Bugera PowerSoak PS1 "Soak" knob is noisy

[stevewf]

Hello Nutz.

The "Soak" knob on my Bugera PS1 makes noise when I turn it down very low. Kinda crackly sound, like when a guitar's pot gets dirty. So I opened it up to see if I could DeOxit the thing.

First picture with the cover open (the knob/pot comes with the cover

Second picture with the pot removed from the cover

Reference marks are inches - it's a big pot! It's got what looks like heat-conductive paste for its contact with the specially-fitted gizmo that's part of the cover, and what seems to be a temperature probe that fits into a notch in that gizmo. "Gizmo" looks like heat management stuff to me.

So I just put it all back together, because I wanted some opinions before spraying anything like DeOxit in there.

Anybody have tips on fixing the crackling noise?

Thanks -Steve

[newey]

Jul 23, 2024 22:54:31 GMT -5 stevewf said:

makes noise when I turn it down very low. Kinda crackly sound, like when a guitar's pot gets dirty.

If it is truly a dirty pot causing the problem, I would expect to hear some variance in the crackling noise as you turn the knob. Does the noise vary when you do so?. Thinking that it might also be a connection issue (which might or might not vary with turning it down).

[JohnH]

These are wire-wound LPad pots (two tracks joined), and as you get low, each turn of the wire is making a big % difference to the attenuation, which is masked by the greater volume at higher settings.

But if you measure resistance as seen across the output jack without speaker (amp disconnected), are you seing intermittent jumps and infinite readings as you turn the pot? Is the sound clear and steady if you don't move the pot?

I don't have one of these type of lpad pots myself, so I'm speculating. But based on the brand that it is, quality may be job no. 256, or it could be normal.

[frets]

Steve,
I have heard before that this crackling issue happens. Maybe you should contact the company. Maybe they could help you out.

[stevewf]

Jul 24, 2024 16:54:07 GMT -5 JohnH said:

These are wire-wound LPad pots (two tracks joined), and as you get low, each turn of the wire is making a big % difference to the attenuation, which is masked by the greater volume at higher settings.

But if you measure resistance as seen across the output jack without speaker (amp disconnected), are you seing intermittent jumps and infinite readings as you turn the pot? Is the sound clear and steady if you don't move the pot?

I don't have one of these type of lpad pots myself, so I'm speculating. But based on the brand that it is, quality may be job no. 256, or it could be normal.

JohnH, thanks. I feel pretty strongly that yes, this is what you've described as a wire-wound pot. I can feel the knob turning through tiny detentes, reminding me of an ancient lightbulb dimmer on a childhood wall. Others on the web have complained about a noise that emanates from the knob as it's being turned, which I think is from the same thing: wire-wound.

I get that the lower the output is turned, the greater the impact each winding has in terms of % of the overall signal. Would that also translate to increased noise when the wiper is moving across those windings? The crackle is audible even when the guitar's volume is at zero; not audible at the higher outputs.

And thanks for the suggested tests. Next time I've got the thing open, I'll disconnect the amp and the speaker and test with both analog and digital ohmmeters. For now, as far as I can tell, the guitar signal comes through normally as long as the knob is left still.

Jul 25, 2024 13:32:29 GMT -5 frets said:

Steve,
I have heard before that this crackling issue happens. Maybe you should contact the company. Maybe they could help you out.

Thanks, frets. I'll do that too! Ya never know. Nearest Bugera dealer is some 350 miles from where I live; I hope they offer a non-traveling option.

[JohnH]

hi stevewf , yes I think so. It's not fully clear to me though. With no signal, there shouldn't be any current running through the pot, so nothing to create the noise.

But with sound happening, you could imagine that the small steps and contact changes as you turn a little might be fairly similar at high and low volume, but get audible swamped when at high volume?

I'm really interested in the design of attenuators and I have some designs based on switched stages that have become quite popular. Usually those based on a simple LPad can have a few issues with consistency and tone, particularly at low volume. I've been working out how to adapt them with a few more parts to make them much better though. I'll post on GN2 about it soon.

[stevewf]

Jul 25, 2024 22:55:52 GMT -5 stevewf said:

The crackle is audible even when the guitar's volume is at zero; not audible at the higher outputs.

No. I was apparently making that part up. Only crackles when there's some guitar sound plus moving the knob while the knob is way down in the quiet end of the sweep.

I'm satisfied that the crackling is part of the normal properties of this type of pot design, and so I'm ready to live with it. It's not like I'm twiddling it during playing, really. It only caught my ear because I tend to want low speaker volumes - hence my purchase of an attenuator to begin with.