New member steps into the lions' den ..... (Pass v. Ayre ?)

13DoW · 9th January 2002, 10:27 PM

Hello,
this is my first post at diyAudio.com so be gentle with me ...

Has anyone compared Aleph and Ayre power amps? Both use two stage all MOSFET topologies but they differ in two important (perhaps?) respects:
Ayre uses no overal feedback and is differential throughout (as far as I can figure) and Alephs are single-ended with overal feedback.

The objective differences are easily imagined (especially as Pass is kind enough to provide schematics) but what about the sound?

Regards
13th Duke of Wymbourne

arnach · 10th January 2002, 12:22 AM

Hello, 13th Duke, do you have a name?

13DoW · 11th January 2002, 03:40 AM

I posted this question at AudioAsylum and got one useful reply - the link is below for anyone interested.

http://www.AudioAsylum.com/audio/gen...es/167308.html

Arnach - thanks for the enquiry. I don't want to spoil the ethereal possibility that I'm more than noble of thought and deed but also noble of blood.
If you're really interested drop me an e-mail.

As I'm new to the board, how do you become a 'diyaudio Prophet' - does it involve growing a big, bushy beard?

Regards
13DoW

AudioFreak · 11th January 2002, 03:44 AM

the status goes like this ..... you start as a Neophyte ... then you become an Acolyte .... then a Prophet ..... then an Elder .... you move up by making posts.

AudioFreak · 11th January 2002, 03:48 AM

also for some insight into this topic see the thread X-Series vs. Aleph

Dave · 11th January 2002, 04:31 AM

Here is a quote from the Ayre Site -

"The audio circuitry must be capable of amplifying the musical signal without alteration. To this end, the Ayre V-1 circuit is a complementary design using no negative feedback. The circuit's elegant topology comprises a cascoded differential input stage followed by a source-follower output stage. This straightforward approach results in remarkable immediacy and musical purity."

This does seem very similar to the X-series.

AudioFreak · 11th January 2002, 04:56 AM

the new XA series from Pass Labs appear not to have any feedback other than Super Symmetry which is non destructive.

promitheus · 14th January 2002, 06:51 PM

Is there a link for the ayre or a schematic to look at ?
It would be very interesting to see it.

Joe Berry · 14th January 2002, 07:50 PM

I've not seen the actual schematic, but Bascom King once described the topology in a 1993 (?) review of the Ayre V3 for the now-defunct American magazine Audio. It's essentially an X amp with a fully complementary front end and no signal feedback loop at all. The output offset voltage is stabilized by DC feedback from each output node to its corresponding folded cascode stage. Another difference is that Ayre uses chokes in the front end and output stage power supplies.

I don't recall whether the review mentioned these details but, given the way the DC feedback network is connected, I would speculate that the front end supply for the V3 is regulated, and that it uses resistors rather than active current sources to bias the folded cascode.

promitheus · 14th January 2002, 09:27 PM

sounds alot like the new XA amp from passlabs.

9th January 2002, 10:27 PM	#1
13DoW diyAudio Member Join Date: Jan 2002 Location: Orange County, Ca.	New member steps into the lions' den ..... (Pass v. Ayre ?) Hello, this is my first post at diyAudio.com so be gentle with me ... Has anyone compared Aleph and Ayre power amps? Both use two stage all MOSFET topologies but they differ in two important (perhaps?) respects: Ayre uses no overal feedback and is differential throughout (as far as I can figure) and Alephs are single-ended with overal feedback. The objective differences are easily imagined (especially as Pass is kind enough to provide schematics) but what about the sound? Regards 13th Duke of Wymbourne

10th January 2002, 12:22 AM	#2
arnach diyAudio Member Join Date: Apr 2001 Location: USA	hmm Hello, 13th Duke, do you have a name?

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11th January 2002, 03:40 AM	#3
13DoW diyAudio Member Join Date: Jan 2002 Location: Orange County, Ca.	I posted this question at AudioAsylum and got one useful reply - the link is below for anyone interested. http://www.AudioAsylum.com/audio/gen...es/167308.html Arnach - thanks for the enquiry. I don't want to spoil the ethereal possibility that I'm more than noble of thought and deed but also noble of blood. If you're really interested drop me an e-mail. As I'm new to the board, how do you become a 'diyaudio Prophet' - does it involve growing a big, bushy beard? Regards 13DoW

11th January 2002, 03:44 AM	#4
AudioFreak Warp Engineer On Holiday Join Date: Oct 2001 Location: Queensland, Australia	the status goes like this ..... you start as a Neophyte ... then you become an Acolyte .... then a Prophet ..... then an Elder .... you move up by making posts.

11th January 2002, 03:48 AM	#5
AudioFreak Warp Engineer On Holiday Join Date: Oct 2001 Location: Queensland, Australia	also for some insight into this topic see the thread X-Series vs. Aleph

11th January 2002, 04:31 AM	#6
Dave diyAudio Member Join Date: Oct 2001 Location: New Zealand	Here is a quote from the Ayre Site - "The audio circuitry must be capable of amplifying the musical signal without alteration. To this end, the Ayre V-1 circuit is a complementary design using no negative feedback. The circuit's elegant topology comprises a cascoded differential input stage followed by a source-follower output stage. This straightforward approach results in remarkable immediacy and musical purity." This does seem very similar to the X-series.

11th January 2002, 04:56 AM	#7
AudioFreak Warp Engineer On Holiday Join Date: Oct 2001 Location: Queensland, Australia	the new XA series from Pass Labs appear not to have any feedback other than Super Symmetry which is non destructive.

14th January 2002, 06:51 PM	#8
promitheus diyAudio Member Join Date: Jan 2001 Location: Germany	Is there a link for the ayre or a schematic to look at ? It would be very interesting to see it.

14th January 2002, 07:50 PM	#9
Joe Berry diyAudio Member Join Date: Mar 2001 Location: USA	I've not seen the actual schematic, but Bascom King once described the topology in a 1993 (?) review of the Ayre V3 for the now-defunct American magazine Audio. It's essentially an X amp with a fully complementary front end and no signal feedback loop at all. The output offset voltage is stabilized by DC feedback from each output node to its corresponding folded cascode stage. Another difference is that Ayre uses chokes in the front end and output stage power supplies. I don't recall whether the review mentioned these details but, given the way the DC feedback network is connected, I would speculate that the front end supply for the V3 is regulated, and that it uses resistors rather than active current sources to bias the folded cascode.

14th January 2002, 09:27 PM	#10
promitheus diyAudio Member Join Date: Jan 2001 Location: Germany	sounds alot like the new XA amp from passlabs.