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Old 9th May 2010, 02:42 PM   #7851
Marra is offline Marra  United Kingdom
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As a matter of interest were did UK builders get their heatsinks from?
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Old 9th May 2010, 04:33 PM   #7852
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Ah! the numerous will this heatsink work with my F5 questions........
It's my intention to build an enclosure that will start out with two of the heatsinks listed below and two F5 channels. From what I've read this heatsink should be quite capable of handling one F5 channel. So my question is. Will one of these heatsinks handle two F5 channels?

The enclosure I'm building will have enough room and power supply for four channels so the above question is key to my future plans.

Opinions anyone?

Regards,
Dan

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Old 9th May 2010, 06:28 PM   #7853
tinitus is offline tinitus  Europe
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Quote:
Originally Posted by dantwomey View Post

So my question is. Will one of these heatsinks handle two F5 channels?
Ehhh, no, I wouldnt count on that barely enough for one channel, but the 70mm long finning helps a lot
Personally I would use two each channel/mono blocks
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Old 9th May 2010, 06:42 PM   #7854
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Quote:
Originally Posted by tinitus View Post
Ehhh, no, I wouldnt count on that barely enough for one channel, but the 70mm long finning helps a lot
Personally I would use two each channel/mono blocks
Yes. After searching through 'millions' of heatsink posts I found post #6969 where it said,
Quote:
For F5 (standard build) the per channel consumption is about 80 watts and temp rise approx 25*C so heatsink thermal rate design is 25/80 *C/watt (= 0.31 *C/w) - plenty of examples of different proportions, widths, lengths, etc. Unfortunately, 2 seperate heatsinks will quite often track at different temps if not tied together via a solid plate for good thermal conduction and alter the behaviour of those carefully matched Fets.
So perhaps add one more inch to this heatsink to meet the recommended .31 *C/w.

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Dan
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Old 9th May 2010, 10:12 PM   #7855
tinitus is offline tinitus  Europe
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Hmm, its not ideal to use such "build up" method with this kind of cooling needed
Keep in mind that this is not a pepped up AB amp, but a real hot running design

With this kind of classA you need the most efficient cooling you can get
Too many "connections" means loss of expencive efficiency

You want to build a 4 channel amp, to save on cost, supply etc ?
I dont like the idea
You will need a HUGE supply to power that amp
Maybe its better to split them up in stereo amps
May even be less expencive, easier to build, and less messy inside

But why 4 channels ?
Also remember that 4 channels gets pretty hot in summertime
It could get unbareable to be in the room
And it could get really expencive with the power

This sounds like your first amp
Better keep it simple
Build a stereo amp, and see how it works
Who knows, maybe you will find another amp attracting next year..... M2 maybe, or BA-1 or 2



Below text is quoted directly from F5 Manual / FirstWatt (read the full manual, 10 times)

-------------------------------------

At 1.3 amps per channel, you will see idle heat dissipation of 62 watts. To keep the
temperature rise of the heat sink to 20 deg C. above the ambient temperature, you will want
a heat sink rated at about .6 deg C./watt for each transistor. An example of this would be a
chunk of finned aluminum, with a series of 2” fins attached to an 8” by 6” base. You will
need two per channel.
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Old 10th May 2010, 06:17 PM   #7856
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solid plate between is fine so long as both surfaces are FLAT and TRUE, and there is adequate "clamping" (screws) between the two surfaces. Keep in mind that screws deform the surfaces!

random aluminum heatsinks and random aluminum plates are not likely to make a good thermal connection. You'll need to make 'em flat... the more the total surface area between the two the less critical that becomes, but it is still not a factor to ignore.

Do not confuse the thermal mass of the backing place (the time it takes to get warm) with the transfer to the finned heatsink extrusion. They're different things.

But, I agree, if it's yr first build keep it simple to start, and make sure it works before getting exotic.

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Old 11th May 2010, 02:56 AM   #7857
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Dale RN50(1/10W) can work fine in the F5? seem like i can't even find out the quater watts RN50. It's for PD PCB.
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Old 11th May 2010, 11:03 AM   #7858
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Sure,
I think the 10R resistors might want to go to 1-2W.
I use them in PD boards just fine.
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Old 11th May 2010, 12:31 PM   #7859
cjkpkg is offline cjkpkg  United States
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I used THESE as PD mentions in one of his posts for all the small resistors. THESE are what I used for my source resistors.
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Old 11th May 2010, 12:35 PM   #7860
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Quote:
Originally Posted by Marra View Post
As a matter of interest were did UK builders get their heatsinks from?
this is a couple of years out of date but I think the references are still valid:

Vitalstates- Amplifiers


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