Someone in LA area want to help me?

[Lindz]

No, I ran it without the zeners to check that myself (in spite of the high voltage) and the hum is still there.

I should qualify that by saying it still hummed more than I thought it should with no zeners - it may very well have been a little quieter without them but I did not literally measure it. I simply disconnected them, fired it up and quickly did a very off the cuff noise check for a minute or so and it did not seem noticeably better so I put them back in to get the voltage back down to a reasonable level for the tubes. Did not seem to be the main issue

The Trinity PT says 290 but is almost 315 actual with my mains voltage at home so I have pretty hot voltage even with an ez81 installed

In any event I at this point I want to go ss rectifier, hence the dropping zeners.

Perhaps I should record the hum so people can hear what I am dealing with?

[M Fowler]

Have you tried the amp in other areas of your home or taken to a friend's home to see if it is just a case of dirty AC line.

I had one hell of a time figuring out what was causing the awful raspy and buzzy line noise in my home but I found it after I had rebuilt several amps and cussing a blue streak for months.

[Lindz]

I am sure that my AC is somewhat noisy - upstairs is worse than downstairs etc - but other amps are much quieter than these two 18 watt builds including a Weber Java that I built so I assume there has to be more to the noise than just the AC??

[M Fowler]

I can't tell from the picture if I am seeing a wire or a shadow but is your buss bar connected to either the input jack then to ground?

Or from buss bar to chassis point near the input jack and input jack also grounded there as well?

I have built a lot of 18w amps using the buss bar method and never had any problems, but I do like the Larry grounding which is close to what Hogy did with the Komet 60 and Concorde. The grounding layout you posted should work too.

[Lindz]

The input jack has a ground to the chassis at the copper lug beside it as does the bus at that point.

My drawing was mimicking the "Larry" JTM 45 you posted but due to the different amp design I was not sure if I correctly grounded all the sections to the various star points, especially the relay channel shunts and some of the grounds near the PI

In any event I will likely try this with one of my builds to see if it helps.

That said, this kind of emphasizes why I wanted a more experienced builder to look at it in person as I feel like I am just shooting in the dark at this point.

I have tried moving grounds on the bus, moving certain grounds to stars, and even running every single ground to a single star near the power section and the amp still seems a lot noisier than it should be (a lot noisier than other amps I have). Maybe I have a bad cap? Maybe I just did something simple incorrectly and keep missing it? I just figure at this point I may be better off with someone that really knows what they are doing troubleshooting it.

It sounds great, I am very happy with it, but its just REALLY noisy

[martin manning]

Perhaps I should record the hum so people can hear what I am dealing with?

What frequency is the hum, 60Hz or 120Hz? If it's 60Hz it's likely filament circuit-related, 120 is the ripple on the HV DC. If it's 60Hz in your amp, consider redoing the filament wiring. Look closely at the filament wiring in the picture Mark posted and compare it to yours. Note the wide loops coming around the tube socket attachment screws, and the approach to the sockets is along a radial.

[pch64]

I also used Larry's ground scheme because there was hum and buzz with the typical 18W TMB bus grounding. I only didn't try connecting heaters CT to point 1. Now my amp is very quiet (it's 6v6 TMB).

The only significant difference I can see with yours is the grounding of the tone and volume pots. I also have 5 grounding points:

1 - Inputs, V1 cathodes
2 - V2 cathodes & Preamp filter, Gain pot, Middle pot
3 - PI tail, Power tubes grid leaks & PI Filter, Volume pots, Output jack
4 - Power tubes cathode resistor, HV CT, Heater CT, PT Screen, Dual cap can
5 - Power cord ground

I have wired V1 with 2 input jacks to switch between single/parallel triode mode and it's common to the two channels (TMB and LiteIIb).

I hope this will help.

Peter

[Lindz]

Martin - it seems like 60hz but when I switch to the tmb channel there seems to be additional 120hz

I did redo the filaments on the preamp tubes - they were originally done as you describe but after reading the Valve wizard article on hum he categorically states to NOT wrap the heater leads around the tube socket and instead twist right up to the socket and go straight across the base of the tube. I thought it was worth a try though did not seem to help or worsen things with my amp

PCH64 - good to hear the Larry grounding seemed to help on an 18 watt build, I think its worth a try. You always learn something with mods, right?

will post after a few changes to let folks know results

[martin manning]

I did redo the filaments on the preamp tubes - they were originally done as you describe but after reading the Valve wizard article on hum he categorically states to NOT wrap the heater leads around the tube socket and instead twist right up to the socket and go straight across the base of the tube. I thought it was worth a try though did not seem to help or worsen things with my amp

Both filament wiring methods can work without excessive hum; it's kind of hard to see details in your pic but I understand what you have now. If you pull the preamp tubes one at a time starting with the first one and finishing with the PI, does the hum stop at some point? This might give you a clue as to where the problem is. The other thing to check is, does the FX loop create the hum? Is there any easy way you can disconnect it to find out? Lift its ground? You might want to try grounding that to the chassis near the loop jacks.