Denon POA-3000, sliding Class A bias rip off?

[RobertS61]

Just bought a mint Denon POA-3000 stereo-amplifier (not the 'Z' or 'RG').
It claims to have a "real bias circuit to realize a high class A amplifier" according to the sales rep. It's a kind of sliding or dynamically Class A amp (7 patents pending they claimed in 1979) like the one Nelson Pass developed with his first amp the Threshold 800A as I remember.
Is this correct?

The amp draws 1 amp continously from the wall when idling and weighs 35 kilograms. It delivers 200 Watts @ 8 Ohms and 400 Watts at 4 Ohms according to a German review (Stereoplay october 1980).
1 amp is not enough for that kind of powerdelivery so it's certainly not a fixed bias amp like the Krell KSA-100 I have.

Any thoughts or comments are welcome.
http://www.diyaudio.com/forums/attachment.php?attachmentid=678280&stc=1&d=1525277662

http://www.diyaudio.com/forums/attachment.php?attachmentid=678281&stc=1&d=1525277662

http://www.diyaudio.com/forums/attachment.php?attachmentid=678282&stc=1&d=1525277662

 

[PRR]

Sliding class A bias is older than the 1970s, was bragged-of in 1947 (link), and is arguably older as an incidental effect of AM radio reception.

MOST patents are not about "the basic idea" but about "a minor improvement". Not "a plow" but "using round-head bolts on a plow for less drag". Read your 7 patents. They start with an overview of the field and the device. But the only PATENTABLE part is the end "I Claim" and a list of very specific details. You patent a round-head plow bolt. I patent a counter-sunk head plow bolt. Fred patents a better way to put counter-sinks in a plow. Sally patents a welded construction. Akio patents a one-piece forging. If Denon didn't find 7 places to put a novel resistor or diode, that Mr Pass didn't claim, they were not trying.

 

[6L6]

Regardless of the performance of the circuit, the meters are beautiful!

 

[RobertS61]

Sliding class A bias is older than the 1970s, was bragged-of in 1947 (link), and is arguably older as an incidental effect of AM radio reception.

MOST patents are not about "the basic idea" but about "a minor improvement". Not "a plow" but "using round-head bolts on a plow for less drag". Read your 7 patents. They start with an overview of the field and the device. But the only PATENTABLE part is the end "I Claim" and a list of very specific details. You patent a round-head plow bolt. I patent a counter-sunk head plow bolt. Fred patents a better way to put counter-sinks in a plow. Sally patents a welded construction. Akio patents a one-piece forging. If Denon didn't find 7 places to put a novel resistor or diode, that Mr Pass didn't claim, they were not trying.

Clear and great comment!
And thanks for the link.

 

[RobertS61]

Regardless of the performance of the circuit, the meters are beautiful!

There aren't any 6L6 tubes inside but the unit becomes almost too hot to touch with the spec idling AC intake.

Yes the meters look nice like the ones on a Threshold SA/1 I once had.
Even with my Infinity QLS maximum output I can bear is approx. 50 Watts peak on these scales around 100 Watts @ the 4 Ohm load nominal that my QLS's present.