Looking for large SILENT fans

Discussion in 'Home Theater Projects' started by Jon_S, Mar 7, 2004.

  1. Jon_S

    Jon_S Extra

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    My Home Theater Gear Setup (as follows) works great for me, but the equpment is in a fairly enclosed space and I don't want the equip to get too warm.

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    So, I'd like to install one or more fans in the back wall of each rack that are SILENT to cool it down. I could have them pulling air out or pushing it in, but I think pulling it out would probably be best. I guess I could hook it up to X-10 control, but maybe I could do something with a thermostat (a later thought). Obviously this is in the living room and we're talking sound system, so fan noise is a major concern. I could go with large or small fan(s), but of course a narrow depth (less than 2-3") would be ideal as I plan to surface mount it/them on the outside of back wall(s). Does anyone have any thoughts? Thanks!
     
  2. anth_c

    anth_c Stunt Coordinator

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    Jon,

    I use several computer fans that run on 12 volts DC power. I have a 12 volt transformer (1.5Amp from Radio Shack) that is plugged into one of my switched AC outlets so that the fans come on when ever I turn the system on.

    Do you really need fans?
    I bought a digital indoor/outdoor thermometer from Walmart for about $10 that has a maximum temperature memory. I used this to see how hot my rack got at various points. Without any fans, the top of my amp would get about 110 deg-F, with the fans, it barely gets above 90 deg-F. The thermomter can also be used if you decide to slow the fans down with a rheostat (see below).

    Some of the quietest fans are made by Panaflo (choose the low speed for the particular size you want). The typical sizes used are 80mm (3.75 inches) and 120mm (5 inches). The smaller fan is about an inch thick, and the larger is about 1.5 inches thick. The bigger fans are generally quieter on a cfm per Decibel basis. You can find them at some of the computer mod websites.

    The fans are mounted to the underside of the metal shelves in my rack by some stick-on magnets that I got at a craft store. They can also be mounted with screws or bolts, but I like the magnets because it allows me to easily move the fan.

    The fans I bought are NMB from www.directron.com. They sold a ten pack of fans for $2.95 each. They aren't the quitest fans in the world, but I have used a rheostat to turn down the voltage supplied to the fans. This makes the fan turn lower and thus make less noise. Visit www.7volts.com and look for rheostat.

    Noise:

    Everyone wants to know about noise. In addition to the four fans in my rack, I have a Samson S-1000 amp that has two built-in fans. When I wake up in the morning and walk into the living room, I can hear the fans running with no source material playing. It is by no means a lound sound, or whine...it is just the sound of the air moving. Once I turn on the TV, the fan sound disappears. When I am watching a movie, even during a silent pause, I can't really hear the fans from the seating position. That is a total of 6 fans running and a seating distance of about 8 feet from the rack.

    The picture below shows two of the NMB fans that are mounted underneath the Samson S-1000 subwoofer amp. I have two Adcom amps sitting underneath the the Samson. You can also see the rheostat at the middle top of the picture: it is in between some the line level input cables and has a green and white wire pair going connected to it. It looks kind of ghetto just stuck onto the back of my tape deck...one of my projects is to mount it into a little plastic box and clean up the power wires going to the fans.
    http://us.f1f.yahoofs.com/bc/3fa4749...Td_SABe2.pMl8b


    I hope this gives you some ides. Let us know what you decide to do. I'd also like to hear about what some of the others members have done.

    Regards,
    Anthony

    Some notes:
    -If you run multiple fans, make sure the output of the transformer can supply the total load of all the fans (typically listed in milli-amps).

    -I thought about using some type of thermostat, but couldn't find a small, compact one...maybe some others will post some sources.

    -Database of fan specs: http://gizzo.8m.com/fans/index.html

    -Generally, you want the fan blowing air out the back, so that cooler air is drawn in the front. On some posts, there is a lot of controversy about blowing in or out. Here is my rationale: I have never seen the fan on a computer power supply pull cold air into the case, it is always pulling hot air out. This is what the engineers at Intel and AMD specify. Granted, some of the higher wattage units have two fans, one on the bottom pushing air into supply and one on the back pulling air out, but they are both moving air out of the case. Also, the noise level is cut down by having the fans blow out towards the rear.
     
  3. Wayne A. Pflughaupt

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    I’m using these snap-disc temperature control switches from Grainger:


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    At Grainger’s home page, do a search for “Manufacturer’s Model Number” and enter “3f05-1” in the field

    I don’t know for sure where to tell you to find them – I got mine from a place I used to work. Grainger is obvious, if you have access to them (I don’t think they do business with the general public – you’ll probably have to go through your job, church, or other commercial entity). You might also try a local air conditioning company or an electronics hobby shop. Maybe you can do a web search on the manufacturer, Therm O Disc, and see if you can come up with an on-line source.

    They make other versions of this gizmo, but you want the one with the 90-130 degree variable range that closes on temperature rise. According to the Grainger page, the manufacturer’s model number is 3F05-1.

    I installed mine at the top of the cabinet, where heat-build up is the highest (that’s where I installed the fans, too – they exhaust hot air out, which is the way it should be done). They should be connected in-line with one of the power leads. The snap-disc is simply a switch - at the proper temperature setting, it will close and complete the circuit, and turn the fan on.

    Hope this helps.

    Regards,
    Wayne A. Pflughaupt
     
  4. Steve Lucas

    Steve Lucas Stunt Coordinator

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    Radio Shack carries both small (about 4" and large ~7") fans in both 12V and 120V. My audio rack is using one of the larger 120V fans plugged into the switched outlet on the back of my receiver so that it turns on with the system. I used one of the smaller ones in my living room set-up for awhile, but found that it was too loud. I think the larger fans can turn slower to move the same amount of air and are therefor quieter. At least that's my experience.

    Steve
     
  5. Jon_S

    Jon_S Extra

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    Anthony, Wayne and Steve,

    Thank you so very much for all the detailed information you have provided. I have been reading your posts thoroughly and am trying to formulate a strategy. I think the main thing I’m now trying to determine is which fan(s) to get and how I want to wire it. I emailed one of the fan companies I found through the fan search tool about what would be a good way to go, but I have done some looking as well. It seems that maybe one (or two) 80x80x25mm fans might work well, if I can figure out how to hook it all up.

    I’m thinking of the Vantec Stealth SF8025L, which is 12V, 0.10 Amp, 1.20 Watt and 27 CFM (cubic feet/minute airflow), at only 21dBA (which I’m told should be nearly inaudible). This fan seems to have the highest CFM to dBA ratio in a test done on amdmb.com:

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    I suspect that this fan should not need to be dialed down because of its low dBA measurements. Heck, it even has a lifetime warranty (on a $7.50 product).

    Vantec product overview page
    Product PDF From Vantec
    PriceGrabber.com Price Link

    So, if I get this fan (or two), then what? Well the fan is designed for computer cases, so I’ll need to figure our how to pull it into something I can plug into my line conditioner’s switched output or receiver. It has the ability to use a “3 or 4 pin connection” with included adapter as can be seen here:

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    From there on it’s a bit foggy to me how I would power the fans. I see that I could use the thermostat from Wayne’s post, but I think that perhaps since it sounds like I’ll be able to get this/these quiet, I might go with the switched power plan Anthony & Steve listed. In that case, it seems like from above that we need a 12V AC-DC converter, but then, how do I make the connections? Thanks so much. I plan to document whatever I do back up here. Anyone else have thoughts?
     
  6. Wayne A. Pflughaupt

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    Just cut the connector off the AC adapter you get and splice it into the cable shown in the picture, using butt splices or something similar (don’t “twist and tape”). You’ll need to keep the polarity right, though. The +12 lead from the adapter will go to the red wire. You’ll need a voltmeter to determine the polarity.

    Regards,
    Wayne A. Pflughaupt
     

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