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In the Forum: Audio Discussions
In the Thread: A datacenter at home and … "sound".
Post Subject: Noise cancellation not likely possiblePosted by Vasyachkin on: 3/9/2010
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 Romy the Cat wrote:
The servers generate noise at more or less constant amplitude and spectra. So, why do not read the noise and inject into the space with servers a contra- noise at opposite phase? This sort of active noise cancelation system might be fully active and to read current noise or it might be manual. Here is where I wonder- are any prebuilt active noise cancelations systems/modules are above out there. Nowadays it is a very simple task and I might correct it if necessary with Behringer DCX2496 (that is good only for this task). Did anybody played with active noise cancelation system and did anyone can point out a ready to go, tested off the shelf solution?
The Cat


constant would be a sinewave, or a couple sinewaves with overtones.  white noise or pink noise is anything but constant - it is random.  to cancel it out in 3 dimensional space would be absolutely impossible.


i have a humorous but very brutal and mean article written on this exact subject ( attacking it mostly from a philosophical, rather than engineering angle ) on my site, which i am not going to link to, due to its ultra-offensive nature.  but if anybody is into self loathing or self mutilation you guys should be able to find it - the title is descriptive.


my computer also has 8 gigs of ram, server motherboard ( dual Xeon ) etc, but it is custom built.  i can actually run it without any case fans because the case has enough ventilation without them.  certainly you could run some 500 rpm noctua fans with it no problem ( as opposed to 3,000 rpm server fans which are about 100X times louder ).


i am using Mountainmods Ascension Extension chassis.  but to be honest it's still loud as hell ( because it is made from very light weight aluminum ) and you would need to further customize it by adding weight and acoustical foam to bring the noise level down.  i was suggesting this to a friend - i told him to get the same case as mine, line the panels of the case ( on the inside ) with 1/4" vinyl sheeting and then another 2" of auralex acoustical foam - but he said it was too much trouble.


watercooling is an option that would allow you to run very powerful gear quietly but it isn't a reliable option so not recommended for servers.


the only problem i can see with Mountainmods approach is maybe you wouldn't be able to find redundant power supplies in ATX form factor.  But i only had a power supply fail once in 15 years and it failed due to clogging up with dust so vacuuming regularly and/or using an air filtration system would have helped.  Mountainmods cases do allow for two and sometimes i think FOUR ATX power supplies to be installed simultaneously so i don't know if that helps or not.


i know i Mountainmods here before but that's because i love that case so much.  i have had a case fetish for about 10 years and nothing beats Mountainmods.


generally speaking Romy my engineering philsophy is to avoid creating problems rather than fixing them.  an ounce of prevention is worth a pound of cure.  this means using the most energy efficient CPUs, power supplies etc - that way you need less cooling.  then use a case with best laid out airflow path ( Mountainmods ) so you can get away with 500 rpm fans.  And only after all that you should worry about "catching" the noise that you did generate.


to produce tons of noise and then try to kill it is just not the right way to go.  that's like buying a V12 car and then riding a bicycle to save gas.

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