Just wondering if anyone out there has tried the heatsink USA's 10.080 inch extrusion heatsinks for a F-5 build. Seems M&M metals wants to double (almost) their price, so I'm looking for other sources. Jeez, I can order Conrad from down under and get them cheaper even with delivery!
Heatsink USA seems to be the only other manufacturer located domestically,
thus I was wondering about sufficiency of their sink for F-5.
Russellc
Heatsink USA seems to be the only other manufacturer located domestically,
thus I was wondering about sufficiency of their sink for F-5.
Russellc
Russell, Do a search.
There are good reports about those heat sinks and what size is adequate.
http://www.diyaudio.com/forums/pass-labs/182966-f5-low-z-loads-12.html
I measured 4 devices dissapating 125W
Even a 6" section shouldn't be any problem at all for 64W
I measured 4 devices dissapating 125W
Even a 6" section shouldn't be any problem at all for 64W
Heatsink Aluminum Extrusion 10.080" Wide x 12" Long - eBay (item 170612188395 end time Mar-13-11 06:11:48 PDT)
one each channel should be fine
but maybe this cheaper one will be adequate too http://cgi.ebay.com/Heatsink-Alumin...608?pt=LH_DefaultDomain_0&hash=item27b9453340
Yes, this ebay seller (Barrredboss) is the same guy as HeatsinkUSA. I saw that profile, but I assumed the other was better since it was the same width approximately, one 10.00 and the other 10.080. but the extrusion you show has 1 inch fins where the other has 2.5 inch fins. It probably doesnt make much difference,
I'll have to compare prices. The 2.5 inch fin version is very reasonable. Also, those are 12 inch lengths, I was looking at the 8 inch section for an amp approx. 8 inches tall. My reading is that the extra height doesnt help much, its more the depth. I can say the M&M metals sinks, 12 inches deep and 6.5 inches tall, stayed at a temp you could keep your hand on indefinitely, at least in a 1/8 inch aluminum chassis. (first F-5 build)
I'm in hopes a section this size on each side would be sufficient,
but it is just shy of Nelson's recommendation in the F-5 service manual/article.
May have to go conrad.
Russellc
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oh, but it does
I just got the impression you didnt have enough money
if you can afford the long fin model, thats the one
one for each channel ofcourse
http://www.diyaudio.com/forums/pass-labs/182966-f5-low-z-loads-12.html
I measured 4 devices dissapating 125W
Even a 6" section shouldn't be any problem at all for 64W
so a 6"+ section of it is sufficient per channel for a stock f5 ?
That's doubtful. It is probably 6" per device, so you would need 2 of these per channel.
Also, someone dismissed the difference between 1" and 2" fins: you want the 2". This does make a difference.
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that's not what i got from flg's post and there's been much bickering about the heatsinkusa sinks . would prefer real stats rather than speculation .
cheers , Woody
Call it speculation if you want, but why not read what Nelson Pass wrote in the F5 service/owner's manual. There is a wealth of information in there that many do not bother to read.
BTW, a number of folks have used the heatsinksUSA product, why not search and see what they had to say. That's honest-to-goodness empirical evidence and not speculation.
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i've not only read it but keep it on my taskbar , referring to it constantly.
you like others here have a closed mind . i want stats .
I've already pointed that out, 8" x 6" per fet, I think all those in this discussion has read the manual. The original inquiry is whether one of these PARTICULAR heat sinks are adequate.( for stock F-5) I seen members elude to them, mostly seemed to run hot. I have seen others who claim its cutting a little close. The Heatsink USA product is available, and I just wanted definitive results (if anyone has them on this piece used with F-5) for all to know.
Thanks for the input flg, much appreciated. I'd love to see the 2 mosfet results, but seems like a lot of trouble. It would answer the question! Thanks again.
Russellc
See post 10 & 11 as a direct comparison between the 1.5" / 2.5" fins:
http://www.diyaudio.com/forums/pass-labs/184508-finished-f5.html#post2493407
The simulations were for 2 FETs each 32W, 12" extrusions, black anodised.
You are right in saying that reducing the length from 12" to 8" may not make much difference.
But I cannot tell you exactly how much, at least not this week.
And even though I have been quite successful in predicting heat sink temperatures, you should always do a test to verify.
Hope this helps,
Patrick
Patrick
http://www.diyaudio.com/forums/pass-labs/184508-finished-f5.html#post2493407
The simulations were for 2 FETs each 32W, 12" extrusions, black anodised.
You are right in saying that reducing the length from 12" to 8" may not make much difference.
But I cannot tell you exactly how much, at least not this week.
And even though I have been quite successful in predicting heat sink temperatures, you should always do a test to verify.
Hope this helps,
Patrick
Patrick
Can the heatsinks for each device of one channel be separated - like on each side of the cabinet (for a F5 mono cabinet)?
Yes, but.
It's a very important "but".
If both devices have been balanced out while at the same temperature (Tj), then the voltage drops across the jFET collector loads have been set to precisely maintain that output stage balance.
With separated heatsinks for the Pch and Nch output devices, it is very probable that Tj does not match as it did at "the time of setting up".
This WILL change Id and your balance will go out the window.
A really good temperature compensator (that ntc as a portion of the jFET collector load) can adjust the Vgs sent to the Gate and try to keep Tj similar to the set up. But they are not perfect tempco. There will be changes.
I think you will find that output offset drifts quite badly if the tempco is inaccurate. A draught blowing on one side could be enough to send the output offset way too high. A lot of testing should be able to confirm if you can get the tempco close enough.
I would add a DC detect to trigger an alarm if you go this route. Oh, and mute the input, so that everyone can hear the "alarm" !
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