Heat sink for Aleph 5 / Aleph 4 - Page 2 - diyAudio
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Old 8th December 2006, 05:51 AM   #11
steenoe is offline steenoe  Denmark
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Vidi, I have a Zapsolute in one of those chassis. They are indeed too expensive if bought alone. My guess is that you can use one for an Aleph 5. If you go for an Aleph 4 you would have to build monoblocks and use both. The heatsinks of the LC chassis are really top quality.

Steen
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Old 8th December 2006, 07:59 AM   #12
Buhl is offline Buhl  Denmark
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Steen: Im very interested - I always wanted to build one of those...how does that class a ZAP sound compared to our sweet Zens, Alephs ect. ? Did I miss anything ?

Vidi: S**t !!! - I have booked 5 days in lillehammer/hafjell i uke 5....damn, I dont want to be sitting in the "hytte", reading old pass labs service manual those days....
The LC cabinet is 530 euros, I calculate it to roughly 4000,- Dks. - but that is still a sum of money....


Cheers!
Buhl
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Old 8th December 2006, 09:14 AM   #13
steenoe is offline steenoe  Denmark
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Quote:
how does that class a ZAP sound compared to our sweet Zens, Alephs ect. ?
Hej Hans. The Zap sounds great, those big Sanken transistors are not bad at all. The amp is also well build. I bought it just before starting building amps myself. I wouldnt buy it today, but i am not much for selling it either
It doesnt quite have the sweet soundsignature as Mr. Pass's amps do. It is very powerfull though, its the strongest 50 watter i have heard. Overall a very nice amp. Also the powerdown function is pretty handy, no need to burn a couple hundred watts when doing the dishes I am using an Aleph 5 in the main system right now and that is going nowhere. The Zen's doesnt really cut it regarding the power needed for the ProAc clones, but the Aleph 5 handles them very well. Maybe I will sell the Zap after all. Here is the Aleph 5:http://www.diyaudio.com/forums/showt...84#post1068284

Steen
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Old 8th December 2006, 10:42 AM   #14
Vidi is offline Vidi  Norway
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Steenoe: Do you mean that I have to use two of the cabinets (one for each Aleph 4 monoblock)? According to WuffWaff, (and Aleph 4 user manual), I will need to get rid of about 400w of heat. Using the mentioned cabinet, with an Rth= 0,0825, will give me a temperature of 33 degrees above room temperature (to a total of about 58 degrees). Isn't this enough cooling? I have not considered the insulators and junction Rth, is this the reason to choose two cabinets?

The reason that I prefer to use a pre-built cabinet, is that I do not have any experience doing metal work, so buying a pre-fabricated cabinet would enshure me a good result. (But, this is not in the spirit of a good DIYer.. )
Time will tell! I will ask the students of mechanical engeneering if they can help me out with the metal work!

Buhl: It may not be to late to get som snow in Lillehammer! Lets hope for the best!
I asume you know about the webcam on hafjell, but I post the link here!
Hafjell Webcam
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Old 8th December 2006, 11:00 AM   #15
steenoe is offline steenoe  Denmark
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Looking at the chassis, I wouldnt think that it can dissipate the heat from a 100 watt stereo Aleph These amps do get very varm. An Aleph 5 would be (just) doable. I bet that will get warm too. I didnt calculate anything, but having build several of these amps, i cant recommend using only one chassis for the Aleph 4.
But you can ofcourse try it out and see how it goes.

Steen
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Old 8th December 2006, 11:12 AM   #16
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Hi,

somehow heatsinks always get hotter than calculated with the specified Rth. This has something to do with the temperature at wich Rth is measured (mostly higher than 55)

I also think that the chassis would be ok for an Aleph5, maybe you can even up the bias a bit wich would be good for your 4 ohm loudspeakers.

If you manage to set the bias to 2.6A as in the Aleph4 you will have just as much power into 4 ohms and dissipate a lot less heat.

William
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Old 8th December 2006, 11:37 AM   #17
AndrewT is offline AndrewT  Scotland
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Hi,
there is a good heatsink paper in the Wakefield site.

The height of a heatsink changes the Rth s-a by about the square root of the height proportional change.
If you want to double the dissipation then you need to quadruple the height. If you have double the height you will get about 140% dissipation.

The Rth s-a is usually quoted at a particular delta T (difference between ambient and sink backplate temperature). Delta T is usually quite high, 50Cdeg to 70Cdeg. Much higher than we normally use. The Rth s-a can be corrected for a different Delta T.

The sink is tested with the whole back plate at the test temperature. An installation can only approach this theoretical dissipation IF the devices are spread around the backplate to try and achieve a nearly constant back plate temperature. A general rule I have found is that the radius from the device to the extreme corner of the backplate should be less than ten times the thickness of the backplate. A very wide or very tall heatsink will not meet this requirement. This is due to the far parts of the sink running cooler (sometimes much cooler) than the hot part under the device.

Orientation of the fins affects dissipation ability.
Colour affects dissipation.
restriction of air flow affects dissipation.
Hope this helps.

BTW. most heatsinks meet the manufacturers specification IF the corrections to Rth s-a are applied. Read Wakefield.
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Old 8th December 2006, 11:40 AM   #18
Vidi is offline Vidi  Norway
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Hi Steen!

No, I don't take the chance to build and try (would be very expensive! ). That's the beuty with diyaudio!
Here I can get first hand tips and information from the state of the art DIY builder!
So, if you say that it probably will get hot, I will take your word on that!
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