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Old 12th February 2005, 03:31 AM   #1
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Default Pass Shoot Out In Salt Lake City

Last Saturday three Salt Lake City Pass fans gathered at my home to listen to and compare four Pass amps. The amps listened to were the Mini Aleph, the Aleph 3, and a pair of Aleph 2's. We also listened to one channel of a Zen ver. 3.0. All amps got at least an hour warm up before any listening was done. First at bat was the pair of 2's which are biased at higher than normal level. The typically neutral sounding 2's lived up to their name and were detailed and had good sound staging and resolution and really excellent dynamics.. However when the Mini Aleph was hooked in it sounded considerably better with increased resolution and sound staging over the 2's. The Mini also had an apparent slightly brighter top end and was able to drive the Dynaudios to decent levels. Next up was the Aleph 3 which was another major step up in improvement in just about all aspects. While its top end was similar to the Mini its soundstaging and resolution has to be heard to be appreciated!! The one working channel of the Zen was next hooked up and initial thoughts were that it had a very tube like sound but Zen again very different from a tube amp. It didn't seem to have the resolution that the Aleph 3 or the Mini posseses but a single channel comparison was not totally meaningful at least to me. The owner of the Zen has promised to repair it and return for further comparisons. But for now the Aleph 3 was the clear winner (pun intended!).

The system consisted of Dynaudio Audience 9 speakers, Rosenblits Grounded Grid line stage, a Pioneer DV-45A multi format CD player, Gotham Audio Star Quad amp interconnects, and Kimber 4TC speaker cabling.

It was alot of fun and showed how good DIY stuff is. Hopefully the Zen owner will return in the next month sometime with his Zen fully working for further comparisons. If any other Salt Lake City Pass fans, Krell fans, or any other Audioaholics are interested in gathering in the near future please contact me. Nelson is of course invited to attend anytime.

The photo shows the amps.....Left to right Zen Ver 3.0, Aleph 3 nesting on top of of one of the Aleph 2's, and the Mini on the right.

Mark
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Old 12th February 2005, 09:35 AM   #2
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Surprising that a 3 "beats" a high biased 2. Any details on how they were build (PS, parts etc)?
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Old 12th February 2005, 09:42 AM   #3
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Old 12th February 2005, 01:45 PM   #4
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The 2's have a standard supply with 120,000 per rail, 760 va toroid.

The Mini has a 320 va standard supply with a single 120,000 Panasonic cap per rail.

By standard I mean there is no CLC or CRC type filtering going on in the supply, just a bridge feeding a capacitor bank.

The 3 has a 500VA toroid with a CLC type supply. A single bridge feeds 54,ooo mfd, then a 2mh toroid choke followed by another 27,000 mfd. All three Alephs used IRFP240 devices, the Zen has IRFP044. I also won't attribute all of the 3's sucess to the CLC supply. This is a design that Nelson hit the nail on the head with. It sure upheld its classic status by quite a margin!!

Mark
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Old 12th February 2005, 02:44 PM   #5
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I hope you have another one next month, and find someone with an AX to join the party.
My AX chassis is only on paper at the moment, and parts are everywhere.
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Old 12th February 2005, 11:35 PM   #6
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I built a pair of the 60 watt X's and was not impressed and sold the boards to another person on these threads. When I ahve more time to spend on them I will make another attempt as I have alot of boards left. Right now the KSA-50 clone is my latest project(Don't anyone tell Nelson!). The X will come about again after that is finished. As for line stages.... its pretty hard to beat the Grounded Grid.

Mark
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Old 13th February 2005, 06:30 AM   #7
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Very interesting comparisons.

I recall Nelson commenting about the Aleph 3 when I was over there. Perhaps there is some magic in there somewhere!

Ian
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Old 13th February 2005, 08:57 PM   #8
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The Aleph 3 has a couple of things going for it. One is that the stock version has the highest proportionate bias of any of the Alephs. Another is that, of the stock Alephs, it has the least number of output devices for the front end to push. I'm not saying that you can't push the other Alephs a little further here and there, but don't count the little feller out just because it's the baby of the family.
The Mini-A isn't a "real" Aleph, of course, nor even a Nelson Pass design, per se. I make no claims for it other than it's a simple project for those who are curious about the Aleph topology. I would certainly urge people to build a genuine Aleph as soon as finances, etc. allow, and not depend on my toy version.

Grey
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Old 13th February 2005, 09:24 PM   #9
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"I would certainly urge people to build a genuine Aleph"


Ahhhhh hum.....

I would certainly argue that point! It sounds dynamite and came in 2nd! And like many have said "its first few watts are the best"....

Mark
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Old 13th February 2005, 10:18 PM   #10
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Mark,

The magic seems to point to a very capable PSU, low parts count and most notable among the Alephs is the 3's high bias of 1A on each output/CCS mosfet.

Allan
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