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Fan on Amp Unbeatable

So, I have an older amp from the 70s. It's a solid state amp and the fan is so loud it's distracting. It's my first largest solid-state amp. I've been using tube amps for the last 15 plus years. I can't imagine fans are supposed to be overwhelming Lee loud. Has anybody else ran into this kind of issue and if so, how did you fix it?
pawlowski6132
sleepwalker65's avatar
sleepwalker65
832 posts
 
If the junction temperature exceeds 90 degrees C, your output transistors will have very short lives. You could monitor their case temperature with an inexpensive (read somewhat inaccurate but close enough for this purpose) IR non-contact thermometer. Refit with better heat sinks and use computer grade thermal compound. 
erik_squires
16,676 posts
 
You know, fans are quieter, especially when new now. :) Cheap too.
mijostyn's avatar
mijostyn
8,570 posts
 
You may be able to replace the fan with a fan exactly the same size that is quieter. Digikey and Parts Express have hundreds of them. Measure the voltage on the fan leads it is usually 110 VAC or 25 VDC. If 25 VDC you can wire a pot to it to adjust the speed then as Sleepwalker suggests track the temp on the heat sinks. I have had several amps like the Krell KMA 100 that had fans you couldn't hear.  
geoffkait's avatar
geoffkait
23,365 posts
 
I used the 5” battery powered O2Cool external fan for both Bada headphone amp and Woo Audio headphone amp. Just point the fan at the tubes and let er rip! Problem solved! 11 bucks on eBay, fast n free!
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