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Post by f456gt on Aug 20, 2020 18:21:37 GMT
Hi Chaps,
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.
Cheers,
Horacio
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Post by MartinT on Aug 20, 2020 19:48:32 GMT
I've never come across a Berning.
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Post by ChrisB on Aug 21, 2020 7:18:46 GMT
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.
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Post by Firebottle on Aug 21, 2020 7:45:30 GMT
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.
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Post by MartinT on Aug 21, 2020 8:15:24 GMT
That is interesting - a valve amp running high frequency into the output trannies? Don't think I've ever heard of that topology before.
Can you give any more info? Does it use PWM or something else?
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Post by ChrisB on Aug 21, 2020 8:43:24 GMT
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Post by MartinT on Aug 21, 2020 8:58:04 GMT
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!
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