DrBunsen
New Member
Registered: Jan 2001
Location: Rockwall, TX USA
Posts: 19 |
quote:
Originally posted by Want1394
Slightly more cooling power for the same dB level as Bunsen has, is available with the Sanyo fans from www.plycon.com.
I'd seen that, but didn't want to go for it. I didn't consider them since I'm suspicious that maybe the noise level would actually be similar to the the Everflow fan (which, as I've said, I've found to be a smidge loud for my tastes (again, realize that I'm pickier than many of you may be - I want my DTiVo's to be dang close to silent from a few feet away, even if I'm listening for them.)) The manufacturers all seem to give CFM and dBA specs, but I'm inclined to think that there's probably a lack of consistancy to how those are measured.
I decided to base my search for a replacement fan on the RPM. The Panaflow's that I got rotate at a speed between the original Delta's (very quiet, when operating properly) and the Everflow (loud for my tastes). I'm just hoping that they work out OK.
A little more background on fan noise - Fan noise is caused by 3 things that I know of:
1) The disturbance of the air caused by the fan blades rushing through the air. The faster they turn the more noise they make. The more sharply pitched the blades the more air gets moved and the more noise is made. Rounded corners and such will help as far as noise caused by the tips rushing through the air.
2) Interruption of the airflow by the veins that hold the motor in place. Anything that gets in the way of the air flow causes noise, so (all other things being equal) a 3 veined mount should be quieter than a 4 veined mount. Thicker veins mean more air disturbance and more noise. The original Delta has 3 veins, the Panaflow and Everflow have 4. However, the Panaflow's veins look more aerodynamic to me than the other 2 so perhaps that'll help minimize the noise a bit.
3) Motor noise caused by vibration. Here's where I think things get really tricky. When I first listened to the Everflow fan that I eventually installed, I just plugged it into the DTiVo to see how loud it was while I was holding it in my hand. It was louder than the default Delta, but not by a whole lot. I figured that with the top of the DTiVo on I wouldn't notice it. However, once in place it's a LOT louder than the Delta. It's even much louder than when I was testing it, and it's now enclosed inside the case! The thing is, it's now acoustically coupled to the tray that it's mounted to. Every vibration by the fan is now transmitted to the tray and causing it to vibrate in sympathy. Fortunately, the tray has those rubber grommets that help dampen the noise so other parts don't vibrate as well, but having the tray vibrate is bad enough.
The motor noise caused by vibration was something that I didn't anticipate. After hearing how loud the fan was when in place I did a little experimenting, since I have another of the exact same fan so that I could understand why it was louder than I expected it to be. When I hold the fan in my hand and have it plugged in, it's semi-quiet. When I press it to any object (e.g. the place where it gets mounted, my stereo cabinet, etc.), it makes way more noise than it does when it's in free air because it causes that surface to also produce noise by vibrating in sympathy. So, any vibrations that the fan has will be amplified by mounting it somewhere, unless that "somewhere" has sound dampening capabilities (by either absorbing vibrations, or having enough mass to not be influenced by the fan).
I'm just thinking that the faster any fan is the more it'll vibrate, and therefore the noisier it'll be once it's in place in a DTiVo. Of course, it could also be that the Everflow fans are not as well balanced as other fans and therefore vibrate more. If that's true then the Sanyo fans, even though they rotate faster, could indeed be quieter than the Everflow, and similar in quietness to the much lower RPM Panaflows. I don't have one, so I won't be able to comment on them. But I think it's safe to say that, all other things being equal, a slower fan should vibrate less than a faster fan.
As soon as I actually get these Panaflow's in place I *will* let you know how much I like/dislike them. 
Bunsen out....
Last edited by DrBunsen on 03-19-2002 at 05:33 AM
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TiVo Community Forum Archive 1 > Underground Playground > TiVo Upgrade Center
03-15-2002 05:22 PM
