Understanding Under-Stands

Clever title eh?

First of all this is a request to PLEASE not turn this into the usual cr@p! This is a genuine post and I'm after opinions/thoughts/knowledge on ALL sides of this. If you don't like or agree with something that's said, please don't go into personal arsey pants! A bit silly that there's a need to say all this really isn't it?

So........

-----------------------------

To my knowledge the three main types of vibrations are: a) Those produced internally, such as transport and other MOving parts. b) Airborn vibrations, such as those produced by speakers, and c) Those passed into the equipment by whatever it's touching, such as the floor, stand, other equipment etc... These can be from anything such as footsteps to those passed into the floor by speakers and such.

The two main options seem to be to try and decouple/isolate the surfaces as much as possible. Or, to try and give a good coupling.

The use of isolation (such as inner tubes/air bladders etc...) seems like the ideal solution to keep away external vibrations. And, with the likes of amplifiers and such which don't produce internal vibrations it seems the best solution to me. But what about with kit that does vibrate internaly? There's no good route for the vibrations caused by internal MOvin parts to pass on?

The use of spikes for coupling (not isolation as is often said), provides a "ground" route for internally produced vibrations. And on a solid suitable surface seems a good idea. But in MOst cases the surface (suspended floor?) isn't ideal, and this coupling works both ways allowing easy flow of vibrations both in and out of the kit.

So to me, air platforms and such seem the obvious route with kit without moving parts, while for the kit which does it's a bit of a trade off. Isolation, but also some way of passing internal vibrations on.

And then with speakers,(I think this is where I'm trying to get?).

The idea is to keep the cabinet as still as possible and have all the driver energy used effectively rather than having the cabinet being pushed and pulled about. So for that purpose alone, a good coupling to a solid surface seems ideal.
But, there's MOre to it than that yeah? We wish to prevent vibrations from the speakers being passed onto the floor and thus the other kit, and also to avoid a sort of cycle where the sound causes vibrations in the floor which are then fed back into the cabinet. This means isolation from the floor. But using one method seems to go against the other.

In brief, do inner tubes uder speakers work? How, why and reasons???

Thoughts? Opinions? Knowledge?

Cheers. MO

 

Isolating CD players by seismic sink or inner tube or whatever does work very well. As for the internally generated vibrations, you damp the casework and mechanisms and everything to absorb those vibrations, as well as to add mass to reduce the amplitude of the vibration.

The same goes for speakers, but speakers are usually damped internally (although the damping materials can be improved in some cases). Also, they tend to be made of MDF, chipboard or in some cases wood (of course there are other materials used as well, but they are the exception for the most part), which is usually significantly less resonant than the thin metal casework found in most hifi components (certainly at a budget and mid range level anyway). Mass loading speakers (in the case of floorstanders) or speaker stands is well documented.

 

I don't want to be a spoil sport, but...

I think it is all serious BS...

 

Lowrider I wish to shake your hand.

I have had a number of supports commercial and made up, I have never noted a difference.

Last weekend I set up a Quadraspire for my step dad, it replaced a Project rack.

I gave it all the BS for a laugh. when set up we heard no difference what so ever, and rightly so.

I use ash now, the only reason: It looks good in our house.

Seriously I think money is better spent on the compnants or more music.

 

Hum.....the phrase cloth ears comes to mind but I'll not say it.

Some gear seems to be far more susceptable to vibration than others.

I have to say that there's only a little difference between good supports. There's a large difference between no support and good support though. A good test is to sit the CDP on squishy inner tube and see if you can hear a difference. Its rare that no one can hear any change, note that i'm talking of differences rather than good and bad !

 

Garyi,

Consider it shaken... :beer:

 

The reason you can hear your HiFi is because speakers generate energy in the form of sound waves. These travel through the air as well as through solid structures like stands, floors and walls. You can try to minimise the effect of structure bourne vibrations affecting other components but the only way to stop airbourne vibrations is to turn your HiFi off. Sort of defeats the object really :crazy:

So you need to do two separate things. The first is provide a rigid platform for the speaker which dissipates stored energy quickly and silently. Second is to support components in a way that isolates them from the vibration of the room yet allows sympathetic (harmonic) vibrations and mechanical noise to be dissipated quickly too. :banghead:

God knows what the solution is, I think it very much depends on what works best with the equipment and what sort of sound you are after. Good luck

 

Supports do make a huge difference. Quadraspire standard versus Project is unlikely to make much of a difference as both are just pieces of furniture that happen to be the right shape and size to park your hi-fi boxes on.

Buy a stand that is specifically designed to make a difference and it will unless you are deaf and/or you don't believe what your ears are telling you.

MO, your opening post was a good one. I find that isolation/damping using compressed air or sorbathane tends to kill the groove (although I've heard a system that grooves just fine and happens to use both.)

I prefer the grounding of vibrations via spikes method.

Mana makes a huge difference - those guys don't pile it up to the ceiling for appearances sake. The question is not whether it makes a difference but whether you like what it does.

QS Ref makes a difference but its presentation is different and again to taste. Some are put off by its appearance and the fact it wobbles. I like its low-resonance and non-ferrous design (again because ferrous metals resonate at critical frequencies as well as create magnetic fields aroud your kit.) I believe these design characteristics contribute to its allowing your system to deliver excellent pitch and timing as well as other things.

I do like Mana under speakers though for reasons of rigidity and grounding. The ferrous aspect is irrelevant in this instance as the speakers themselves have huge magnets, and are passive devices that resonate to order.

Garyi, I suspect you are suffering from sour grapes syndrome - the grapes are sour because you can't reach them. If you wanted some Mana would your missus let it into the house I wonder?

 

Mr Toy, I have heard mana in a number of configurations, if I wanted it I could afford it and my fiance would be fine about that.

I don't want it, so thats even better.

Theres plenty in my life to be sour about that dosn't involve a peice of furniture

 

I think supports definately can make a difference, but like so much in hifi everything gets so ridiculously blown out of proportion.

For example.. putting my gyrodeck on a solid wooden box makes it sound the same as the top shelf of my target stand, and it also sounds the same on the floor.

Putting some Michell cones/cups under my CDP made a small difference.

I saw one bloke on this forum say he could hear the difference between different types of rock when used as a base on his rack!!!! Im sorry, but I strongly doubt that this was anything other than psycho-acoustics.

Concrete pavers under the speakers makes a real difference too, in fact isolating the speakers made the biggest quantitative diffference IMO - compared to isolating other parts of my kit in the past.

your mmv of course

 

If you ,ve got concrete floors then you might not notice much difference using air isolation under your speakers .
if you have wooden floors , then you could be in for a bit of a suprise .
it,s well worth trying for the price of a couple of inner tubes and a couple of slabs ?bits of mdf .

using air plats under speakers tends to "relax" the sound a bit , but in the context of making the sound seem less hard , rather than less groovy . (or are these one and the same? as i,ve a feeling that some people mistake strident for groove )

 

Bottle neck, I totally agree about speaker isolation and believe it is very important. The differences here are not subtle and most likely quantifiable. Lets put it this way, my girlfriend can hear the difference!

I used to have some cone things I got from the cornflake shop, they sucked the bass right out, most disconcerting.

I have tried all sorts, including stone underneath, but found this to extend treble to much. I just spike direct to floor now.

 

Richard, hi mate long time no see I think Steve was referring to component isolation rather than speaker.
Garyi I do understand your feelings, however a simple demo is easy, one which I can do when you visit. WM

 

I found that putting granite/inner tube under my CD/amp stack when it was on my desk massively improved the groove. However, obviously a fairly standard desk isn't an ideal support.

Supports can make an enormous amount of difference. The thing is that most cheap ones aren't designed to. They are just designed to be some shelves for the kit to sit on. That is why I spent around £140 building my semi DIY rack to my own design, rather than just going out and buying one from a hifi shop, which I could easily have done for that money.

Garyi - I recommend taking WM up on that offer... eyes will be opened.

 

This is a brilliant post that sums up well the issues involved.

Don't spread this around too much but I use a simple, cheap isolation device for my equipment. I take four door-stoppers and place superballs on top of them with the equipment on top of that. This combination works quite well for me. For my turntable I use squash balls in the door-stoppers. These give a simple air support without the levelling problems that you can get with inner tubes.

Guys, for a few bob a throw, it's worth a try. Don't you just know I'll be putting these things on to the market in gold-plated boxes at £299 per set? :MILD: :shady:

More generally, I suppose that the answer could be to perfectly couple all equipment to a heavy floor that would act like an electrical 'earth'. Tricky to achieve though so we experiment with different supports and coupling/decoupling arrangements until we get something that works for our kit (and our ears).

Getting to speakers, I think that MO's right again. Spikes couple and hold rigid. We don't always want the coupling but we need to hold the speakers still. I don't like to turn this thread into another advert for a certain small British speaker company so suffice it to say ...

This problem is more a question for speakers that handle low frequencies. Compared to the mass of a speaker, movement at higher frequencies doesn't produce enough force to cause significant acceleration and thus movement.

The way I've gone with the subwoofer (which handles up to 100Hz) is to mount the driver so that it fires up and down. This way, I don't have to worry about forward and backward movement and can thus decouple the speaker from the floor without any worries. Spikes are then not required, an isolating base or isolating feet are preferable.

Steve

 

Hi MO, we don't talk often enough

To try and go back to your questions
rather than the usual crap..

The trouble is that the original thinking
behind all this isolation kack gets re-spun
in every direction so here goes:

Speakers rock back n forth in the plane of the
bass driver..If your speaker is on spikes then this
rocking will supposedly "inject" less energy into a
springy floor versus the speaker on the carpet.
The spikes also dig in, so might reduce straight
front/back movement. Finally, they lift the
speaker weight off the carpet, allowing the
carpet to lightly touch the speaker base
which damps said rocking backnforth faster
than it otherwise would..OK so far?

Spikes arrived in the time of turntables, when it was easier to hear the effect of vibration because, the unwanted sound is the same signal type as the music [real time vibrations].
Floor bound vibrations could be picked up especially by a turntable. If digital kit is affected, the effect will be less predictable. The "bits" being read at any instant are not the ones you are hearing at the same time, as data is scattered across the CD [cross-interleaved].

Speakers also produce unwanted sound from their walls flexing, and from the sound bouncing in the box impacting back on the bass cone thereby giving a [boxy] sound.

The rocking motion is a pendulum movement, with
the energy caused by the bass driver. The rocking itself is bad, because the mid and treble are doppler shifted [vibrato] by it.

If you made the top of the speaker out of a heavy mass, you would lower the frequency of the rocking [which is good].
If you sat a heavy mass on top, with something soft to avoid
scratches on the speaker, this is even better - the rocking energy
will be lost as friction in the cloth between the speaker
and the slab above, as the speaker rocks and the slab doesnt
[because it has a diff resonant frequency]

I have been using heavy slabs UNDER narrow, deep floorstanders
for years. It is the effect of placing directly on a concrete floor. I use flat rubber feet on the speakers - not spikes.
On a springy floor it also damps the floor moving [mass<>carpet<> mass] so reducing the room problem. I can see this last issue being the only benefit under a tall stand as it wont reduce rocking in the speaker stand.
I have no experience with diddy little speakers at home, except on shelves.

Floor vibration reaching hifi:
Obviously, a TT cares a lot about vibration pickup. I have a DAT recording where you can here me talking via a Rega 3 TT.
I would make an effort to reduce floor bound pickup to a low level by
a] Putting kit as far from the speakers as poss [via lots of dirt cheap wire]
b] Not putting kit on the floor, piano, sideboard etc
c] A false upper shelf for the kit sitting on a shelf, with a sandwich of
something lossy [carpet/socks/newspapers etc] - inner tubes if you are
desperate

Airborne vibration:
Shelves should be light and skeletal [or damped with a lossy sandwich as above], don't put any kit in a closed back box. Damp vibrations in kit if you are desperate..

Just take sensible precautions and then forget about it. I would buy stands for practicality first, looks second, and not worry much about vibration if you take sensible steps to reduce it.

 

Speaker stands should hold a speaker as rigid as possible also is is desirable to have the energy put through the stand to be dispersed into the floor. Some decoupling will change the sound as the energy remains within the speaker/stand system. Is this sound better - hard to say as what is happening is energy becomes radiated into the room. Some may like this as it is could add some 'warmth' to the sound - but is is a distortion.

The amount of energy a speaker will add to a normal floor is tiny. Road traffic or the harmonic vibrations of the various components within a house will give far higher levels of vibration. Air borne vibrations will excite TT or CDP depending on sound pressure but it is difficult to isolate effectively from this type of pressure.

Adding mass at the top of a speaker will only increase the instability of a speaker, it would be far better to add mass at the bottom of the speaker cabinet to reduce its centre of gravity.

Steven

 

Turntable damping/coupling

I've carried out an interesting experiment with my record deck:
Michell Mycro/Origin Live Silver arm/Ortofon Rohmann ...

I placed the arm and stylus onto a stationary LP and turned the amp right up. Then, I tapped the glass base of the turntable and listened to the sound that was picked up by the cartridge and replayed through the speakers.

I got a tone that took some time to decay - quite frightening really.

I tried this:
1. with the original Michell hard cone arrangement from the turntable base to the equipment stand (coupling)
2. with squash balls mounted on door-stoppers as supports between the base and equipment stand (isolating)
3. with superballs in place of squash balls (half way between the two?)

Tapping the edge of the base caused the loudest sound with the squash balls and the quietest with the Michell cones. However, when I tapped the base nearer the platter the results were the other way around.

Listening to an LP, the difference was subtle. If I had to, I would say that the sound on the Michell cones was slightly brighter and perhaps a little harsher. With the squash balls, the sound was a little darker and quieter.

What does all this tell me? I don't know. Perhaps that the turntable/support/floor needs to be designed in an integrated fashion. In practice I will use the squash ball supports because they offer some isolation from movement, whereas with the Michell cones, the stylus jumps whenever anyone walks across the room (even lightly).

Incidentally, if I make the taps while playing music I can't hear any tone as it is below the threshhold of audibility. With the original tests the volume was up full.

I wonder whether it would be worth damping the Mycro's glass base with dedsheet or similar (at least in the centre where it wouldn't be visible).

I think I'll stick to speaker design.

Steve

 

Why do Shahinian speakers work??

I have been playing the stand game for about 20 years, I bought one of the first sets of Target Speaker stands back in the early 80s and Target TT table, couldn't afford the Sound Organisation one (I was a student).

With regard to Speaker Stands I personally think that there biggest beneifit is getting the speaker to a decent height and positioning so that the speaker has plenty of air around it (or against a rear wall if it was designed for that)

With regard to equipment racks, I agree that often a difference can be heard but it isn't always better, just different.

I now have a pair of Shahinian Speakers (Arcs) and have also heard Shahinian Obelisks (fitted with castors by the manufacturer). Both sets of speakers are absolutly fantastic, neither have stands or spikes. So why do Shahinian flout our 'normal' understanding and produce some amazing products???

I agree with some of the other posters, that there is a lot of smoke and mirrors with regard to stands.

I personally belive that good electronics are always preferential to phaffing about with stands and once you have got the equipment you desire, by all means play around with the supports until it sounds better to your ears, thats only common sense.

Mr Perceptive

Meridian 200/203, Naim 62/SNAPS/140, Arcam DAB Tuner, and assorted AV gear all stacked on the lower shelf of a coffee table, oh and some unstanded, non-spiked Shahinian Arcs. To me its great and I'm well happy.

 

Re: Turntable damping/coupling

Hi Steve

I used to have that until I bolstered up the floor with additional boards and sound deadening panels.

Have you thought of a wall shelf? - got a brick wall behind the TT to facilitate?