Berning ZH270 help

Thanks for your kind and appreciated help. I've forgot to tell I tried to swap the tube, power first and pre after but the problem persist on just left channel. It remembers me once when I had one cap gone with another amplifier...
I'm in contact with a good service here in Italy, I'll take my ZH270 there.
Hey Allan, I'm Paolo from Italy...you may not believe but I've not yet received your post. It should arrive anytime these days....Italian Post Office....

Paolo, the noise you describe really is conducive to that of a tube problem, you need to take your time and switch one set at a time, and make sure you are changing them from one channel to another, as well, did you do any mods to the amp?
The ZH-270 is not a user friendly mod device by any means.

I hear stories from Europe of people cutting off the wrappers on caps and other stuff.

When you get the other set of tubes, we can go through the switching, so we can make sure it's in opposite channels.

Thanks Allan,
Just received your tubes and kit today, I'll install and see if it solve also the Left channel problem.
Anyway, no mods made on my ZH270, only preampli stage tubes swap. Im my ampli there was 1x 12AV7 RCA Electron Tube, 1x 12AV7 Internation Service Master (2 different!) and as 12AT7 2x WC GE and 2x JAN Philips.

As mod I'm thinking on signal cabling upgrade with better cable (the one used is quite bad actually) and maybe a better potentiometer, I could heard astonishing improvement with an Imai (Audiotekne) precision carbon resistor one.

I had to service it one year ago when a transistor in PSU was dead, but in the case the ampli didn't wanted to turn on: always red leds.

Paolo

OK, just replaced existing unknown output tubes with the Allan Sylvania and the problem seems over. I had only one hour listening, so i need more time for last word.
By the way, either the Sylvania and the ERS kit does inprove the ZH270 sound!

Paolo

Paolo you might want to talk to Allan about the cryoed hybrid wire upgrade if you think the tubes and ERS improve the sound. The wire upgrade improves resolution and truly improves the sense of ease to this exceptional amp. The only problem is you are in Italy and you need to have very good soldering skills for this mod but it is sure worth the trouble.