View Full Version : Hi or Low Mass....discuss
21-03-2004, 05:06 PM
It's my understanding that you want a speakers drive units to move and the cabinet to stay still. So....
Things with more mass have greater inertia I believe. So would it not be correct to assume that once a high mass stand starts moving (and it surely will) it will be hard to stop it. How does this relate to good audio quality from a stand? or indeed a speaker, please discuss....
21-03-2004, 05:24 PM
An excellent thread idea Gordon :thumbup:
With speaker stands you want them to start moving very slowly (F=ma and all) and stop moving very quickly (critical damping).
Steel and aluminum are good at the former, not so good at the latter. Wood is generally the opposite.
23-03-2004, 10:19 AM
I was shocked at the difference in weight between my new Leema's and my old Ruark Preludes. OK, the Preludes were slightly smaller generally but the Xaviers are literally double the weight. Whether or not that's a factor in the actual sound quality being better or not, I don't know. What I do know is that they certainly give the impression that they mean business.
23-03-2004, 10:36 AM
Got to say i am surprised there hasn't been more debate about this. The best speaker stands I ever heard were of low mass which is why I asked. Everytime I filled or tried filling stands with sand or customers/manufacturers brought in mass loaded stands they always sounded worse than the light, open frame rigid stands we used for the small speakers we sold.
I am trying to understand it all like everyone else so please don;t shoot me if you use stands filled with frass...
23-03-2004, 10:45 AM
Isn't it usually the case that those speakers considered the very best (I'm talking the kind of speakers that come in similar price brackets to small houses) tend to weigh an absolute ton?
23-03-2004, 10:59 AM
Ah, but do they weigh a ton due to the cabinet size and the need to make it stiff and non-resonant or because they want them to be massy. It's a bit hard to not have a heavy speaker idf you stick lots of large diameter bass units in a large cabinet I'd have thought
For instance what about 805sig's on low mass stands with a DD18 sub. I'd rather have that than any Wilson speaker I've ever heard.
23-03-2004, 11:11 AM
Lower mass stands probably get closer to critical damping.
In energy terms, damping is the rate of loss of energy. For two stands of roughly the same volume, it will be roughly the same (energy being lost through the stand bending and radiating into the surrounding air). If one stand is denser, it will bend less AND store more energy, so it will take longer to get rid of that energy (I'm ignoring the heating of the stand through it bending, it's not as important in this case).
Putting a stand on isolation cones is an interesting idea, it stops the stand dumping that energy through the floor for the most part, so it all has to be lost through radiation of sound. :twisted:
I admit that I dont bother filling my stands.... a quick ponder on the idea always draws me to the conclusion that the floor (in my case) is going to be subject to the greatest degree of movement, so why on earth would I want to couple to that with a heavy stand?
So im approaching from a different direction. Im considering that the energy coupled to the stands from primary sound (i.e. cone movement) is going to be totally negligible when you consider that coupled by the room and its resonances..... im not a specialist, but that seems a fair assumption to me from a purely energetic viewpoint.
Another thing that could be interesting (though a tag hazardous) is liquid filling the stands.....
09-04-2004, 09:41 AM
If the ideal is to de-couple the speaker from the stand ie using MoPads or such, does it matter so much (within reason) what the stands mass is?
09-04-2004, 03:10 PM
Gordon hit on the key factor - Resonance.
With speaker stands you want the resonant frequency outside the audible range. Otherwise you get a beat frequency that can distort the output of your speakers. The easiest way to change the resonant frequency is to increase the mass. The clever way is by designing them properly from the right materials. Unfortunately a speaker stands resonance frequency will change depending on the mass and C of G of its load, or speaker.
Decoupling can have problems as if you don't decouple properly then you end up with in effect two structures that can have different resonant frequencies. Therefore two distortion patterns to contend with
A point to ponder, if you jump on water you get a wave and the energy is transferred. If you jump on sand?
That is why liquid is not a good dampener. Although wet sand is better than dry, up to a point.
if you jump on sand, the energy is still tansferred..... its just done in a different manner.
Also we could consider that there are different forms of damping: under, critical and over damping. Air is under damped, sand is over damped.....
11-04-2004, 07:00 PM
Keep going keep going...it's more interesting now.
11-04-2004, 08:04 PM
With FEA* you could probably build a stand with a nice spread of resonances, which would be less audible than modern stands with only one dominant one (a single pipe style stand). When you fill a stand with sand you lower its resonant frequency AFAIK (haven't done the math on that one)
On the subject of high mass vs low mass speakers, I think it's not so much the weight/mass, but the size of the panels. Bigger panels have a larger radiating surface, and therefore will transmit any internal resonances much better. Of course a case design that has intrinsic structural strength (pyramid, sphere, tube, anything but a square box basically) helps. It's all very well to talk about a cabinet with no internal standing waves, but that's pretty useless when the SPL inside the speaker is far higher than that outisde the speaker. You don't need internal resonances to hear cabinet colouration.
I'm surprised that domestic hi-fi leads pro-audio in terms of cabinet design, since studios are far less likely to baulk at a wierd looking monitor than the average spouse.
*FEA = Finite Element Analysis
15-04-2004, 07:27 PM
Back in the 70's there was a big fuss about isolating your turntable from feedback from your speakers and the big buzz at first was a hole in the floor filed in with concrete. Then either more concrete, or if you could afford it a marble plinth. That way everything was on as firm a stand as possible.
Then over night it changed and we were suspending it all hang from piano wire from the roof, the turntable and speakers not the listener, I think.
Is this a Movement or a Revolution, name that film.
you know where would be absolutely fantastic for a sound system? Space..... set your gear very carefully in the arangement you want, it will just float there looking at you unless you happen to apply a force to it (and lets face it, you'd be an eedjet to do that). All your gear will be totally isolated, you wont even have to worry about seats and ceiling mounts and that nonsense, just let it float there! If you were very clever you could even add an atmosphere so you could listen to your system :D~:-D~:grin:
as silly as this sounds, it opens my mind to soooo many interesting and totally implausible possibilities!
16-04-2004, 08:18 AM
Wouldnt a cd/dvd player start to move due to the disk spinning?
Wouldnt a cd/dvd player start to move due to the disk spinning?
the great thing is that that cant really be answered :D~:-D~:grin: It's all relative!
It would be easy to stop anyhow, just need something doing the opposite.... ie. a second spinning disc :D~:-D~:grin:
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