Is this a proper heatsink for AV800

radu8982 · 8th January 2011, 08:26 AM

I want to use this heatsink to built the AV800 and i want to know if it is big enough

AndrewT · 8th January 2011, 09:13 AM

Hi,
what do the internal fins look like?
Is the fan working efficiently at pushing cold air through the sink tunnel?

radu8982 · 8th January 2011, 09:55 AM

The efficiency of the fan is 50%,and here is a picture of the fins

AndriyOL · 8th January 2011, 10:36 AM

I guess this is not a heatsink. It's more likely looks as a piece of granit rock to be used as heatsink!
Btw, good idea, considering high prices for precious metals, granit electrical non conductivity there is no need to use any kind of washer only thermal compound!
One thing left to calculate a formula of its thermal conductivity to obtain a C\W ratings.

AndrewT · 8th January 2011, 10:49 AM

Quote:

Originally Posted by radu8982

The efficiency of the fan is 50%,and here is a picture of the fins

are the fan blades clean? Are the sink fins clean?
Are the inlet and outlet ports clean?
Is the oil in the fan bearing clean and to specification?

Are you still sure about your cooling efficiency?

SpeakerScott · 8th January 2011, 10:57 AM

Find out what the thermal resistance of it is, both the Cordell and Slone book tell you how. Here's a quick answer:

Get known value power resistors, and clamp it well to the heatsink

Dissipate a known power in the resistor for a long period of time. For your heatsink, you'd want to use multiple resistors on both sides to distribute the power like you will when you bolt a lot of output transistors to it.

Measure the temperature rise of the heatsink over the course of a few hours. Calculate C/W rise using the measurements of rise and power.

Determine how much output power you think you'll dissipate in the AV800 stage.

Figure out if you can live with the temp rise you'll have.

radu8982 · 8th January 2011, 12:02 PM

I do not think I know how to calculate C/W and the other stuff and I dont have how to calculate them picose i didn built the amp ,i will built it but first i need to make some money,I have the transformer suply capacitors pcb.

radu8982 · 8th January 2011, 12:39 PM

For andrewT everyting is clean , i aproximated the eficency by comparing the power of the air flow when the fan is in the air and mounted

Lee Knatta · 8th January 2011, 03:19 PM

I looked at specs from heat sinks that look similar and would guess this one could have something like 0.3 to 0.2 K/W which should be sufficient for an AV800 amplifier.
I'd give it a try.
Just my opinion.

8th January 2011, 09:13 AM	#2
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Hi, what do the internal fins look like? Is the fan working efficiently at pushing cold air through the sink tunnel? __________________ regards Andrew T.

8th January 2011, 10:36 AM	#4
AndriyOL diyAudio Member Join Date: Jul 2008 Location: Lviv	I guess this is not a heatsink. It's more likely looks as a piece of granit rock to be used as heatsink! Btw, good idea, considering high prices for precious metals, granit electrical non conductivity there is no need to use any kind of washer only thermal compound! One thing left to calculate a formula of its thermal conductivity to obtain a C\W ratings. __________________ If for pristine and pure adoration - it's diyAudio dedication!

8th January 2011, 10:57 AM	#6
SpeakerScott diyAudio Member Join Date: Jul 2008	Find out what the thermal resistance of it is, both the Cordell and Slone book tell you how. Here's a quick answer: Get known value power resistors, and clamp it well to the heatsink Dissipate a known power in the resistor for a long period of time. For your heatsink, you'd want to use multiple resistors on both sides to distribute the power like you will when you bolt a lot of output transistors to it. Measure the temperature rise of the heatsink over the course of a few hours. Calculate C/W rise using the measurements of rise and power. Determine how much output power you think you'll dissipate in the AV800 stage. Figure out if you can live with the temp rise you'll have. __________________ www.stuffscottbuilt.com

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8th January 2011, 12:02 PM	#7
radu8982 diyAudio Member Join Date: Nov 2009	I do not think I know how to calculate C/W and the other stuff and I dont have how to calculate them picose i didn built the amp ,i will built it but first i need to make some money,I have the transformer suply capacitors pcb.

8th January 2011, 12:39 PM	#8
radu8982 diyAudio Member Join Date: Nov 2009	For andrewT everyting is clean , i aproximated the eficency by comparing the power of the air flow when the fan is in the air and mounted

8th January 2011, 03:19 PM	#9
Lee Knatta diyAudio Member Join Date: Apr 2010 Location: Germany	I looked at specs from heat sinks that look similar and would guess this one could have something like 0.3 to 0.2 K/W which should be sufficient for an AV800 amplifier. I'd give it a try. Just my opinion.

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