The Bear's new Aleph-X

Well, I did it. Fired up my pair of 100+W Aleph-X's about two hrs ago. I don't know what else to say,

really.

I'll try to remember averything I've got going on here:

12 IR IRFP244 per ch. running almost 8A total
16.5V rails
Absolute offset is hovers +/- 100mV around zero
Rel Offsets are 10mV and 25mV running balanced and DC coupled to my mixer.
Dual discrete schottky bridges
Surplus 475VA trannies with dual 17V secondaries
Heatsinks: Wakefield's I got used on the net (no idea what model). 6 per channel and only $10 a piece
(total $120) and they get pretty warm but not so hot that I have to take my hand off.
CRCRC C's are 47000uF panasonic TH-HA series and R's are two parallel 0.22 ohm 10W power resistors
(only one side has the R's right now-the one with the R's has absolutly no audible hum, the without has some hum that cannot be heard more than about 2 feet away. Tweeters hiss some on both though (don't know if this is normal, but, like the hum, it can't be heard more than a ft or two away.)

But don't ask me about the sound! I wouldn't exactly know how they are supposed to sound. I'm not really an
audiophile and I have never listened to any high end systems. I was thinking about buying an amp about a year ago and couldn't afford anything good. Eventually I ran across the PassDiy site and this forum; I started reading and thought, "I can do this!" So I can only compare it to my roomates pioneer receiver and
mine sound better! I wish I had better speakers to run these through- guess I'll have to build those next.
I'm running these through my roommates definitives (no clue on the model).

I want to thank everyone involved with this forum for sharing all the info making this possible, especially Grey for his original contribution.

And I want to thank Mr. Pass personally for not just letting me, but allowing everyone here a chance to build such a wonderful amps through his generousity.

Now I just have to make them look nice. . .
 
a few pics
 

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The transformers are very iffy and I'm planning on buying some new ones as soon as I can, but I wanted to make sure everything worked before I dropped the cash on the most expensive part of the amps. (I have another thread about the poor performance of the transformers which are sagging about 4V under a light load.) As far as the power supply goes, I would still like to add some bypass caps across the last big cap in each supply to quicken them up a little, but I can't decide what to do (how much F, brands, types, etc); any suggestions?

Also these amps are pretty darn loud for my small room right now and I am thinking about making these amps switchable between aleph current source and constant current source. This theoretically cuts the output power in half if I understand things correctly. Or am I wrong? Can someone verify, please? I also seem to remember reading that all I need to do to accomplish a constant current source is to break the connection between C1 and R12, and C6 and R34 (using greys original schematic). Anyone tried this?
 
Sbear,

Great job! You have something I don't, a finished Aleph X. I have the electronics done for a AX-100 but the metal working is taking forever. I built a breadboarded low power version which isounded great and it inspired me to build the 100 watt version (I just added some more fets on some external boards). Keep up the good work and best of luck with it. If you never listened to a piece of high end equipment before, you are now. Try it with other speakers if you have them.
 
kilowattski said:
Sbear,

Great job! You have something I don't, a finished Aleph X. I have the electronics done for a AX-100 but the metal working is taking forever. I built a breadboarded low power version which isounded great and it inspired me to build the 100 watt version (I just added some more fets on some external boards). Keep up the good work and best of luck with it. If you never listened to a piece of high end equipment before, you are now. Try it with other speakers if you have them.

I have a similar situation, I have the boards finished for an Aelph-X something and all the caps and power supply parts, but no Real metal work or transformers. I was planning on building a low power version first to see what it is like. Unlike Sbear, I do not have any $10 super heatsinks kicking around. I am thinking of passing on the low power version and going striaght for the one wil Bullocks. :) :)

Congrats on your efforts Sbear, Please take Netlists advise and spend some time on cleanup.

Regards

Anthony
 
Regarding the heatsinks, I spoke too soon. They weren't used, they were new. I'm not kidding. I got them from a guy who bought a whole batch of what I believe were a screwed up order from the factory that they needed to unload. I had to drill and tap all the holes though. Don't know why I said they were used, didn't notice I typed it until jleaman replied. I must be in the habit of saying I got it used because most stuff I buy on the net is used. Not these though. Wow, the more I think about, they ARE a great deal. To put it in perspective though, I did spend about 4 months looking just about everyday for a good deal before these popped up, who knows how much I paid for these if time is money. Persistance pays off sometimes. . .
Regarding the metal work, I agree with everyone else, it sucks and sucks baaaaddddd!!!!!!!!! Who would of thought the hardest part of building an amp is making the stupid BOX!! I just don't have the right tools and the right tools for that are especially expensive.
I will clean these up but I'm going to get better trannys first so I can find out how to route everything.
By the way, the hiss I talked about early is from earlier in the chain; disconnect the input and it's gone!!!
Now I need a better pre. . .
 
sbear said:
it sucks and sucks baaaaddddd!!!!!!!!!

sbear,

i have all the right tools and grew up in the metal industry.
And still it sucks, i am currently constructing a modular chassis that should serve for the next 5 projects or so.
Maybe that will help to manage the stack of boxes, i have difficulty with parting from stuff i made.
$10 for those sinks is amazing.
J.