Well, I think I searched and covered my basis so I got to throw it out there and see who has better eyes/brain than me.
SO built this a while ago, sounds great but always was pretty noisy. I get a low hum, fairly strong, doesn't change with volume.
Grounding scheme....
Pot buss>>>grounded at the input
PS Cap ground middle
Power ground other end
Toneslut transformers, Heater center tap grounded
Pretty damm sure I have the metal grinded around the input and speaker outs as well...No insulated jacks
Connecting a meter to the power jack ground to any other ground point...no resistance
So is it the nature of the beast, or I miss something?
Thx folks
Mark
Grounding Sanity Check
Moderators: pompeiisneaks, Colossal
Grounding Sanity Check
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Re: Grounding Sanity Check
Wouldn't think so.And i have used the can caps and VVR and its been probably even quieter then others. Can't tell around your bias section.So is it the nature of the beast, or I miss something?
Do you have the bias coming off the pot? I don't see a wire attached to the end you normally take the bias from.
Anodized chassis.... got to make sure you have good contact at all groung sections.
I would not trust those black sprague you have used in the bias section,as far as i could trow them.
But the first thing is always easiest,try different tubes. Some tubes can cause the same thing. you also might see if you still hear a hum when each tube is pulled,so you know its most likely to be in the later section.
Re: Grounding Sanity Check
The TS trannys - the 'original' versions made about the time you built yours - had a fair amount of filament wind hum from the PT. As in turn your amp on, leave the Standby off, and see if you don't hear the kind of hum you refer to? Eh, they just hum, and much more than say a Hammond PT. Now whether this noise is what becomes exaggerated within your circuit is for you to say.
And then looking at your chassis population, you are pretty busy. If Richie says he has built something similar and it is very quiet then I believe him, but I would also imagine his layout is a little different than yours. Richie? (And, BTW, what do you suggest in place of the Spragues?)
I see the Evidence cable on V1, good choice, BTW.
So what you didn't report is what happens to the hum when you start pulling preamp tubes? And you would do this to find out where the hum is coming from, provided it is within the preamp. First off I would strat with pulling V1 and V2 - leave V3 and the power tubes in - to see if your PI and power tube section is quiet. If it is, leave V3 in and add V2, etc., until you find the source of the hum. Of course, if when leaving V3 in you hear the hum, then this is the area you need to concentrate on. Check you 'Cut' control and Presence control wiring. Since I use the LarMar MV and not the VVR circuit, I cannot report on what to do to trouble shoot this. But there are plenty here who do. OH, FWIW, PULL V3 AND CHECK FOR HUM AS WELL. This last is probably not necessary but you never know.
All this said, if the hum exists within the output section, i.e., with V3 and the power tubes in, you might want to consider changing your power tube grid stop resistors to a higher value than stock. Your tone won't suffer, and it may be that proximity to the VVR or that strange looking cap in the IEC area might be causing a parasitic of some kind. I would start with 4.7K to see if anything changes, and you can always go back to stock. That's all I got and good luck.
And then looking at your chassis population, you are pretty busy. If Richie says he has built something similar and it is very quiet then I believe him, but I would also imagine his layout is a little different than yours. Richie? (And, BTW, what do you suggest in place of the Spragues?)
I see the Evidence cable on V1, good choice, BTW.
So what you didn't report is what happens to the hum when you start pulling preamp tubes? And you would do this to find out where the hum is coming from, provided it is within the preamp. First off I would strat with pulling V1 and V2 - leave V3 and the power tubes in - to see if your PI and power tube section is quiet. If it is, leave V3 in and add V2, etc., until you find the source of the hum. Of course, if when leaving V3 in you hear the hum, then this is the area you need to concentrate on. Check you 'Cut' control and Presence control wiring. Since I use the LarMar MV and not the VVR circuit, I cannot report on what to do to trouble shoot this. But there are plenty here who do. OH, FWIW, PULL V3 AND CHECK FOR HUM AS WELL. This last is probably not necessary but you never know.
All this said, if the hum exists within the output section, i.e., with V3 and the power tubes in, you might want to consider changing your power tube grid stop resistors to a higher value than stock. Your tone won't suffer, and it may be that proximity to the VVR or that strange looking cap in the IEC area might be causing a parasitic of some kind. I would start with 4.7K to see if anything changes, and you can always go back to stock. That's all I got and good luck.
Most people stall out when fixing a mistake that they've made. Why?
Re: Grounding Sanity Check
Well just a little different, the one i built is more along the line of stock,except for VVR and can caps. Dana has built a few of these too, so its more his layout that i followed.
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Re: Grounding Sanity Check
Well that pic looks pretty damm close to mine...probably stole your ideas 
Thanks for all the ideas, makes it easy to get quicker perspective on figuring it out with other voices in my head
Anyway, interesting...go to put the tubes back in to play pull the tube chase yje noise game, fire it up and the low end hum is gone, replaced by a typical high hiss (pull V1 out and that goes down a factor...pretty dead quite).
Got a few amps I rotate so maybe my memory isnt quite right, but this high end hiss seems more familiar.
Anyway, intermittent low end hum tube going?
Thx
M
Thanks for all the ideas, makes it easy to get quicker perspective on figuring it out with other voices in my head
Anyway, interesting...go to put the tubes back in to play pull the tube chase yje noise game, fire it up and the low end hum is gone, replaced by a typical high hiss (pull V1 out and that goes down a factor...pretty dead quite).
Got a few amps I rotate so maybe my memory isnt quite right, but this high end hiss seems more familiar.
Anyway, intermittent low end hum tube going?
Thx
M