Grouding Multi Sectional Capacitor Can

[EETStudent]

I need some tips on how to properly ground my circuit using a single multi-sectional cap can. Its a 40/20/20/20 can made by JJ. Saves a lot of space, but Im getting some obvious grounding issues. Im getting a buzz a both extremes of the volume pot, and the tremolo controls also buzz terribly when disengaged. The circuit is modeled after a 5G9 Tremolux with some minor component tweaks

The can itself is located next to the PT, and I currently am running the common ground at the nearest PT bolt along with the cathodes, bias ground, and HV center tap. At the other end, I ran a buss wire along the backside of the pots. I ran each local ground to its point on the wire, and I then ran a single wire to the input jack ground located at the chassis.

For the most part, this is how I did my previous build and it turned out great. Except then I was running individual caps and I split off the grounding to acheive a proper grounding scheme. I dont have that option with a single cap can. What do I need to differently to acheive better grounding?

[trobbins]

Have you followed any commonly accepted grounding schemes from any good references?

[Jazz P Bass]

The mulisection can is grounded at one point of the can.
Where 'that' wire connects to ground does depend on your specific grounding scheme.
I would monitor what the individual caps are doing.
Are they reducing ripple like they should.
You 'may' have a bad section.

[Tonewood]

"buzz terribly"
Does that sound like 60 or 120HZ?

"I ran a buss wire along the backsides of the pots"
"I currently am running the common ground at the nearest PT bolt"
"I then ran a single wire to the input jack ground"
I'm not understanding this scheme so it's hard to come up with ideas, is the can grounded to the PT bolt? The pots & input jack connected to the chassis?

"to acheive a proper grounding scheme"
Depending on what you mean by proper, you may not get a "proper grounding scheme" using a can and a buss wire along the backsides of the pots. For me, keeping the first cap in a tight loop with the PT center tap and away from the other stuff helps. Maybe you could give it a cap of it's own.

Good luck

[Steve Conner]

Try connecting your HV centre tap directly to the negative lug of the capacitor can. That's probably the single biggest change you could make.

It may never be as quiet as if you had used separate capacitors.

[Chuck H]

It's very telling that your not reporting "hum". You can isolate buzz by pulling tubes. Once you isolate the buzz you could try changing some lead dress or grounding schemes for that circuit.

[EETStudent]

"buzz terribly"
Does that sound like 60 or 120HZ?

"I ran a buss wire along the backsides of the pots"
"I currently am running the common ground at the nearest PT bolt"
"I then ran a single wire to the input jack ground"
I'm not understanding this scheme so it's hard to come up with ideas, is the can grounded to the PT bolt? The pots & input jack connected to the chassis?

"to acheive a proper grounding scheme"
Depending on what you mean by proper, you may not get a "proper grounding scheme" using a can and a buss wire along the backsides of the pots. For me, keeping the first cap in a tight loop with the PT center tap and away from the other stuff helps. Maybe you could give it a cap of it's own.

Good luck

Sounds like 120hz for sure. The pots and local board grounds are essentially being grounded at the input jacks. The ground lug on the can is being tied to the nearest PT bolt, where the cathodes, bias grounds and HV CT are also being grounded. Im starting to feel I need to separate some of these caps and their grounding points. Cant seem to fix the issues. thanks guys

[R.G.]

Does it use solid state or tube rectifier?