change voltage rails Aleph2 J

[jerolee]

Hi everyone,


Building the Aleph2 J from the attached schematic, i got a question about front end component values. Since my speakers have 3 low points of 3 Ohms and a max of 8 Ohms, i like to match the amp to this impedance.


Using the excel sheet, turned out a rail voltage of about 37V is fine with bias of around 0,67A the power output should be like 140W at 4Ohms. The rig runs a little slower, wont need that much power and produces less heat (i hope🙂
the junction temp was fine too. (according excell sheet around 100-110C)



Do i have to change any values of components in the front end to compensate for this lower voltage rails? When yes, which parts?


(see schematic)


Thanks a bunch!



ps im designing the PCB's they are almost done and i might have a few spares if anyone is interested?

 

[Zen Mod]

no need to change any values

though , I didn't check your schm. except looking for rails voltage ( 45Vdc)

 

[jerolee]

Thanks Zen Master! I can start ordering the parts soon. just double checking packages, pads, etc.


The schematic i got from audio4fun

Decided on the Aleph 2, what psu should I build?



regards,
Jeroen

 

[vitalica]

Please tell me, in which variant is the connection C9 (Audio4Fun) and C2 (ZenMod) correct? Thank you !

 

[Zen Mod]

ZM's , of course

right - audio4fun schmtc-that dot , connecting C10 on bjt emiter line , is mistake

so , not just C9 .........

 

[coolnose]

vitalica,

those photos of screen just gave me eye cancer of similar.. 😛

Max

 

[vitalica]

I apologize for the image above 🙁
Now I have corrected and hope it is better

 

[jerolee]

Thanks Vitalica. Im correcting my schematic and PCB layout now too. /tiphat!

 

[jerolee]

Hi Zen mod en Vitalica,


I searched on the schematic and found this original one, which has the C9 on the output line? Now im confused as you can see.
Also there aint a zener over the transistor in the original.



Can you explain please what difference it does do here?


Thanks.

 

[Zen Mod]

that is not relevant difference , so called bootstrap of Q5 collector line works in both ways

though , Aleph CCS modulation cap , that one going to base of Q5 - that is critical mistake in fun4... schmtc

 

[jerolee]

Cleaned up the board, according updated schematic. when all components are in house im gonna final check drillholes and dimensions so no surprises when soldering.


Im gonna open a build thread when time is there.
Thanks again for your help sofar!


Regards,
Jeroen