Anybody having trouble in finding heat sinks for his project, here is an interesting approach to cool the amp.
Very innovative and cool looking.
, lots of work too, I guess.
http://www.passdiy.com/gallery/a75-p2.htm
Very innovative and cool looking.
, lots of work too, I guess.http://www.passdiy.com/gallery/a75-p2.htm
It looks like he used U-channel aluminum which is what I am planning on using for my Aleph 5. I am planning on constructing the amplifier vertically and mounting it on a plinth, a bit like the monolith from 2001.
The U-channel is readily available from the likes of Home Depot and Revy, it is available in 18mm, 25mm and 37mm. I was thinking of using the 37mm.
Tony D.
The U-channel is readily available from the likes of Home Depot and Revy, it is available in 18mm, 25mm and 37mm. I was thinking of using the 37mm.
Tony D.
Hello Tony, it is far too expensive for this type of work, it is good for finish work, but if it is not going to show pick it up at Metal Supermarkets.
http://www.metalsupermarkets.com
This is my A75 Chassis
An externally hosted image should be here but it was not working when we last tested it.
That's similar to the way i'm rebuilding my JLH now. I'm using 6mts of an Al extrusion that's been cut in 22 pieces which will be bolted to a Cu sheet to form the 4 "sides" of the box. The extrusion itself (http://www.sannellaaluminio.com.ar/planos/xvarios/1804.gif) was arround $4-$5 us dollars, and after drilling and doing some sanding and leveling i'll have it all black anodized.
All in all, the finished amp will be quite small (180x180x220 tall), but if it performs as expected it wont rise more than 30-40°C over ambient. It's quite a lot of tedious work, but if done well it will perform very good at a VERY modest price.
All in all, the finished amp will be quite small (180x180x220 tall), but if it performs as expected it wont rise more than 30-40°C over ambient. It's quite a lot of tedious work, but if done well it will perform very good at a VERY modest price.
Very nice design, Coulomb. Rather elegantly proportioned. Kind of looks like an Pass Labs Aleph on steroids! Or, "stacked Alephs"!
You must have a lathe, because it looks like the feet are turned down a bit to a soft point. My A-75 (which is built but does not yet work) is in the old conventional style with sinks on the sides and a big ole' rectangular plate on the front. I like to see things like yours that push the mechanical design envelope. Especially when the result, like yours, has a hint of understatement about it. The radius'd corners on the top and bottom plate are a nice touch.
Did you do a thermal calculation exercise for this or just say "we don't need no stinking calculations" and throw aluminum at it? I took the latter approach, but that's because I found humongous sinks on some surplus RF equipment for $20 US each (flat backs mated through polished surfaces to 5/8 inch thick aluminum plates.) and figured (looking at some other folks' examples) "this just has to be enough sink". Next time I want to go to the Aavid page on how to do the calc's and try that.
By the way. I found this Aavid thermal interface material in a stick. Its like wax, with better thermal transfer coeff. than that nightmarish grease. It is in DigiKey's catalog and is very easy to apply. Unlike the grease, it doesn't bleed, and cleans up easily.
You must have a lathe, because it looks like the feet are turned down a bit to a soft point. My A-75 (which is built but does not yet work) is in the old conventional style with sinks on the sides and a big ole' rectangular plate on the front. I like to see things like yours that push the mechanical design envelope. Especially when the result, like yours, has a hint of understatement about it. The radius'd corners on the top and bottom plate are a nice touch.
Did you do a thermal calculation exercise for this or just say "we don't need no stinking calculations" and throw aluminum at it? I took the latter approach, but that's because I found humongous sinks on some surplus RF equipment for $20 US each (flat backs mated through polished surfaces to 5/8 inch thick aluminum plates.) and figured (looking at some other folks' examples) "this just has to be enough sink". Next time I want to go to the Aavid page on how to do the calc's and try that.
By the way. I found this Aavid thermal interface material in a stick. Its like wax, with better thermal transfer coeff. than that nightmarish grease. It is in DigiKey's catalog and is very easy to apply. Unlike the grease, it doesn't bleed, and cleans up easily.
The link is here:
http://info.digikey.com/T022/V5/0398.pdf
and the part number is HS243-ND. Costs $17.50 per stick, but properly applied you can cover 1000 sq inches with that.
On the linked page, it is in the extreme upper left of page.
http://info.digikey.com/T022/V5/0398.pdf
and the part number is HS243-ND. Costs $17.50 per stick, but properly applied you can cover 1000 sq inches with that.
On the linked page, it is in the extreme upper left of page.
I have not run a Class A Amp on them yet, but my 300 Watt AB Amp runs quite coll on two of them. See Picture below.
Active surplus only has one more, I bought everything he had including his warehouse stock. I purchased the bare aluminum ones as the black ones are 20% smaller and are predrilled not blank.
There is definitely sufficient area in my design for a Class A 75 Watt Amp. I will post a follow up when it is running.
Anthony
An externally hosted image should be here but it was not working when we last tested it.
I have two kinds of boards. One is double sided, only front end and Fets mount on chassis as here http://www.diyaudio.com/forums/showthread.php?s=&threadid=3353 . I'm asking $100 CAD for those.
Then I have another set of boards with regulated power supplies included (copied from Mark Levinson 23.5) and layout based on original article. One sided, heatsinks on Fets and Holco resistors. You would need about 2x50V AC for PS. I would be asking a bit more for those boards. Those boards are tested and guaranteed to work OK.
Then I have another set of boards with regulated power supplies included (copied from Mark Levinson 23.5) and layout based on original article. One sided, heatsinks on Fets and Holco resistors. You would need about 2x50V AC for PS. I would be asking a bit more for those boards.
Those boards are tested and guaranteed to work OK.Attachments
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