Reduce HDD idle noise?

Hagr · Post by **Hagr** » Wed Jul 29, 2009 9:27 am

Hi, first of all I am sorry if this has been brought up already. I did a search but couldn't find anything regarding this.

Anyway, I'm looking for a solution to reduce the idle sound from my hard drives. I use 2 spinpoints, which are rubber mounted, so the seek sound isn't really bothering me. But I'm trying to get rid of the idle "hum" from the drives, as that is almost the only sound source of my pc.

I've been thinking about purchasing 2 scythe quiet drives, but im not sure if it will help.

Any help would be very appreciated

Matija · Post by **Matija** » Wed Jul 29, 2009 9:56 am

The hum happens because of interference between the two drives. The platters in them don't rotate at the same frequency, which then causes resonance, and which is then transferred to the case. Rubber gromets won't do anything about that.

You need to suspend the drives.

Hagr · Post by **Hagr** » Wed Jul 29, 2009 10:21 am

Yes I thought of that too, i used hddscan to spin down one of the drives. The other drive still makes a sound, but it is greatly reduced

swivelguy2 · Post by **swivelguy2** » Wed Jul 29, 2009 11:39 am

Even with just 1 drive, rubber mounting is simply not nearly as good as elastic suspension. First, try that, then if it's still not good enough, you can begin to think about drive enclosures.

halcyon · Post by **halcyon** » Wed Jul 29, 2009 10:31 pm

I know this must have been covered before, but to make sure what's the state of the art these days:

What's the favorite elastic suspension material used by suspension gurus here at SPCR?

Some rubber materials oxidize and get brittle -> unsafe and also lose their elasticity, i.e. less damping.

What would be a safe, reliable and well damping material to use?

swivelguy2 · Post by **swivelguy2** » Thu Jul 30, 2009 4:20 am

The good stuff is:

- "Stretch Magic" which is available at fabric and craft stores in different diameters (generally smaller diameters). It's round and transparent

- "Clothing elastic" which is also available at fabric stores. It's white and flat - a typical size would be 3/8" or 1/2" wide

- Bungee cords, which are available at hardware and automotive stores. These are usually round and tend to come in larger diameters than Stretch Magic, but if you can find it as small as for example 3/16" diameter, it's good.

Shamgar · Post by **Shamgar** » Thu Jul 30, 2009 5:45 am

Do you think suspension has a negative impact on bootup and access times? Reason I ask is I previously suspended my notebook drive and the bootup time was terribly slow. I placed it on foam at the bottom of the case instead and bootup times improved significantly. That is where I keep the drive now. It stays cool without any fan directed towards it -- currently 30C according to S.M.A.R.T.

I would like to suspend drives in the future, especially desktop drives, but want to know if there is any explanation why the performance may be affected by suspending. Is it because it is less stable, and the heads have to take more time to get to the right tracks etc?

BTW is Stretch Magic a universal product or only available in certain countries/specialty stores? That looks like a reasonable alternative to clothing elastic to me, since that can wear out over time. I would like to avoid having to go the bungee cords route, as that looks like more screws, nuts and bolts work which I invariably dislike doing.

Chang · Post by **Chang** » Tue Aug 04, 2009 10:58 am

Shamgar wrote:BTW is Stretch Magic a universal product or only available in certain countries/specialty stores? That looks like a reasonable alternative to clothing elastic to me, since that can wear out over time. I would like to avoid having to go the bungee cords route, as that looks like more screws, nuts and bolts work which I invariably dislike doing.

I suppose you could consider Stretch Magic as a "universal product" found where you'd find other hobby / craft / beading supplies. Its main use is in making "stretchy" bracelets and necklaces (if that helps you find it locally). Best I can tell, it's available in Australia.

Post by **MikeC** » Tue Aug 04, 2009 11:39 am

Shamgar wrote:Do you think suspension has a negative impact on bootup and access times? Reason I ask is I previously suspended my notebook drive and the bootup time was terribly slow. I placed it on foam at the bottom of the case instead and bootup times improved significantly. That is where I keep the drive now. It stays cool without any fan directed towards it -- currently 30C according to S.M.A.R.T.

I would like to suspend drives in the future, especially desktop drives, but want to know if there is any explanation why the performance may be affected by suspending. Is it because it is less stable, and the heads have to take more time to get to the right tracks etc?

This is not normal. I've been suspending HDDS for nearly a decade, and I've never seen this with dozens of drives. There's been a lot of research by the HDD companies themselves (esp. Seagate whose docs I've quoted many times in SPCR) which shows that with modern drives there's no performance difference between softmounting and hard mounting.

If what you saw was really happening, then just how "soft" was the suspension in comparison to the foam? If the acoustic results are similar, then you'd think the "softness" was about the same, which means there should be no difference in performance either if your HDD is unusually sensitive. If the suspension was really loose -- like the ride in an old 60s Caddilac -- then I could see some problems but otherwise...

whiic · Post by **whiic** » Wed Aug 05, 2009 3:45 am

MikeC (about Shamgar's problems): "If the suspension was really loose -- like the ride in an old 60s Caddilac -- then I could see some problems"

I don't think that'd be a problem. From HDDs perspective, laying the HDD on foam or rubber suspension is all the same, no matter how soft the suspension is. This is because all decoupling methods are VERY soft to begin with. Seek that lasts 10ms duration is just that: a 5ms acceleration pulse followed by 5ms of decelarion. This 0.005 seconds is used to wind the suspension. During 0.005 seconds of deceleration, this stored energy could affect where the seek ends. But how much energy can be stored to soft decoupling with a displacement of less than 1 millimeter and a spring force that is a fraction of a gram... Not much.

Any effective decoupling has a vibrational frequency far below that of seeking (which is in range of 50-200 Hz depending on seek distance). Because soft suspension cannot really store vibrational energy of this high frequency, the biggest potential problem could be lack of mass attached to HDD cast. HDDs may rely on cast remaining stationary when arm is moved to perform the seek. If cast accelerated to the opposite direction, seek distance could end up overshooting (if HDD designed relied on spring force to "bounce" HDD cast back to it's original position before seek ends). This would be a problem even if HDD was magically floating in mid-air with no spring force of decoupling.

There was a study, made by Seagate (if I remember correctly), that concluded that semi-rigid mounting is far worse than soft-mounting or rigid mounting. Since "rigid" in that study meant bolting it into a few kilograms of metallic mass, this mounting isn't really realistic for computer cases...

The worst case scenario is a semi-rigid mount, like "hard-mounting" on 0.5mm thick steel case. Yes, the mounting which we consider secure, is the worst-case scenerio for seek stability. The fact that majority of computer cases absolutely love to resonate at 120Hz doesn't mean the mount has 120Hz vibrational frequency, merely that the side panels, or any pieces coming into contact with them, do. Still, even though being able to hear non-decoupled vibration is not conclusive evidence of HDD mount itself amplifying 120Hz, it think it's still more reasonable to assume hardmount's vibrational frequency is clores to 120Hz than softmount's vibrational frequency which is probably in range of 1...50Hz.

Less than 1 Hz for extremely loose rubber band "cradle". The type we don't really use because HDDs are so loose they may actually fall down accidentally.
Up to 5 Hz for decoupling with tightened rubber bands.
10 Hz with foam.
Up to 50 Hz with rubber softened semi-hard-mounts.

These are of course just guesstimates of mine. Place the HDD in it's suspension and push it sideways or rotate it... and let it unwind. Especially with rubber band decoupling, you can see it bounce back and forth repeatedly in very low frequency (that doesn't correspond to anything induced by drive itself). Of course, if you do such testing, don't do it with computer powered on.

Conclusion: "Hard"-mounting HDD in computer case = about equally bad.
Small rubber pieces for decoupling purposes = ineffective (may reduce vibration-borne noise a bit, but may actually worsen the HDD's own vibration more than proper decoupling and more than "hard"-mounting).

The best possible solution for random access performance would be 20 kilograms of lead bolted to HDD. With that much metal, decoupling it like sandwich would be impractical but also unnecessary as 20 kg really can't vibrate enough to be audible. For practical silencing, any solution having vibrational frequency <20 Hz should have very little wind-up effect. And to reduce risk of overshooting seeks due to HDD casts free rotation (at least in microscopis scale, of course it can't rotate 360 degrees in any suspension), sandwich it with <500 gramms of metal... (<100 gramms for laptop HDDs). More than that would be definite overkill.

Did it make any sense? I kinda started ranting...

Anyway, I don't think it's vibration issue. If decoupling with rubber cause bad access time compared to decoupling with foam, I'd probably say it's due to WHERE the HDD was mounted (HDD or CD bay compared to computer case floor) and EMI (ElectroMagnetic Interference) between computer components. Decoupled HDDs aren't properly grounded with metal screws and all grounding is done via power connector. Adding additional grounding strip from HDD cast to computer case may help.

Another EMI related explanation could be related to Faraday cage. If your HDD works ok inside HDD tray for example, it may be that the tray is shielding the HDD from external electric, magnetic and electromagnetic fields, as opposed to decoupling in CD bay which have no metallic material blocking EMI coming from direction of motherboard. You could try decoupling the HDD again, but placing a metal grille around the HDD, making sure the grille is properly grounded to computer case. Also verify that your PSU is properly grounded to computer case!

I honestly doubt it's anything mechanical. It's probably not due to mechanical decoupling but about electrical decoupling. Also, if the drive is failing, it may be due to some component tolerances that make them more vulnerable to EMI than working HDD specimens. But before you conclude HDD in any way faulty, check grounding issue, run SMART tests, etc.

If problem is really ONLY with seeks, then it could possibly be mechanical as well. Then I'd like to hear more about how tight you made the rubber decoupling, etc. Also: to conclude it really is related to seeks, do synthetic random access tests. You can start the test with HDD decouple with rubber, and let the test run... then grab the HDD by your fingers trying to reduce vibration and see if seek time improves. This should keep EMI and grounding about the same as your hand don't significantly affect either. (Just make sure you're not carrying any static electricity while touching a HDD, especially when it's running.)

jhhoffma · Post by **jhhoffma** » Wed Aug 05, 2009 7:48 am

I think MikeC's point was more that swinging and rocking back and forth on a loose suspension is likely to cause some problems of it's own if the gyroscopic balance of the platters is offset.

Shamgar · Post by **Shamgar** » Thu Aug 06, 2009 6:25 am

Thanks for your feedbacks on my problem. I haven't been keeping an eye on this thread as I didn't expect a significant response.

I will have a look at this problem again when I have the time and patience to do so. There may be something particular about the drive I am using. Could the suspension have been a little loose? I didn't think it was. A problem with cabling? Again, a possibility. But... I really don't know. I am on the most part not a technically minded person, so sometimes, responses from those who are are a little beyond my layman's understanding.

FWIW, I am happy with laying this HDD on foam. The case is a reasonable distance away from my self; the only noticeable HDD noise I hear is when it parks. The PCB is facing upwards so it can benefit from some airflow from inside the case.

P.S. whiic, I read your suggestions again (forgive me if I didn't the first time as my time here is limited today and I am a bit tired). The EMI issue is an interesting one. I will check to see if that may be a problem, and if it is, whether it can be improved. You also mentioned disk errors and failing drives. This drive has experienced several disk errors on a particular partition. I don't know whether this is a related issue or simply a common occurence easily dealt with by reformatting and repartitioning.

Besides that, my setup is working fine for me at this stage. I cannot test the suspension v hard mounting v foam etc now as I have swapped cases and back to using my old computer. When I get my new setup working some time in the future, I will report back if by that time, I would have isolated the cause of the problem I expressed earlier.

Thank you again.