Mini Aleph heat sink, more than F-5?

[Russellc]

hello, I've decided to build another F-5 and use the much debated HeatsinkUSA 10.08 inch extrusion, several here thought it was enough, albeit borderline. Euvl states in one of his posts on the topic that it should be good if Kerafols are used. I have obtained a supply of those pads, and thought I'd do a build. I feel they will be fine, no doubt a little warmer than my F-5 using M&M metals larger extrusion.

Now my question is, If the sink does prove to be a little short, would it still be sufficient for a Mini Aleph build? I have the boards and parts to do one of those as well. I thought if marginal, I could use them for a Mini Aleph. Then it occurred to me that I dont know what a Mini Aleph needs to dissipate.

A search found a post from Vdi-nenna who said he used 150 x 430x 50, which should be roughly 6 inches x 17 x 2, somewhat larger than the 10.08 by 8 inches by 2.3 inches of the heatsinkusa. From this it looks as though Mini Aleph may make as much or more heat then F-5?

Thanks for any input,

Russellc

[Bill Fuss]

The Mini-A isn't a well defined amplifier, it depends on your rail voltage and bias choices. Go back and look at the original thread

I agree with Euvl, they should be big enough for an F5 if properly finished.

Best, Bill

[jupiterjune]

I have case that was built with 6" wide and 10" long heat sinks running front to back, with the fins sticking out horizontally, "the wrong way". It dissipates enough heat for my F5. I had mini aleph boards in the same chassis prior to making the F5 boards, and it was enough heat sink for that as well.

I got he sinks from Russ Boss -- I think he is heatsinks USA now.

JJ

[jleaman]

Originally Posted by Bill Fuss

The Mini-A isn't a well defined amplifier, it depends on your rail voltage and bias choices. Go back and look at the original thread

I agree with Euvl, they should be big enough for an F5 if properly finished.

Best, Bill

Mini a is a awesome amplifier.

[cjkpkg]

I had a mini a in a 2U case from hifi2000 and the sinks just got warm to not quite hot.

I had also changed the source resistors to 0.39 from 0.47.

These sinks were rated at 0.45C/W

[Woody1911a1]

Originally Posted by Russellc

hello, I've decided to build another F-5 and use the much debated HeatsinkUSA 10.08 inch extrusion, several here thought it was enough, albeit borderline.

i believe the only people that said it would be borderline were people that hadn't even used them , but were just speculating .

i'm using 7" high slices and biasing higher than normal at over 1.4 a and they never get hotter than 40 c . i believe it was flg that was playing with some and he said that a 5" high pair should be enough for a stock f5 .

cheers Woody

[Russellc]

Originally Posted by Woody1911a1

i believe the only people that said it would be borderline were people that hadn't even used them , but were just speculating .

i'm using 7" high slices and biasing higher than normal at over 1.4 a and they never get hotter than 40 c . i believe it was flg that was playing with some and he said that a 5" high pair should be enough for a stock f5 .

cheers Woody

I suspected as much, especially with these 8 inch pieces and kerafols. I've had more than one member tell me they worked fine. I also intend to use them for a Mini aleph build as well.


Russellc

[Bill Fuss]

If you mean the 10 x 2 7/8 extrusion, I have 60 watts into a six inch long piece and it doesn't get more than a satisfying warm. I put a couple light coats of flat black on the fins and it made a real difference.

[WithTarragon]

Originally Posted by Bill Fuss

If you mean the 10 x 2 7/8 extrusion, I have 60 watts into a six inch long piece and it doesn't get more than a satisfying warm. I put a couple light coats of flat black on the fins and it made a real difference.

Well, there is a always a possibility the aluminum is not getting hot because the heat is not getting transferred from the output device to the heat sink.

On a more serious note, does the paint stick to the aluminum pretty well. Does it scratch easily or did you have to use some exotic primer?

[Bill Fuss]

The paint sticks pretty good if you clean the sinks well, but it's not very durable. Easy to touch up though.

Good point about the heat transfer. That's the one area in these builds where it pays to be a little anal, especially if you're pushing it. I generally work the area down flat with a fine mill file before I do any polishing.