New TMB w/reverb Build

[foreverstrung]

1) The 10k resistor is in series from pin 7 to the PCB board port marked V4P7. (This resistor was originally attached with shielded wire. I wanted to clean it up so I replaced replaced it with 20g wire. Should it be shielded?)
2) The .001 cap is from pin 7 to ground. (Is this cap part of the "grid blocker" or did my guy add that? Should this cap be in series with the 10k resistor? Do I keep it to ground?) The picture I posted earlier today shows both the 10k resistor and the .001 cap at Pin 7 of V4. Cap to ground and resistor to PCB board
3) The green wire you asked about is what connects P3 and P8 to the port on the PCB board. Small green wire jumps from p3-8 and then the longer green wire is connected to p8-PCB board
4) The voltages all check out "except", the AC voltages A, B, C and D. IDK what the hecks going on here, but there not picking up barely anything. I mean like A is 4.4v. No, not kidding. B is 0v. C and D as well. I even used another DMM and the readings were the same. I'm getting the correct AC voltage at the heaters, PT in and out, just when it gets to the cap can, I'm getting notta. I tried and retried. At least a half dozen times. I even hooked everything up and had the guitar and speaker active and checked AC voltages here and got the same readings.
5) I'm attaching the voltage chart
6) Lastly is attached a video of sound

https://youtu.be/-NhPIxDyq1g

voltage chart 3.21.jpg

[JMPGuitars]

Try removing the cap to ground and see what effect it has.

A,B,C,D need to be read as DCV. I'll look over the rest tomorrow, it's past my bedtime.

Thanks,
Josh

[foreverstrung]

4) The voltages all check out "except", the AC voltages A, B, C and D. IDK what the hecks going on here, but there not picking up barely anything. I mean like A is 4.4v. No, not kidding. B is 0v. C and D as well. I even used another DMM and the readings were the same. I'm getting the correct AC voltage at the heaters, PT in and out, just when it gets to the cap can, I'm getting notta. I tried and retried. At least a half dozen times. I even hooked everything up and had the guitar and speaker active and checked AC voltages here and got the same readings.

Duh. DCV attached for ABC and D

A.B.C.D.jpg

[JMPGuitars]

Your B+ and tube dissipation are too high. Do you have any 5W Zeners? I would drop 15 to 20V on the B+ line. Put 2 10V 5W Zeners in series between the 1st and 2nd filter caps.

You're using a 180 ohm cathode resistor for the power tubes, correct?

[foreverstrung]

Your B+ and tube dissipation are too high. Do you have any 5W Zeners? I would drop 15 to 20V on the B+ line. Put 2 10V 5W Zeners in series between the 1st and 2nd filter caps.

You're using a 180 ohm cathode resistor for the power tubes, correct?

Yes, I've got 2 of the 5W Zener Diodes. Should I add a 3rd? (pic attached)
I am using 180 ohm cathode yes

What is the formula to figure dissipation?

Would this noise possibly be from the amp being too hot? Should I bring the tube dissipation down first and if noise is still present, remove the .001 cap at V4P7 to ground and see what happens? Or remove it first and recheck voltages?

[JMPGuitars]

Yes, I've got 2 of the 5W Zener Diodes. Should I add a 3rd?
I am using 180 ohm cathode yes

What is the formula to figure dissipation?

Would this noise possibly be from the amp being too hot? Should I bring the tube dissipation down first and if noise is still present, remove the .001 cap at V4P7 to ground and see what happens? Or remove it first and recheck voltages?

My assumption is that he added the cap thinking it would help with the noise. Remove the cap and see if it actually has any effect on the noise at all.

You need to get your B+ down to 345VDC. Are your Zeners pointing the stripe towards the voltage source (rectifier)? If they are oriented correctly, add at least 10 to 20V more in series to get B+ into the correct range.

Tube bias calculator: https://robrobinette.com/Tube_Bias_Calculator.htm

Yes, the amp being too hot can contribute to the noise. No, it's not guaranteed if that is the cause or not. Getting your voltages correct is the first step.

Thanks,
Josh

[Bieworm]

Don’t know if it’s the case… but reverb tends to bring noise into the circuit at the recovery side. In my experience the one tube reverb is pretty noisy. The blackface reverb is a lot more quiet while delivering a ton of reverb. I added one to my latest single ended EL34 Tremolo TMB Reverb amp.. and it’s dead quiet. The only noise is the single ended character, but that is a pretty normal noise imho…

[foreverstrung]

My assumption is that he added the cap thinking it would help with the noise. Remove the cap and see if it actually has any effect on the noise at all.

You need to get your B+ down to 345VDC. Are your Zeners pointing the stripe towards the voltage source (rectifier)? If they are oriented correctly, add at least 10 to 20V more in series to get B+ into the correct range.

Voltage looks good at B+ now (Before Zener Diodes, 378.3v After Diodes 347.4v)

When I removed the cap, the oscillation came back. I determined this by the reverb acting like it was before the modifications.
So I reset cap and thought I'd try swapping out reverb tanks. For some reason this seems to have made a big difference, the sound is much quieter. Very reasonable. Reverb is spot on.

Amp sounds great now. For now. LOL. Time to finally build this cabinet and move onto the next project.
Thx

[foreverstrung]

https://youtu.be/_Aizr8kfo80

Demo. Tried to get an array of sounds. Hard to get across with an Iphone recording
Background noise is pretty quiet now. Reverb is great. Tremolo too. getting just clean sounds I still struggle with. Volume low, they can be got, but this amp has crunch. I feel like it's meant to be loud. It's like riding my Harley. Very difficult for me to go slow on open highway. My bike operates best at 85+ mph. Like this amp, IMO, operates best, with volume and gain.
Thx

[JMPGuitars]

https://youtu.be/_Aizr8kfo80

Demo. Tried to get an array of sounds. Hard to get across with an Iphone recording
Background noise is pretty quiet now. Reverb is great. Tremolo too. getting just clean sounds I still struggle with. Volume low, they can be got, but this amp has crunch. I feel like it's meant to be loud. It's like riding my Harley. Very difficult for me to go slow on open highway. My bike operates best at 85+ mph. Like this amp, IMO, operates best, with volume and gain.
Thx

Sounds great for a phone recording! Here's what you need to experiment with to get your cleans:
Turn the gave knob all the way off, and turn the volume knob to a good level to play. Then roll the gain knob up until you get the preamp dirt you want, or leave it back if you like the clean, or would rather push the power amp.

Now, either way, you need to experiment with pick attack and the guitar volume knob.

The guitar volume knob can take most of the dirt out.

So can pick attack. Try playing gently with fingers, compared to a pick. Try pick lightly vs. plucking hard. You should hear an array of tones and dirt without needing to touch the amp.

Congrats on getting the circuit done!

Thanks,
Josh