Berning ZH270 help

Thanks for the hint Tubegroover, actually Iàve already contacted Allan for the that. Living in Italy doesn help this.
Anyway I ve found what I consider the best option for cables: Sublima an italian manufacturer, He's cables are mervelous to preserve harmonic richness and correct timbre reproduction. So sooner or later I'll have my ZH270 cabled by Alessandro Cereda of Sublima.
Another thing I'm thinking to is to get rid of the potentiometer an switches. A friend of mine has done it with the Berning Siegrfried I sold him and the results were quite big.

By the way, the noise on the left channel came out again, I definetely need to service it. Even if my suspect is onot on components but maybe a soldering point no more good or a signal path on the audio board with breaks.

Paolo

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....

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

Thanks again Allan,
The noise on left channel appears even without anything connected to input, definetely not dependent on pre o input cables.
The way it disapear it make me thing about a cap that cannot full charge properly, with a quick turn off/on it probably doesn't discharge much and get the current peak again to force him charging full. Just an idea.

Yea I agree, it is not easy to mod ZH270 without loose its great flexibility. In real I seldom use other tha 12dB feedback, it is the setting better delivering bass performance and best highs extension (I've Tannoy monitor golds 15" drivers, and dumping is a matter of quality here even at 94dB efficency).

The 25K pot in the signal path does indeed effect the quality of sound. Maybe inprove it with a switch matrix of very good carbon resistors.