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DC Cooling Fans for Vintage Tube Amps

Discussion in 'Tube Audio' started by Rbradio, Apr 22, 2018.

  1. Rbradio

    Rbradio AK Subscriber Subscriber

    Messages:
    53
    Location:
    Ontario
    Anyone out there have a source for a nice, quiet cooling fan I can plug into either the accessory outlet of my Amp or Power bar that won't leave any hum behind?

    Want one in the back of the Amp (Scott 299B) and one in the back of the tuner (Scott 311D).

    I have seen them but not sure what a good source would be.
     

     

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  2. Rbradio

    Rbradio AK Subscriber Subscriber

    Messages:
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    Ontario
    this picture gives an idea of what I am looking for
     

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  3. s-petersen

    s-petersen Scott Subscriber

    Messages:
    4,521
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    Middletown,New York
    I haven't seen too many quiet AC fans, but have used 12v fans on 6v wall warts so they are quiet.
     
    x3workshop likes this.
  4. whoaru99

    whoaru99 Epic Member

    Messages:
    40,944
    Location:
    LoTL
    Digi-Key, et al, have a big selection in various voltages, sizes, and air flow ratings.
     
  5. eiraved

    eiraved AK Subscriber Subscriber

    Messages:
    2,217
    Location:
    Antelope Valley, CA
    You can find used computers for cheap at thrift stores which have quiet fans similar to what you've shown. I just removed a pair of fans from my 2013 era computer a few days ago, work perfectly fine. No plans for them at this time...;)
     
  6. Lavane

    Lavane AK Subscriber Subscriber

    Messages:
    7,185
    Location:
    northern cal.
    Also discount computer and computer parts sites sell them. Do a search for whisper fans . I have some I use in my gaming rig running 12 volt that are very quiet. Some even come with removable, cleanable filters. Some even have clear blades with colored LED lights if thats your thing.
     

     

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  7. Gibsonian

    Gibsonian Super Member

    Messages:
    3,514
    Location:
    Iowa
    Digikey Mouser Newegg or Tiger Direct. Lots of quiet ones out there they cost a smidge to a lot more. Just bought a pair of 24 volters for Crown amp replacements.

    20 bucks for pair, think 19 db noise level. Way quieter than originals
     
    drtool likes this.
  8. jwrosenthal

    jwrosenthal AK Subscriber Subscriber

    Messages:
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    Location:
    Baltimore, MD
    I did a pair of 12v fans and cut and spliced a 12v wart from a junk bin with appropriate power rating for both (think they were 400ma and I used an 800ma Wall wart). Never occurred to me to use a 6v to slow it down (800ma+ I assume as well)- very clever idea. They do run at full tilt and sound like your running a fan in the room-go figure!
    The fans really do work. I have an ARC D51 that gets smoldering hot (they were known to cook the caps in the first few years), and with the fans laying on top of the cage, I can put my hand on it and it’s only slightly warmer than room temp.
    One point to note- isolate them someway. At first I thought the fans were really noisy and it was a deal breaker- but then realized as I moved them while they were running, that they were vibrating the cage. A set of stick-on rubber bottomed feet took care of that.

    Also, those plastic blades can draw blood- on both thumbs!
     
  9. s-petersen

    s-petersen Scott Subscriber

    Messages:
    4,521
    Location:
    Middletown,New York
    Actually you could series those fans, and half speed them.
     
    Bill Ferris likes this.
  10. jwrosenthal

    jwrosenthal AK Subscriber Subscriber

    Messages:
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    Help me wrap my brain around that one. I have both red and black wires on both fans twisted together and into a female miniphone connector. The wart has a male plug that goes into the female connector. That would make them in parallel-correct?

    How would I wire them in series if there’s only one hot, one ground per fan?
     
  11. whoaru99

    whoaru99 Epic Member

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    Connect black from one fan to red of the other.

    Connect the remaining black and red from each fan to the power connector.
     
    DChen likes this.

     

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  12. Poultrygeist

    Poultrygeist Lunatic Member

    Quiet as a church mouse and $7 from Walmart.

    P6270014.jpg
     
    AlTinkster92 likes this.
  13. jwrosenthal

    jwrosenthal AK Subscriber Subscriber

    Messages:
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    Location:
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    Click! That was my brain getting it! Just like a string of Christmas lights.
    Thank you!
     
  14. DLudington

    DLudington AK Subscriber Subscriber

    Messages:
    112
    Location:
    Northern Virginia
    I rigged this up about 10 years ago: 2 fans in parallel with a resistor to drop the power, so that the fans are quieter. It’s angled slightly down to apply air directly to the power and rectifier tubes. I also added a switch back there too with a barrel power input plug.

    Works very well keeping the transformers and tubes cool.
     

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  15. Westy56

    Westy56 A symphony of paradox

    Messages:
    6,612
    Location:
    Abq, NM
    I wouldn't worry about running AC fans.

    This one is only an inch or two from an unshielded bottom.
    No electrical hum, but I can hear the fan blades when no music is playing.

    [​IMG]
     
  16. jwrosenthal

    jwrosenthal AK Subscriber Subscriber

    Messages:
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    Location:
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    So I rewired mine as suggested (in parallel) and they are indeed about half as loud as they were before. Still not whisper quiet but hey-they were free. I place mine directly on top of the cage above the output tubes pulling the air up and out and it makes a huge difference. Probably giving this ARC another 45 years without cooking the caps this time. I would have mounted them to the back using wire but there is a heat shield (or should I say heat retainer) between the front and back (output tubes are up front).

    I feel this is an essential mod for those of us with space heater tube amps and the cost of the fans/ PS are offset by not having to replace output tubes and dried up caps as regularly.
     

     

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  17. PakProtector

    PakProtector AK member

    Messages:
    3,671
    Location:
    Ann Arbor, MI
    With AC fans the speed is dependent on the line frequency, so slowing them down takes both a reduction of frequency and voltage. Not exactly simple.

    DC, is speed based on voltage, so reducing the voltage results in a reduction in speed, and thus spins slower, moves less air, and yields the principal objective of quieter operation.
    cheers,
    Douglas
     
    drtool and Retrovert like this.
  18. Rbradio

    Rbradio AK Subscriber Subscriber

    Messages:
    53
    Location:
    Ontario
    Wow, I got called away after I wrote this and am just getting back on line now. Great information, thanks to all!
     
  19. cgutz

    cgutz AK Member

    Messages:
    3,393
    Location:
    SE South Dakota
    I use this with a cheap usb charger, plugged into the switched outlet or on a power strip behind the tube amp. Very quiet, especially after I wrapped the flex shaft with a rubber band.


    https://www.amazon.com/Arctic-ABACO...d=1524595642&sr=8-4&keywords=usb+fan+flexible


    I tried a fan similar to poultryguist, quiet, but not as quiet at this option. I also tried dc muffin fans in series as above, etc. This flexible usb fan is the quietest.

    Caveat - speed on this usb fan is not adjustable per the ad, but runs quietly and moves enough air through the cabinet to keep things cool. From 3 feet away I cannot hear the fan running in the back of the cabinet.
     
  20. markn2wae

    markn2wae Mark T N2WAE

    Messages:
    3,020
    Location:
    Scotch Plains, New Jersey
    I used two small computer fans at the back of the cabinet of my Sansui1000A to keep it cool.

    One behind the output tubes and a larger one behind the output tubes of the other channel and the large power resistors.

    They are powered by a small bridge rectifier, and a capacitor, delivering about 9 Volts to a 12 Volt fan, the rectifier is getting its AC input from the 6.3 Volt heater string in the receiver, both are blowing out and are mounted OUTSIDE the perforated cover.

    Someplace on AK there is a spot with all my pictures for my posts but I don't remember where to find it!? (I wanted to post a link to them).

    Mark T. :music:
     

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