awkwardbydesign
Officially Awesome
I made a set of Seismic type feet made, tuned to about 3Hz. They isolate above that frequency, even though they rock slowly. They work.
Anti Vibration Devices
- Thread starter Whizzy
- Start date
Over simplified untruth. We can hear timing and phase differences that don't show on that magnitude only frequency response. Now stop and think for a moment please Keith. Put down your instant responses that demonstrate a lack of thought. If there is a difference in vibration similar to suspending the speaker in the air, what does that tell you about how much vibration is no longer going in to the floor?
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John Phillips
pfm Member
Keith, you seem to be over-focussed on FR. May I suggest you look at BBC research department report 1977/3 on loudspeaker cabinet design. If you look no further, see in particular the curve in fig.12 where BBC research is summarised in tentative criteria for the audibility of cabinet resonances. You will see that audible cabinet resonances are well below what would be seen in FR. Audibility is not all about FR.
I have not personally tested vibration isolation. I don't perceive a need in my situation. However, it certainly seems plausible to me that an undamped suspended floor with larger area than a loudspeaker cabinet could be vibrated audibly by a loudspeaker in a way that would be improved by vibration isolation.
Audible? If so, does it matter? I don't know but for someone else it's their hobby and their experience, not mine or yours.
sq225917
Bit of this, bit of that
The difference in IMD shown is interesting, not sure it's audible though, but stack a load of small differences together across all of one's tweaks and maybe the end result is. I dunno.
Putting a subwoofer on blocks of wood and then on compliant feet and claiming a win isn't a real test, a subwoofer needs spiking to the floor, ideally on three not four spikes, that's the opposite of a compliant mount, blocks of wood is no reference to anything.
Putting a subwoofer on blocks of wood and then on compliant feet and claiming a win isn't a real test, a subwoofer needs spiking to the floor, ideally on three not four spikes, that's the opposite of a compliant mount, blocks of wood is no reference to anything.
Purité Audio
Trade: Purite Audio
The first thing to remember is that the speaker is always vibrating wherever and however it is positioned, it is the loudspeakers’ designers job to ensure the design doesn’t store energy which could lead to resonance and hence audibility.
The next question is there enough structurally transmitted vibration ( from the loudspeaker to the floor) to create an audible resonance.
In the measurements we took in various rooms there wasn’t .
Keith
The next question is there enough structurally transmitted vibration ( from the loudspeaker to the floor) to create an audible resonance.
In the measurements we took in various rooms there wasn’t .
Keith
Alex S
carbon based lifeform
I’m somewhere in the middle: speakers - sometimes, TTs - sometimes, everything else - no not really. Seems very close to using basic common sense.
I used to have a simple barometer: Roy Gregory. Anything he thought was essential, VTA to 0.1mm, Nordost whatever, Iso this and that, I immediately knew was bollocks.
I used to have a simple barometer: Roy Gregory. Anything he thought was essential, VTA to 0.1mm, Nordost whatever, Iso this and that, I immediately knew was bollocks.
Ayya Khema
pfm Member
Properly loaded sorbothane is the right tool for the job
almost spring like absorption. Perfect for speakers and turntables decoupling
Extremely cheap, works ten times better then garbage isoacoustic stands
almost spring like absorption. Perfect for speakers and turntables decoupling
Extremely cheap, works ten times better then garbage isoacoustic stands
NickofWimbledon
pfm Member
That's another interesting point - what would be perfect speaker isolation? Is it a 500kg speaker hanging from long ropes or would it be attached utterly rigidly to a concrete floor (with rugs to cut reflections) or would those two be the same?
Presumably, the best isolation answers change (for a given sound volume) as the speaker's mass falls - so how should I view my 36kg B&Ws? What does putting a layer of (say) Sorbothane under them do? Are we simply trying to prevent a vibrating speaker from making the floor shake, which then means that the speaker is shaking, which then...?
John
Rack’em Up!
I’m very pleased with this arrangement on a suspended wood floor. MDF wood stands filled with sand sitting on a cork floor. Under the loudspeaker, a Symposium Svelte Plus absorption platform sitting on Symposium RollerBlock Jr’s, the bottom cup screwed into the wood stand. The speakers sound phenomenal!
John Phillips
pfm Member
You do need to specify the problem you want to solve. Blanket application of a solution to one problem may have no impact at all on another problem.
For stopping speaker vibrations getting into whatever your floor, if that is what matters, given the mass of the loudspeaker and the number of springs you can choose the spring rate to give a spring-mass resonance at 2 to 5 Hz (as per @awkwardbydesign's post and as per my discussion at a show with the late Max Townshend). I believe that from a few times that frequency upward (maybe from 10 to 25 Hz) the spring-mass system will be increasingly lossy to vibration, so preventing transmission from cabinet to floor above that frequency. It's well-known engineering.
I do assume loudspeakers cabinets will vibrate - Newton's third law. Nothing to do with specific resonances.
Max in salesman mode tried to persuade me it would be useful to do this for my concrete floor. I wasn't convinced. My loudspeakers remain firmly spiked.
Riotvan
Snoofer in the Woofer
I use sorbothane under my subs. They are also on several concrete slabs sandwiched with rubber due to the suspended wooden floor. The difference was dramatic.
My mains are crossed over quite high so i haven’t bothered putting it under those yet.
Was also planning on putting it under my Freya+ tube amp if only to lift it up to reduce heat in tube mode but i prefer passive mode atm which stays cool.
My mains are crossed over quite high so i haven’t bothered putting it under those yet.
Was also planning on putting it under my Freya+ tube amp if only to lift it up to reduce heat in tube mode but i prefer passive mode atm which stays cool.
NickofWimbledon
pfm Member
Exactly -it’s surely one variable among many. IIRC, Dick Shahinian was a violinist who regarded stopping all box vibration as both impossible and undesirable except for lazy designers. They work well, but so do lots of very inert boxes (Wilson?). I am struggling to understand what we are trying to achieve/ prevent and how one answer can cover lots of vastly different speakers.
Arkless Electronics
Trade: Amp design and repairs.
Isolation/anti vibration devices are a total waste of time and money for solid state electronics.
heidcase music
pfm Member
Blue tack ?
You are correct in saying it is loudspeaker designers job to consider vibration in the design of the speaker. If you think any of them completely ameliorate all vibration you are wrong. Then there is the room to consider, come on Keith, you usual bang on about it. So you have an imperfect speaker, that does not just magic all vibration at all frequencies away. What happens to it? Some of it couples in to the floor, and resonates that if it can, some of it reflects around the cabinet and resonates that if it can. Is any of that in your previous frequency response? Possibly if you watch the phase too and have in room response as opposed to anechoic response. But mostly you need to look at a waterfall spectral decay. Seen those before? Sure you have. I don't read ASR speaker review but surely Master Amir does these. Now, do you honestly think plain old magnitude only Frequency Response has told you all you need to know or do you realise the folly of your previous position?
Purité Audio
Trade: Purite Audio
Direct coupler.
Keith
It is fair to say Dick was not in the mainstream approach to reproduction. I happen to really like Shahinian speakers I have heard. However I don't think considering Shahinian will help here. I am not sure his use of the word stupid is at all helpful.
What "we" are trying to do, for those that have issues, is prevent unwanted energy from the speaker entering the room via direct coupling with spikes. If you have an inert solid floor like concrete these may well not be for you. If you have a floating floor or floorboards or are in a first floor or higher flat you might well want isolation and not coupling. Trying not to energise the room more than you have to is a Good Thing.
What "we" may also be trying to achieve is reducing the amount of vibration that does not couple through spikes and gets reflected back round the cabinet resonating the speaker itself and perhaps out the speaker time smearing the sound. Hence the waterfall spectral decay plot's purpose.
EDIT: To answer your earlier question, I don't think anybody is suggesting hanging speakers on ropes is a good idea, they will flip about and time smear too, IsoAcoustics just did that to show that is another way to reduce the measured vibration as in that swing set up there is no reflections from the floor spikes either. If you have concrete or other very solid floors and can really well couple the speakers I think that is probably job done for most folks. If you cannot then what do you do? Isolation. Gaia is just one solution, Naim SL2 have some weird spring isolation in them, their CD players too, their other new kit too I think, your LP12, then there is Townshend speaker podiums and platforms and I am sure many more examples that I am unaware of. I am not here to argue isolation is needed everywhere but speaker isolation is clearly audible. a friend has some big old PMC MB2 and he had them on Gaia to stop the room singing along when he turns the wick up, and boy does he.
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