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North America Heat Sink Group Purchase

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Hi Everyone,

I have found a heat sink distributor for Seifert extrusion number KL-271:

An externally hosted image should be here but it was not working when we last tested it.

With the fins oriented vertically, this heatsink measures 12" wide, 8" long, 3.25" thick, and has a 1/2" thick back plate. A singe 8" (200mm) length of this heat sink with black anodize and natural convection is rated for 0.18c/w :bigeyes: or approximately 140-150 :hot: watts dissipation with a 25c temperature rise.

One of these would comfortably run a stereo Mini-Aleph. Two of these sinks would provide 0.09c/w of cooling that can dissipate approximately 280-300 watts and should be sufficient for a 100wpc Aleph-X monoblock or even an Aleph 2 monoblock.

The distributor has a minimum order of 10 pieces, which is more than most people might want, so I have inquired about the possiblity of a group purchase and different quantities and price points.

To give you an idea of cost, the unit price for 10 of these heatsinks is approx $60 each (not including shipping).

I will be able to provide more details shortly...

Any interest?? I will post more details shortly, and if there is sufficient interest, I'll set up a wiki...

I'd be interested in four pieces, if the price can be brought down with higher quantities.

I had purchased 12 pieces of extruded heatsinks from M&M Metals for about $300 shipped. The heatsinks were 8" in length, 6.695" tall with alternating 2.2" and 1.2" fins, with a base thickness of 0.2". Obviously the one you're suggesting is much larger, but I could buy four of the other heatsinks for the price of two of the larger ones. In case you want to look up the extrusion I used, it's MM11645 located here:


You'll need to scroll down just a little bit to find it. The thermal resistance they list (0.8C/W) is for a 3" length.
Retired diyAudio Moderator
Joined 2002
Here is an amp that uses the 200mm version:

Ignoring the piles of large heatsinks in my basement, I would be interested if the price dropped. I am sure that if you checked different vendors, you could a similar extrusion for cheaper.

I also like the MM heatsinks that Rob (maxhawk) used, and they have been used in by others for Aleph 2 amps:

Rob's chassis:

Chassis I helped another friend make:

MMM might also have more beefy extrusions if you give them a call.

Retired diyAudio Moderator
Joined 2002
kestrel200 said:
IS it difficult to cut these into smaller lenghts, ie. reduce the 8" length to 3.5 to 4"? Can a table saw do this?

I cut some 5" x 2" heatsinks on my tablesaw once without issues. It helps to have a sliding table and a non-ferrous blade. That is my current setup. If you are just cutting them in half lengthwise, the original finished side can stay on top, without much loss in appearance if you don't look at the bottom of the amp.

Retired diyAudio Moderator
Joined 2002
Here are some of the chassis that I have made for Class A amps, but never finished...

The smaller one in the front is made from cutting one of the bigger black ones in 1/2. I bought these with Rob and his chassis is made with 5 heatsinks.

(aluminum not finished yet.. needs some work to get the scratches out. I built 2 of the large ones with surplus heatsinks, originally for Aleph 2 monoblocks)



  • chassis.jpg
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gengis said:

Try a vertical metal band saw with some hard plastic (polyurethane, or..) on each side before the clamp to protect the finish. The band saw will have thinner kerf and should not bend the fins if cut from the base side.

Unfortunatley I don't have a band saw:xeye: So I'll have to figure out the best way to do it with my table saw.
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