Quiet 40 mm fans! (maybe)

[Tyrdium]

*cough*

Anywho, I got my copy of the Digikey catalog yesterday, and found these. Granted, Digikey is hella expensive, but you can probably find them elsewhere for cheaper. 40x40x20 mm, and rated for 6 CFM at 18 DBa, with a 10-14 V range, according to the specs. Thoughts?

PDF link

Edit: Huh... Are they Papsts?

[nici]

At 6cfm they might be sufficient to cool the northbridge.. yes? no? Currently the heatsink on my northbridge is about 65*C, i think thats a bit on the hot side..

[Tyrdium]

That, or the PSU in a Shuttle. Unfortunately, I looked again, and it turns out most 40 mm fans are 40x40x10. >.<

I did find this while looking for fan sizes, though...

Edit: And this. 3.36 CFM at 14 dBA.

[nici]

Papst seem to have 40x40x20 fans. 18dBA 5.9cfm for example.
Check out their whole list at http://www.papst.de/english/products_lu ... ial01.html They have a huge line of fans btw! How about this, 172x51mm fan at 65dBA and 353CFM, 50Watt

[wing]

Edit: Huh... Are they Papsts?

Yes, these are Papsts. "ebmpapst" is the same company as Papst.

[Twill]

Are these really 18db tho?

they would be perfect for my shuttle psu if they are...but at $13 each...ouch

BTW, digikey seems to be the cheapest place to get them, mouser and a couple of other stores have them for $16-$18

Twill

[nici]

According to Papst site(the link i posted) they are 18dB(A), 3.8bels. But 3.8bels should be 38 decibels, decibel should be a tenth of a bel. Or am i wrong again? What does the (A) stand for really? Anyway, i doubt any fan is as quiet as the manufacturer says, if it is the airflow isnt probably as good as they claim.. CORRECT ME OH MIGHTY SPCR GURUS!

[wing]

According to Papst site(the link i posted) they are 18dB(A), 3.8bels. But 3.8bels should be 38 decibels, decibel should be a tenth of a bel. Or am i wrong again? What does the (A) stand for really? Anyway, i doubt any fan is as quiet as the manufacturer says, if it is the airflow isnt probably as good as they claim.. CORRECT ME OH MIGHTY SPCR GURUS!

Yes, a decibel is a tenth of a bel, but for some strange reason the current convention is to use them for different things (B for sound power level and dB for sound pressure level (SPL); the "(A)" indicates "A-weighted sound-pressure level"). Because of this convention, we have the strange situation where even though 10 decibels is a bel, 10 decibels is also not equal to a bel

(Googling for this, apparently the convention is recent and still not so "dead set", and it is possible to use dB or B for either. This strange convention seems to aim to "reduce confusion": For example, see this explanation by VIA. See also this incomplete explanation or this explanation for examples that the dB and B units really can be used in a "normal" way.)

All this just means that "18dB(A), 3.8bels" is just a shorthand for "A-weighted sound pressure level is 18dB [1.8B], but sound power level is 3.8B [38dB]". Two different things are measured, but they happen to use the same unit of measurement, and you are supposed to "just know" what is being measured because they are following the recent convention of using dB for one thing and B for the other.

BTW, the mystery of the name "ebmpapst" is solved on the company history page for the decade 1990 (the year 1992 to be exact).

Edit: Added cross-references and some minor things

[Devonavar]

There is no direct correspondence between bels and decibels (although I can see where you got this idea; if they were consistent with the metric system of prefixes, you'd be right).

The decibel scale is a measure of sound pressure at a specific location and must specify a distance from the source to be a complete measurement. Sound pressure (as I understand it) is the amount of vibration at a given location. Therefore, whenever we measure the sound level of a fan, we specify a recording distance of 1m. dB measurements that are closer or further from the fan will be correspondingly higher or lower.

A measurement in bels, on the other hand, is an absolute measurement of sound energy. A given source (your fan, for example) produces the same amount of sound energy in bels, irrespective of where it is measured from. Practically, bels are very difficult to measure/calculate but, in theory, a given source would give the same bel measurement no matter where it was measured from.

Because bels and decibels actually measure different things, it is impossible to consider them directly comparable, even though they seem to measure the same things.

So far I have only explained dB. dBA is an attempt to make raw dB measurements more comparable to our actual experience of a source's loudness. Because dB only measures sound [i]pressure[/i] (i.e. vibration), even frequencies at the edge of or beyond our threshold of perception contribute to a dB measurement. This means that a sound that we can't actually hear might be "louder" in decibels that a clearly audible sound. The "A" in dBA represents a standardized modification of the dB scale that incorporates an approximation of the responsiveness of the human ear in its calculation. This makes the dBA scale fairly comparable to our actual experience of the relative loudness of various sounds, although it is no longer a direct measurement of the magnitude of the vibration that we perceive as sound.

Hope this helps. Also, if any true sound engineers find an error in my description, please post it! I'm merely an audiophile in training ... I'm still learning this myself.

[Sizzle]

From my first hand experience with Papst and Adda 40 mm fans, none of them qualify for silent. However, I have two of these that I think would make a good case for being called silent fans.

http://www.silenxusa.com/productcart/pc ... Category=6

I have the 40 by 10 mm fan, the 40 by 20 mm is new.

[wing]

From my first hand experience with Papst and Adda 40 mm fans, none of them qualify for silent. However, I have two of these that I think would make a good case for being called silent fans.

http://www.silenxusa.com/productcart/pc ... Category=6

But aren't SilenX fans made by Adda?

[Sizzle]

From my first hand experience with Papst and Adda 40 mm fans, none of them qualify for silent. However, I have two of these that I think would make a good case for being called silent fans.

http://www.silenxusa.com/productcart/pc ... Category=6

But aren't SilenX fans made by Adda?

Not sure about the 40mm's. Looking at the sleeving on the fan tails, they do have a resistor in them undervolting them. I had on a Thermalright NB-1C and one in my OTES on a Abit motherboard. I could not hear them above any other fans in my case which were all Nexus.

[nici]

Devonavar-->
Ok thanks for clearing that up

[Slaugh]

There's a good explanation of decibels and bels here too...

The Bel represents quite a large change, so it is more common to talk in terms of Decibels (dB), which are 1/10 of a Bel. Whereas the Bel is a factor of 10, a Decibel is a factor of 1.26 (If you multiply 1.26 by itself 10 times, you get 10). The Decibel therefore is a logarithmic quantity, which matches the way our hearing works.

[mco_chris]

From my first hand experience with Papst and Adda 40 mm fans, none of them qualify for silent.

I second this! I've owned several small and large Pabst fans and have always had much better success with Panasonic and other brands of fans.

I wouldn't use the manufacturers specifications to compare fans - they don't seem to use the same measurement standards.

There are other threads on this board that agree that Pabst fans are not the quietest.

[nici]

A bit off topic, but so far the only fan manufacturer i have found that reports how the sound is measured is Noiseblocker, "
Sound level dB/A values are measured according to German DIN standards - 100 cm distance, loudest position, highest value - with power supply fully warmed up. Highest result = full load.