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Old 9th March 2010, 04:29 PM   #7291
cviller is offline cviller  Denmark
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Hi Ron, I find that with the type of heatsink you have, this is very dependent on how you place the amp. If your wife forces you to put the amp inside a shelf, then it will be much warmer.

One word of caution though - make sure that your mosfets have a good thermal contact with the heatsinks, because they can only handle the heat on their own for a very limited time...
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Old 9th March 2010, 04:48 PM   #7292
sekess is offline sekess  United States
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Default Heatsink Temps

Hey Ron,
Number one - like Christian said - make sure you have good thermal contact between outputs and the sink.

However -- I'm not done building mine yet. But, I do have an Aleph J that I built and I notice a difference in the heatsink temeratures with respect to the ambient temp. The heatsinks always get warm. But, they are noticeably hotter when the ambient temp is hotter.
So, I don't know where you have your amp. But if the surrounding temp if it's kind of low, then maybe that would explain the barely warm sinks.

Steve
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Old 9th March 2010, 04:48 PM   #7293
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Quote:
haven't scanned them with the laser temp gun, but when I put my hand on them after hours of playing they are barely warm. Is this nOrmaL?
It will get hot eventually. It runs real cool, until BLAMO! It starts cooking. It shouldn't get so hot that you can't keep you hand on it. Ambient temp has a lot to do with it. I found mine gets real hot during the summer.

Run some bass heavy material thru it and see if it heats up more.
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Old 9th March 2010, 05:04 PM   #7294
tinitus is offline tinitus  Europe
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Strange
I would expect it to get hot, no matter what
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Old 9th March 2010, 05:25 PM   #7295
Renron is offline Renron  United States
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Thanks guys,
My ambient room temp is 66*F. The amp is on the floor with 2 feet of free air space above it. (the wifee is good about component placement, speakers ect.)
I am using silicone pads for insulators. Should I use a compound like Artic Silver between the heatsinks // insulators // Mosfets ? I suppose it couldn't hurt. I am using a large washer to displace the clamping force from the bolt.

Thanks,
Ron
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Old 9th March 2010, 05:47 PM   #7296
GoranB is offline GoranB  Poland
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Hi
Does someone here build the Power Follower 99? (by Andrea C.) Is it sound much different from ZEN amplifiers?
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Old 9th March 2010, 06:36 PM   #7297
tinitus is offline tinitus  Europe
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Quote:
Originally Posted by Renron View Post

I am using silicone pads for insulators. Should I use a compound like Artic Silver between the heatsinks
Not needed

Please dont touch it
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Old 10th March 2010, 08:36 AM   #7298
AndrewT is online now AndrewT  Scotland
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Quote:
Originally Posted by Renron View Post
Do anyone else's heatsinks just barely get warm?
I haven't scanned them with the laser temp gun, but when I put my hand on them after hours of playing they are barely warm.
Can you feel or measure the temp difference between the output FETs and the heatsink?
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Old 10th March 2010, 10:17 AM   #7299
osscar is offline osscar  Latvia
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Hi Andrew!
I also want to know about the temperature differences:

In my F5 Between heatsink and FET body is a 10-degree difference approx.(heatsink about 40-50; body about 60 - 65-i measured with IR thermometer some time ago) I use the silicone insulation pad which not the best. It is thought to replace the Mica or kapton but I can not pull oneself again for rebuilding
Do I have to worry about it ?

thank you,

regards
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Old 10th March 2010, 10:38 AM   #7300
AndrewT is online now AndrewT  Scotland
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Hi,
the FETs are dissipating about 30W each (1.3A * 24V).
A temp difference of 10 to 15Cdegrees is about normal.
Ts-Tc=15Cdegrees indicates an insulator resistance, Rth c-s = 0.5C/W
Ts-Tc=10Cdegrees indicates an insulator resistance, Rth c-s = 0.33C/W
I doubt the best insulator can better Rth c-s = 0.2C/W
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