| beady |
My local Radio Shack is closing and getting rid of everything. I can get either of the two heatsinks with attached fans for $3.00 each. With the fans running I'd think it'd be plenty of cooling. But, I'd rather not use the fan if I don't have to. Would two of these heatsinks (one for each chip) be enough cooling for a LN3886 Dual Mono gainclone? Since they are only $3 each, I could get 4 for $12. No shipping or minimum quantity since it's local.
CPU heatsink and fan #1
CPU heatsink and fan #2
Thanks for any thoughts,
Mike |
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| mike.m216 |
I'd go for the first one.
You'll probably have to use the fan to get enough cooling. CPU heatsinks have the fins fairly close together.. better for use with a fan. |
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| jaycee |
Best would be to get 4 and bond them to a plate. Then attach the chips to the plate.
Alternatively if you have any old Slot 1 heatsinks, they often do quite nicely |
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| BrianDonegan |
| Most of the smaller CPU coolers (like the ones shown) have VERY noisy fans. You will definitely hear it (them) over the music, unless you turn it up. |
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| facundonu |
my gainclone is a lm1876, and is atached to a pentium II cpu heatsink (i guess that's "slot 1").
at first i was using the fan as well, and it kept the chip really cool. but noise was really noticeable. i had the obvious air turbulence noise, and also electric noise in my amp because of a bad PS design for the fan.
later i removed the fan and the heatsink turned out to be enough to keep the chip at a reasobable temperature, and of course, noises were gone.
mine looks like this one:
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| lgreen |
My LM3886 amp is using a CPU heat sink about the same size as the one above (the one facundonu is using), no fan. My opinion is that this is just large enough.
Based on my experience, you will need 2x or 3x the size you have. Or use the fan. I would not spend money on those radio shack heat sinks. Hmmm.... I've got some similar ones with and without fans, can send them to you if you like.
The option of using a metal plate and multiple small sinks will also work.
By the way, for standard computer heatsinks I usually try goldmine-elec.com, like this one. |
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| AndrewT |
Hi,
why can't we buy at Goldmine prices in the UK? |
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| Shoog |
The smaller the fan the noisier it will be. Wisper fans will help but cost about £10.00
Running your fan at 5-6v will reduce its noise by more than half and it should cope well. Just use a simple LM7805 to derive your supply.
Shoog |
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| Christer |
For those who are interested in using silent cooling for PCs in their amps (or why not in their PCs? :) ), this is the place to look for advice:
http://www.silentpcreview.com
One of the newer and popular technologies in CPU cooling is heatsinks using heatpipes. I had a discussion with a friend yesterday and he asked, mostly out of curiosity I guess, if it would be possible to use heatpipe technology for amplifiers. I said that it would most likely work, but since we usually have many output devices, it would probably be expensive and problematic. However, for chip amps, where we only have one chip per channel, it would be sufficient with two CPU coolers using heat pipes, so there it could be an option. There are good ones now that aren't that terribly expensive. I think the one I bought for my new PC was around 20 Euro, including fan. Considering that a modern CPU is rated at a much lower max. temp. than an amplifier chip, I would guess it would work well to skip the fan. These coolers usually tend to be a bit bulky, though, so you need a large case. Or, if you like exotic looking equipment, put them like two towers on top of the case. |
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| DJ Exprice |
Fans = :(
I think they're almost like cheating - and they're annoying.
Just use one of those heatsinks per chip. It depends how hard you'll be driving it. I've tried using skimpy heatsinks before and it has come out fine. A lil toasty but nothing to worry about. |
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| Shoog |
One possible option would be to include fans, but have a power switch to allow their use only when driving the amp hard. In normal use they could be switched off.
Shoog |
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| BrianDonegan |
| ...or use a thermal switch on the HS to turn the fan on and off. |
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| DJ Exprice |
Not a bad idea!
That also gave me an idea:
Auto fan for that:eek:
Use a pulse osc. w/ a transistor as a relay of the output and then as soon as you start driving it a lot, the fan will turn on for about a minute, then shut off exactly 1 min. later after it stops driving really hard. :cool: |
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| Christer |
| Temperature controlled fans are alredy plentiful in the PC world, so if you are anyway considering a CPU heatsink, buy one with a temp. controlled fan. |
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| Shoog |
| quote: | | Temperature controlled fans are alredy plentiful in the PC world, so if you are anyway considering a CPU heatsink, buy one with a temp. controlled fan. |
Aren't they CPU controlled?
Shoog |
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| Christer |
| quote: | Originally posted by Shoog
Aren't they CPU controlled?
Shoog |
Not all of them. There are many that have their own sensors nowadays, and some people seem to prefer that to CPU control.
I think there are also separate temp. control kits for fans you can buy. |
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| DJ Exprice |
Auto temp. controller ones w/o a big cpu thing going on is a good idea! :)
Either that or no fans would be my idea.
If you do that auto temp fan, make sure to add a manual termination and initiation switch! Control is sacred! |
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| SpittinLLama |
At one time (years ago) National played around with putting a temp. sensor in the LM3886 package, or so my friend told me. He worked for National in the 90s. The idea was to control a fan. The temp sensor had two trip points so you could have off, low, high. I think there just wasn't much demand for such a thing since most people avoid fans because of all the noise they introduce. A couple of the amps I built use fans running at low speed but they still caused me some headaches, even with completely separate supplies. I had to also use sheilded wires to keep any noise from getting in on the inputs. Hate fans but these amps were in very small cases so too hot without some fans.
-SL |
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| beady |
Alright, I'm convined, I won't go with those heatsinks :-)
Thanks,
Mike |
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