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Old 12th January 2015, 03:58 AM   #1
Blues is offline Blues  United States
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Default The Aleph Design Reloaded

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Originally Posted by Nelson Pass View Post
I will post a thread on the latest thinking about this circuit in a day or less.
Greedy boyz (includes me) are highly anticipating this Mr. Pass...
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Old 12th January 2015, 07:42 AM   #2
Zen Mod is offline Zen Mod  Serbia
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that rings me that J2 is going out of production ........
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Old 12th January 2015, 08:11 AM   #3
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Old 12th January 2015, 11:58 PM   #4
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Quote:
Originally Posted by Blues View Post
Greedy boyz (includes me) are highly anticipating this Mr. Pass...
Count me in as a member of the Greedy Boyz club!
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Old 13th January 2015, 12:22 AM   #5
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Quote:
Originally Posted by Zen Mod View Post
that rings me that J2 is going out of production ........
Interesting.
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Old 13th January 2015, 02:55 PM   #6
Blues is offline Blues  United States
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I'm hoping NP's new thoughts will all still fit in my original Aleph 3 chassis...
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Old 13th January 2015, 03:00 PM   #7
Zen Mod is offline Zen Mod  Serbia
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be sure that Papa is not going to make it even more inefficient
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Old 13th January 2015, 06:02 PM   #8
Zoef is offline Zoef  Netherlands
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I'm with you Blues, my plan was to heat up the soldering iron tonight. But....i think i wait a few days with building my aleph 3.
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Old 13th January 2015, 07:36 PM   #9
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OK, here we go.

Last month I collected some "junk" Aleph 30's and 60's from the back shelves
of the storage space (the same one you remember from Raiders of the Lost Ark)
with the intention of salvaging the heat sinks drilled for TO-3 devices for use in
another project (yet another Sony SIT amplifier).

Opening them up, I discovered that they were in good enough shape that they
were worth keeping with a little cleaning and repair.

You will perhaps remember that I previously posted an update to the Aleph 3
which incorporated Toshiba 2SJ109 Jfets on the input stage, and while this
is still a worthy update there are two problems with it; first, it's difficult to
get these parts, and second, they only work on the lower voltage amplifiers
which leaves out most of the other Alephs.

However on these I decided to try my favorite small power Mosfets, the
Toshiba 2SJ313's. Apart from a different package and pin-out in some
amplifier models, they will drop right in as replacements, and they need to
be matched for Vgs at 10 mA.

The Toshiba's are preferred, but you can make do with other comparable
modern Mosfets if you can't get these parts.

Noting that some units had zener noise with R105 at 4.7K, I dropped that
value to 3.3K, and you will note that I optionally deleted Q104, the over-
current protection. Also, I moved the chassis ground connection directly
to the AC Earth ground.

The addition of the Toshiba Mosfets made for an immediate improvement
in power supply noise rejection, dropping it typically by a factor of 4 to 6, to
as low as 50 uV unweighted output. This alone justified the effort.

Also, as a tweak, you can replace the 220 uF caps with the silk caps from Elna.

Listening tests showed a significant improvement over the originals, and I
gave copies of these to my business partners for Xmas.

Attached Images
File Type: gif ALEPH 3 JFET.gif (82.3 KB, 1324 views)
File Type: gif ALEPH 2015.gif (78.6 KB, 1270 views)

Last edited by Nelson Pass; 13th January 2015 at 07:39 PM.
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Old 13th January 2015, 07:42 PM   #10
dady is offline dady  Argentina
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Thanks Mr PASS
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