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Old 27th December 2016, 04:57 PM   #1
lykkedk is offline lykkedk  Denmark
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Default AlephJ Mimi! (Mini)

Hi all here.

First off merry christmas and soon a happy newyear

While rebuilding my poweramp (F5 at moment, F6 at desk)... i was feeling that it might be a way better idea to lower the power, and going for smaller heatsinks; also i would like a smaller chassis to be honest.
I think i can get along fine with ~15Watt with my current speakers/preamp. (Speakers 90dB, Preamp DCG3 with gain X 2).

The heatsinks i have now, can "easily" blow away 200W (F5, AlephJ etc.) for a stereo setup. If i split them, i will end up with half of that approx.

So an Mini Aleph, uses around 100W for a two channel setup, which would be fine. -But when i was surfing around i also read about a mini alephJ, and mini Babelfish, -soo this could be very interessting to build i think. -I just cant seem to find good information regarding those?, also the Mini aleph is difficult to find right information about. So i would be pleased if someone here has some schematic, links, whatever about such mini amp.'s

I prefer something like mini aleph, but maybee a newer version with jfet's.
Also the babelfish mini i am very currius about!

Jesper.

EDIT : Name of thread!
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Old 27th December 2016, 05:25 PM   #2
grimberg is offline grimberg  United States
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Follow the link below to the original thread:

The Mini-A
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Old 27th December 2016, 05:40 PM   #3
lykkedk is offline lykkedk  Denmark
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Thanks... i read allready a lot in this thread!

Jesper.
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Old 27th December 2016, 05:49 PM   #4
Dennis Hui is offline Dennis Hui  Canada
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AlephJ Mimi! (Mini)
Hi Jesper,

I think you can modify a mini-a to use a jfet front end using the same
modification for the Aleph 3. The latter modification is shown in the
first schematics in this post:

The Aleph Design Reloaded

Cheers,
Dennis
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Old 27th December 2016, 06:13 PM   #5
Zen Mod is offline Zen Mod  Serbia
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lykk

read this
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Old 27th December 2016, 07:25 PM   #6
lykkedk is offline lykkedk  Denmark
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Thanks.. all!

So this schm. Babelfish it's possible to run this at lower rail's?

Jesper.
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File Type: jpg base-pcb-sch.jpg (159.0 KB, 1529 views)
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Old 27th December 2016, 10:27 PM   #7
Zen Mod is offline Zen Mod  Serbia
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as said zillion times , for any mosfet based output stage - do not use lower PSU rails than +/-15V , or you're having trouble due to increased nonlinearity of inherent mosfet capacitances

then use whatever Iq you want , but I wouldn't go lower than 1A

yes , this schmtc can be used for Mini , in which case you can skip cascodes for input JFets ...... or leave them , but with necessary change in voltage biasing

few other resistor values need to be optimized , strictly for rails and Iq one intend to use .....
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Old 27th December 2016, 10:49 PM   #8
didiet78 is online now didiet78  Indonesia
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Quote:
Originally Posted by lykkedk View Post
Thanks.. all!

So this schm. Babelfish it's possible to run this at lower rail's?

Jesper.
Anything to change if i use j176 or j103 to replace j271?
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Old 28th December 2016, 12:02 AM   #9
res07njc is offline res07njc  United States
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In one of the Zen articles Nelson said he liked the sound of a mosfet running 40 watts (current times volts).

Last edited by res07njc; 28th December 2016 at 12:06 AM.
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Old 28th December 2016, 12:16 AM   #10
Zen Mod is offline Zen Mod  Serbia
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Quote:
Originally Posted by didiet78 View Post
Anything to change if i use j176 or j103 to replace j271?
there is ancient pdf I made (almost 10 yrs ago) , floating as attachment in several posts here

anyway , here it is again

I remember I included J176 on list because few boyz tried it and they were satisfied ; however - I remember also funny listening tests revealing (sound) difference between various parts used in CCS above input LTP ...... where I can understand difference betewwn bad CCS and good (enough ) CCS ...... but frankly I cant grasp differene between two good (enough) ones

so , I didn't tried J176 and I have reserve about other ppl experience (see above)

disclaimer - my ZMengrish isn't much better now ,than it was then

however ,comparing to Toshibas and even to J271 , J176 is somewhat wimpy in one of most important parameters - xconductance (read-gain)

if you must use it , double it - use 2+2 in input LTP ..... all 4 matched of course at , say , 2.5mA

J103 (you asked for) was , I believe typo - you probably meant on 2SJ103 ; answer is no - xconductance is waaaay too low
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File Type: pdf convert your lousy aleph to less lousy babelfish j.pdf (68.8 KB, 218 views)
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