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revoltec 3,4" control causes fans make strange noise

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September 15, 2006 8:00:10 PM

hi!

i just got a new revoltec 3,5" fan controller. i plugged it in and i think there is a small problem with it.

(a little intro here)
i have 4 fans in my case (gpu 60 mm - a zalman clone called pentagram, front - kama bay 120 mm, rear - an 80 mm arctic cooling, and an 80 mm coolink front bottom to blow over hdd and into nb heatsink). the gpu fan and rear fan were controlled with fan controllers in the back of the case (one controller per one fan). these old controllers allow to feed 5 - 12 v and work perfectly fine all this voltage range, but make me dive under my desk each time i want to up or down the speed (up when gaming, down when idle). the front kama bay and coolink are v low speed and i didn't need to slow them more.

so, after a lot of searching i found this blue (matches my white/blue case) revoltec controller with four knobs highlighted with red LEDs, bought it, got it today and immediatelly installed.

when i connected my 4 fans to it, they all started to make irritating sound when i lowered their rpm just a little below max. actually, only when on max rpm (12 v) they don't make the strange and annoying sound (sth like high pitch buzzing, like a fly or a bee). i've never heard this sound before from any fan on any speed. and it certainly didn't happen with my old back-mounted controllers. the sound ceases only when the knobs are set to max. when turned down just a wee bit - it starts again. when at minimum, just the same. i tried plugging the fans in different configurations, all at once, one by one and so on.

also, the red LEDs are supposed to fade when the voltage is set to low - but they don't. maybe that's supposed to means sth? ( i don't care about the LEDs, i don't need them, but they seem OOO as well).

oh, the revoltec thing supplies 7 - 12 v (not 5 - 12v!)

once again - the fans are ok, perfect when working just pluged to the mobo or with the back controllers.

has any one of you had this kind of problem before? have you heard about it?

or maybe you know what causes it because you deal w electronics and such? (i'm no good with electronics, don't even have a soldering iron)

thank you for any advice that you could have for me!
September 16, 2006 2:07:03 AM

Sounds like the PWM duty cycle is out of whack.

Here's an explanation of PWM for kater:

The fan controller doesn't lower the voltage, it chops out little portions of it. If, for example, it turned the power off 10% and on 90% of the time the fans would run about 10% slower.

If the controller is correctly designed then this chopping of the voltage happens fast enough to be smoothed out be the mass of the fan blades and the inductance of the motor windings. (A similar method is used to dim LED displays and is smoothed out by your eyes' persistance of vision.) But, the controller can be poorly designed. An extreme case would be a controller that turned the fans off for 1 hour and on for 9 hours when set to 90%.

Now some fan motors just don't like PWM at all, but given the fact that every one of your fans makes this noise, it's probably the controller.

Also, if you are young and haven't been exposed to a lot of loud noises your hearing in the upper frequencies will also be more sensitive. You could just wait ten years.
September 16, 2006 11:16:46 AM

brer, thanks for replying quickly and PWm explanation :) 

by saying the controller is "out of whack" you mean it's faulty or badly designed or a lemon or... ? i mean - are there any chances that a replacement will work properly? or is it just a poorly designed and built piece of hmmm equipment that will never work with my fans?

the vendor says he can replace it but will first contact the manufacturer/supplier and ask for possible explanation. i'll forward him the info i've gathered already (from you and from spcr)

i did some googling and one of tom's articles/reviews says PWM controllers caused similar problems, but with small fans. here, it's big fans. oh, and the smallest one (gpu) actually behaves decently - when in low rpm this strange sound is nearly inaudible, and when in high rpm it stops completely (but then it's just a loud high rpm fan)

do you think an electronics-savvy geek/modder would be able to replace the PWM piece with a simple voltage regulator (4 of them actually)? i like the looks of this revoltec, it's really nice, and would like to keep it, at least it's body - maybe it's possible to retrofit just a couple of those simple yet effective 5-12v regulators? what do you think?

once again, thanks for your help!
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September 16, 2006 9:29:23 PM

Oh, I forgot, PWM stands for Pulse Width Modulation.

I'm guessing it is marginally designed. The frequency is close to the range of human hearing and you are cursed with good ears.

It is possible that this is just a faulty unit, you have to balance the annoyance of full RPM versus the annoyance of trying another unit.

The pictures I see of the Revoltec front panel show it to be pretty simple. I'm not even sure you need any skill in electronics. With a little care you should be able to mount some other unit in the panel.

Yes, it would be pretty easy to design a 5-12 controller at about 5 Watts. I would say about two hours work. Engineering consultants bill at about $150 an hour and up, so you may want to find a standard unit somewhere.

I'm guessing your native language is not English because "Revoltec" just sounds too close to "Revolting", I would avoid the unit just based on the name.
September 16, 2006 9:52:20 PM

i found some info on pwm in spcr forums and related links - helped me a bit. there seem to be pros and cons for using pwm and for using voltage up/down adjustment

talking about the sound volume - trust me, you can hear this dreadful whining from another room! a few meters away - it's really loud. one has to be my grandma not to hear it ;) 

i just hope this particular unit is just faulty and the replacement will be ok - i just can't imagine a company like revoltec (big one, renowned and all) selling fan controllers that cause fans to make such annoying noise. just doesn't add up. and by now i think i could have found some negative feedback on that particular one - been googling a lot, talking to people, browsing forums and so on (i mean when i was searching for a 3,5 panel in the first place - not now)

no, english is not my native language. i'm from poland. and work as an interpreter pol/eng eng/pol ;)  so it's pretty close to be my second language

if - IF - the unit turns to be ok and and is just supposed to work in that way, and if my vendor refuses to make a refund, which i doubt can happen, i think i'll visit a couple of local shops for electronics maniacs, talk to some people and find a guy who will gladly accept the challenge of turning this unit into a properly working rheobus - and for a sixpack :) 

i'll try it tomorrow with my brother's computer and his set of fans, maybe it'll be different there

well, i sure hope i can still walk away victorious

thanks again!
October 5, 2006 1:10:51 PM

ok, so it's like that

i read a lot on pwm control and think it's what caused all the noise, as hinted by many others here and there

my vendor checked the controller i returned and found it ok, but agreed to replace it with a voltage control akasa 3,5 (silver, 3 controllers + 2 x usb). this new one works perfect and will match the silver/white p150 that's due next week (two weeks?) so esthetically it's ok, and it also works like it should - no more diving under the desk to adjust for gaming vs officing, no more back pains

meanwhile, i found and contacted a couple of revoltec 3,5 owners and they confirmed they had some problems with noisy fans - tho in most cases were able to find fans that were somehow compatible - fine for them

i checked mine with almost 10 different fans, various sizes and makes, and only one worked fine - too bad

well, that's all, folks

once again a BIGTHANKYOU with a pint of your frosty, favorit local to all contributors
!