Deluxe Micro Build Issues

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I finally finished the deluxe micro build. Just powered it up today. Sounds pretty good. My fourth custom build.
Point to point handwired housed in a 40's silvertone radio cabinet
Drives a 16ohm jensen 6x9 speaker from the 60's (sounds even better thru a 12").
12ay7 is new, 12au7 and 6ac4 are vintage tested good.
Stayed true to Robinette schematic, skipped the 6ca4 backup diodes, skipped the preamp output and Headphone jack. Connected the 6.3vct to the 12au7 cathode (for less hum I'm told) https://robrobinette.com/images/Guitar/Deluxe_Micro/Deluxe_Micro_Schematic_small.png

I have a couple of issues.
1) there is more buzz noise than I would like with guitar plugged in. Less when I ground strings with my hand. Very loud with master and volume turned up. I did my best to keep HV and heaters isolated. And have three star grounds for AC, PreAmp and HV /Power Amp.
2) there is a distinct change in the tone pot between say 9 and 10 something changes and gives a extreme bright tone. doesn't sound right, like the circuit is being pushed too hard.
3) same thing happens with the master pot almost like they are driving the circuit into unatural saturation or something. Pots are new for this build.
4) I shouldn't expect much clean headroom in this design but any suggestions to squeak some more out?

with 120vac in, voltages are 265vac out of xfmr, 295v out of 6ac4, 287v B1 230v B2

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Cabinet before and after.
Used original tweed and Fender oxblood grill cloth
Sourced a third matching knob for master

[Latole]

Clean lead, amp need better wire dress.

Too long yellow wires with caps going to tubes. Solder caps at tube socket.
Replace some yellow wires with shielded one.

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I moved the caps closer to the tube
interestingly it seemed to fix the issue I was having with the pots
I think the noise issue is from the lights as it is reduced when lights off.

[PRR]

from the lights as it is reduced when lights off.

[Latole]

I moved the caps closer to the tube
interestingly it seemed to fix the issue I was having with the pots
I think the noise issue is from the lights as it is reduced when lights off.

Good news;
Many kind of lights using transformer (neon, halogen) may induce noise if amp is not well shielded or grounded.

Your yellow wires act like a antenna if they are too long and not running close to the chassis.
 
Short answer; All wires ( from the signal path) and /or going to volume and to tube grid must very short or shielded

[ac427v]

That is absolutely ultimate cool. Great project!
If there are still noise problems, I suspect the switch on the pot next to the input jack. Is that the power switch?  If so, you could try relocating it to the other end of the amp away from the very noise-sensitive input jack and wiring.

[Latole]

Issue is from long black wires with resistor, not power switch IMO .

Too much long ( and unshielded) wires every where

[vampwizzard]

That looks awesome! if thats an aluminum chassis you may have a shielding and or grounding issue. You may want to look into some foil for the open end of that chassis.

Truly inspiring build.

[Williamblake]

If there is a difference whether you touch your strings or not your guitar is at fault or the input jack is not groundend properly. Ground you guitar strings directly to the chassis and hear the difference.

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Would the shielded wire in the pic I attached below work for the shielded wire?
Would I use this for all the signal path (long yellow wires and black wires from input jack)?
Do I need to ground the wire shield? Any issue with wire length after this mod?
BTW - Lights in room are all LED.

Chassis is aluminum (same one in the "how to age aluminum" post)
Other than the chassis mount is there a proper way to ground the jack?

Where does the foil shield go for the "open end of the chassis"?

The switch on the pot is power which means AC is running essentially the entire chassis length. Could that be the culprit? Would shielding the AC wires be any benefit? Or just move it away from Signal Wires?

[Latole]

1-Would the shielded wire in the pic work?
2-Would I use this for all the signal path (long yellow wires and black wires from input jack)?
3-Do I need to ground the wire shield?
4- Any issue with wire length after this mod?
   BTW - Lights in room are all LED.

Chassis is aluminum (same one in the "how to age aluminum" post)
Other than the chassis mount is there a proper way to ground the jack?

 Where does the foil shield go for the "open end of the chassis"?

The switch on the pot is power which means AC is running essentially the entire chassis length. Could that be the culprit? Would shielding the AC wires be any benefit? Or just move it away from Signal Wires?

1- Wich wire are you talking about ?  Mine with arrow ?  If not, show picture with arrow.
2-3 yes
4- Hard to say, need amp in front of me or better pictures.

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here's what did....
shielded with foil the AC wires to switch - no change
shielded with foil the OT - no change
shielded the bottom of the chassis - no change
used shielded wire on signal path: 1) input to preamp grid, 2) vol pot to driver grid 3) grid stopper at master pot to power tube grid 4) both coupling caps to grids. Couldn't really tell if much changed as the buzz was still present. The pic doesn't show temp clips used to ground the shield. Will be adding perm grounds.

The buzz is much lower when I use the Egnator 12" Cab with its monster speaker wire.
Tried foil shield on the 6x9 speaker wire but it had no affect. Maybe the bigger speaker lowers the tone of the buzz to make it less noticeable. BTW - This little guy (~1watt) sounds really awesome thru the 12. Sounds good thru 6x9 but the 12 really adds a great depth.

The guitar still changes the buzz but only when being held/played, less with hands on strings. With guitar on stand buzz is less. The lights on/off has affect only when guitar is held.

As a point of reference, the buzz is with all amp pots and guitar dimed.
When I back off the master pot setting to <8 the buzz is mostly gone.
   Does this say the 470k grid stopper to 12au7 should be higher?
   What grid voltage would be right on the 12au7? could this voltage be too high?
Guitar pot, and Amp Vol and Tone pots do not affect buzz (only to make it less loud), only master between ~8 and 10.

I suppose I could live with that setting but it seems that their is a secret hiding somehwere in the master.

[sluckey]

Looks like the shield braid is not connected to anything. If that's the case you probably just made it worse.

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Looks like the shield braid is not connected to anything. If that's the case you probably just made it worse.

Temporarily using clips when operating, removed for the picture.
Would you recommend grounding all together like I bundled with tape and then to the preamp star ground?

[Latole]

Repairing an amp is not easy.
Turning on an amp that never performs well is even harder.

Doing it from photos is even more difficult. It's all in the details that you can't see and the tests that you can't perform.

[PRR]

> grounding all together like I bundled with tape and then to the preamp star ground?

Shields generally should not go to each other. That can increase crosstalk and sneak-back.

They should go to a 'ground' at the place the are going. For a grid lead, usually the bottom of the cathode network.

[scstill]

I did the shield grounding before I read PRR post (pic below). It sounds decent now. 
   All shields go to preamp ground, same as preamp and driver cathodes
   Power tube cathode grounds to pwr supply ground (is this ok?).
   Should I move shield ground of power tube grid stopper?

The buzz is tolerable, although somewhat buzzier than the other amps in same room with same connection (remember I dimed all pots so it is worst case). And when the settings are where you play in middle of the range it is quiet and sweet. BTW - this room has the network server with a cooling fan always going, so that likely contributes. When I tried in another room with another guitar and cable somewhat less buzz.

I will continue to fine tune, as always your advice is priceless thank you.

Do you think I could swap the power tube 12au7 to 12at7, ay or ax to get more clean?

[shooter]

the ax can't handle the same Pdiss as an AU


get a more efficient speaker for better clean