another Aleph5 (Upgrade from ZEN)

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...and here is another Aleph5 clone

As an 'upgrade' project I converted two stereo ZENs into two mono Aleph5s using Kristijan's boards, new heatsinks and most of the rest of the ZENs.

The ZENs were build in '97 and worked without any problems bi-amping my Beck BK3 (4Ohm) speakers. The desire to have some more power and the daily temptation reading about all the projects in this forum got me started.

As you can see in the picture, bottom, back & front remain the same (also top), the sides are entirely new. I have mounted one FET per heatsink element (but coupled the heatsinks via a massive (40x12 mm) aluminum bar). The FETs are matched. I will take temperature measurements to check if the temperature of the heatsinks is similar. The gate resistors are soldered to the FETs. Since the Alephs have to drive 4 Ohm speakers, I followed 'wuffwaff's' direction and sure was glad that he shared his findings.

The picture shows an intermediate step - one ZEN down, one Aleph to go...

In the meantime I completed the second unit and started to listen.

My first impression is that the music is clearer and more dynamic. It seems that the speakers are better controlled - a certain 'preciseness' without being sharp or harsh is a weak attempt to express my initial findings. Listening is pure fun (especially after removing the small but noticeable noisefloor by separating signal ground from 'protective' ground via a 10Ohm resistor...:blush:).

Thanks to all who contribute to this forum - especially to Nelson Pass for sharing his knowledge and experience. I am most impressed by your patience and willingness to discuss your designs !

Best regards,
Andreas
 

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here is another picture of the Aleph - you are right, the caps are on top of the transformer (toroid, 300VA 2x30V). I made some temperature measurements - temperature at the heatsinks is approx. 42.5C after one hour (temperature is within 1 centigrade when measured at the same spot on each heatsink). The caps surface measure 26C at the same time (ambient temp is approx. 19 C).

Regards,
Andreas
 

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JasonL, '1' is the side of the transformer, '2' is the blue potting (actually the top of the transformer) the transformer is filled with. It is a toroid mounted into a plastic can and then filled with the blue stuff (some sort of colored epoxy). I purchased them in '97 at Schuro in Germany. Today's version is black.

Roddyama - the 'cute' coils are rated at 2mH and allow 5A current(because of the core). I doubt that they do much good - however, since the amp is dead quiet I left them in when converting the PSUs for the Alephs.

Regards,
Andreas
 
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Joined 2002
Pedro,

Most metal suppliers will cut the metal to size for a price. Then it is mostly drilling, filing, and sanding. Certainly the availability of a mill makes things much easier, particularly if you want to get fancy. You’ll notice the beveled slot in the front of Andreas’ mono-blocks. This is most likely milled with a vertical mill.

Do you know any machinist?
Rodd Yamas***a

P.S. Did you get my email with the file?
 
My 3mm alu plates are also cut by a metal shop witha hydraulic gilhotine, but I was refering to the holes and stuff.

I find that's very dificult to make precisely positioned holes and if the plate is very thick, then corecting them is hell on earth :redhot:

I usually draw the board in autocad, print it and with a punch, and drill after. The problem Is that in this process I usually get errors wit +-0.5mm that I correct with a round file, but with those thickness... I dunno!


P.S. - Yes I recieved the file and it was ok(there is some kind of block in there that damages the file, but I managed to correct it. If you want I have a new version of the file with the back pannel also.
 
Pedro, thanks for the compliments - Rodd is right, I got the frontplates cut to size. When you need proper edges, you have to use a saw to cut the aluminum instead of doing it with a hydraulic press. Edges and surfaces had to be sanded with wet sanding paper and as a finishing touch I 'satinated' them (I do not know the proper expression in English - it is like sanding but with a very fine metal mesh while applying some aluminium cleaner).
The mounting holes and the slot were milled with a machine that I have access to.
I doubt that I can work all that precisely with the tools I have at home - I usually try to build my stuff in a way that my mechanical shortcomings are not immediately visible on the finished device...
Regards,
Andreas
 
A very clean and nice looking layout, really.

Pedro, as for the precision needed for cutting holes (assuming you are drilling exactly where you punched... and punched exactly were you had to... ;) ), a good deal of imprecision comes from vibrations, either from the piece itself (not firmly seated), or from some lighthweight drill press stand. Even if there are (almost) no vibrations, another reason arise from a not perfectly centered bit holder, from it's teeth... more common than would appear.

If there are no vibrations, thick plates in my experience are easier than the thin ones, requiring only more time to get through.

ciao,
Roberto
 
hey all,
sorry i'm coming in late, but i read this post and am wondering what the ideas were that 'wuffwaff' offered for driving a 4 ohm load? can someone point me in the right direction to check them out, before i try searching "aleph".. as i'm sure that'll bring up a mountain of hits.

thanks for any info,
cheers,
scott
 
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