On the verge: help with Aleph 30.

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Colescuttle

Colescuttle

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Joined 2006
#1
I've gotten my "dumbest" question answered. Now I need some help with some simply "dumb" questions.

I've spent a couple of weeks reading every post in the "Mini_A PCB" thread and most of the posts in other threads referenced in that thread, pored over multiple schematics, including Algar_emi's very helpful one, and am ready to order parts.

Attached below is the Mini_A schematic.

I'd like to build a pair of Aleph 30 monos with Brian GT's latest boards based on this schematic, and start out with both amps running at maximum bias, so I'll omit R13. I'd like to substitute a trimmer at R12 so that I can adjust AC gain, and another one at R8 so that I can adjust DC offset. What value trimmers should I use at R8 and R12?

I'll use Brian's PS boards with 20-0-20 trafos and 99,000uF per rail and will not permanently install the CRC resistors until I can run the completed amps under load and adjust their resistance to achieve 25 volt rails. What value CRC resistors should I start with in the power supply (I can't get PSU Designer to work correctly on my 64 bit desktop)?

Thanks for your help.

George
 

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#2
make :

R8 - 150E +100E pot - in series

R12 - 470E + 1k pot - in series

R28=R27=R23=R24=R25=R26 = 0R33, so - you'll have around 2A Iq

if you want more - decrease them to 0R27

Iq~ Ube/R28 (where Ube is 0V65 - for Q5)

CRC - 0R47/5W WW is good enough
 
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