Quote from hi-fi News:
Any flies in the ointment? Hum and [FONT=Praxis Com,Praxis Com][FONT=Praxis Com,Praxis Com]noise is fractionally high in this early sample (yielding an A-wtd S/N of 78dB re. 0dBW, 104dB re. 300W [/FONT][/FONT]
[FONT=Praxis Com,Praxis Com]
Is A-weighting S/N standard practice, or is it marketing?
vac[/FONT]
Any flies in the ointment? Hum and [FONT=Praxis Com,Praxis Com][FONT=Praxis Com,Praxis Com]noise is fractionally high in this early sample (yielding an A-wtd S/N of 78dB re. 0dBW, 104dB re. 300W [/FONT][/FONT]
[FONT=Praxis Com,Praxis Com]
Is A-weighting S/N standard practice, or is it marketing?
vac[/FONT]
It looks a lot like an amp without a global loop feedback - or one that is not the usual 20+db or more... thus the rather high output impedance and the way it looks in the distortion specs/graphs. The paralleled output devices will help drop the output Z and distortion... not a bad way to make a bipolar amp, all things considered. Very "tube like"?? 
_-_-bear
PS. think I will just pick one up so that we can open the case and see what is inside!
PPS. wouldn't it be funny if there were maybe 6 transistors per channel in there on a tiny 1" square SMT board?? HA HA!
_-_-bear
PS. think I will just pick one up so that we can open the case and see what is inside!
PPS. wouldn't it be funny if there were maybe 6 transistors per channel in there on a tiny 1" square SMT board?? HA HA!
This topology seems to be close to that topologies from Anders Thule.
There is no global feedback (only local feedback despite low idle current through the output) through virtual Class-A. Check out this threads:
http://www.diyaudio.com/forums/soli...ss-b-thule-audio-topology-also-used-teac.html
http://www.diyaudio.com/forums/solid-state/126352-what-happen-thule-audio.html
http://www.diyaudio.com/forums/soli...-amplifier-ia-120-ia120-schematic-wanted.html
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Oh! Yep. I missed that little pic down on the bottom of the page the first time!
Ok... now I see...tnx.
_-_-bear
Maybe someone can explain it to me - I seem to be drawing a blank.
How can the current mirror that is floating on the speaker output cause the output devices to NOT switch off?? I can see it MAYBE on one rail, but on both??
Clearly I am missing something in this design as to how it works... then too, how does the DC offset correction work, if one rail is being hauled away from zero/ground potential? I can see that the DC correction would cause the opposite polarity OPs to have to turn on in response to the other side being hauled high to prevent switch off. But then you have a tug of war between the two circuits, with the difference manifesting itself because of the time constant differences between the two (current mirror vs. DC offset servo)??
Seems interesting.
I'd bet that Dan D'A has something similar or identical going on... seems likely anyhow...
So, tiefbassuebertr, you've had ur hands on some of these Thule amps, how do they sound??
_-_-bear
This amps sounded very good inside of the category of Class AB amp (from my view one of the best). But Anders Thule don't conjure. Thus the sound is very bad compared to each good constructed Single Ended and Push-Pull pure class A amplifier.Maybe someone can explain it to me - I seem to be drawing a blank.
How can the current mirror that is floating on the speaker output cause the output devices to NOT switch off?? I can see it MAYBE on one rail, but on both??
Clearly I am missing something in this design as to how it works... then too, how does the DC offset correction work, if one rail is being hauled away from zero/ground potential? I can see that the DC correction would cause the opposite polarity OPs to have to turn on in response to the other side being hauled high to prevent switch off. But then you have a tug of war between the two circuits, with the difference manifesting itself because of the time constant differences between the two (current mirror vs. DC offset servo)??
Seems interesting.
I'd bet that Dan D'A has something similar or identical going on... seems likely anyhow...
So, tiefbassuebertr, you've had your hands on some of these Thule amps, how do they sound??
Therefore I want to know a Class AB topology with low idle current through the output power stage, that sound is close as possible to class A and have start this thread:
http://www.diyaudio.com/forums/soli...opologies-100ma-idle-sound-closest-class.html
The only amp, that sounds like pure class-A is the HCA power amp MX-10000 from Yamaha about
http://www.diyaudio.com/forums/soli...lic-conversion-amplification-hca-circuit.html
Concerning the DC offset topology I haven't made any investigations concerning the correction behaviour, because I haven't until now discover unwanted effects.
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Until now nobody can't explain the basic topology resp. the simplified schematic (or have I overlooked this anywhere ?).
Marketing of a product may be more difficult if a fair share of your commercial contacts are part of a company's dealership, with a management that wiggled in at the back entrance to throw you out at the front door.
(speaking from personal experience with private equity organisations)
I think he can design pretty well and has lot´s of experience. He has good people for mechanics though. I heard the amp in Milano with Serblin´s new smaller boxes and it was good though not exceptional. It was not my kind of music, pretty soft and a very average room. I talked to Ken Kessler at length though and he is convinced that he got the best sound so far with the Momentum on his Wilson´s especially in the bass. They are very pretty and quite small. Surprising small.
They have a kind of Eco mode that draws little current. If i had the money i would even consider buying them, so impressed i am.
They have a kind of Eco mode that draws little current. If i had the money i would even consider buying them, so impressed i am.
I would say yes (at least partly) because not only in the output stage there are parallel switched devices (like most previous Krell designs).
There are various events concerning this amp creation in the follow weeks over the autumn days and the christmas-/wintertime (Evenings of Audio Connoisseurship with Dan D'Agositno, found on his homepage):
Paragon Sight & Sound
October 6, 6 – 9 p.m.
RSVP 734.662.3595
3780 Jackson Road, Suite H, Ann Arbor MI 48103
HiFi Centre
November 3, 5 – 9 p.m.
RSVP 604 .688 . 5502
578 Seymour Street, Vancouver BC V6B 3J5 Canada
Music Systems
November 11, 5:30 – 8:30 p.m.
RSVP 786.331.9012
2854 NW 79th Ave, Doral FL 33122
HiFi House
November 16, 5:30 – 8:30 p.m.
RSVP 302 .655 . 4780
2304 Concord Pike, Wilmington DE 19803
JS Audio
December 3
RSVP 301 .656 .7020
4919 St Elmo Ave., Bethesda MD 20814
Aurant Home Theater
January 20, 2012
RSVP 801 . 467. 591 8
Salt Lake City UT
Innovative Audio Video
January 25, 2012, 6 – 9 p.m.
RSVP 212 .634 . 4444
150 East 58th Street, NY NY 10155
Definitive
February, TBD
RSVP 206.524.6633
6206 Roosevelt Way NE, Seattle WA 98115
Perhaps some of the US members can visit one of this event and discuss several things personally with the developer(s).
About
Ultra High-End Audio and Home Theater Forum
I read , that Miller Audio Research's test results are now available online.
Who can open this site?
About
avcat AVnews 2011”N1ŒŽ�`3ŒŽ
you will find a pic from the associated preamp (btw - also Nelson's "Concept" monaural power amps with an outdoor power supply)
and here the associated PDF:
http://www.dagostinoinc.com/documents/Preamp-release-1-11.pdf
About
http://bbs.headphoneclub.com/thread-165117-1-1.html
could be interesting informations, but the translation losses to German language are too large.
Attachments
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Nico, I was referring to the Thule design, which MAY be the basis for this neo-Krellian creation...
Otoh, I do have x-ray vision, using my x-ray vision glasses and in the presence of almost any amplifier, save the lead encased ones, see exactly what is going on inside the box.
Thank you.
_-_-bear
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My own personal view based only on my limited interactions with him and what I have read and heard and seen is that he is not a "circuit designer" at all. I could be completely wrong, of course.
_-_-bear
I think, you mean this exhibition resp. audio show:
http://www.stereophile.com/category/rmaf-2011
The loudspeakers seems to be a model from Wilson Audio with an uncoated metal tweeter inverse dome from Focal (Watt/Puppy?). Also thick and expensive main power cords and speaker cable are in use. But there are not to see any source audio components and a preamp.
I hate metal and ceramic diaphragm speakers but OTOH, by this kind of tweeters you will perceive small audible amplifier differences increases as by a look through a magnifying glass.
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