pots in my amp and can now say it was definitely those vintage pots that were the issue. I am still a bit baffled that two vintage pot behaved exactly the same in my amp. When I installed a new CTS 1meg the static issue went away and my amp became quite a bit brighter and gainier sounding. I guess I got used to the darker rolled off sound of my amp before. It was almost like the sound of turning the volume down a bit on the guitar. I know those vintage pots can sweeten up the sound a bit but I don't know if I want to hassle with trying to use one as a master volume if even a little wear on them can mess up the sound of the amp. I tried changing my negative feedback resistor to 3k3/270 ohm(when the suspect pot was in the amp) and though it made the amp sound dull but now that I have way more brightness than I want, I am going to try it again. I think I prefer the sound of the CTS to the Alpha although the difference is very slight.
CW

[Structo]

Yeah, I had a couple 1M NOS Allen Bradley pots that were defective and noisy from the get go.

That confirmed to me that I should measure every component before installing them in an amp.
It can prevent problems that may be difficult to trace out.

[vibratoking]

Yeah, I had a couple 1M NOS Allen Bradley pots that were defective and noisy from the get go.

That confirmed to me that I should measure every component before installing them in an amp.
It can prevent problems that may be difficult to trace out.

Tom, what are you measuring/checking for to uncover bad pots?

[Charlie Wilson]

Yeah I was wondering that also. My pots measured fine for value and I will even sometimes put a VTVM across them in ohms mode and watch the needle for jumps as I slowly rotate the wiper. I just think now that the master volume position is such a sensitive spot in the amp that any wear on the carbon track can cause issues. I mean it was night and day after I put a new CTS pot in and that was after going through two vintage Fender ones.
CW

[Structo]

One was out of spec and the other went to 100% before it was halfway up.

At first I thought it weird that the clean tone wasn't that clean.

Turns out the volume pot was bad.

Although I kind of liked how it sounded at the time.

Now I measure total resistance, sweep and taper.