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-   -   Rookie questions (http://www.diyaudio.com/forums/pass-labs/219357-rookie-questions.html)

Jallhalla 8th September 2012 09:02 PM

Rookie questions
 
Hi,

I have a year off on my studies, and one of my goals is making some good diy hifi. Im not a rookie in electronics, since I already have a degree in electronic engineering, and have made a tube preamp and a dac some years ago.

I have some mini aleph pcb boards from chipamps.com that I have lost the parts list and documentation for. Is it possible to get this from some of you guys? And is this the aleph 30, or is it some other amp?

Second, I have access to some broken hifi equipment at work. I recently butchered a nad t773, with some rather huge torodials inside. The schematics are avaliable online, but does anyone know the exact specs on these? And what amp should I build with them? :cool:

I have tried to find answers online, but there is just so much info, I could not find exactly what I wanted.


Thanks!

AudioSan 8th September 2012 09:31 PM

it is most unlikely that you can use that transformer for any class A amp.

wirewiggler 11th September 2012 05:18 AM

The boards you have can be built as a mini aleph or aleph30 if you use the daughter boards. If you pm me your email address I will send you a spreadsheet for the parts bom, and the schematics. Be sure to check the 220uf caps polarities against the schematics one is backwards on the silkscreen on my boards. You will need a 18V transformer Brian still sells the power supply boards as well.

Bill

AudioSan 11th September 2012 06:42 AM

acctualy one can build any aleph with those boards.
aleph mini, aleph30, aleph5, aleph60, aleph2, aleph1.2. it is all the same regarding the front-end.

Uunderhill 11th September 2012 01:27 PM

Quote:

Originally Posted by Jallhalla (Post 3157406)
I have some mini aleph pcb boards from chipamps.com that I have lost the parts list and documentation for. Is it possible to get this from some of you guys? And is this the aleph 30, or is it some other amp?

Class A MOSFET amps sound very good.
However, understand the amount of power they will dissipate just sitting in idle.

Suggest buying a pre made case - make sure the heat sinks are large enough.

I'd say the Aleph j looks like the one to build.

With the high currents in the power supply, star grounding is important.
Many power supply articles don't mention this.

Here is a good article to read over.
Earthing (Grounding) Your Hi-Fi - Tricks and Techniques
.

Andersonix 11th September 2012 03:43 PM

Quote:

Originally Posted by AudioSan (Post 3157445)
it is most unlikely that you can use that transformer for any class A amp.

Are you sure, AudioSan? MAYBE it has dual primaries, in which case one might wire them in series and get half the voltage?

AudioSan 11th September 2012 03:53 PM

yes i am sure. first of. you can only do that on 115V mains.
sec. then you also half the VA rating. wich will make the transformer even more useless in class A amp:)

Jallhalla 28th September 2012 10:28 PM

Thanks a lot for the replies so far!

So i got some parts info on the mini aleph boards. I have decided to make the aleph j. Im ordering the first pile of parts over the weekend, so I need to know what parts that have changed value. I am sure I can find this info somewhere on this forum, so do you have any pointers?

I have a 14x30x5,5 cm heatsink made for fan cooling. Two heatsinks, half the depth, put together. I know this is not optimal, but if I can skip buying heatsinks and make a smaller aleph fast, I think its worth it.

Do you think its enough? There will be small fans along the length of the sinks, running (hopefully) at sloooow speeds.

Audiosan, you dont happen to live in/around Trondheim?

And at last, the question you all have been waiting for, where can I buy properly matched mosfets and jfets?

AudioSan 28th September 2012 10:55 PM

do you know how to replace the irf9610's with J-fets? sj74 or sj109?
matched J-fets sj74 you can ask spencer if he have some:)
i happend to live IN trondheim:) bysen.

Jallhalla 30th September 2012 08:23 PM

I tried to contact spencer, but apparently I cannot pm him.

Is there some kind of "official" bom for the j? I want to begin hoarding parts so I can hear a prototype.

Audiosan, I have never listened to pass labs designs before, please pm me if you could help me with that! I understand if its too much! :)


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