AlephJ Mimi! (Mini)

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#22
Zen Mod said:
use 2x15Vac xformer , resulting in 18Vdc rails
set iq to 1A2 or something like that

use one pair of IRFP240

choose pcbs of your liking (any Aleph type) , post here what's your choice and exact schematic for that pcb and I'll wrote what to change for your needs
Click to expand...

You are very kind ZM... Thanks.

I allways did like the alephJ; my F5 and this AJ has been in and out of my amp. some times last few years, and really we like the AlephJ most. But amp. is to big 🙂

I have an 15v x 2 transformer (2x5A ~120VA), which could be big enough for testing one channel. When testing is done, and everything is good, the amp will be dual mono in one chassis.

I have attached the AlephJ schm. and the BOM from the DIYaudio store here, but i really would have liked that the values was written on the schematic instead. If you need that, then i can go to my work and print it out, write the values on the schematic, and scan it up again?

Again thank you for helping me ZM (and all others here too)

BTW.: I dont need balanced input, if it makes any difference (maybee schm. will be more simplified

Edit: PCB Will be Diy AS allways

Jesper.
 

Attachments

  • AJ Skema BW.png
    AJ Skema BW.png
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  • BOM-Aleph-J-UMS.pdf
    BOM-Aleph-J-UMS.pdf
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#27
Morning all.

I started a layout for this proto mini alephj tryout 🙂

Maybee someone could have a look at attached schematic? -I have removed one pair of output mosfets (IRFP240).

If one look at the connections of the original dual output schematic, there is a connection from transistor q4 to q5 (upper half of circuit) and a connection from q3 to q8 (lower half of circuit)

The connection from q8 i removed and connected it to q7 instead (See attachments)

Is this correct? -Maybee someone could explain? -I mean i don't understand why connection from q3/q4 only goes to one of the output pairs on original AlephJ schm, 😕

Jesper.
 

Attachments

  • Dual-pair_AJ BW_Value.png
    Dual-pair_AJ BW_Value.png
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  • Single-pair_AJ BW_Value.png
    Single-pair_AJ BW_Value.png
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#29
lykkedk said:
-I mean i don't understand why connection from q3/q4 only goes to one of the output pairs on original AlephJ schm, 😕

Jesper.
Click to expand...

It controls the voltage at the gate of both mosfets, it does not need to be connected to both mosfet source pins to achieve that.

I would leave off Q3 altogether. It's only there for fools who abuse their equipment.
 
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#30
Thanks...

I found the original schm.

There is added an extra pot in diyaudiostore's schm. for adjusting around R27,

I see in original schematic, the connections i was in doubt about, goes excatly like i changed it too 😀

Youre proberly right about q3, but i cant tell!

Jesper.
 

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#35
Zen Mod said:
as far as I can see , everything is OK
put trimpot (as variable resistor) +resistor combo instead of R7 and instead of R27
Click to expand...

I did, it's also in diyaudio store schematic.

I attached the schematic i use for reference.
About removing Q3,R13,R14 (overcurrent protection), i will post later

Thanks both of you!

Jesper.
 

Attachments

  • Single-pair_AJ BW_Value.png
    Single-pair_AJ BW_Value.png
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#40
Zen Mod said:
looking at that schematic :

- remove R8'
-remove R27B, use R27 and R27A
-put R7 and R7' in series in drain

will tell you exact values later , still on first morning coffee
Click to expand...

Yes..

I understand.

When you got time to calculate resistors ZM; I will make layout with all the changes we agree along the way. No need to rush; i am not able to make much more today, as i have got to prepare for newyears eve now :cop::drink::drink::smash::scared::flame::hypno2::cheers::cheers:
 
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