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The Top SPCR Quiet 120mm Axial Fans Compared + 120mmAC Fans.

Posted: Sun Oct 17, 2004 9:46 pm
by DrCR
Last update: July 2009

Note: For each dimensional category new additions are appended the list, so look towards the end of each category to view the more current choices.
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First off, most of the info here has been tapped from guys on this forum so a big thanks to you, you probably know who you are. I decided to post this since I don't really know of a one stop comparison of quiet 120mm fans, and it seems like 120mm axial fan threads keep popping up. If a moderator could make this a sticky that would be awesome. A big thanks to ferdb for his insight in the 120x25+ extra thick axia fan sector!

Quiet 120mm x 25mm Fans (Standard Case Fan Thickness)

The Papst 4412 fans are very nice when undervolted on DC current. They are one of the best quiet 120x25mm fans for restrictive environments. They don't like PWM though. Purely noise wise, they fall in the quiet, but not the most quiet category. The Nexus and Globe (and the more recent additions to this list) options are quieter, but remember, the 4412 is moving a good bit of CFM.

Note: Both the Papsts and the Panaflos seem to be degrading in quality overall. The Panaflos seem to be degrading more so then the Papsts though.

The Evercool / Titan 120mm aluminum 120mm fans are pretty good quiet fans for a low restrictive environment @ <5V DC (lower than most other fans can undervolt). They also, like the Papsts, don't like PWM very much.

The Nexus "Real Quiet Fans" are astounding fans in the 80mm, 92mm, and 120mm categories. They work flawlessly on PWM and undervolt on DC fairly well considering their low 12V CFM. The only potential negatives about the 120mm is its orange color, its lower 12V CFM numbers (not an issue at all for most everyone though), and price compared to the Globes. Not as good as the Papst 4412 in a restrictive environment. It's one of the quietest 120mm axial at the standard 12v on the market and also one of the quietest 120x25mm case fan on the market at minimum RPMs. You can buy them at endpcnoise or siliconacoustics for a cool $20 per fan, but that might get the best $20 (times n number of fans bought) you've ever spent on your computer. The extra cost may be in part due to excellent quality control. The Nexus is predictably quiet, not requiring "cherry-picking" like other fans.

Edit 2-15-06: Note the Nexus fans are now available in a swanky black-and-white.

The Globe S1202512L-3M works flawlessly on PWM, undervolts on DC very well, and is one of the quietest fans around when operated with either of these two wattage regulators. Some chatter/clicking has been reported even at the lowest settings though. Doubt it works in restrictive environments as well as the 4412. With its ~65CFM at 12V, it is an excellent choice for when you�re willing to give up some quietness for extra CFM (i.e. max overclock bragging rights or converting a Delta screamer dude). You can buy them at mnpctech for only $8 per fan. If you looking for the absolute quietest fan and are willing to lay out the money, you really will want to spend the extra on the Nexus to avoid the Globes slight bearing/motor noise at the lowest RPMs.

Edit 3-16-05: There is now no known source for this fan, but Aleksi is working on it. (link)
Edit 5-11-05: Aleksi delivers! (link)

The AcoustiFan AF120CT is closely related to, if not the same fan as the Globe (link). One differentiating aspect compared to the Globe is that the AF120CT is transparent--a plus for LED/Cathode lovers. Note, however, the clear plastic is a little noiser material though. You can find them at siliconacoustics.

The Enermax 120mm (like this one) is apparently a Globe relation as well (link1, link2). Most Enermaxes use ball bearings rather than the quieter sleeved the quieter Globes and AcousticFans use (BB equals louder bearing noise). However, what's pulling for these fans is they are available from just about every wide-selection PC vendor and as a resultant have very good name recognition among the general computer savvy. In addition, they are usually bundled with some sort of simple speed controller. I believe this fan would be correctly considered decently quiet. On the quiet side of loud, but on the loud side of quiet. It seems to be pretty popular among "quieter" computing guys who have not yet tasted the fruit of a genuinely quiet fan or are not quite as intent on a truly quiet setup. Spend your money elsewere IMHO. Just including it here so you know where it stands.

The Yate Loon D12SL-12 is used by 3R systems, the Korean company that builds most of Ahanix's cases. They can also be found in some Fortron power supplies. The Nexus 120mm is a Yate Loon under another label, only the Yate Loon spins faster than the Nexus at 12V and the Nexus's fan blade design possibly has a slighly little more curved leading edge. Unlike the orange Nexus 120mm, the Yate Loon is black. Can be rather difficult to find. Probably the ideal quiet fan as it still retains the ability to crank a bit more CFM on demand but lack the bearing/motor noise of the Globe (assuming the Yate Loon's noise charactersitics is the same as the Nexus 120 in the Nexus's RPM range).

Edit 1-18-05: Looks like the are relatively readily available now! See this thread.
Edit 12-5-05: Available from jab-tech, frozencpu, pctekonline, and tekgems. D12SM-12 Blue LED from case-mod
German vendor: silencio- gives a discount if you mention spcr.

Coolermaster SUF-S12 / A12025-12CB-5BN-L1
*Quote from frankgehry*:
Great fan with no bearing noise whatsoever. Motor noise was unobtrusive. Not quite as smooth as the Yate Loon models but [according to FG] every bit as quiet. If you are sensitive to bearing noise this may be a better choice that the Yate Loons.
(link)
Thanks for your input FG!

GlobalWin NC Bearing 1202512L
Relatively loud at 12v, at 5v this fan can quiet down potentially even more so than the ubiquitous Nexus. The CFM values at 5v, however, are apparently noticeably inferior to the Nexus at 5v. So probably best as a case fan rather than on a heatsink, except maybe as an aternative to purely passive. A better choice for inhospitable environments (PSUs) than the Nexus or YateLoon due to its bearing design. Some bearing rub may be present with this fan though. The fan is also reportedly PWM intolerant.
Info here and here.

Scythe DF Series
A solid fan series made by Young Lin. The 1200rpm sleeve bearing version is in the ranks of the Yate Loon D12SL-12. The 1600rpm version may be a solid choice for delta screamer converts not quite ready to give up their old ways - a nice addition now that the Globe S1202512L-3M has for all pratical purposes become unavailable.
Discontinued, but lives on in its spiritual-successor, the Slipstream series.

Scythe S-Flex
Makes use of "Fluid Dynamic Bearing" technology. The non-800rpm models are excellent, albeit noticeably more expensive than the
DFs (archaic) Slipstream series. The S-Flex with its finer-pitched blades can be the superior choice in more restrictive environments that the Slipstream, and more durable in horizontal orientation. The 800rpm @ 12v stock version of this model, The Scythe S-FLEX SFF21D, initially looked to be the choice for the quietest 120mm axial at standard 12v voltage, and good samples are indeed excellent, but this particular version's quality inconsistency gives the nod to either the venerable Nexus or nowadays the newer the Slipstream for this particular sector. The 1200rpm model S-Flex (with resistor) gets the most attention of the series.

Noctua NF-S12 Series
Excellent air flow to noise ratio, with efficient fan blade design. The same fan blade design however, specifically their coarse pitch the spacing between the blades, makes the fan unsuitable in more restrictive environments such as heatsinks and radiators. Fan undervolts well, with a nice, whooshing noise character -- though a potentially unnerving "presence" nature of the fan, present long after the fan had otherwise reached inaudible levels, is noted in the Nov06 Offical 120mm Report.

Scythe Slipstream Series
*Quote from Mike Chin*:
The [Scythe Slipstream 800RPM, SY1225SL12L] was tested for noise characteristics. We didn't do a full range of airflow / noise tests, but SPL and RPM measurements were taken at various voltages. The overall noise signature of this nine-bladed fan is very smooth and quiet, mostly broadband turbulence with no tonality at all even at 12V. At 9V, it's already inaudible. Of course, spinning at just 660 RPM, it isn't moving that much air, although Scythe says the nine blades produce greater airflow at the same speed than seven blades. For many users, this fan can probably be run full speed; it's that quiet.
Mike Chin
Looks like Scythe hit a home run on these guys!
Edit May '08: Attack of the 120 Scythes

Quiet 120mm x Thicker than 25mm Fans

The Panaflo L1A 120mm, unlike the Japanaflo L1A 80mm fans, is not really considered in the most quiet fan category. It still can be pretty quiet though, esp. a 'good' one on a lower undervolt, and it is not uncommon to see it being used by some of the more hardcore quiet gurus. Most (basically all) will want to look at other options though unless you are willing to accept a lot of not so good to pretty bad samples in the hunt for good ones.


The following are slightly edited quotes of Ferdb's posts in this thread. I highly recommend you take the time to read the original posts too! Thanks for your input Ferdb! :) A word of warning to the not too technically oriented, the following are AC fans. You will want to sick with DC fans, which are highlighted red.

Quiet 120mm x 38mm AC Fans

The Globe Motors A47-B15A-15T2-100 is an 120V AC fan. If you connect 2 in series across 120V they run about 950rpm and are very quiet, comparable to a Nexus undervolted to about 9.5-10v. They flow substantially more air than the Nexus and since they are thicker they should handle backpressure better but I have not actually tested their performance with backpressure yet.
Note: Ferdb has seemed to have dropped this fan in favor of the Sunon 2123XST.

The Sunon DP200A-2123XST (2123XST) is a 240V AC fan and runs 1300-1350rpm on 120V. At this speed it makes more noise than the Globe Motors fans but only because of the higher RPM. Slowed down to around 900 rpm it is almost inaudible at 1 meter in open air and pushes a good amount of air. Even at the 1300rpm level it is much quieter than the Panaflo L1A DC brushless. Almost no motor or bearing noise, it is all airflow noise. Easily the best airflow vs noise ratio of the 120x25+mm lot. Probably one of the best 120mm fans available when undervolted. It has a better airflow to noise ratio than the Nexus (for a given airflow it's quieter than the nexus / for a given quietness it moves more air) and performs gloriously in restrictive environments. Reduce the RPM with a series resistor to desired level.
For more information see ferdb's posts on page 2 and <this> thread by ferdb.


Addition 1-18-05:

The Sunon A1123/A2123 HST, unlike the 5-blade 2123XST, is a 7-blade fan with about 25% better flow at 0.2in H2O pressure difference. Air flow is rated at 112/124 CFM at zero resistance, and volume is 43/46 dBA [DrCR: At 240V I assume]. A bit louder, but I'm guessing most of that is probably air flow noise. There are several other fans that could fit the A1123 model number, so be careful to make sure you get the right one. It's got an Aluminium alloy frame, is described as "High Air Flow", and rated at 0.28/0.31 in H2O peak pressure.

Compared with the Nexus 120 and Sunon 2123XST at similar rpms, the A2123 make a little more noise than the 2123xst but the higher airflow more than makes up for it and it comes out ahead on CFM/noise. At comparable CFM through the radiator the A2123 has a better CFM vs noise ratio than the 2123XST or Nexus 120. The A2123 fan blade's shape is much different than that of the 7-blade Nexus, but the CFM vs RPM ratio of the two are very close. The Fan noise is a higher pitched than the 2123XST at the same rpm because of the two extra fan blades, and is similar to the Nexus in tone. The A2123HST has almost no bearing noise at all (in my [ferdb's] samples).

For Radiator applications the A2123 comes out as the best performer, the advantage over the Nexus or 2123XST being moderate. Both the A2123 and 2123XST are heavy metal 38mm thick fans which 'weigh' against them from a mounting and weight issue [DrCR: Very punny. ;)].

Bottom line is that the Sunon A2123 is the best airflow to noise ratio fan I've found for radiator use. If you want the ultimate performance, you can achieve it with this fan. However the Nexus 120 is fairly close in performance and has the added convenience of being light weight and running on 12V.


And additional note by pdf27:
The fans have a little bit of 50Hz hum (I think I can hear it @ 2m in free air, but only with a fluorescent light @ 4m turned off!), and the rest of the noise is vibration. The fan bodies are aluminum (look like castings) so are fairly heavy, and that should help vibration when installed.


Special thanks to pdf27 in addition to ferdb for his input on the A1123 and his offer to order some for all us State-side. :) For more information on the A1123, see the second half of this thread.


AC Cons:
Not as easily speed controlled and a 120V relay (such as a pump relay) may be needed to switch the fan(s) on with your machine. Note, vibration isolation/isolators is essentially required to avoid a ton of vibration noise. Also, the A1123 has a metal frame/case and could present mounting issues due to its weight.



To the newbies, feel free to post questions! To this forum's core, feel free to comment on if you believe any aspect of this comparison to not be correct. If a fan is not on this list then it's probably not a quiet fan (e.g. Vantec anything-but-Stealth), but most assuredly go ahead and ask anyway, esp. if it is a more obscure fan or if the same fan is also marketed under a as of yet unknown to me different label.

Also, bear in mind there are multiple choices in quiet fans, but it would be extremely hard to say which is the 'quietest' as there are so many other factors like CFM, resistively, character of noise, technique of lower rpms, etc. In some cases 'hard-core' silence gurus simply have to agree to disagree and realize the variation in circumstances and a fans' attributal consistency. Things are less subjective in recent times now that there are many proper reviews completed by MikeC and co (look for the fan roundups).

For you new guys having a hard time choosing and don't want to undervolt, buy the Scythe Slipstream 800RPM or the Nexus, both very solid quiet fans at the default 12v, with the Slipstream edging out the Nexus. If you are willing to undervolt and/or want those extra rpms for whatever reason, the higher RPM versions of the S-Flex like the S-Flex SFF21E 1200rpm or nowadays the Slipstream SY1225SL12M is the route to take (I'm a fan of 1200RPMers @5-6v myself). For budget builds, the cheaper priced YateLoon D12SL-12 is choice now that in recent times they are common and gloriously affordable. Their quality control isn't as good as the cherry-picked Nexus fans, but their higher 1350rpm speed over the Nexus is perfect for running straight off a 5v line rather than a variable resistor. In general though, the superior and also reasonably affordable Slipstream is the route to take for all but the most budget of builds.

If you have the electrical and perhaps modding know-how, room for a thicker fan, the need for higher pressure, and don't mind AC, by all means go for the Sunon!


Note: Most quieter computing guys will never need more CFM than ~1000rpm as half that will often suffice with proper heatsinks, and there are numerous solid options mentioned above for the guys a little too timid to try undervolting right off. Still though, the Globe S1202512L-3M (archaic) Scythe SFF21F or Slipstream 1600rpm are perfect for Delta screamer converts as their undervolted quiet potential is far better than most other fans with such 12v CFMs. The Sunon is perfect for heatercores or other high-restrictive environments, but you have to be prepared to take on its AC and AC-related undervolting issues.

DrCR

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Update June '07: Hard to believe this thread is 2.5years old now. We're starting to get serious lab results nowadays thanks to Mike & Co. A _big_ thanks to you guys! Be sure to check out the Fans and Controls article section for the latest testing results in this sector!
Edit 9-13-07: I have absolutely fallen in love with the S-Flex SFF21E 1200rpm for when you are willing to spend the premium over the wonderfully cheap D12SL-12 YLs. Recommended with a variable DC-voltage controller like the FanMate though.
Edit 2-28-08: Comments added for the excellent Slipstreams and reorganized a bit.
Edit 5-20-08: Official Slipstream Fan Roundup added and thread reorganized a bit.
Edit 7-9-09: Supplemental comments (black text) added, removed, and modified as needed. S-Flex comments clarified.

Posted: Mon Oct 18, 2004 6:08 am
by ferdb
The Papst 4212L (120x38mm) that I got recently is not a quiet fan. It has significant bearing and motor noise and is worse than both the Panaflo and Sunon 120x38mm fans. I found the Sunons to have the least motor noise (they are 6 pole motors vs most 4 pole motors) but considerable bearing noise. The Panaflos have the least bearing noise but considerable motor noise (a sort of diesel idling sound).
Globe makes a 120x38mm fan, but I have not found where to buy any yet. If somebody comes up with a source please post it.

Thanks DrCR for the 120 fan summary.

Posted: Mon Oct 18, 2004 6:49 am
by burcakb
ferdb wrote: Globe makes a 120x38mm fan, ...
Where did you get that information? Globe does NOT make 120x38mm fans.
http://www.globefan.com/DC.htm

Posted: Mon Oct 18, 2004 12:33 pm
by Becks
Wonder where you could get globe's 1000rpm fan.. that yellow one? Well don't know if its yellow but I've never seen a 1000rpm globe or a yellow globe fan.

Posted: Mon Oct 18, 2004 6:45 pm
by DrCR
ferdb wrote:The Papst 4212L (120x38mm) that I got recently is not a quiet fan. It has significant bearing and motor noise and is worse than both the Panaflo and Sunon 120x38mm fans....Globe makes a 120x38mm fan...
You got the model numbers for those Sunon and Globe axials? I'll add them to the list.
Becks wrote:Wonder where you could get globe's 1000rpm fan.. that yellow one? Well don't know if its yellow but I've never seen a 1000rpm globe or a yellow globe fan.
Never heard of those. You got a link to a forum thread or something? You've roused my curiosity lol. :)

DrCR

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Posted: Mon Oct 18, 2004 7:36 pm
by Becks
On globe's page, linked above, click on the 120x120x25 link and theres a pic of a yellow fan, and in the table at the bottom one of the fans spins at 1000rpm...

Posted: Wed Oct 20, 2004 5:30 am
by DrCR
Oh, OK, model B/S1202512L (1K). Found some non-North American vendors (example) for the S1202512L 2k, but none for the 1K.

DrCR

_______

Posted: Wed Oct 20, 2004 6:36 pm
by ferdb
Ok Finally got some of the Globe 120x38 fans in. Part number is D47-B15A-04T2-100. Preliminary impressions however are that they are not much better than the rest of the 120x38 fans. I also got some of the old model blue label panaflos in. They seem better than the new Panaflos but they still don't approach the noise of the Nexus or globe fans.

I also got in a couple of 120x38 globe 115Vac fans.
Model numbers are
A47-B15A-15T1-100 5.5W, 1450rpm
A47-B15A-15T2-100 10W, 2600rpm

VICTORY! Now we are finally talking. I ran both undervolted and they both run very quiet. Oddly enough the quieter of the two was the 2600rpm model. At 60Vac it's about as quiet as a 120x25 Nexus running at 7v but moves considerably more air. I have not yet had a chance to compare them with backpressure (mounted on a radiator) and these are just my first impressions. The only downside is that although it's easy to set up a fixed undervolt with a transformer, it's not as easy to make it variable like the DC fans. Of course if you don't mind extra stuff hooked to your computer you can always get one of these cheap variacs for $50.
http://www.allelectronics.com/cgi-bin/c ... type=store
I think I may set up my computer with a couple of undervolted AC fans on the radiator and back it up with some DC fans on an automatic temp controller for some cooling insurance.

Posted: Wed Oct 20, 2004 6:44 pm
by ferdb
DrCR wrote:
ferdb wrote:The Papst 4212L (120x38mm) that I got recently is not a quiet fan. It has significant bearing and motor noise and is worse than both the Panaflo and Sunon 120x38mm fans....Globe makes a 120x38mm fan...
You got the model numbers for those Sunon and Globe axials? I'll add them to the list.
_________
The Sunon fans were KDE1212PMB3-6A 12V, 3.2W 120x38mm
The Globe Fans I listed above.

I'll do some more listening tests tomorrow when the background noise level goes down around here.

Posted: Wed Oct 20, 2004 6:51 pm
by ferdb
burcakb wrote:
ferdb wrote: Globe makes a 120x38mm fan, ...
Where did you get that information? Globe does NOT make 120x38mm fans.
http://www.globefan.com/DC.htm
http://www.globe-motors.com/d47t15.pdf


Now we could have a problem with the fact that these may be two different fan companies with almost the same name.

Posted: Wed Oct 20, 2004 10:59 pm
by burcakb
Yes, this company is not the famous Globe we all love. The famous fan-maker Globe is the one I listed.

Looking over the globe motor site, I got the feeling that these guys make the motors and some metalworking but have little or no experience with plastic moulding. Probably, they make the motors and have them fitted in a fan by some other company. Those fans do suspiciously look like dynaeon or colorful fans.

Globe on the other hand is a HUGE manufacturer of fans.

Posted: Thu Oct 21, 2004 8:01 pm
by Wex
I also just got some OEM 120mm Panaflo's in. They are accually really quiet. Well at least mine are. They are unaudible when undervolted at 5 volts and still push enough air to decently cool my case. At 7v you can just hear the whooshing of air and at 12 you hear a slight humming if you put your ear 1 foot away. There's also the air noise obvously at 12v. Overall I am very satisfied wih my purchase.

Posted: Fri Oct 22, 2004 11:04 am
by ferdb
Wex wrote:I also just got some OEM 120mm Panaflo's in. They are accually really quiet. Well at leat mine are. They are unaudible when undervolted at 5 volts and still push enough air to decently cool my case. At 7v you can just hear the whooshing of air and at 12 you hear a slight humming if you put your ear 1 foot away. There's also the air noise obvously at 12v. Overall I am very satisfied wih my purchase.
Where did you get your 120mm Panaflos at?

Posted: Fri Oct 22, 2004 5:56 pm
by DrCR
Yes, please tell. :)

Posted: Fri Oct 22, 2004 6:55 pm
by Wex
www.thermalfx.com Got here in two days. I live in the San Jose area, Cali.

Posted: Sat Oct 23, 2004 1:12 pm
by ferdb
I got 3 of those also, they were a little quieter than the current Panaflo's but they still have a lot of motor noise for me. Compared to the Nexus and Globes 120x25 they are pretty noisey.

I've kind of given up on finding a quiet 120x38 brushless DC fan. I'm either going to use Nexus or Globe 120x25's and hope the pull enough air through the radiator, or put them on both sides of the radiator, OR.... use AC fans. I have a few more types of 120x38 AC fans enroute, hoping to find a good 240v fan that runs nicely at 120v.

I already have some very good 120Vac fans from Globe motors that run nicely with 2 in series across 120V. I'm very encouraged so far with the undervolted AC fans as they are as quiet as the Nexus fans yet push considerably more air. Also I can back things up with temp controlled Nexus or globe DC fans.

The only drawback is that they are not easily speed controlled automatically with temperature. However I usually just set up the fans to run quietly and then clock and Vcore the CPU appropriately to get things running at an acceptable temperature range.

Posted: Sat Oct 23, 2004 7:19 pm
by DrCR
Very interested in how those 240V fans turn out. Keep us posted! :)

Posted: Sun Oct 24, 2004 8:27 am
by mshan
120mm x 38 mm M speed Panaflo's $3.99 at BGMicro:

http://www.bgmicro.com/
prodinfo.asp?sid=0439120370370372437235191&prodid=FAN1080&page=3&cri=fan&stype=3&time_out=44

Posted: Sun Oct 24, 2004 9:22 pm
by DrCR
Wow, that's cheap! They're all probably from the same batch though. Even so, for the same price as a Nexus, you could buy a bunch of these. Tempting, very tempting...

Posted: Mon Oct 25, 2004 5:41 am
by Ralf Hutter
120mm M1A's are quite loud, even at 5V. I'd think twice about using them, although for $4, you're not losing much.

Posted: Mon Oct 25, 2004 12:01 pm
by Prozzaks
I recently bought 3 FBA12G12L1A and 3 FBA08A12L1A. I bought them on www.digikey.com. The price for the one 120mm is about 24$ and 11$ for one 80mm.

I believe what I have received to be OEM fans. I was under the impression that they were quiet fans. Upon testing the following became quite obvious :

1. They are not quiet @ 12V ( I expect it, but I didn't think they would be THAT loud! )

2. They make a loud kind of clicking noise. It's regular so I don't think it's the bearings. I think it is noise generated by the fan switching. @ 12V it's unbearable!

It does get less noisy when they are undervolted but it still remains. When undervolted, it more of a vibration than a noise. I can really feel it when holding the fan in free air. However, if it's mounted directly in a computer casing, it makes a lot of noise.

The 120mm generate a stronger vibration than the 80mm. I think it's simply because the mass of the rotor is grater and that the torque must also be greater.

My test suggest that many ( 2 or 3 ) undervolted FBA08A12L1A move just a much air a single undevolted FBA08A12L1A.

3. The FBA08A12L1A fans I have make a lot more noise than the one MikeC has recorded. This goes to prove that not all fans of a given model are made equal. It also make me wonder what kind of qulity testing Panasonic does to ensure that the fans their fabs produce respect the specs they publish.

Do they publish specs that lists more noise and less air flow than most their fans to be sure that the fans produced fall within the specs given? Are they playing dirty and selecting the best fans to come out of production to use as reference for the spec?

The bottom line is that I am not satisfied of the fans I have bought from digikey. Although the list price is good on their site, the shipping and custom fees gave me a bitter invoice for fans that did not live up to my expectations.

Posted: Mon Oct 25, 2004 7:41 pm
by ferdb
This was my experience also with the 120x38mm Panaflo L1A's. The noise you are refering to is the coil switching noise in the motor. When the coils switch on they deliver a sudden torque pulse to the fan and the whole thing sounds like an idling diesel engine. This is aggravated by the large motor hub.

I chewed my way into the back of a one of these panaflos and modified the coil drive circuits to slow the switching and mellow out the noise and it does help a great deal. However it's only suitable when the fan is undervolted, when you run the fan up near 12V it runs rough and the drive circuits get excessively hot. I shelved the idea as less than ideal (the Panaflos still have a good amount of bearing noise anyway) and started tinkering with AC fans (after buying and trying a large number of other dc fans with little success other than the Nexus 120x25 and the Globe 120x25).

I've tried a number of AC fans now and come up with some real winners.
Globe Motors A47-B15A-15T2-100 are 120v AC fans
If you connect 2 in series across 120V they run about 950rpm and are very quiet, comparable to a Nexus undervolted to about 9.5-10v. They flow substantially more air than the Nexus and since they are thicker they should handle backpressure better but I have not actually tested their performance with backpressure yet.

Sunon 2123XST is a 240 Volt fan and runs 1300-1350rpm on 120V. At this speed it makes more noise than the Globe Motors fans but only because of the higher RPM. Slowed down to around 900 rpm it is almost inaudible at 1 meter in open air and pushes a good amount of air. Even at the 1300rpm level it is much quieter than the Panaflo L1A dc brushless. There is almost no motor or bearing noise, it is all airflow noise. These Fans also only cost $9 ea from Allied Electronics.

Unfortunately I could not get a Sunon 2123HST, 2123MST, or 2123LST which are the slower 220 fans. Since the majority of equipment in the US are 120v the selection of 240v fans is limited. Those other models are available in australia and europe. If those other fans could be found they would run at a lower rpm on 120V than 1300 and maybe down around that almost silent 900-1000 rpm range.

I'm going to try a series resistor on the 2123XST fans to adjust their speed down a bit when I get a chance. If this works well then the 2123XST may end up being the best fan to use because it will be easy to set the desired speed with a resistor ( 2W at a few hundred ohms should do it).
One last important note on finding quiet Fans:
Sleeve bearings are good (much less bearing noise)
Ball bearings are bad (much more bearing noise)

The ball bearing fans spin easier and a run a little faster, but they have a great deal more bearing noise than the sleeve bearings.

My current recommendation list for 120mm fans is as follows

1) Nexus 120x25 - because it's 12V, easily speed controlled and very quiet. The big caveat is the weak airflow, if it's insufficient to do the job look below.
2) Globe 120x25 - 12V, easily speed controlled and quiet ( not as quiet as the Nexus). These you can crank up faster than the Nexus to flow more air but at the price of even more noise.

3) Sunon 2123XST on 120V - This easily has the best airflow vs noise ratio of the lot. The only quiet 120x38mm fan. Probably performs better than the others against backpressure. Reduce the RPM with a series resistor to desired level. Cons - it runs off 120V, not as easily speed controlled, You may need a 120V relay (such as a pump relay) to switch it on with your machine.

Posted: Tue Oct 26, 2004 9:28 am
by Prozzaks
Are there Axial 12V DC fans bigger than 120mm?

I'm designing a new computer enclose and I want it to be as quiet as possible. I'm starting to think about unsing a bigger fan with a suitable quiet DC motor with a belt to drive the fan.

Posted: Wed Oct 27, 2004 5:31 am
by ferdb
There are axial fans much larger. However all the DC brushless fans larger than 120mm that I've tried are not quiet even when undervolted, (they are noisier than even the worst 120mm fans). If you want to use a large fan on your case I would definitely get an AC fan and undervolt it. You can find AC axial fans that are much quieter than the DC ones. Or you can use multiple 92 or 120 fans such as the Nexus or globes.

Posted: Wed Oct 27, 2004 6:49 am
by DrCR
Ralf Hutter wrote:120mm M1A's are quite loud, even at 5V. I'd think twice about using them, although for $4, you're not losing much.
Ah, my bad. Those are Ms, not Ls.

DrCR
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Posted: Wed Oct 27, 2004 7:16 am
by MikeC
A quick & dirty summary of 8 samples of the Nexus 120 fan from recent testing in the SPCR lab: (WARNING -- noise obsessed language / attitudes ahead!)

12V : 38~41 cfm : 22~23 dBA/1m
9V : 31~33 cfm : 19~20 dBA/1m
7V : 23~24cfm : <18 dBA/1m
5V : 15 cfm : <17 dBA/1m

It does not start reliably at 5V; ambient temp may have an effect. 5.5V is usually OK, but 6V is probably safest. All new samples seem to take around 10 mins of running at 12V to run at rated cpm/cfm. Once this was done, they seem to get there right away at 12V in subsequent starts. It may be the bearing becoming seated? Not positive whether when left static for a while the start voltage rises higher -- this needs to be checked. There is no variation between the samples that I could detect -- 2 of which were obtained at different times months ago while 6 just arrived last week.

It is the quietest of all the 120mm fans I have on hand at 12V by a big margin. There is virtually no bearing noise of any kind, just the noise caused by the spinning blades against the air. The ramp down in noise is almost perfectly linear -- lower the voltage, and the fan noise just gets quieter. No clicking, no buzzing. There is a soft low frequency humming sort of noise that you can hear more of as fan speed is lowered -- only when you get really close -- like 6". This effect seems to be just the fan blades against the air, like wings beating against air? -- it's not a bearing noise. All the 120mm fans exhibit this loise at low speeds.

At <7V, it is subjectively quieter than most 80mm fans at similar speed (blowing half the air). It may actually be quieter than a good Panaflo 80L. YMMV -- may depend on who's listening and whether there is any impedance (grill) nearby. If there is, the smaller fan will sound quieter because it will be pushing much less air & have less turbulence.

This Nexus 120 + Thermaright XP-120 is absolutely killer.

The Globe and AcoustiFan 120s are also very good at low enough speed but they show some evidence of bearing noise. I don't have as many samples of those, and my samples may not be perfectly representative. Still, I have to say that except maybe at the lowest speeds, I can hear the high freq, more prominent buzzing resonance of the clear plastic in those fans. A bit reminiscent of aluminum case panel hum & quite annoying to me at all speeds above ~1000 rpm. Maybe I am hypersensitive to this.

Keep in mind that most of the subjective reactions above are from listening to the fans very closely at very close distances. The differences between this fan and others may be less pronounced at greater distance and more casual exposure (as opposed to intent listening). I will have an article on new reference fans with sound files and the whole fan testing rig / operation in about a week.

Posted: Wed Oct 27, 2004 1:30 pm
by Ralf Hutter
FWIW, from my own recent testing of 3 120mm Nexus fans and 12 120mm Globe fans I can say that I agree with MikeC's evaluation 100% (except for the raw dBA numbers 'cause I have no SLM).

Posted: Wed Oct 27, 2004 2:30 pm
by ferdb
I'll second that motion. Nexus is the quietest with almost no motor or bearing noise, mostly wind noise. Globes have more bearing noise at all speeds, but a lot higher airflow at the top end if you can put up with the noise at those rpms.

Basically use the Nexus 120mm fans unless they just can't supply enough airflow to meet your needs.

The rest of the 120mm fans out there are much worse than these two options. That means Panaflos, Sunon, Papst, T&T, Globe motors, Comair, Vantec, and NMB. I have multiple samples of all of these, even the old OEM panaflo blue labels.

Personally I'm going to be using Sunon 2123XST AC fans undervolted, which are even better than the Nexus and push more air. You do need to use vibration isolators when mounting the AC fans to get them their quietest.

Posted: Wed Oct 27, 2004 7:55 pm
by DrCR
MikeC wrote: The Globe and AcoustiFan 120s are also very good at low enough speed but they show some evidence of bearing noise. I don't have as many samples of those, and my samples may not be perfectly representative. Still, I have to say that except maybe at the lowest speeds, I can hear the high freq, more prominent buzzing resonance of the clear plastic in those fans. A bit reminiscent of aluminum case panel hum & quite annoying to me at all speeds above ~1000 rpm. Maybe I am hypersensitive to this.
Oooh, very interesting. Did your non-clear Globe S1202512L-3M samples have the same high freq as the clear AcoustiFans?

Do you have any samples of Yate Loon fans? Perhaps then, based on what you said above, the Yate Loons would be the better 'silent with the ability to crank some CFM on demand' fans rather than the Globes. Too bad they're so hard to get a hold of. Still though, I doubt any of the SPCR following would ever need more CFM than the Nexus at 12V, and for the not quite so silent/quiet dedicated, the Globes would good enough, perhaps more than good enough.

Oh, and ferdb, man am I glad I mentioned SPCR to you! ProCooling must have been a pretty hard place for you to talk quiet related (at least it is for me). You are now my official 120x25+ axial fan guru! Not that that means a whole lot... :lol: Thanks for your contribution here! I just may use 120V axials in my quasi-external rad box...

DrCR

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Posted: Thu Oct 28, 2004 6:52 am
by Prozzaks
I'm remembering now that a few years back ( before I was a silent PC PhR34K ) I had bought a 150mm 12VDC metal fan. It was rated form 8V to 14V. It ran pretty quiet @ 12V and moved A LOT of air. The blades where perfectly balenced. On the rotor, you could see that they milled away small hole to make sure it was balenced.

There was of corse the whoooossshhhiiinnnggg noise and a little of bearing noise. But overall, it ran without any vibration ( until I accidentally dropped it :( ). I wish I could remember the brand so I could check out their products. I'm sure that undervolted such a fan could be pretty quiet and still move a lot of air.