Vintage tube amps - Cooling fans & keeping them cool

ssouci

Well-Known Member
I'm wondering what others are doing to keep their vintage stereo tube amplifiers running cool, eg. older tube units by The Fisher, HH Scott, Eico, McIntosh, Marantz, etc.

most were designed to run on historically-lower mains voltages so will run hotter now because of today's higher volatges, but some will inherently run hot due to the component layout (companion and radiant heating, poor air circulation, no heat shields, etc.) and because of how the power transformers, output tubes and other components are be driven

I've recently acquired 3 vintage amps (Eico HF-81, Fisher X-202, and Electrohome console pull), and all start to heat up progressively while playing, and after approx. 1-1/2 hours will be pretty darned hot... and after 2-3 hours, you really have to start wondering if they're running too hot to be safe and/or damaging tubes and components... (however, they do seem to sound better when really hot... or is that just me?)... note: my wall voltage is ~118VAC, so not even as high as some, which I've heard can reach up to 125VAC

to experiment, I rigged in a small computer fan on my Electrohome console pull amp, and it works surprisingly well... I can now play it for unlimited hours, and it reaches a "very warm" state, but then doesn't go beyond that

now I want to add something to cool my (more valuable) Eico and Fisher amps, but want to do it not just effectively, but also attractively... I want minimal mess and wiring, and it's got to look professional and "cool"... nothing hokey

Q: how have you done this... did you add cooling fan(s)?... if so, how and where?... how do you power it?... attached or standalone?

Q: just how detrimental is the high heat many people seem to experience with these tube amps?... some claim it doesn't really matter, others say it greatly shortens the life of tubes and components


please send your feedback, experiences -- and hopefully some PHOTOS of what you did

thanks!

PS: here are photos of the fan I added to my console pull... a bit of a science experiment yes, and not the most elegant installation, but works very well... fan cost $15 and runs dead silent (Silenx brand, 80mm, 12V)... powered by an old cell phone charger transformer that I epoxied underneath the chassis(!)... hooked into main power feed internally, so it always runs on whenever the amp is switched on... btw, this little SET 6BQ5 amp sounds excellent

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I do what you do, especially during the summer.
I rigged a temp controller @ $16 on amazon, to switch it on and off by temp settings, and stick a prob to the chassis near the power transformer.
I only blow a light air flow onto the power transformer. Never had issues and can listen to music 8 hours straight without having second thoughts. Piece of mind has no price :)
 
I am building a base for the amps to sit on. Computer fan that will blow up. The bottom cover will be off the amps. I do have a nice 1912 GE fan ,but that just blows on me. It has a nice hum my amps are lacking.
 
12vdc box fans run at 9v does the trik. quiet too.
I blo em on the PT as it costs most to replace.
tubes are supposed to get HOT.
I only use one as I only use amp at a time.
I move the fan to the amp in need.
Works for me.
 
My Latino VTA ST-120 power transformer could get hot enough after extended playing that I really couldn't touch it for more than a second or so. I decided to try a small 6-inch 12-volt box fan to cool it. I tried various voltages to run the fan which I placed behind the power transformer on a vibration absorbing pad. At 7-9 volts, the fan noise was still noticeable. However, at 5 volts, the fan is virtually inaudible, still provides a good air flow, and the power transformer stays very cool. It can't but help component longevity. An excellent $8 investment.
 
I'm starting to think about this myself now. I am having some custom casework done for a house remodel that will house a new audio system, including a tube power amp of my own making. For various reasons, I have no choice but to have a shelf above where the power amp will go, so want some sort of active cooling solution. I was also considering a 12V computer fan that I could power from, say, the filament transformer, attached with screws to the inside of the perforated cage, and drawing air up (which should pull room temperature air from out front of the chassis).
 
Yes, Those 12V fans are sure nice (one Eico HF-12's etc.) with lower voltage wall warts! Use fans also on my SS electronics like 4G wireless unit for phone/internet to make it last for longer so far than many according to the internet.
 
Fisher anticipated the use of fans in some of their receiver console configurations. Check out the Owners Manual for the 800-C, for example.
 
There are a couple of decent ways to cool things down.

The fans are an obvious choice. Just remember they work best when blowing directly on the component(s) with greatest cooling requirements, and when you control the magnitude and direction of the airflow. I've encountered a few beautiful consoles where owners had added fans in a manner that did little to help because airflow in the amp or receiver compartment was so restricted. The consoles had obviously been through catastrophic failures from overheating, probably before and after the addition of fans. Of course, that allowed me to pick them up at a much lower price.

If you have multiple tube components, adding a variac to control voltage for all your tube components can do wonders for cooling. Nothing like running old gear at the lower end of its original voltage range.
 
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