Aleph 2 power supply

[MikeZ]

I am working on the power supply for an aleph 2 monoblock and I am trying to learn electronics as I build the amp. The toroid purchase has me a little confused. I want a 1000va toroid, thats my preference per Nelson Pass response to a post prior "You can, of course, always get away with less, and it
also depends on the conservativeness of the manufacturer's
ratings" , but what do I use for the output voltage, 30+30, 33+33 or 35+35 etc. What dictates the value of the output voltage.

that brings me to my next question, when I call a toroid manufacturer what do I tell him I want for example "a shielded 1000va 33+33 toroid."

And finally I read in the post about noise in the amplifier due to the power supply and using inductors to recuce this. As I am learning electronics, does a circuit diagram exist which shows the power supply circuit with said inductors.

 

[kristijan-k]

Hello MikeZ,

Here is the one example of the circuit diagram for the Aleph 2
power supply.

Hopeing that will help you.

Best regards.
Kristijan Kljucaric
http://web.vip.hr/pcb-design.vip

 

[MikeZ]

Kristijan, So if I understand your schematic, It calls for a 1000va, 37+37 toroid? Thanks Mike

 

[Peter Daniel]

I have two 1000VA toroids from Victoria Magnetics which were custom made specifically for Aleph 2. I plan on Aleph X now, so I want to get rid of those trafos. If you are interested contact me. I'm asking $100 USD ea. plus shipping.

 

[jleaman]

please email me

jleaman@citytel.net

i want them.

 

[fcel]

JasonL ... I hope you mean it this time ... just kidding.

 

[jleaman]

last time some one else got them : O ( sniff sniff.

 

[kristijan-k]

Hello MikeZ,

For the one channel-monoblock of the Aleph 2
power supply, you can use transformers from
at least 600 VA and up.

The 1000 VA transformer is very good choice
for the Aleph 2 amplifier and I would use it
without a seccond tought.

Best regards,
Kristijan Kljucaric
http://web.vip.hr/pcb-design.vip

 

[Mark A. Gulbrandsen]

Mike,
Best of luck building yours....don't hesitate to post here with questions. I've built alot of different amps over the years but the Alsph 2 is something VERY special as you will eventually find out. I used a 769 VA toroid that I was able to buy locally and it works just fine. The Victoria Magnetics toroids are very good, so go for it......I know some of the people down there at the factory and I will be using their toroids on my future projects.
Mark

 

[grataku]

Mike,
Krystian PS is excellent, be sure to understand how it works, what type of coil you need, the wire gauge for this coil, how to arrange everything in the enclosure so that the coils don't disturb the low level input signals etc. It's going to be VERY BULKY, heavy, and expensive. Do you have the heatsinks?

 

[jleaman]

If i may ask what do the 3,9mh Coials do in the psu section. Do you have to use them.? What happens if i dont have a set up like Kristians. im planning on useing 4 x 70k cap 80v 4 per mono block ( for my aleph 2's ) Is this ok. Im going to buy peter's vc magnetics transformers. and use them i have done lots of research and found that they will work awsome. And they look niceer too. : O )

 

[MikeZ]

Thanks for all the input. I have heatsinks already. I am in the process of getting some of BrianGT aleph boards. I wont have any trouble stuffing the boards but I am at a disadvantage understanding some of the basics of the power supply, I am planning on victoria magnetics shielded 1000va. I am planning on using the power supply kristijan-k supplied earlier. I want to purchase my toroids now for two monoblocks and I dont know what output voltage to I use? Per kristijan-k schematic I get the impression I must use 37+37.

Is 37+37 correct for the toroid output voltage for the kristijan-k circuit? Or can I use 35+35 or 33+33 or something else? Or do I just call victoria magnetics and say "I want a shielded 1000va toroid"?

Thanks Mike

 

[jh6you]

Instead of the multiplier of 1.414, we normally use the ideally approximated value of 1.20. For example, if V(rms) is 37, V(peak) is estimated as 37x1.2 ~ 44.4 V(peak). Therefore, the secondary of 37+37 is quite ideal for the +/- 45 Vdc we want to have.

35+35 and 33+33 could be used if we are ready to accept somewhat reduced maximum output powers.

The transformer supplier will always ask us about our requirement of power rating, primary voltage and secondary voltage, etc.

 

[fcel]

Mike,

When you are ready to order, just tell the transf manuf the following informations in this manner:

1000va transformer (I assume you're ordering 2)
120v primary
37v-0-37v sec
& shielded

 

[jh6you]

Instead of the 37v-0-37v secondary, I would tell them 2 x 37v secondary. Two 37v secondaries make both possible, i.e. (1) the original Aleph 2 PSU or (2)Kristijan-k PSU.

JH

 

[MikeZ]

Thanks so much for the ordering information, this is all very helpfull! I will now order the toroids.

Now for my next question on the power supply, G1 and G2 on kristijan-k schematic are rectifiers I believe, can anyone tell me what would be the best part number for this from digikey or mouser?

Thanks Mike

 

[harvardian]

Any 30 to 35A 400 to 600V bridge will work


Digikey part numbers

36MB60A-ND

GBPC3504DI-ND

 

[MikeZ]

Thanks harvardian.


For the capacitors what is the minimum voltage rating I should use?

On the Kristijan K schematic what does the MKP by the 4.7uF cap stand for?

Thanks Mike

 

[dshortt9]

50 volts for the capacitors. The MKP is for Polypropylene as far as I know. 4.7 uf. anything from 3 - 10 should do well.

 

[MikeZ]

how close to the actual values do the 68000 and the 47000 need to be?