Noise in Rocket/AC-30 type amps?

[Mark]

I was wondering if anyone can help me out.

I have this small hum in my (15 watt version of an) AC-30/Rocket amp.

To put a value to the noise, when I measured it with my Fluke 77 meter it measures 0.2vac.

I know the hum isn't coming from the pre-amp as I removed the pre-amp stages prior to the tone controls.

The fault occurs at it's worst when the tone controls are turned up (even when the pre-amp stages have been removed), doing this places a 2M resistance prior to the P.I. input cap.

When the wiper of the treble pot is earthed the amp is dead silent.

I did try removing any input to the P.I. and the hum/noise got worse. I tried using shielded cable and there isn't any signicant difference.

I find when I turn the treble control down so the wiper contacts to the top of the bass control the amp is much quieter.

Is this typical of an AC-30, or do I have problems?

Thanks for all your assistance.

Yours Sincerely

Mark Abbott

P.S. Is the bass pot in the TUT version of an AC-30 wired backwards?
I think it must be.

[Bear]

Mark, are you dropping the reverse engineered Rocket pre circuit you did [posted in the schem section] next to a standard Vox output circuit, or has the reversing gone further? Very interested in this project, especially at 15 watts.

Bear

[Mark]

Dear Bear

Sorry for the lenghty delay. The circuit is my best guess at the Rocket circuit given information that I was able to find out.

I haven't been able to find out any more from Rocket owners here at the TWreck page, but thats cool, it's their amp and they are free to do what ever they like with it.

Still, you'd think they'd send Omar some cool (external) shots of the amp though.

Yours Sincerely

Mark Abbott.

[Omar]

Mark,
Unfortunately no Rocket pics have come my way. The Rocket and Liverpool really seem rare compared to the Express.

Did you ever fix the noise problem?

Omar

[Bear]

Mark, not a problem. I think I need to do some smaller things before attempting a 'Wreck, but I like to stay aware of these things for the back burner.

Bear