AlephJ Mimi! (Mini)

[Dennis Hui]

most important thing Papa gave us is zillion of puzzles/legos and recipe use your brain and play

Totally agreed.

 

[lykkedk]

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

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.

 

[didiet78]

Aleph J with value.

 

[Zen Mod]

will reply later tonight , with edited schm for your needs

 

[lykkedk]

will reply later tonight , with edited schm for your needs

Guess i Will start my diptrace pcb layout now 😎

Jesper...

 

[lykkedk]

ZM.

Whenever you got time and place. I was hoping that one output pair would suffice for this mini-AlephJ ?

Good day.

Jesper.

 

[lykkedk]

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.

 

[2 picoDumbs]

Referring to Bablefish J (not Aleph J), is Q3 a recent modification?
I don't think I noticed that the last time I checked it (a while ago).

 

[2 picoDumbs]

-I mean i don't understand why connection from q3/q4 only goes to one of the output pairs on original AlephJ schm,

Jesper.

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.

 

[lykkedk]

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.

 

[2 picoDumbs]

You're modded circuit is perfectly ok (just in case you're still worried).

 

[lykkedk]

You're modded circuit is perfectly ok (just in case you're still worried).

Thank's... youre explanation cleared it out.

I am doing some layout at moment... still long to go through

Jesper.

 

[2 picoDumbs]

Great to see the effort you are putting into this.

 

[Zen Mod]

as far as I can see , everything is OK

you can excludeQ3,R13,R14 (overcurrent protection)

put trimpot (as variable resistor) +resistor combo instead of R7 and instead of R27

 

[lykkedk]

as far as I can see , everything is OK
put trimpot (as variable resistor) +resistor combo instead of R7 and instead of R27

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.

 

[Zen Mod]

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

 

[2 picoDumbs]

You could simplify ccs feeding jfets with a fixed resistor, 800 Ohms would be perfectly fine.

 

[Zen Mod]

leave it as per Papa's schematic

he's having damn good reason for these values

 

[2 picoDumbs]

leave it as per Papa's schematic

he's having damn good reason for these values

Yeah exactly, no need for trimpot BS

 

[lykkedk]

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

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