I am pretty sure I will buy a Art Audio Quintet from a friend in the UK, 240VAC, [it operates in pure class A, putting out 15 wpc in triode and 25 wpc in pentode]. I will need a Hammond auto transformer, Step Up, 230 VAC, 1.5 kVA to be safe, it is made in Canada not the other country.
Nevertheless, it came to my attention a Berning EA-230 prototype, 30W/Ch [ZOTL] for sale in Louisiana, been on the market for 109 days. The Quintet will be £1.4 - £1.5K plus $300 for the transformer, the EA-230 costs £2.400. I had a Berning EA-230 before but never heard the Quintet.
I'd worry a little about buying a used prototype from a private individual. I would contact Berning before buying to be sure he would be happy to work on it, should it develop problems in the future. Otherwise I'd walk away from it.
Article 94: It's OK to drop the cow, but not as a weapon.
The Berning is a clever design, I came across it some time ago.
However the OTL tag (output transformer less) is technically incorrect. There is an output transformer but it is operating at RF, 250kHz or 500kHz depending on model. So it is AUDIO (frequency) Transformerless, a bit of a skewed description.
Thanks, Chris. Looks like it's AM (Amplitude Modulation) of the oscillator signal using the oscillator input and through the power valves across the smaller output transformer. The signal appears to be bridged to create a control voltage altering the amplitude of the output. Intriguing.
At first guess I would have predicted it to sound poor!