Andrew,
Any idea how this cutt-off issue fits into Circlotron output stages?
There are claims that these stages don't suffer from cut off (and associated distorsions).
The Thorens design by Frank Blohbaum has a circlotron output stage.
In the 6moons review I read:
"Because the Thorens' monolithic output transistors never switch off to have a constant well-defined drain-source current, there are no crossover or switching distorsions and "the amplifier behaves sonically like a class A amplifier buth with much lower power consumption".
Any idea how this cutt-off issue fits into Circlotron output stages?
There are claims that these stages don't suffer from cut off (and associated distorsions).
The Thorens design by Frank Blohbaum has a circlotron output stage.
In the 6moons review I read:
"Because the Thorens' monolithic output transistors never switch off to have a constant well-defined drain-source current, there are no crossover or switching distorsions and "the amplifier behaves sonically like a class A amplifier buth with much lower power consumption".
I don't know the Circlotron.
In a Push Pull amplifier stage, both the upper and the lower output devices must actively control the output current sent/sourced to/from the load.
A device that is hardly changing in effective impedance as the other does almost all the work cannot be sharing the ClassA load.
The post from Hugh, showed just such an example where the very slow cutoff of the Lateral device appears to show extended ClassA operation. That is a topology trick that cannot be used as a generalised "rule" for defining ClassA. That why I posted what I did.
I wonder if Circlotron does a similar trick.
Some of these (not quite turning off and soft turning off) remind me of the cheapskate Japanese designs where they refused to fit the PSUs and Output Stages and Heatsinks of a proper ClassA amplifier yet wanted to trade on the reputation of ClassA by adopting various names for their new topologies in what, I believe, were attempts to "con" their customers
In a Push Pull amplifier stage, both the upper and the lower output devices must actively control the output current sent/sourced to/from the load.
A device that is hardly changing in effective impedance as the other does almost all the work cannot be sharing the ClassA load.
The post from Hugh, showed just such an example where the very slow cutoff of the Lateral device appears to show extended ClassA operation. That is a topology trick that cannot be used as a generalised "rule" for defining ClassA. That why I posted what I did.
I wonder if Circlotron does a similar trick.
Some of these (not quite turning off and soft turning off) remind me of the cheapskate Japanese designs where they refused to fit the PSUs and Output Stages and Heatsinks of a proper ClassA amplifier yet wanted to trade on the reputation of ClassA by adopting various names for their new topologies in what, I believe, were attempts to "con" their customers
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