Red Plating??

chinook9 OP


Yes you have 10v higher mains, you must be nearer the big pole/sidewalk mount transformers that have many taps and boost or lower the voltage on your mains line. The nearer you are to them the higher the mains voltage, the further away the lower the mains voltage gets.
You could complain to get it bought down, but they’ll just say the houses at the end will then be too low (100v). I got it bought down from 250v to 230v for Australia because I also service medical equipment and used that as a bargaining tool, the real point was, way back I was going though many incandescent light globes, they’d last sometimes not more than a month.

As for a different mains transformer, that’s for a specialist to do.

As I said before get it changed to a self adjustable bias much cheaper, that way you set yours bias 10% lower and will stop the plates glowing red, and you’ll get more power from the amp also compared to auto biasing.
Hope also your power supply capacitors have a bit of max volt head room for this extra mains voltage you have as they will be be up 10% also.

Cheers George

chinook9 OP

Red plating is not good even slight, because both are doing the same it means the tubes are being pushed to their max, either because the tubes are overrated or the mains voltage in your area is higher, than where the amp was built, in Au we can have up to 30vac mains differences in different areas.
Best is do what I said and get it converted by a competent tech to a bias system you can adjust yourself (to 10% less), which we in Au call fixed biasing as you fix the bias point manually, and you'll get more power.

Cheers George

Sorry didn’t see you have cathode biasing, (auto bias).
You could get them converted to fixed biasing, by someone close to you that’s good with tubes, could cost around 2-3hrs labour, up side is you’ll get a little more wattage also.

Cheers George

I just noticed that they red plate a bit.

Drop the bias 10%

Cheers George