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Old 7th September 2005, 02:06 AM   #11
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Hi anatech,

It uses a typical (albeit cascoded) diff'l input followed by a high gain Vas and miller comp which kills HF PSRR so it needs clean supplies to sound any good. Class A does that (and linearises the outputs). There are far more elegant ways of achieving the ends without resorting to Class A.

I don't see any surprises here - nothing to hunt one down to audition. It should sound smooth - I guess because it faces none of the hard challenges but sidesteps them with Class A.

This is Sooo characteristic of the monster amps that solve nothing really well and can be easily blown away with a sweet little low bias Class AB 1/10th the size.

I guess what really irks me about such products is that they perpetuate the myth that this is necessary to achieve audio nirvana when all it really does is salve small appendage syndrome or a need for excess, neither of which I believe in.

Cheers,
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Old 7th September 2005, 07:24 AM   #12
bra is offline bra
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here is circuit
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Old 7th September 2005, 07:39 AM   #13
bra is offline bra
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little better
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Old 7th September 2005, 08:04 AM   #14
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Hi Bra,

Are all these parts available in your country? Why would you choose such a dinosaur to copy when it can easily be seen off by inspired Class AB design, a handful of BC546/556 and some everyday output MOSFETs.

It's Kitsch value??

Cheers,
Greg
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Old 7th September 2005, 08:52 AM   #15
bra is offline bra
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I want to use parts from onsemi (samples) if it is possible. It is AB design - idling current is only 40 mA per one transistor.
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Old 7th September 2005, 08:53 AM   #16
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Personally i would love to see the entire service manual (I know someone with a pa7).
Any chance of getting a scan of the whole thing ?.
Will give you my email addy if you like.

This friends PA7 responded very nicley to me replacing al power supply wiring with heaveir gauge.
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Old 7th September 2005, 10:20 AM   #17
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Default Very interesting...i also here guys.... good to see old friends here.

hehe.

regards

Carlos
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Old 7th September 2005, 11:33 AM   #18
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just want to make clear:

is there no global negative feedback fo the said amp?

or is it already the one that is through a trimmer res. from the pre-driver with vbe multiplier
stages?

rgds,

hienrich
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Old 7th September 2005, 01:28 PM   #19
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Quote:
Originally posted by bra
little better

Can we see where does it go that path going down from the output?


Carlos
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Old 7th September 2005, 02:29 PM   #20
bra is offline bra
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there is no global negative feedback.
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