Some new test equipment

I noticed that the Scythe's have exactly the same frame as the other Adda based fans (e.g. Globalwin, or Acoustfan, or ArcticCooling). I wonder how many similarities are really there.

As for rubber mounts, I ummed and erred over this, and just decided to mount everything without grommets or dampening rubbers. I've been taking notes as to which fans cause the most excitation, and I'll likely go back and revisit those fans with isolating silicone pads.

Rather than fit fans with any provided vibration dampers, I figured that this wasn't a level playing field. I want to see what the base fan is like without damping material.

You are right in that the Scythe F has very low to moderate excitation. The CoolerMaster in comparison had moderate to high excitation almost through the entire range, with only a couple of low points, and it is this which primarily is seen in its poor noise performance.

The bulk of the Scythe's noise/flow performance purely derives from its efficient blade design. It pushes more air through the radiator per RPM than either the Tricod or the Coolermaster, and lower revs means less noise.

What I'm also measuring is power draw too, with the goal of not only finding a quiet fan, but if two fans are very close together, then I'll separate them later and pick a winner decided through their power draw.

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Originally Posted by ranker

But any sort of undervolting with my Sunbeam Rheobus at the time would resort in all sorts of clicking/mechanical noises.

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Sounds like something that a PWM controller would do. I'm using a lab bench PSU. Don't know exactly what electrical mechanism it's using to allow me to vary the voltage, but I know it's not PWM. Alternately you can get weird noises from a rheostat if the power signal has a lot of ripple in it.

Just by wiring some caps (1000uF, 1uF and 0.1uF) across the 12v-ground lines you can cancel out almost all power ripple and should quieten down any fans experiencing strange noises. Should even work okay for fans driven from PWM controllers too, but don't hold me to that.

It wouldn't surprise me at all if most rheobus's you buy don't make any attempt to properly control ripple.

Just finished flow-testing the (direct from) Yate-Loon D12SL-12 with the curved blades. Subjective observation is that excitation was very minimal, about on par with the Tricod Science, but the motor is still noisier (subjective). Will conduct full sound level measurements in 3-4hrs when it's late night here.

Interesting observation about the curved blades' flow vs rpm efficiency is that it's definitely than the Tricod Science, with the Yate-Loon's curved blades achieve the same flow as the Tricod, but at 100rpm lower. Noise measurements will now be interesting to see if this is enough to overcome the increased motor noise - I reckon it's going to be really close.

The Scythe F still holds a 50rpm advantage over the Yate Loon though, in that it achieves the same air-flow at 50rpm's lower.

This, to me, is really the hidden gem in all of this work. If we can isolate the best motor with the best blade design, for purposes of operation on a radiator, then all we need is for one fan manufacturer to listen to our needs and they'll wipe the floor with the rest of the market competitors, and give us all the perfect watercooling application fan.

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I have also not come up with a good, consistent, low-cost way of recording sound....been searching for awhile now If I find anything, you'll definitely be one of the first to know Cathar

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All down to the microphone... I'm a firm believer in using flat-response Active Ribbon Mics for this purpose... run direct into digital recorder, not via any preamp or channel strip. Problem with recording fan noise, everyone has a volume knob at playback. All results become relative, and influenced by the characteristics of the speakers being used to play back that noise. You can never produce a fair representation that will be consistent regardless of playback medium. All you'll find is a level of compromise.

Anyways - have a read... source: http://www.vent-axia.com/knowledge/h...ion2/noise.asp

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In-duct, Open - inlet/outlet, Spherical radiation, Hemispherical radiation.

A fan manufacturer can publish noise information for various installation conditions.

It is important to consider the use or installation conditions of a fan when checking a manufacturer’s noise data. The information given may not always be appropriate and it is as well to check. As is the case with Sound Power Levels, Sound Pressure Levels must be quoted or each Octave Band if a complete picture of the effect of the noise on the human ear is required.

*SNIP*

THE ENGINEER MUST CLEARLY DISTINGUISH AND UNDERSTAND THE DIFFERENCE BETWEEN SOUND POWER LEVEL AND SOUND PRESSURE LEVEL. HE MUST ALSO APPRECIATE THAT dB RE 10-12 WATTS AND dB RE 2x10-5 Pa ARE DIFFERENT UNITS WITH NO ABSOLUTE FORMULAE CONNECTING THEM.

It is impossible to measure directly the Sound Power Level of a fan. However, the manufacturer can calculate this level after measuring the Sound Pressure Levels in each octave band with the fan working in an accepted acoustic test rig.

What he cannot do is unequivocally state what Sound Pressure Levels will result from the use of the fan. This can only be done if details of the way the fan is to be used, together with details of the environment it is serving, are known and a detailed acoustic analysis is carried out.

A disadvantage of the Decibel scale is that values cannot be added or subtracted using the normal arithmetic rules. Decibel values must be converted back into absolute units of power (Watts), when they can be added or subtracted directly before re-converting back into ecibels. However, this tedious process can be avoided by using the following simple but approximate method. Column 2 shows how much must be added to the higher of two sound powerlevels to obtain the equivalent combined level, when the dB difference between the two levels is shown in Column 1.

*SNIP*

As an example, if one fan has a sound level of 50dB, and another similar fan is added, (the sound level is doubled). The combined sound level of the two fans will be 53dB. If two more fans are added, i.e. the sound source is doubled again, the resultant sound level from all four fans will be 56dB.

If the first fan had a sound level of 50dB and another, larger fan with a sound level of 55dB was added, the difference between the two is 5dB, so 1dB is added to the higher figure, giving a combined level of 56dB.

To estimate the effect of distance from a sound source the rule of thumb calculation is very simple. Sound normally weakens by 6dB each time the distance from the sound source is doubled. i.e. a sound level measured as 60dB at 1 metre will be 54dB at 2 metres and 48 at 4 metres.

Smaller fan sound levels are sometimes measured at 1m, whereas the industry standard is becoming standardised at 3m, for comparison purposes. The difference between 1m and 3m is therefore 9dB. (41dB@3m) and 50dB@1m are in effect the same).

*SNIP*

Unfortunately, the majority of fan manufacturers indicate the noisiness of their products by Sound Pressure Levels expressed in dBA (or dBC). These figures refer to the Sound Pressure Levels which would be experienced by an observer at a distance of 3m (or occasionally 1m or 3 x fan diameters) from the fan if both were suspended in an infinitely large and empty volume (technically called Free Field). To say the least, this is a very unlikely set of conditions and these dB values must only be used to compare the noisiness of similar types of fan!

It cannot be stressed too often, that on no account must the engineer be tempted to assume that the Sound Pressure Levels quoted in manufacturers’ catalogues will in anyway be similar to those achieved in practice. Depending on circumstances, they can be substantially exceeded or reduced.

Thought of objectively, using dBA to describe the noisiness of a fan is as absurd as stating the output of a heater in terms of the temperature it would produce three metres from its face if it were suspended in space! It will be better for all involved when only Sound Power Level information is used to specify fan noise. In the meantime, engineers must always be careful to check how noise information is expressed.

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Just updated the graphs in this post with the curved bladed Yate Loon D12SL-12 (obtained from PTS, sourced direct from Yate-Loon).

Ambient noise-wise it matches the Scythe S-Flex F up until we start getting above 12v (33cfm was at 12v for the D12SL-12). The S-Flex F did have more low-volume excitation occurring, so even though the S-Flex F had a lower sound-pressure level in the 5cm tests, it was generally more annoying in terms of the general ambient noise it generated.

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Originally Posted by Marci

All down to the microphone... I'm a firm believer in using flat-response Active Ribbon Mics for this purpose... run direct into digital recorder, not via any preamp or channel strip. Problem with recording fan noise, everyone has a volume knob at playback. All results become relative, and influenced by the characteristics of the speakers being used to play back that noise. You can never produce a fair representation that will be consistent regardless of playback medium. All you'll find is a level of compromise.

Anyways - have a read... source: http://www.vent-axia.com/knowledge/h...ion2/noise.asp

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Thanks for the advice & info Marci. You're exactly right in that unless someone has a set of monitors (the speaker type - not the visual displays) hooked up to their PC, they're not going to hear the same thing.

I'll look into an Active Ribbon Microphone.

A big concern for me is also the ability to record the sound quietly. Even my laptop makes more ambient noise than some of these fans do at lower rpm's. I can't record onto my main PC 'cos of the fan in the PSU and the hard drives.

I would pretty much have to run a cord from the mike in the room to my laptop outside the room to adequately isolate the fan noise. I'll dig into it, but if it's going to cost too much, I'll just settle for describing a subjective interpretation of the noises.


Next up on the testbed is a Zalman ZF1225ASH (aka ZM-F3). This fan clearly originates from the XinRuiLian factory fan mold, but the fan blade design and motor noise is different. I suspect that while it's a rebadged XinRuiLian fan, much like what Nexus do with Yate-Loon, the Zalman fans are being built to Zalman's specific requirements, and I'm satisfied that the Zalman fan is in fact a distinct fan in its own right from other XinRuiLian fans.

The Zalman fan from initial observations has a noisier motor than the the Yate-Loon L (it's a significantly more powerful fan at 12v as well), but pushes almost as much air per RPM through the radiator as the Scythe F, but excites the radiator/enclosure much less, with minor excitation throughout the rev range. So more motor noise than the Yate-Loon but able to push more air at a lower rpm, vs slightly less air per rpm than the Scythe with comparable motor noise but less excitation.

I reckon Zalman just might give the Scythe & Yate-Loon a very good run for their money. Coupled with its ability to push more air at 12v than either fan, might it just be the fan for low-noise and mid-range use?

Results in 5-6hrs from now.

I have 3 Tricod's in my rig as i happened to stumble across your thread in OCAU last year... let's see if your ear is as good as this amazing test setup! :D

Zalman tests are now complete.

I'll repeat the graphs here. I'll add in the 1m graphs too. The Zalman is an excellent fan. Like the Scythe F, you can see in the bumpiness of the graphs how it is prone to some excitation of the devices, but overall it had fewer excitation points than the Scythe F, and the excitation was of a lower magnitude.

Also, quite interestingly, ~1550-1700rpm was a real "sweet spot" for the fan, where the fan just didn't seem to care that much about the rpm's being changed with respect to pulling air-flow through the radiator. Around the same air flowed at 1550rpm as at 1700rpm, so overall, you could just stick the fan at 1550rpm and enjoy less noise but the same flow as at 1700rpm. 12.00v is at the 49cfm mark. The 54cfm point requires 13.7v. For all of these graphs, the right-most 10% of the curves represents over-volting the fan past 12v.

Overall, the Zalman looks extremely strong. Subjectively I'd place it ahead of the Scythe F, because it excites less, offers more air-flow at 12v for those who like to do the occasional benchmark run, and behaves extremely nicely when undervolted. As a general purpose work-horse for low-noise use, it's leading the pack to date, IMO.


Noise vs Airflow through PA120.1 radiator at 5cm

http://www.employees.org/~slf/curves...-noise-5cm.png



Noise vs Airflow through PA120.1 radiator at 1m

http://www.employees.org/~slf/curves...w-noise-1m.png



Ambient Noise vs Airflow through PA120.1 radiator

http://www.employees.org/~slf/curves...-noise-amb.png



I'll see if I can find a way to graphically place the rpms and voltages onto the graphs for each curve. That may require individual graphs for each fan though to prevent clutter.

I replaced the stock zalman fan that came with my v7700 cpu cooler for a yate loon b/c the motor noise pissed the :banana::banana::banana::banana: out of me. And the motor noise wasn't constant, sometimes it would be worse and sometimes less.

I'll have to check if it's the same fan as you tested, cathar. I still have it lying around somewhere.

Cathar,

i know it might be meaningless, but what's the batch # on your YL-SL? Do you have a sticker on both sides of the fan?

What's important is that is has the "curved blades," but I'm still just curious...

Zalman fans are crap quality. Usually bearings fail after short time of usage. My experiences are from friends 80mm Zalman fans and the fans that they use in their coolers.

Before we go ahead and paint all Zalman fans as bad, remember that they do just buy OEM fans from different manufacturers, get them made to their own specifications, and slap a Zalman badge on it. The fans are not made by Zalman, and not all Zalman fans are made by the same company.

The 80mm Zalman fans cannot be compared to the ZM-F3. Reading over at SPCR, a lot of people have had a bad experience with Zalman's 80mm fans, and some of their older 120mm fans, but they also noted that those fans are NOT from XinRuiLian.

The XinRuiLian based Zalman fans (i.e. the ZM-F3) seem to have grudgingly earned some respect over at SPCR. They are the same basic fan as the Fander FX120, albeit the Zalman spins at 1800rpm instead.

I did some digging. The Zalman CNPS7700 CPU cooler fan uses ball-bearings, which are almost always known to drone and make horrible noises. That's a totally different fan.

Please, unless you have direct experience with the exact fan model in question, refrain from trashing the fan based upon unrelated items in the Zalman range. You just may overlook a decent choice.

thanks, that's good news... although with 1800RPM @ 12v... the RPMs might be too high to leave on during the night @ 5v...

@ 5v what's the zalman fan spinning at? 1000RPM?

For the Zalman:

5v = ~875rpm, at around 13cfm on the graphs
7v = ~1175rpm, at around 27.5cfm on the graphs.

Minimal start voltage was 3.40v, which was also its minimum running voltage. Any lower and it'd stop. It's not like other fans which will typically still run at a lower voltage than they start at.

Further evidence that the Tricod Science is a different motor to the Yate-Loon is that the Tricod Science will start and run at 2.8v, while the Yate would only start at 4.8v

I see that I'll need to provide some voltage vs rpm graphs, and rpm vs airflow graphs for each fan to provide more complete info. I'll do that in the final article.

Picked up a laser tachometer today, so I can take the RPM measurements of the fans without a tachometer wire attached. This includes the Papst & Panaflo fans.

Therefore, next up on the testbed is the Papst 4412FGML, a fan that performed very strongly in Vapor's recent tests. Am looking forwards to seeing how it performs in comparison to the S-Flex, Zalman, and curved-bladed Yate-Loon. My pre-test perceptions are that it is a strong flow vs rpm challenger, but its motor/bearing noise may be the deciding factor.

So those dips and mountains in the 21F and Zalman 1m curves are the excitation intervals?

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Originally Posted by Jedda

So those dips and mountains in the 21F and Zalman 1m curves are the excitation intervals?

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Yes. They're not as prominent in the 5cm lines 'cos the fan motor & blade noise is the dominant factor there. In the 1m test, you're mostly seeing the excitement of the radiator+shroud coming to the front in the mountains. In the ambient level measurements, the undulations are more caused by general enclosure excitement, but it's muted 'cos the sound meter isn't pointed at the fan.

For the CoolerMaster, it was exciting everything almost everywhere, so rather than seeing any real undulations, it's more like a higher plateau.

You're uncovering some of the factors that have led to users with different cases reporting conflicting fan experience, I believe.
To what degree could case rigidity, case natural harmonics and mounting methods between users' installations vary a fan's excitation behavior but not similarly another brand?

Also need to remember that once both radiator and fan are mounted within a chassis, the backpressure becomes affected by the chassis... if the chassis is restrictive to airflow at the exhaust, and the rad is mounted at the inlet, then radiator fan performance will suffer... and vice versa.

So we have resonance affecting the auditory side of things, and restrictivity/backpressure of anything enclosing the "unit" (rad+fan) affecting the airflow side of things.

Papst 4412FGML results are now in the graphs.

The graphs are getting very cluttered now as a number of fans are all criss-crossing each other.

In terms of excitement, the Papst fared very well, and indeed far better than I initially thought giving the fan noise in free-air. I'd still have to give the nod to the Zalman, but by golly the Papst 4412FGML is close, in terms of best performance for noise coupled with minimal excitation.

Another thing the Papst graphs don't show is that at 1700-1750rpm the fan blades hit a "sweet spot" and push more air through the radiator at this point than at 1800rpm. Also, this co-incides with 12.0v being fed through the fan too, so it seems like the Papst engineers have done their homework, and have engineered a fan that peaks at its normal operating voltage. It's not until we feed the fan more than 13.0v does it start to exceed its 12v performance, and of course it's making a lot more noise by then.

There's also a second sweet-spot at 7.2v, which may also coincide nicely with a 7v mod.

The only real drawback to the Papst is that its bearings emitted a muffled ticking noise which never really went away, and fed through the enclosure. It is this noise that prevented the Papst from excelling in the very low volume area. At >22cfm (>6.75v, >1075rpm) the general blade noise starts to overwhelm the motor/bearing noise and the fan comes into its own.

Overall, I liked the Papst. I wouldn't pick it for anyone wanting to achieve very low-volume cooling, but for those who don't mind running their fans at >1100rpm speeds, it's an extremely strong performer.

Break graphs up into upperCFM and lowerCFM...? Tricod, Yate and CM on lowerCFM graph, Zalman, Scythe and PAPST on upper (as those three move far more CFM's at 12v than the other 3...) thus creating a low CFM @ 12v bunch & mid CFM @ 12v bunch...?

If he's going to do that, I could lend a new D12M from Petra's to try for more of the spread of D12 L-M-H, if you think it worthwhile Cathar?

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Originally Posted by Jedda

If he's going to do that, I could lend a new D12M from Petra's to try for more of the spread of D12 L-M-H, if you think it worthwhile Cathar?

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Sure, I'd appreciate that. Still, something to consider. Petra's is based in San Jose California, and I'll be back over there (in SJ, CA) come September, depending upon how my healing goes, and I'll just pay Alex a visit and grab some of him then. PTS is about 10 minutes drive from my office when I'm there.

I take it the graph representing noise from 1m is a more of a real life scenario for most?

Would motor noise affect the dbA at 5cm?

It's weird with the S-Flex, at 1m they really fluctuate - and so do the Zalmans to a certain extent.

Would both these fans use the same motor kind of motor? I know scythes are supposed to be unique with it's fan assembly.

Many thanks for the time and effort so far :)

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Originally Posted by Mekrel

I take it the graph representing noise from 1m is a more of a real life scenario for most?

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It depends. The 1m graph would be having the radiator fan pointed at your ear, but from 1m away.

The ambient noise test is done with the noise-sensor positioned 1m above, 1m in front, 1m to the left of the test box, and pointed at right-angles to the test box, so not towards it or away from it. The ambient noise test would be a bit like having the PC sitting on the floor beside a 4-legged desk.

The 1m test would be relevant to people with the PC sitting on the desk beside them.

The 5cm test is meant to be the "I had my ear up against the fan!" test.

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Would motor noise affect the dbA at 5cm?

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Most certainly. Well, it's a factor in the dBA at all positions, but at 5cm, blade noise and motor noise are more dominant than excitement noises because the sound meter is much closer to the fan while the enclosure/shroud is (relatively) further away.

At 1m, relatively speaking, the fan/shroud/enclosure are almost equidistant and so we're seeing more of a full mix of the noises.

In the ambient tests, the meter isn't pointed right at the fan, and so the fan/motor and shroud excitement noise more becomes background noise as it has to bounce around the room to reach the meter. The enclosure (that the radiator/shroud is sitting in) masks the excitement noise from the shroud/rad, but is itself radiating noise in all directions from its own excitement, and so it becomes the dominant noise, muffling the effects of shroud excitement.

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It's weird with the S-Flex, at 1m they really fluctuate - and so do the Zalmans to a certain extent.

Would both these fans use the same motor kind of motor? I know scythes are supposed to be unique with it's fan assembly.

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The Scythes appear to be OEM'd from Adda, and may very well be built using some special equipment Adda has set up just for Scythe's demands. The Zalman ZM-F3 is most definitely a XinRuiLian OEM fan, so I highly doubt that the motors are the same.