Transformer rating for Aleph 4

[macka]

Nicholas,

I was planning on using 20 of the 15,000 uf per channel.
ie 150,000 uf for each positive and negative rail and have a sift start delay circuit to avoid damage from the in ruch current.

NOS is an abreviation for - new old stock. They measure about 1 3/4 x 2/ 38 inches(they have not arrived yet however).

I hope they will be okay. I saw a scanned picture from the vendor and they were sealed in a carton so I expect the deal is good but will have to test them when the arrive.

If the final version I was going to use some 1 uf Axon film capacitors to bypass the main filter cap bank which would be arranged on a double sided board (so as to have two rows of 5 top and bottom with thick 1 inch pads.

This will keep track paths short and make it compact. I understand from the Master the layout for the capacitors is not overly critical as long as path lengths are kept relatively short.

I expect your approach of 8 x 2200 Panasonic will work well.

I will use similar film capacitors on the main board and perhaps Nichicon Muse Gold KZ series for the 220 uf electrolytics and some 1000 uf 63 volt for supply rail decoupling.

I propose to order the 625 va toroidals when the capacitors arrive. I prefer mono blocks for heat and space reasons

I already have in total sufficient heat sinks from a pair of Aleph 5's to test one mono block Aleph 2 and will measure the temperature rise above ambient before ordering the new heatsinks.

I am not sure yet if I will make it like the Aleph cube or the Aleph 60 yet. But will make the case from scap aluminium L angle and 5 millimetre plate.

I am making the simpler - 1st version of the Aleph P as a trial in balanced mode. (This used IRFP 244's from the power amp)

I will then decide on either the Aleph 1.7 or the Pass DIY balanced line stage.

regards

macka

 

[nicharis]

I think Master recommend IRF240 for Aleph amp if I am not wrong. I have not order my IRF yet.

I think rectangular will look nice, attach pic of passlab x series, can't remember which model.

I am think of David Broadhurst, Auckland, New Zealand Single Ended Class A Balanced Pre-amplifier which I found in one of the thread in this forum. Any comment of the preamp, Aleph P looks very complicated to me as I am electronic idiot, I don't understand the circuit diagram. There is a thread on passive preamp. Do you think it will sound nice Aleph? Maybe a foolish question. Thought to ask him. I have some problem in the output stage of Aleph 4 on the layout. Is it possible for you to assist me?

The sense from the driver.. is it connected to one one of the paralleling output mosfets or should I parallel it to all the mosfets?

Thanks

 

[Gabster]

Please, let me bring everyone's attention here:

http://diyaudio.com/forums/showthread.php?s=&threadid=2642

 

[mefinnis]

IRFP244s are fine .... these are what I have used. Nelson did say he would recommend (and does use) the IRFP240s, but the former are fine.

Multiple smaller caps in parallel will be fine and provides for some variation in layout which cannot be attained with fixed larger caps. In fact, the peak current performance will likely be better, but in this application is of minimal concern.

cheers, mark

 

[promitheus]

Mark Finnis is right. In this project it doesn´t matter so much. you have high current all the time because of class A operation.
I also used the IRFP240 with very nice results.
The small caps are easier to play around with but only with a pcb board. The big caps are easier to install IF you have the space.