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Steel quieter than aluminum?

Posted: Tue Mar 16, 2004 4:57 pm
by Bluefront
I seem to hear that around these forums frequently. But is it true? There is nothing inherent in aluminum that makes it noisier than steel....that I know of anyway. A thin rattly steel case makes about the same amount of noise as a thin rattly aluminum case. So what's the difference?

It's all in how the parts are put together. You buy a good quality aluminum case, and it's likely to be as quiet as a quality steel case. You mod an aluminum case for noise're going to end up with a quiet setup.

IMHO....the choice of metal doesn't matter, the quality of the case does.

Posted: Tue Mar 16, 2004 5:06 pm
Most of the opinion is steel is quieter than aluminium -- I was restling with the same buying decision but ultimately I bought LIAN LI PC-61 case because of ease of working -- everything in PC-61 is removable including mobo and hence it is easy to build DIY computer especially for the first time builder. However I am using all other silent features like grommet for HDD and FANS. Hope this helps

Posted: Tue Mar 16, 2004 5:13 pm
by Trip
Aluminum appears to resonate more, is lighter, and perhaps flimsier than steel.

I have a steel Sonata case and an aluminum ATC-600. The ATC uses thicker metal than the Sonata and resonates worse. There are other factors of course, YMMV and also aluminum is more beautiful 8)

Posted: Tue Mar 16, 2004 5:23 pm
by Bluefront
Hmmm...let me rephrase that question. Would a case made of ten pounds of aluminum make more noise than a similar case made of ten pounds of steel? If so, why?

Posted: Tue Mar 16, 2004 5:37 pm
by aphonos
Bluefront wrote:Hmmm...let me rephrase that question. Would a case made of ten pounds of aluminum make more noise than a similar case made of ten pounds of steel? If so, why?
That seems like a rather theoretical question unless you are building a DIY case. One of the reasons that aluminum cases are more resonant is that case-makers don't use "ten pounds"....they make aluminum cases to be lighter (and maybe prettier) than steel cases. AFAIK. the issue around here between aluminum and steel cases is not really a matter of the metal. Rather, it is a matter of resonance. Taking into account the ATX cases available in the wider market today, a steel ATX case is going to, in general, be heavier and therefore less resonant than an equally sized (note I did not say weight) aluminum case.

But feel free to pursue the question some more, since you may be asking for theoretical reasons and since I'm not a metallurgist, I'll just hush up now. 8)

Posted: Tue Mar 16, 2004 6:21 pm
by Rusty075
Bluefront wrote:Would a case made of ten pounds of aluminum make more noise than a similar case made of ten pounds of steel? If so, why?

Cases don't make noise.


But what they do is either dampen or resonate. (or sometimes both) If an Aluminum case were constructed exactly the same as a steel case (same design that is) only the Aluminum panels were thickened to account for the differences in density until the total weight was equal for the two cases....I would bet that the aluminum would dampen sound just as well as the steel. I happen to have a 34lb aluminum case, and it seems to dampen noise just as well as the 32lb steel case that I have. (I bet that very few people can make that statement :roll: )

But aluminum cases aren't made that way. Aluminum cases big selling point is the reduced weight. If you would make an Aluminum case as heavy as a steel case you would lose its big selling point. Plus it would be more expensive than its equally wieghted steel version, so why would anyone buy it?

So the real question is closer to your first question:

All other things being equal (quality, design, fit-and-finish, etc) besides material and weight, would an Aluminum case be noisier than a Steel one?

To that question I think the answer is yes, thanks to the lighter weight (equals less dampening) and reduced rigidity of the side panels (more resonance) of the aluminum case.

Posted: Tue Mar 16, 2004 6:51 pm
It is a fact that aluminium cases resonates!

It is tough to get a girlfriend who is both intelligent and beautiful

Having said that one can take precautions to minimize resonance like:

1. Making sure that all drives are grommet mounted (dvd drives, floppy drives etc.)
2. Making sure that all fans are mounted using fan grommets
3. Making sure that PSU are mounted on damping materials and use a silent PSU

I myself researched and finally bought LIAN LI PC-61 because of ease of working like removable mobo and tool less!

Posted: Tue Mar 16, 2004 6:57 pm
by Trip
Rusty, what case is your 34lb. aluminum case?

How thick is it?

Posted: Tue Mar 16, 2004 7:06 pm
by josephclemente
I have a Cooler Master Wave Master.

I recently applied black electical tape along the inside edge of each side panel. This way, the panels make no metal-to-metal contact with the rest of the case.

It does sound better. Also, if I knock on the side, it does not rattle anywhere near as much as before - kind of like I applied heavy Dynamat to the entire panel.

It is nothing to jump up and down over, but it did help and was very cheap, simple and clean.

Posted: Tue Mar 16, 2004 7:09 pm
by exxowire
I have a aluminum ANTEC P160 and a steel Sonata. Before I bought the P160, I doubt that the case will be silent because logically steel is heavier and quieter than a lightweight aluminum. Most of all I think it depends on how you mount your psu and case fan in the right position. I used a 3M double side tape for my front and rear case fans.

Posted: Tue Mar 16, 2004 7:10 pm
by Bluefront
Maybe the point of this is somewhat unclear. It's not the material (aluminum) that makes a particular case noisy/resonate, but rather the quality(weight) of the panels.

IMHO ......If you want a quiet case, don't judge it by the type of metal, but rather by it's weight, and the quality of it's construction. Simple enough to me. :wink:

Posted: Tue Mar 16, 2004 7:17 pm
by Trip
I doubt there'd be a direct relationship between weight and dampening simply because there'd be other variables: material characteristics (density, malleability, strength). thickness but who knows.

Oddly enough I recently bought 3 ply aluminum to dampen my aluminum case! :?

Posted: Tue Mar 16, 2004 7:55 pm
by Edward Ng
Remember that from a physics point of view, it takes greater amounts of force to make a larger mass move. Steel, being denser, is of greater mass for the same volume, and thus does not vibrate as much as an aluminum panel of equal thickness (volume) when having the same amount of force applied.

This is also a part of the reason why denser acoustic dampening materials are more effective; it is more difficult to translate sound wave vibrations through the denser (higher mass) medium.


Posted: Tue Mar 16, 2004 8:11 pm
by Rusty075
Bluefront wrote:Maybe the point of this is somewhat unclear. It's not the material (aluminum) that makes a particular case noisy/resonate, but rather the quality(weight) of the panels.

You're right...all you need to find is an Aluminum case that weighs as much or more than a steel one of similiar quality.

But the generalization that Aluminum is not as quiet as steel does hold true, since 99% of the Aluminum cases out there are lighter weight than a similar sized steel case.

Trip, my 34lb aluminum case is the SuperPower "Superb Aluminum Case", who's review those of you who are speed readers got to read. :wink:

Posted: Tue Mar 16, 2004 9:24 pm
by Trip
haha, I remember that review - not suprised it was pulled.

It went the way of the Neo Classic

Posted: Tue Mar 16, 2004 10:46 pm
by Ephemeral
Well, couldn't find anything that directly applied, but these seem to partially explain why steel is better than aluminum regarding resonance. Most of it was too tough to decipher, but a pattern was there in the simpler summaries & diagram descriptions.

In short, since steel is more rigid compared to aluminum (even given equal mass), it will vibrate less in response to waves striking it (sound or mechanical), thus requiring much more vibrational energy to cause it to resonate. At least this interpretation/misinterpretation is good for fodder.

The guess I'm going with is that adding damping material would work well enough to cancel out aluminum's greater elasticity effect on increased resonance. At the very least, if you added enough damping material to aluminum so that it equaled the weight of a steel system (with less damping material), the aluminum system would be less prone to resonate (that visceoelastic stuff has got to be much better than any solid metal in damping vibrations before they have a chance to build up to audible resonance).

Link discussing the choice of materials for a wave guide tube.
This figure shows the lowest order mode prediction from Lafleur and Shields for a heavy walled steel tube, plus time off light measurements made in our lab. Notice that for this case,the dispersion is only about 1.3% over the entire frequency range, where for the thin aluminum it was > 10%.
There are three significant phenomenon that appear when the waveguide walls yield.

1. With rigid walls, the lowest order mode is truly a plane wave mode, as discussed previously, but with elastic walls, the lowest order mode exhibits a dispersive sound speed, which is at all frequencies slower than the free field value.
2. With rigid walls, the higher order modes exhibit a cut-off frequency, that is, there is a frequency below which each higher order mode will not propagate, hence at low frequencies, the plane wave mode exists alone. With elastic walls, this is no longer true. At least one higher order mode can exist down to zero frequency.
3. Because the wall can yield, a radial particle velocity is introduced, and wave fronts of even the lowest order mode are no longer plane. They exhibit a radial dependence
Link talking about lab tables designed not to resonate
Although honeycomb cores may be constructed from either steel or aluminum, steel typically provides greater vibration control. The comparison is best illustrated by looking at compliance curves (Fig. 2). Basically, compliance curves show the displacement amplitude of a point on a body per unit of impulse force applied. The greater the compliance, the more easily the structure moves as a result of applied force. The compliance curve for the steel tabletop in figure 2 demonstrates that the table bending with the same force is about 1.8 x 10-1 mm N-1, or roughly a factor of 11 more rigid than the standard aluminum honeycomb tabletop of the same size.

Posted: Wed Mar 17, 2004 6:16 am
by Edward Ng
Imagine, if you will, a case made from Damascus forged & folded steel...

Posted: Wed Mar 17, 2004 7:10 am
by Ralf Hutter
Edward Ng wrote:Imagine, if you will, a case made from Damascus forged & folded steel...
Mmm, it'd sure be pretty but you wouldn't want to use smokeless powder in it...