Berning ZH270 help

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.

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

Paolo.
Switch the input interconnects to the amp from left to right and right to left, see if the noise stays in the same channel.

The ZH-270 is different from the Siegfried, as is has different feedback settings, if you remove the pot, then you will have problems with sensitivity in low and maybe medium feedback, you will most likely hear pre-amp noise.

You might be able to do it if you are running a CD player direct but there are few pre-amps made, especially tubes ones that the ZH-270 will not pick up the noise without having to reduce the sensitivity of the input to the amp, the only other alternative is to find the exact resistance needed to which feedback you use and put a fixed resistor.