@DrMario2007baka You are right in that the sound is in the air. In fact without air, we wouldn't be able to hear at all! :) Sound dampening foam mats will (and do) still help, because they absorb the sound with disregard to its source. The base frequency for the sound the air makes through these fans is calculated as "RPM / 60 * fan blade number * strut number". Since these particular deltas will be going at 5500rpm and have 9 fan blades and 9 struts, our base frequency would be 7425Hz.
zniffstamp, I agree with you. I have exactly the same fan (Delta PFB1212UHE-F00) and it's incredibly loud. As you pointed out, it is the air that makes deafening roar - sound dampening foam will do little since the motor itself is completely silent (except for very faint bearing whines when running at full speed). Cool, but useless...
Not to mention the unnecessary stresses on the fan motors... They draws nearly 5 Amps so the likelihood of popping MOSFETs in them would be quite high, as they aren't mounted on heatsinks at all.
The sound frequency seems dead-on. It sounds kinda like a turbofan engine when you run it on 12V. Also, I wouldn't recommend to run it at 5V as those MOSFETs didn't like it (I have tried it - so warm on the motor cover, but is still alive, though) so I would have to run it at 6 - 7 volts as a minimum due to Gate charging voltage requirement. And I personally think the sound-dampening material should be carefully chosen because we are taking moving air in account too. Neat project, though.
Very well done!
@DrMario2007baka You are right in that the sound is in the air. In fact without air, we wouldn't be able to hear at all! :) Sound dampening foam mats will (and do) still help, because they absorb the sound with disregard to its source. The base frequency for the sound the air makes through these fans is calculated as "RPM / 60 * fan blade number * strut number". Since these particular deltas will be going at 5500rpm and have 9 fan blades and 9 struts, our base frequency would be 7425Hz.
zniffstamp, I agree with you. I have exactly the same fan (Delta PFB1212UHE-F00) and it's incredibly loud. As you pointed out, it is the air that makes deafening roar - sound dampening foam will do little since the motor itself is completely silent (except for very faint bearing whines when running at full speed). Cool, but useless...
Not to mention the unnecessary stresses on the fan motors... They draws nearly 5 Amps so the likelihood of popping MOSFETs in them would be quite high, as they aren't mounted on heatsinks at all.
The sound frequency seems dead-on. It sounds kinda like a turbofan engine when you run it on 12V. Also, I wouldn't recommend to run it at 5V as those MOSFETs didn't like it (I have tried it - so warm on the motor cover, but is still alive, though) so I would have to run it at 6 - 7 volts as a minimum due to Gate charging voltage requirement. And I personally think the sound-dampening material should be carefully chosen because we are taking moving air in account too. Neat project, though.
What are your intentions for the use of this?
nice