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Tony D. 17th April 2002 10:29 PM

Spec on transformer for Aleph 5?
Hello All, I am thinking of building the Aleph 5 and I am wondering if anyone can tell me what size, voltage rating etc. transformer I should use?

Thanks for any information.

Tony D.

wuffwaff 17th April 2002 10:42 PM

Hello Tony,

Im also building an Aleph5 (just finished drilling the pcbs).
I will use one 600VA 25volt transformer per channel. This will give me the possibility to increase the bias current (if my heatsink arrangement will allow;) ).
The transformers are fully impregnated so I hope the mechanical noise wont be too high......


Tony D. 17th April 2002 11:51 PM

Hi william, thanks for the info.

Plitron has a 625va, 25-0-25, 12.5amp transformer that looks good. How much capacitance are you using in the power supply?

I have decided to go ahead with the project and I will be gathering parts over the next couple of weeks.

I think I will use the circuit boards available at and make a custom enclosure.

Tony D.

fcel 18th April 2002 12:30 AM

Tony: you do know that you can get it locally ... done by Brian ...... in the Trading Post thread ....?

BrianGT 18th April 2002 12:35 AM

I have about 6 sets left for sale. View my webpage for more details:

They should be done on the 30th and then I will ship them out.


Tony D. 18th April 2002 12:56 AM

Doh! I did not know that I could use this board for the Aleph 5. Thanks for putting me right.

I assume it is just a matter of scaling up and down?

Tony D.

BrianGT 18th April 2002 01:41 AM

Yes, the boards will work for most aleph amplifiers, with a variation of the output devices, and a few resistor changes.

View the owners manual at and you will see the same basic circuitry for all of them.


protos 24th April 2002 01:35 PM

tony d,

How can you use a 25 v trans when the supply for the a5 is 34v?

I am also looking for a trans for my a5 project and can only find the following 1)500va 35-035 7.14A
2)625va 40-0-40 7.81A
3)2x 300va 35-0-35 4.28A each?

What is recommended by the ones that know ?
By the way can you make two power supplies to power the two sides of the circuit or did I say something stupid ?

stadams 24th April 2002 01:49 PM

The ratings for transformers are almost always listed as an AC rms voltage. Therefore, you must divide by 0.707 or multiply by 1.414 to determine the peak voltage that the transformer delivers to the rectifier for your power supply. Calculate the voltage drop the rectifier has on your AC voltage and that is to what your capacitors will be charged. So,

{(25V*1.414)-1.4}=33.95V .

Pretty close to 34V.

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