Problems with my Berning ZH270

And one last thing George, if Allan hasn't talked you into the ERS as Khogugo notes, the cryoed 6jn6 outputs will move you up a notch but the ERS will just knock you out. It is the single largest improvement I have heard with this amp including various NOS input tubes, dampers, still points etc. The ERS really lowers an already low noise floor to allow you to hear further into the music. It sounds like you have your hands full for now but definitely consider this in the future, you won't regret it.

Thank you. Have you tried the 12AT7 Brimar black plates or the 12AT7/CV4024 Mullard CRYO ??. Would I have a warmer sound from them?. This is my first tube amp and I just learning. Thanks again.

George.
Please contact Andy at Vintage tube services, the RCA's seem to be the best bang for the buck.
Andy is the only other person besides David Berning and myself that have the perimeters of the amp and what the tubes require to be, Make sure you tell Andy it's for a ZH-270.

Hi Allan. How can I contact Andy?. Thank you.

George, my observations match those of Allan. If you follow his advice, and still have a problem with the high frequencies, I would again direct you to the Marigo dots, especially on windows.

You are in for a treat with Andy Bouwman's matched tubes. I recently put a pair of Andy's Sylvania 6SN7 tubes in the input section of my OTL amps and the high frequency performance was just outstanding. I have a complete set of Andy's Sylvania 6SN7's in my preamp and they were a great upgrade as well. His tubes are expensive, but well worth the cost IME.

If you end up trying the Marigo dots, I would enjoy hearing about your results. BTW, do you have windows in your listening room?