"Inverted" Aleph J?

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Hi,
Inspite of the fact that the LSJ74 is temporarily available, isn't it possible to "mirror" the aleph J and replace n-channel with p-channel and vice a versa. This way one could use the sk170 (or even sk389) for the front end which are still easier to get. Also the ciss/crss for sk170 are lower which I have been told is a good thing for low distortion.

Is this possible to redesign it in the inverted way or do I miss something?

Thx
Joe

p.s. As I already have the diystore boards and got my hands on two SJ75 (which is 2 times sj74 glued together in a metal housing) I will probably build it as is, so this is more a educational question.
 
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Thx guys. Good link.

Could not find a jfet called (2s?)j271. Is the spelling corect?

Btw, do you have experience with sj75? I measured idss of the halfes and they are 10% different which I find disappointing.
Still need to messure the pinch off voltage to ensure the parts are genuine.

Joe
 
Hi,

If anyone else is considering an "inverted" Aleph J, the amp I built following juma's schematic (in the thread he linked to) sounded very good. I haven't used it for a while (for various reasons I've been listening to music on my diy DAO headphone amp) but I intend to rebuild it in a new and (hopefully) improved version as soon as I can. (I have Toshiba output devices I got from buzzforb... The delay is due to a recent move to the USA, meaning all my diy stuff is in packing crates...)

I'd be interested to hear from anyone else who has tried an "inverted" Aleph J...

Nigel
 
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Very nice, thanks for the design. Indeed, I have lots of BF862 and IRFP9240 is easy to find.

143566d1255518211-mini-aleph-using-bf862-pch-gif
 
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BF862 is interchangeable S & D

This would be a real cute teeny-tiny inverted micro-Aleph J HPA in an all SMT job with ZVP4525G outputs and SOT23 BJTs. Could probably replace Q4 with BSP129 in SOT223 package to get better heat sinking, Q1 could be SOT223 DZT5401, also for more heat sinking and higher dissipation.
 
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....... wrong answer .... :)

however , you cheated - edited post later (new schm) , without trace

:rofl:

I saw your question after I updated the schematic as I got to the later post where Juma corrected it.

The manufacturer’s spec sheet says it’s interchangeable. I have built circuits thus and that appears to be a true statement. Why is that the wrong answer?

https://www.nxp.com/docs/en/data-sheet/BF862.pdf
 
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