Aleph 30 schematic and tweak suggestions?

[Colescuttle]

I've just purchased a set of Brian's boards to use as the basis for a pair of Aleph 30 monoblocs. I've searched and been able to find a schematic for the Mini-A, but not for the Aleph 30. Could someone point me to one, if such exists?

Also, if anyone, including Mr. Pass, has suggestions for proven tweaks for this circuit, could you list them for me? Please note that I prefaced all my posts on the Sym-a-sym forum with "Dummy Alert," so suggestions more sophisticated than "replace part X at position A with part Y" or "remove the part at position B" are likely just to crease my scalp.

I'm planning to use the choke filtered power supply described by Rod Elliot on his excellent "25 watt class A amplifier" webpage with 50,000 to 75,000 mF of capacitance. Will that be enough?

Thanks.

George

 

[Zen Mod]

- I'm puzzled - why you didn't ask Brian for schematic for his boards ;
that will give you at least parts nomenclature ...

or these boards are for mini , which you already mentioned ?

anyway - just ask , and somebody will send you file .....

or search for aleph30.pdf here ........ handy file , made by Algar_emi .

tip - make Aleph J with these pcbs ; that's best tweak you can find.

 

[hifimaker]

Please use search, this has been discussed in great detail already.

Here's an example:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=12923&highlight=

Also please search for mini-A in the Pass forum, very long thread with probably everything you are looking for.

-David

 

[BrianGT]

I've just purchased a set of Brian's boards to use as the basis for a pair of Aleph 30 monoblocs. I've searched and been able to find a schematic for the Mini-A, but not for the Aleph 30. Could someone point me to one, if such exists?

Drop me an e-mail, and I can give you the schematic. The parts list is available here:
http://www.chipamp.com/diyaudio/mini-A.xls

--
Brian

 

[wirewiggler]

take a look at this as well.

http://www.diyaudio.com/forums/showthread.php?s=&threadid=12923&perpage=10&pagenumber=2

 

[Nelson Pass]

That's the first thing I would do.

 

[Colescuttle]

A plan comes together...

Thanks, everyone. With your suggestions, and those from Zen Mod in another thread, here’s the approach I will follow. BTW, Mr. Pass, having you “look over my shoulder” is extremely encouraging and confidence inspiring.

1) I can’t afford to do the in situ mixing and matching of active devices that Mr. Pass suggests, so I will order matched devices from Tech DIY and hope for the best. I do have a Duoyi FET matching meter with which I could match devices myself, but I know from experience that that route is also quite expensive and time consuming for a one off project.

2) I’ll :

a. use matched Caddock MK 132 resistors in the signal path, PRP and Vishay/Dale resistors everywhere else;

b. use 220uF Silmic II electrolytics (available from Digi-Key), bypassed by .47uF Panasonic film and foils, at C1, C2 and C3; Panasonic film and foils at C5 and C6 and a silver mica at C4;

c. bypass Z5 with a 1uF Panasonic film and foil, and since my input will be single-ended omit Z3 and Z4;

d. shooting for a bias of about 2.4 amps, omit R13 and use 0R27, 3W metal films at R23-R26, R35-R40, R47 and R48;

e. start with trim pots at R8 and R12, and after adjusting AC current gain and DC offset replace them with the appropriate value
resistor.

George

 

[wirewiggler]

What i usually do is build the amp stock first establish a baseline and them make mods from that point. This way you will know how the designer intended it to sound and move from that direction. I have found Mr. Pass's design to be so solid that throwing boutique components to be to some degre waistfull. One worthwile upgade I made on my Aleph 30 was to convert the power supply to a pi filter.

I have managed to build 5 aleph minis in multiple component configurations (my nephews love their graduation gifts) and they for the most part sound identical (very good by the way Thank you Nelson and Grey).

My 2 cents

Bill