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Old 30th July 2005, 07:31 PM   #1
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Default My new mini-A. I really like it!

First: Thanks Nelson, Grey, and Brian!

Hello,

I am proud of the true completion of my solid state project. It is a Mini Aleph based on Brian's recent boards.(very nice boards)

I am using 2 irf150(to-3) devices per channel. My psu is dual mono with 2 220VA +-14.6v toroids. They were +-20v but I unwound them a bit. I am using <-2*15,000uf-.5R-1*15,000uf-> crc per rail. There is negligable to no hum or buzz.

The to-3s are mounted on a 10mm copper plate each which is bolted to the heatsink with a .5" alu spacer and 16*8-32 machine bolts. All surfaces were lapped flat on a glass plate and of course grease was used. The sinks are~7"x6"x1.5" and a total of 4 sinks in the Aleph 3 style.

All I/O is on a nylon plate routed into the rear sink...with the exception for AC in, which comes in the bottom. The legs are lacquered red oak..

I have lifted r13(r19) for full bias and that works out to be about 1.3A with my 16.8v rails. Heat sink temp tops out at 48c under any conditions and actual temp at the device has not exceeded 52c! The whole thing works super!

The sound tops anything I have heard (biased opinion of course) here provided the volume kept reasonable. Actually, I can't believe how this ~10watt amp can belt it out. It truly sounds tremendous. This will run my eminence psd2002 compression drivers in a Beta 12 scenario. I'm building an Aleph slightly smaller than the 30 to run the woofers. Active XO.
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Old 30th July 2005, 08:28 PM   #2
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hmm, it won't let me put more pics up!
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Old 30th July 2005, 08:31 PM   #3
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Very nice!

Dennis
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Old 30th July 2005, 08:49 PM   #4
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try this way...

psu:
Click the image to open in full size.

internal:
Click the image to open in full size.

before boards installed:
Click the image to open in full size.
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Old 30th July 2005, 08:54 PM   #5
Taco is offline Taco  Netherlands
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I like the chasis very much, looks like a original Aleph with wood accents.
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Old 30th July 2005, 09:18 PM   #6
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Thanks guys,

I way overcomplicated the chassis construction. I won't do that again, it took WAY too long! and for no real benefit.
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Old 30th July 2005, 09:57 PM   #7
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Quote:
Originally posted by mpmarino
Thanks guys,

I way overcomplicated the chassis construction. I won't do that again, it took WAY too long! and for no real benefit.
Ah, but it also looks way cool!

Dennis
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Old 31st July 2005, 12:03 AM   #8
TroelsM is offline TroelsM  Denmark
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Default Is that an earth-con on the bolt for the toroid?

Ok, I'm a bit drunk (don't ask..) but it seems to me that you could run into trouble and make a short on the transformer with that white wire running from the bolt...

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Old 31st July 2005, 12:16 AM   #9
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Default Re: Is that an earth-con on the bolt for the toroid?

Quote:
Originally posted by TroelsM
Ok, I'm a bit drunk (don't ask..) but it seems to me that you could run into trouble and make a short on the transformer with that white wire running from the bolt...

TroelsM
Denmark (01.03, saturday..)
you are correct. The short would have to occur after the coated wire, insulation covering the wire, insulation covering the transformer, and coating over the transformer secondaries is permeated. Then, you are correct, there would be a problem
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Old 31st July 2005, 12:24 AM   #10
TroelsM is offline TroelsM  Denmark
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Default He he...

I don't think that you see my point. (Maybe there isn't one at all..)

If the bolt in the center of the transformer is connected to GND (the case?) and you make the bolt the "star-ground" of the whole amp, then you would have a big problem if the GND-speaker-terminal (or the input-GND) for some reason is connected to the case. That would make a shorted winding on the transformer and a fuse will (hopefully..) blow.

Please correct me if I'm wrong.

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