Heat Solution Challenge

revrun

Senior Member
Everyone who gets into vintage audio sooner or later discovers that heat is perhaps the biggest threat to their equipment. Cooling vintage gear efficiently can be a tough proposition in terms of cost and convenience. There simply aren't any really small, efficient cooling fans that can be placed where they can do the most good.
Well, there are a lot of computers that have small cooling fans built into them to cool the cpu. Now, if you were able to design a circuit that would step down 120vac to 12vac these little fans could be placed in a very attractive, thin wood case and put on top of a receiver or amp to provide some much needed circulation.
And by using the switched plug in on the back of the unit, the little fan would only be in use when the gear was turned on.
So, knowing that there are some very talented electronics techs on this board, I'd like to ask if this can be designed?. You design it, I'll build it and make it available at cost to anyone who needs it and if there is any profit, it gets donated to AK.
Any takers?.
 
I assume you mean 12 VDC for comp fans. This should work, and it reduces the voltage to about 9 VDC which means the fan will be more quiet. All the parts are available at radio shack. At least I think it should work, its late and I'm tired so someone should double check for me.
 
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Interesting. But most 'puter fans are indeed 12VDC, as David points out.

Another point is that, unless you are running Class A gear, or a poorly designed amp, cooling really shouldn't be an issue. Admittedly, most of our SS gear is Class AB, which has a worst-case power dissapation at 1/3 rated power. So for a 100WPC amp, maximum power is dissapated at 33 watts. More or less power than that and the amp runs cooler.

Now, consider that 33 watts ought to be a fairly high listening level for most speakers, excepting many of the exotic units. Most people do not listen at these sustained levels for extended periods. Additionally, consider the dynamic nature of music itself. Unless you are playing a test tone, the music level is rising and falling, allowing the transistors to cool.

I see your point, but there is really nothing to gain for the vast majority of gear. Those who really push their gear for extended periods and actually bump-up against their thermal limits from time to time might consider a 80mm or 120mm 120V fan sitting on top of the unit to pull air through it (could even get fancy and have it thermally triggered). Several are made that are nearly silent in operation, and much much more reliable than the typical computer fan (one of the most failure-prone components in a computer...)
 
Thanks Dave and Echowars!. I see your point about the real need for a unit such as the one I proposed, it's a maybe yes, maybe no proposition. I was right , however, in stating that there are some very talented individuals in this group. I think I'll try building one anyway, just 'cuz, and let you know how it turns out.
Not having done this before, it should be fun (till I plug it in:)).
I've already located some upscale fans with great laser cut covers, and presume the whole thing could be done for less than
$30.00. We'll see...
 
David,

I believe you should have be feeding the input side of that bridge rectifier from the top and bottom output from that 12v transformer and leave the center tap uncommected. Then again, it is 3:30AM and my eyes may not be awake yet...

Ken
 
Originally posted by Silver Fan
David,

I believe you should have be feeding the input side of that bridge rectifier from the top and bottom output from that 12v transformer and leave the center tap uncommected. Then again, it is 3:30AM and my eyes may not be awake yet...

Ken

I think I would tie it to ground not the center tap, then add a couple 470uF caps to smooth out the dc a bit.

Then again, it's 5:10AM and haven't finished my first cuppa yet.

X
 
Might be best to edit or delet that schematic as all it will ever do is blow the fuse as the secondary winding ends are wired together, a direct short.

As to the need for a fan, each installation and environment is different. I have found that most vintage gear to be pretty rugged and I have never seen a problem with my installation regarding heat build up. One exception would be the Yamaha CA-2010 amp when ran in the Class A mode. That baby cooks, even though it never seemed to complain. I decided that as long as I could not detect a difference in sound, that I would keep it in class AB mode.

I like to listen at low volumn on many of my music selections and never liked to hear fan noise. Even the little fan in my lap top bothers me if I have music on.

But the point of heat being the enemy of electronics is well taken. Mostly it's not so much how hot it gets, but rather the need for some kind of air flow so that heat can excape. As long as you allow a path for the raising heat to leave you should be ok.

Lefty
 
hmm is that better? Thats what happens when I do stuff late at night. I used a 12.6 VCT transformer cause they're available at radioshack for $10 each.

I run my fans off an old computer power supply. I only use them when I know I'm going to crank the volume. One time I had 4 fans placed on top of my Onkyo TX-8211 during a party. It was on for 4-5 hours, the last 2 hours the volume was at the 1 o'clock position, driving a four ohm load. After the cops came and we turned it down I felt the top of the case. It was barely warm, about as hot as it gets when it idles for an hour. Using fans with vintage tube amps is a good idea, not all of them have a lot of ventilation.
 
I'm inclined to think that when it comes to vintage hi fi receivers & amps and the exceptionally high quality with which they were built, that the heatsinking system on most of them is more than sufficient.

I think some common sense should be used in this matter and in doing so, there shouldnt be any problems with a vintage amp/rcvr ever overheating. Common sense meaning: if you listen to music at average volume levels thru average speakers, then a 45 W Pioneer SX-780 (as an example off the top of my head) should be just fine through 4 ohm speakers. But if youre someone like our 'beloved' member, THOR, and the music is gonna be BLASTING SUPER LOUD- ya know- everything on full max, take it to eleven kindve deal, then obviously you'd probably need a more powerful amp for the task. And its usually the case, that the larger amps will naturally have provisons for the heat- dissipation either internally or via the fins in the back- such as the 9090DB.

And if its for real heavy duty use- the manufacturer will know beforehand that the unit needs a fan built in (in addition to the already massive heat sinking it has) such as the BA-5000:
 
I think if heat is a concern, then the first thing to do is check the bias current in your unit and see what it measures in comparsion to the reading listed in the service manual.

Nonetheless, if you want to use a fan anyway, then I dont see any objections to that. Perhaps its a good idea, particularly in the Summer and you have all of your hi fi gear in a room that gets hot & humid. In which case even getting an external fan from R Shack and putting it in the vicinity of the unit will cool it down noticeably.

W/o a doubt, with everyone running their air conditioners in the area, its a sure thing that the outlet voltage will get low in the summer - as Ive seen often on a Furman Pl Plus I have which has an outlet voltage led display. In the summer, it would often go below 110V.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=2534516808&category=23792
 
My marantz and sansui equipment seems to have good heatsinks. The marantz 1060 has them on the inside which causes the case to heatup quite a bit when it is running (not at idle). The sansui has them on the inside as well as a row of them on the outside. The ones on the outside have never gotten much above room temperature. It is a 4000 Receiver.
 
All my amps get warm, but I do like to take it to 11, the one Luxman amp I have that the liquid leaked out of the heat sink/pipe thingy has two 4" fans on it, a noisy powerful one for music and a quiet less powerful one for HT and each is plugged in so that the needed fan comes on according to task. Someday I would like to put "quiet" fans on all my amps. They probably can take the heat fine but I would feel better if they all stayed cool. The Luxman with the fans on it never even gets warm and stays cool to the touch.
 
My equipment cabinet has glass doors and a covered back, and since my better half closes the doors I figured some kind of fan was indicated. I had a couple of small 110 voly fans, but they sound like a 737 on take-off. Lots of 12 volt fans, so I tested for the quietest one and picked up a 12 volt wall wart from RatShack. Plugged this into the switched outlet of the receiver and made up a disconnect between it and the fan so I could pull the back panel and problem solved.

Rob
 
I used to work at a computer store, and I hung out in the tech shop whenever possible, so as to avoid customers. they were always finding websites by people who had overclocked shit processors to insane speeds (taking a 400mhz celeron to nearly a gigahertz, for example). those people came up with some seriously insane hardcore cooling methods, such as cooling the thing in a tank of liquid nitrogen.

try that :D
 
why not just use one of them wall adapters and get one that puts out 12 volts. and hook up a couple fans in a nice little box. there ya go.
 
For what it is worth ESP has a circuit for a temperature operated cooling fan, only runs if things get too warm.

Rob
 
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