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Re: Noctua to use Active Noise Cancellation in new Fan

Posted: Sat Jun 02, 2012 7:46 am
by Reachable
ces wrote:
QuietCat wrote:it doesn't seem to reduce the rushing air sound pressure levels by very much,
It should reduce whatever sound the microphones pick up.... provided it is tuned to operate in that frequency range. So it is all about microphone placement and circuit tuning. Though my guess would be that as the mass of the blades increases, it will be less able to work with higher frequencies.
It's the low frequencies (quite present in the larger fans) that are the hardest to block with insulation. Even if this technology were effective with those fans only in that frequency range it would be a huge blessing. I wonder, though -- would it not take a huge amount of power to work with blades that massive?

Thanks for the explanation of how it works.

Re: Noctua to use Active Noise Cancellation in new Fan

Posted: Sat Jun 02, 2012 8:00 am
by ces
Reachable wrote:It's the low frequencies (quite present in the larger fans) that are the hardest to block with insulation. Even if this technology were effective with those fans only in that frequency range it would be a huge blessing. I wonder, though -- would it not take a huge amount of power to work with blades that massive?
It shouldn't take to much power. If you are targeting lower frequencies, it would seem easier to do compared to higher frequencies. Low mass, high flexibility fan blades are what is key.

Re: Noctua to use Active Noise Cancellation in new Fan

Posted: Sat Jun 02, 2012 8:07 am
by Just an ordinary rabbit
I think that the fan is based on the similar principles to this:

Re: Noctua to use Active Noise Cancellation in new Fan

Posted: Sat Jun 02, 2012 8:39 am
by MikeC
This is obviously off topic, but....
Just an ordinary rabbit wrote:I think that the fan is based on the similar principles to this:
That is an amazing device, and a truly unique technology! Too bad it's so focused on high end and reproduction of sound down to 1 Hz. Like we all really need that. Note the pricing:

TRW-17 transducer $12,900.00
Motor Controller $450.00
BT-42 Amplifier and crossover $1050.00
Design and installation, typical $8,000-$12,000*
Total $21,950-$25,950

Re: Noctua to use Active Noise Cancellation in new Fan

Posted: Sat Jun 02, 2012 8:53 am
by ces
MikeC wrote:Note the pricing:
Looks like people aren't getting in line to purchase it. The site hasn't been updated in a while.

Re: Noctua to use Active Noise Cancellation in new Fan

Posted: Sat Jun 02, 2012 9:29 am
by MikeC
About the only worrisome part of this project is that the chosen NF-F12 fan that Noctua & RotoSub are working on isn't exactly what I'd call great sounding. It has a bit more tonality (audible peaks) at every speed than most quiet fans, some of which can be heard in our recording of it made for the Noctua NH-L12 low profile cooler. http://www.silentpcreview.com/files/sou ... 0v-12v.mp3

My hunch is that those "eleven stator guide vanes that straighten, channel and focus the airflow" which Noctua crows about are responsible for this tonality. 11 struts right up against 7 spinning blades -- they have got to create tonal peaks. In the spectrum view, I saw them at 200Hz at 550rpm, then 200 and 400Hz at 700rpm, etc.

Yes, I know, I'm talking about hearing this at 1-2' distance in an anechoic chamber, but many other quiet fans don't make this sound, they are less tonal. My point being that if the ANC is employed to help reduce this sound so that the fan can be run at higher speed, perhaps its benefit for a more conventional quiet fan would be much less, because they have less tonality to begin with.

All conjecture tho. The proof will be in the final product.

Re: Noctua to use Active Noise Cancellation in new Fan

Posted: Sat Jun 02, 2012 10:55 am
by ces
MikeC wrote:My hunch is that those "eleven stator guide vanes that straighten, channel and focus the airflow" which Noctua crows about are responsible for this tonality. 11 struts right up against 7 spinning blades -- they have got to create tonal peaks. In the spectrum view, I saw them at 200Hz at 550rpm, then 200 and 400Hz at 700rpm, etc.
That perhaps make it a good candidate for quieting.

Question, if you are going to use the fan by placing it up against the fins of a heat sink, shouldn't those fins generate some tonality? Is not, to some extent, the struts substituting themselves for the tonality that would be generated if you placed the fan up against the fins of a water radiator (without the use of a plenum).

At least with the struts, the fan manufacturer gets a chance to tune the fan to minimize the problem? Would that not be so.

Does the nexus pick up tonality when paced against different types of heat sink fins?

Re: Noctua to use Active Noise Cancellation in new Fan

Posted: Sat Jun 02, 2012 11:19 am
by MikeC
ces wrote:Question, if you are going to use the fan by placing it up against the fins of a heat sink, shouldn't those fins generate some tonality? Is not, to some extent, the struts substituting themselves for the tonality that would be generated if you placed the fan up against the fins of a water radiator (without the use of a plenum).

At least with the struts, the fan manufacturer gets a chance to tune the fan to minimize the problem? Would that not be so.

Does the nexus pick up tonality when paced against different types of heat sink fins?
It's the regularity of the radially placed "spokes" which generates tonality as the fan spins. In a typical heatsink, even though the fins are butted right up against the fan, the positional relationship between each fin and each blade varies quite a lot as the fan spins. There isn't the same kind of regular metronomic pass by each fin across each strut. The spacing between the HS fins is also way too tight, so rather than one or two tones, many are generated.

Which answers your last question, no, mounting any fan on any heatsink increases turbulence noise, not tonality. The latter sometimes occurs, usually when a fan is spinning pretty fast, but its caused by vibrating fins on the heatsink, not the regular air-borne interaction between blades and fins.

As for the second question, I'm not sure. But... Taking away the tonality that is caused by the extra struts doesn't necessarily eliminate tonality that might be caused by external impedances in actual usage.

Re: Noctua to use Active Noise Cancellation in new Fan

Posted: Sat Jun 02, 2012 12:10 pm
by ces
MikeC wrote: It's the regularity of the radially placed "spokes" which generates tonality as the fan spins. In a typical heatsink, even though the fins are butted right up against the fan, the positional relationship between each fin and each blade varies quite a lot as the fan spins. There isn't the same kind of regular metronomic pass by each fin across each strut.
So in your opinion, something like the Nexus beam air is not so likely to generate resonance while straightening as air current
http://www.nexustek.nl/NXS-nexus-beamair-airguider.htm
as opposed to the approach taken by Noctua and silverstone
http://www.newegg.com/Product/Product.a ... 6835220046

Re: Noctua to use Active Noise Cancellation in new Fan

Posted: Sat Jun 02, 2012 12:14 pm
by ces
MikeC wrote:It's the regularity of the radially placed "spokes" which generates tonality as the fan spins.
It would seem the predictable tonality type of noise, is the very type of noise that this system would be most easily be able to be tuned to block.

Do you agree or disagree?

Re: Noctua to use Active Noise Cancellation in new Fan

Posted: Sat Jun 02, 2012 2:00 pm
by MikeC
ces wrote:
MikeC wrote:It's the regularity of the radially placed "spokes" which generates tonality as the fan spins.
It would seem the predictable tonality type of noise, is the very type of noise that this system would be most easily be able to be tuned to block.

Do you agree or disagree?
But on the other hand, if the spokes were not there or if they were better designed, there would not be this tonality to begin with.

Re: Noctua to use Active Noise Cancellation in new Fan

Posted: Sat Jun 02, 2012 2:06 pm
by MikeC
ces wrote:So in your opinion, something like the Nexus beam air is not so likely to generate resonance while straightening as air current
http://www.nexustek.nl/NXS-nexus-beamair-airguider.htm
as opposed to the approach taken by Noctua and silverstone
http://www.newegg.com/Product/Product.a ... 6835220046
I have not heard the Nexus product, but have heard the effect of honeycomb filters, and iirc, they do not increase tonality, or at least not much. Turbulence noise does go up.

I have the Silverstone fan, and its tonality is not bad, mostly turbulence noise (mainly white/pink or random noise) seems increased a bit. It does have some tonality, at certain range of reduced speeds, the tone appears around 450Hz, but it's not very loud.

This is not to say conventional fans don't have tonal aspects; they do, they all have some tonality at some speeds. It's just that this particular Noctua seems to have more than is usual for a "quiet" fan.

Re: Noctua to use Active Noise Cancellation in new Fan

Posted: Fri Jun 08, 2012 4:09 am
by Mats
Availability is 12 - 18 months away, price at least €40.

http://www.pcgameshardware.de/aid,88955 ... lung/News/

Re: Noctua to use Active Noise Cancellation in new Fan

Posted: Sat Jun 09, 2012 12:47 pm
by CA_Steve
More on this via The Tech Report.

Tiny magnets embedded in the fab blades and a coil in the frame to deflect the blades a small amount. Cute.

Re: Noctua to use Active Noise Cancellation in new Fan

Posted: Mon Jun 11, 2012 3:49 pm
by MikeC

Re: Noctua to use Active Noise Cancellation in new Fan

Posted: Mon Jun 11, 2012 5:42 pm
by CA_Steve
Nice. Active noise cancellation has come a long way. I was involved with an ANC application in the late 80's. Needless to say, the component count and cost was a tad higher.

Re: Noctua to use Active Noise Cancellation in new Fan

Posted: Tue Jun 12, 2012 3:43 am
by Jens Lyn IV
MikeC wrote:around 90 dB ambient
:shock: Bloody sodding hell! Remind me never to go near a trade show... :mrgreen:

Re: Noctua to use Active Noise Cancellation in new Fan

Posted: Tue Jun 12, 2012 6:18 am
by MikeC
Jens Lyn IV wrote:
MikeC wrote:around 90 dB ambient
:shock: Bloody sodding hell! Remind me never to go near a trade show... :mrgreen:
:lol:
Yeah, most are pretty noisy. People, hawkers, music, sound effects, etc, all in huge great halls w/o a stitch of damping. Truth is, downtown Taipei itself is such a noisy place that when I get back home, my ears ring and I have that numb sense around my hearing for a couple of days. Not so different in many big cities, though.

I do remember thinking the first time I went to Taipei, "No wonder nothing quiet ever comes out of here, they have no idea what quiet is!" Then I was introduced to a top story room in a building Shuttle called their quiet room. About 10x10' w/ a very high ceiling -- 12' maybe -- all lined w/ ordinary eggcrate foam, which I know does almost nothing. Then a jet plane flew over & no one could hear/say a word for a minute or two. It was quite comical, really.

Re: Noctua to use Active Noise Cancellation in new Fan

Posted: Wed Jun 13, 2012 12:59 am
by gb115b
so retail availability looks a bit far off for now? when do you think you'll get a hands-on, Mike?

looking forward to what corsair have to offer as well :)

Re: Noctua to use Active Noise Cancellation in new Fan

Posted: Wed Jun 13, 2012 6:02 am
by faugusztin
"but we're working hard to achieve this goal within the next 12 to 18 months."

In other words - Q3 2013 or later.