A lot noise on three channels, not preamp valves (Help)

[steve_k]

On the other side of the board (from where you found the hum trim), next to the Midi controller, you will see 3 trimmers. A is for the inside pair of tubes, B for the tweeners and C for the outer pair. You also mentioned noise getting worse when you faced the amp. Turn the other direction. That hum trimmer is something you shouldn't have to mess with. Buy a better preamp tube for V1 with lower microphonic characteristics. The new Tung Sol 12AX7's are quiet as a mouse. Also, I assume when you are testing that you are bypassing all that routing and plugging straight into the amp. Ground loops can cause lots of nightmares and one's wallet to slowly empty.

Steve

 

[jemmx]

Yes I see the trimmers, its a little bit different than picture, I can regulate from outside , right now I'm sure

Thanks Steve_k for your recommendations!!

When receive the bias rite in this days I can check and know the reason of my problems... I hope :/ , maybe not...

If not...

Peter save me please!!!

I feel frustrated with this

 

[MARK2C]

Yes I see the trimmers, its a little bit different than picture, I can regulate from outside , right now I'm sure

Thanks Steve_k for your recommendations!!

When receive the bias rite in this days I can check and know the reason of my problems... I hope :/ , maybe not...

If not...

Peter save me please!!!

I feel frustrated with this

Relax. This can happen with any and every tube amp you ever own from a Crate to a Dumble.
It's a great learning experience, so hang in their and you will have a better understanding of tube amps
when everything is back to normal.

 

[jemmx]

...well finally the bias rite has come.

Right now I tested for first time all tube values.

first pair from the left 32.4/37.8, and the others are relative the same variation.

I tryit to put same value for itch valves in all pairs but when change to 34 for A tube, B grow to 39 aprox. Can't put exact same value in any pair. It's normal?

Yes only try once time for all.

Voltage Plate around 448-465v.

All fuses are replaced.

All preamp tubes are replaced.

I tested different positions with the hum trigger, and nothing.

The noise still there.

more suggestions?

Thanks for all that posted here!!

 

[nbarts]

Where is the mp3 clip?

 

[Me]

first pair from the left 32.4/37.8, and the others are relative the same variation.

When you say first pair from left make sure you know what are the pairs. They're the far right and left tube is one pair (1&6), then the 2nd and 5th, then the 2 middle ones. The pairs are not next to each other, ok?

I testing more time, but the noise grow when put the level up, isn't playable when I close to the amp.

I changed again the instruments, but is not the problem.

You say it is unplayable when close to the amp? It's not the mag field being picked up by the pickups is it? Did you try humbucking guitars from a few metres away, and different cables? What then?

Other than that I'd have thought tubes, bias, hum trimmer, or a bad mains supply maybe with bad earth.

 

[jemmx]

When you say first pair from left make sure you know what are the pairs. They're the far right and left tube is one pair (1&6), then the 2nd and 5th, then the 2 middle ones. The pairs are not next to each other, ok?

Yes I understand, I have a doubt after these. When I have first pair (1&6) which of three bias adjustment pot need to touch?

You say it is unplayable when close to the amp? It's not the mag field being picked up by the pickups is it? Did you try humbucking guitars from a few metres away, and different cables? What then?

well, instruments is not the problem, because without any guitar, the hum noise still there. I changed all cables too.

Other than that I'd have thought tubes, bias, hum trimmer, or a bad mains supply maybe with bad earth.

mains I don´t think so, when playing before don't do this, maybe hum trimmer is the problem, I touched and don´t ear any differences.

I go to the tech and forget this, any way I learned too much with this.

Thank you!