Aleph 2 parts

[JayV]

I just got six 2*38V, 1500VA Transformers For you in sweden i can reccomend microtraf!! I Paid 5000kr (540€) for these, including shipping!

I'm going to build six Aleph2's and i look for psu caps now, will four Evox-Rifa PEH-200, 22000 uF/63V be enough per amp? It get a bit expensive if i use four 47000 uF instead :/

 

[loovet]

Hi JayV,

Your transformers look just great.

I’m also planning to build Aleph 2. As a supplier of transformer I’ve had microtraf on my mind. And it makes me really happy that you can recommend them.

I haven’t given the caps any thought yet. I’m a little bit more worried about finding appropriate heat sinks, at least at a reasonable prise. Have you bought your heatsinks yet? And if so, from where did you by them?

BR

loovet

 

[jleaman]

Here is my current setup for aleph 2's as i'm still in the building faze..



http://24.71.244.254/Photo/view_album.php?set_albumName=album17

 

[JayV]

I have read somewhere that microtraf make transformators for Copland.

Nope havent found any affordable heatsinks yet, but i'm thinking about cutting out "heatsinks" in foam with a hobby cnc mill, dip them in plaster (gips?) and then cast them myself.. Only about 150€ in materials cost! And then i get them exactly as i like... Also i would make really cool 3d frontplates

 

[UrSv]

JayV, you could easily have saved a bit on the transformers as 1500 VA is plenty if it is one per channel. An Aleph 2 draws only 300 W.

The factory Aleph 2 uses 4 pieces of 22.000 uF so that should be OK. A bit more won't hurt but don't give it too much IMHO. Try to get PEH169 instead of PEH200. You would need 24 of them. Price for 47.000 uF instead is not even close to double at Elfa. Check that. BC does nice things. The 22.000 uF cost for 24 pieces would be about EUR 600. Call MJS Electronics and buy the lot of 400 pieces of 4.700 uF/50V ELNA caps for about EUR 250 is an option. Use some and sell the rest and caps are for free...

Lots of sinks around. Try Siefert or the Fischers at Schuro.

 

[jleaman]

i'm using 6 x 37,ooo mf caps


111000.mf per rail per amplifier. : O)

 

[JayV]

I like it BIG! hehe, acutally i don't think it was so expensive! I mailed toroid about an equal transformator and i belive it was 3 times as expensive!

I have read that PEH169 is better for audio, but i can't find any 63V on their page.. Perhaps i should mail them and ask!

I wonder what the temperature will be in my listening room No problem in the winter tough as we often have -25C (or even -30C) hehe

 

[Loris]

Hi JayV, could you explain us something more about that "plaster" you mentioned?

Seems Interesting, at least in different applications.

Thanks

 

[GRollins]

38VAC secondaries will give you rails somewhere in the vicinity of 50VDC (I think stock was 45V, but I don't have a schematic handy to check). Heat dissipation will rise accordingly, so watch your heat sinking. You'll also get a bit more wattage out of the circuit.
Offhand, I can't think of any parts that will need to be changed to accomodate the higher rails.
With a 1500VA transformer you could run two channels and still have power to spare. Considering that you've got six, you could go for twelve channels total...were you thinking surround, by any chance?
Or you could run the bias up. Yes, they sound better that way. I've got mine set so that I can vary the bias over a wide range. When the bias is low they start sounding thin, anemic, high-fi in the wrong sense of the word. Increased bias fills in the sound so that the ribs don't show. I typically run mine about 10% over stock.

Grey

 

[JayV]

I'm going to triamp linkwitz phoenix or somthing like that but with a digital filter/dsp (Behringer DCX2496).

Hmm i belived the "real life" formula was about 1.2 as in 38*1.2 = 45.6V nevermind, never wrong with more power ;D I'll just cast som really big heatsinks...

For casting info just search for "lost foam casting" on google or something...

 

[promitheus]

You sure will need a lot of heatsinking with higher voltages on the rails. Extra current headroom is always good by power tramsformers. Normaly you should use 2-3 times more current capability so that means 2-3 times more power on the toroids than you will be using. I have my aleph running on 4 mosfets per voltage rail ( 8 for each channel) at 0,5A. Thats 2 A bias at +/- 41Volts. Thats 160 Watts per channel. I used 500 or 600 VA toroids for each channel so thats 3-4 times more. It works just great.

 

[tomchaoda]

For the "real life" formula of a transformer is to multiply by "1.2" or "1.25", is this a formula derived by real life experience or by theory? (like the one using on Hard drive size, the theory is not the real life size...)

Thomas

 

[jouch]

I just read this intresting tread. I'm also leaving in sweden and have some problem to find suitable heatsinks. Was wondering how you are going to cast your own one? I would be glad if i could do the same.
Thanks for your help.

Christopher

 

[Blues]

The formula is Vpk=Vsec*2^1/2; where: Vpk= peak unregulated voltage (voltage after passing through a diode bridge either V+ or V-), Vsec=transformer's secondary voltage; 2^1/2=square root of 2.

 

[tomchaoda]

Aleph 2 bi-wire output?

I noticed that the original Aleph 2 is a bi-wire RCA output. However, I also noticed that most of DIYers simply install one set on each block. Is this something not in the original schematic (I downloaded it, but haven't study it yet!), or it is hard to implement (cost, technical issue, etc.)?