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got a similiar problem with a Ceri@tone lighting clone. Mine buzzes on the low E string with the guitar volume on 10............back it off and it goes away. I'm no tech, so been looking for someone to correct this.

At this stage, I'm half tempted to tear out the board and recheck everything...

I'm at a loss for what the problem is...

-F

I notice your 6.3 heater wiring runs over your OT leads in a couple of places; could that contribute to it?

Um,

honestly, I doubt it. I've got a similar scenario on another amp here, and it's frankly the quietest amp I've every known. In some amp layouts, crossing leads with the 6.3 twist is inevitable.

Also, as previously mentioned this problem is largely dependant on where the volume knob is...and will manifest itself at any master volume position...from whisper quiet to WFO.

Also, this afternoon, I noticed that the sizzling got worse/better depending on what I did with the input wires.

I firmly believe this problem, given the above symptom is resting squarely in the preamp somewhere....In fact, I'm convinced that the input wiring is to blame....I am now experiencing an old problem that I thought was licked, which was the amp whistling when there's nothing plugged in.

So I'm going to tear out the current input jacks, verify their functionality and rewire....but this time, use some more reliable input wire (monster guitar cable I've got here), place the 68K resistors directly on v1....and make sure the switching to 1mg is correct...

Hopefully, this will give me better insight to the origins of this problem.


I'll be in touch...

-F

Frank, make it simple, just wire in a single input jack to start with.
Nigel

Nigel, VERY Good idea...

I'll do that...simply 1m pull down going into one 68K that hits v2...

If that works, I'll be convinced its the input wiring!

Hey folks...

I *finally* licked this problem...

After months and months of minor buzz to the nasty sizzling that you heard on the above posted mp3, I'm done with this amp.

My last ditch fix, was going to be tearing out the board and rewiring everything...before I did that, however...I tore out the input lead...and both input jacks..I sucked off all the old solder and started from scratch.

Then I basically reqired things...but instead of having the 68K resistors at the input jacks, I have them coming off of a 3-connection terminal strip at the socket...and the resistors are soldered right to the socket. I also junked the input cable I was using and used some scrap Monster brand guitar cable I had lying around....the leads on this cable is a little meatier...other than that, no difference from the stuff I normally get from doug hoffman.

Once everything was wired up, I fired up the amp....absolutely DEAD quiet, no buzz, no noise....just beautiful matchless tone! I'm in love...


Much thanks to everyone that helped me think this problem through!!!

-frank

Well done Frank! now you need that A/B/Y switch
Nigel

Good Deal Frank. I thought it was starting to point to the inputs.



Guys - that's the way the layout specifies how to do it. Learn from this experience! I know some people say it doesn't matter blah , blah, blah, but apparently it mattered in Franks build!



Always use [good quality] shielded cable. Don't use solid/stranded/unshielded. Again, blah, blah blah.

Frank, where did you solder the ground of the shielded cable?

_________________
Stephen
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Yep, it most certainly did. I was starting to suspect this as well..my house is a hotbed for alot of airborne junk thats radiating off the power lines. I've been in a seemingly constant fight with the power utility and they've been largely unhelpful....

Regardless, as soon as I moved the 68k resistors to the socket, it quieted up like no ones business!



You know, the stuff i had in there, wasn't bad stuff. Its probably used in a large percentage of the diy amp builds out there...but the monster guitar cable that I had lying around was no-BS cable, with a thicker center lead and a tighter ground braid. If, by chance, the cracking/sizzling happened to be as a result of a crimp/break/etc in the original cable, I might solve the problem with the cable switch. Worst case, I could just say that my amp inputs had Monster-brand cable.... LOL

As far as where the ground of the shielding went, I grounded the shielding to the same lugs on the input jack, which proceed to the input star ground.