Speaker isolation - An eye (ear!) opener

OK I've measured the vibration effects (my newer 'phone is more reliable than the old one) using pink noise and frequency sweeps at 65dB SPL, then taking the greater value of the resulting vibration measurement.

Sub:
Sub cabinet   - 20g @ 12Hz & 24Hz (& 6g @ 32Hz)
Sub to Plinth   - 12g @ 12Hz & 24Hz
Sub to floor   - 4g @ 8Hz, 12Hz & 24Hz
Sub to HiFi Rack   - 2G @ 8Hz, 12Hz & 24Hz

Main Speakers
Speaker Cabinet   - 12G @ 12Hz - 45Hz (main resonance @ 15Hz)
Speaker to Plinth   - 0.2g @ 12Hz - 45Hz
Speaker to floor   - 0.04g @ 8Hz - 12Hz
Speaker to HiFi Rack   - not measurable (i.e. within noise floor on spectrogram: <0.01g )

Conclusion:

Sub:  Placing the sub on a compliant suspension may be worthwhile.

Main Speakers:  These are more disturbed by their own movement than by outside forces and have no detectable effect on the HiFi rack.  Using a compliant suspension here would be counter-productive.

Nick from Suffolk posted:

Huge posted:

Nick from Suffolk posted:

I thought that the principles behind Townshend seismic sinks and the Gaia isolation feet were to be solid above a certain (low) frequency whilst being compliant below that frequency, which would not see any speaker move in response to reproducing an audible note. But then I am a bit of an effwit.  

But in that case they won't give any 'isolation' either!

They can't have it both ways!

I did qualify my post by noting that I am a bit (no, make that complete) effwit, devoid of any logic or reasoning skills beyond the basic abilities to eat and breathe and nothing else.

Yebbut you do make nice coffee...

Jonas Olofsson posted:

I guess all/most speakers will improve with a better “base”. Tony did mention SL2 and Ovators as two speakers that might not improve because of their design. 

Funny enough I have owned and used both of them, with and without added base. 

SL2, used on a suspended wooden floor, in two different apartments, really benefited being put on some special made Mana stands. Tighter bass, more open midrange for sure.

Same thing with Ovator 600, this time on a pair of Sonority speaker shelves. The Ovators become a LOT better IMHO, highly recommended!

Today I use the same Sonority platforms but under a pair of Kudos Titans 808. Better? For sure!

//Jonas

Hi Jonas, following others' experiences with Sonority, I was quite keen to try these, but unfortunately they'd have to be specially made for my speakers, at considerable cost. I wasn't prepared to risk it.

Interesting what you've posted regarding Ovators. I'd assumed, given their inbuilt suspension, that additional isolation would have little effect. I always felt that the excellent performance of my old SL2s was partly attributable to their suspension system.

Huge wrote -

Main Speakers:  These are more disturbed by their own movement than by outside forces and have no detectable effect on the HiFi rack.  Using a compliant suspension here would be counter-productive.

I don't see the logic in this conclusion. Using a compliant support under speakers can change the sound. It might not reduce the amount of vibration getting to a hifi rack, but I don't think that is the point of putting supports under speakers. At least not in my opinion.

Dozey posted:

Huge wrote -

Main Speakers:  These are more disturbed by their own movement than by outside forces and have no detectable effect on the HiFi rack.  Using a compliant suspension here would be counter-productive.

 

I don't see the logic in this conclusion. Using a compliant support under speakers can change the sound. It might not reduce the amount of vibration getting to a hifi rack, but I don't think that is the point of putting supports under speakers. At least not in my opinion.

If it's not to reduce the mechanical excitement of resonances in the floor and the onward transmission of that energy, then what is the point of doing it?  Allowing the speaker boxes to move on a compliant suspension, and hence vibrate more, adds colouration to the sound (i.e. the sound made by the speaker cabinet vibrating).  So if not from reduced energy delivered into the floor of the room and into the electronics on the rack, where's the payback?

My actual experience is totally different to your predictions. There is far less bass resonances and colouration, the payback is in the listening experience. 

I'm really interested to know how it can reduce colouration.

Putting vibrations into the floor (which can be heard due to the large surface area of the floor), yes I get that that's a possibility in some cases; likewise those vibrations getting into the rack and electronics and exciting microphonic components, yes I get that as well.

Anything else...?  I'm open to suggestions...

In terms of bass resonances, I've already pointed out that the reduced bass efficiency of the speaker and reduced bass coupling to the air mass of the room can excite the fundamental room resonance modes less.

Huge posted:

I'm really interested to know how it can reduce colouration.

Putting vibrations into the floor (which can be heard due to the large surface area of the floor), yes I get that that's a possibility in some cases; likewise those vibrations getting into the rack and electronics and exciting microphonic components, yes I get that as well.

Anything else...?  I'm open to suggestions...

In terms of bass resonances, I've already pointed out that the reduced bass efficiency of the speaker and reduced bass coupling to the air mass of the room can excite the fundamental room resonance modes less.

I’m not sure it’s worth analysing - best thing is to try it. Might not work in many circumstances - the dealer I borrowed them through told me their experience was mixed but weighted towards improvement. Isolation has its benefits in other equipment - turntables and CD players being the obvious. The 552 is the only black box preamp (ignoring the Statement) to have a suspended sub-chassis. Why should the same approach be such a no no for speakers - if properly designed. I’ve experienced the difference and I’m a bit of a sceptic.

Huge,

I have no idea why or how and am not particularly interested, as I have mentioned along with others it just does. I am always looking to improve the SQ of my system  and am dissapointed on many occasions. I tend towards the opposite of placebo I.e. expecting no change at best. On occasions I can detect a change but it is not always clear whether this is beneficial or not. 

With regard to the impact of the isolation bars this it is far more evident, it removes overbearing bass and yet the bass is more prominent and distinctive, colouration is reduced with vocals and instruments being much clearer. This is far less subjective than “it sounds much better” 

I have experience with 12 different loudspeaker systems in 6 different rooms, but now can appreciate that there has always been bass distortion to some degree.

No idea why,

but have never been more certain of SQ improvements. 

I respect your technical knowledge, and have benefitted from many of your posts in the past, however the evidence from my experience with the the isolation pods suggests to me that your measurements do not align with actual results. 

I do not wish to offend but can only feedback my experience.

Indeed, I didn't say that it didn't or couldn't work, rather that it would work in certain circumstances and not in others.

In respect of the use with speakers, in appropriate circumstances, it's entirely possible to reduce the coupling to the acoustic resonances of the room and also reduce the total colouration in the room, however, in other circumstances compliantly mounting speakers will reduce the overall sound quality.

It all depends on the circumstances, the room, room contents, audio equipment and the listener themselves.

tonym posted:

Jonas Olofsson posted:

I guess all/most speakers will improve with a better “base”. Tony did mention SL2 and Ovators as two speakers that might not improve because of their design. 

Funny enough I have owned and used both of them, with and without added base. 

SL2, used on a suspended wooden floor, in two different apartments, really benefited being put on some special made Mana stands. Tighter bass, more open midrange for sure.

Same thing with Ovator 600, this time on a pair of Sonority speaker shelves. The Ovators become a LOT better IMHO, highly recommended!

Today I use the same Sonority platforms but under a pair of Kudos Titans 808. Better? For sure!

//Jonas

Hi Jonas, following others' experiences with Sonority, I was quite keen to try these, but unfortunately they'd have to be specially made for my speakers, at considerable cost. I wasn't prepared to risk it.

Interesting what you've posted regarding Ovators. I'd assumed, given their inbuilt suspension, that additional isolation would have little effect. I always felt that the excellent performance of my old SL2s was partly attributable to their suspension system.

Hi Tony, what’s quite interesting is that SL2 + Mana was better, but not a game changer by any means. Ovator + Sonority was A LOT BETTER! 

So, was it because SL2 decouples better then Ovator or that Sonority is far superior then Mana? Or a combination...?

To make it more interesting: Sonority shelf’s instead of the glass in a Fraim: Huge difference (better for sure if you ask me)!

Have fun!

//Jonas

It's interesting that there are still several completely different approaches to vibration isolation being promoted for HiFi components (with some use case examples):

Acoustic impedance change at a small contact area
Metal spikes or cap-nuts or ball bearings against hard non-metalic surfaces,
Used by Fraim (Wood <> Steel/Steel <> Glass).  Spike systems where the user places the spikes against a hard surface.
Vibration energy is reflected at the impedance change boundary.  These work best at removing higher frequencies but do little at lower frequencies.  Cheap to implement.

Visco-elastic polymers
Sorbathane, soft rubber feet
Used on a lot of 'cheep & cheerful' products.
Works by using internal damping to absorb vibrational energy.  Allow all three translations and all three rotations, but in a very limited manner.  Cheep but often not so cheerful as they often result in a deadened sound characteristic.

Spring and damper
Air spring contained in a visco-elastic polymer or metalic spring (usually damped by a visco-elastic polymer)
Used by most suspended sub-chassis turntables, Townshend 'Seismic Sink' products.
Allow all three translations and all three rotations.  The properties of these supports need to be carefully matched to the load in terms of both storage and loss modulus.  If the visco-elastic damping is too great they can also 'deaden' the sound - they should be underdamped, with only sufficient damping to meet the stability requirement in the given circumstances.

Gravity centred 'roller' systems
Rollers or balls that allow lateral movement
Used by Sonority Design systems
Work for larger lateral movements (stiction prevents useful effect for low force & small movements).  High cost due to the need for extensive research to minimise both stiction and friction.  For vertical vibration these rely on "Acoustic impedance change at a small contact area", but this requirement can conflict with the stiction and friction requirements.

There may also be others...

What works best (or even simple rigid mounting!) is probably highly dependant on the prevailing circumstances!

Thank you Richard for re-opening this thread.

Ever since the early 1980s, I have bought into the logic of grounding the loudspeakers with the most rigid, inert stand possible, ideally coupled to the floor with properly embedded spikes.  After all, if the speaker cone is trying to push against a  wibbly wobbly speaker cabinet, then only bad sounds can possibly emerge. 

This impression was reinforced in the 1990s when I auditioned a pair of tiny Ruark Epilogue speakers, which produced no bass at all in the dealer demonstration until they were rigidly mounted on a set of filled Target R1 speaker stands.  Yes, those impossibly heavy and rigid ones.  Then the Epilogues sounded brilliant, as did the Proac Tablette Signatures that followed them.  After all, stands to reason (as it were) ...

Then I noticed Naim try to partially decouple its Ovators from the floor via a suspension system built into the speaker bass.  That can't be right, as the Ovators were less than happy in our living room.  Bass boom ruled. 

Then I tried a pair of Brodmann VC7 floor standers.  Boomed like a boomy thing on a boomy day when mounted on their beautiful built-in spikes.  A little dismayed and with little sense of hope, the dealer tried a set of decoupling feet on the VC7s.  A complete transformation, like a thoroughly different speaker altogether.  That got me thinking, even though the Proacs were very happy on their Target R1 stands.

Roll forward a few years and the ART Alnicos have been one of few full range speakers that have been fairly resistant to room boom in our living room.

A combination of curiosity, the lack of dabbling over the last 2 years and positive results from some "sensible" fellow Naim forum members got the better of me, so time to find out if the system would benefit from some form of isolation.  We know that our living room floor (a large concrete raft) does like to sing along when the volume is turned up a bit...

Townshend Audio probably make the best known speaker isolation platforms (and the intriguing explanatory video on their web site) but those platforms would be deemed unacceptable on aesthetic grounds.  So the search moved on the isolating feet.

The ART standard feet are a solid aluminium turned block that screws into the speaker base and can, at the owner's discretion sit on top of a large ball bearing, as below:

  After much searching and a helpful conversation with Alastair at Signals, he kindly sourced a set of IsoAcoustic Gaia II speaker feet.  There are 3 sizes, the middle being the right one for the 50kg of each speaker.

The Gaia feet, adaptor threads and tripod carpet spike platforms all come in well presented boxes:

 The adaptor screws come in 3 different sizes as standard to suit a wide range of speakers.  The ARTs need the M8 screw threads, shown here pre-assembled in to the feet:

 Finally, the four Gaia feet installed under each speaker:

But do they work?

As a mechanical engineer by training, I can fully appreciate why they wouldn't and also why they would.  So forget the contradictory theories and just spin up some vinyl to listen.

Ooh.

Bass.  Much clearer, more pistonic, better defined bass.  Less vibration through the floor back to the listening sofas.  I can turn the volume up higher before the sound start to harden.

Imaging.  Crikey that's ridiculously clearer and sharper  I hadn't realised that the imaging was so-so before.  Bigger, wider, deeper soundstage, with each instrument sitting in its own stable space.  I'm liking this!

Voices and cymbals all much clearer too.

These may well be keepers after a more extended trial.

Others' impressions most welcome.

Regards, FT

Very interesting FT. Am looking forward to reading more about these isolation feet.

Sorry I missed you at the show.

Very discrete. Only an expert eye would spot them.  Having recently tried Quadraspire QPlus ref interfaces under my black boxes and been very surprised and pleased with the improvement they brought I'm entirely open to the idea of speaker feet bringing benefits.

Interesting FT, so these are feet replacement rather than feet isolation supports?

Foot tapper posted:

 

 

ART do build some gorgeous speakers. Lovely. 

Thank you James, very kind.

Hi PB, these ones screw into the same threaded sockets that the ART feet screw into, so to that extend they are replacement feet.  However, worth looking at the Isoacoustics website, as they do platforms as well (they started with platforms).  The Townshend Audio website is also well worth a look, as they to tremendous platforms as well.  Finally, it might be worth a call to Kudos to see what they recommend for your 808s, as Track Audio also do feet which are supposed to have some form of isolation as well.

You are welcome to pop round one weekend to hear what they do for our system, though I strongly suspect that their effect is very dependant on the construction of the floor.

Best regards, FT 

I have been using IsoAcoustic ISO-series with a pair of  active AE22 studio-monitors.

Just bought Gaia for the ATC floorstanders.

I have always felt ”had” when buying, but they do deliver.

i am using Finite Elemente Ceabases under my speakers and i am very pleased with them.  I can report the same effects as Foot Taper.

I have also finite elemente cerapucks under my naim fraimlite rack.

One of the best effective are probably the stillpoints ultra, but they are very costly.

Isoacoustics gaia have a lot of very good reviews, on press or forums.

I am using the Gaia II with my Dynaudio Confidence C2 Platinum. They do deliver. 

Here's an unconventional use: I just got a single set of the Gaia III and am using three os them in place of the spikes under my Clearaudio Ovation TT. I unscrewed the spikes from the feet and screwed in the Gaia feet. So far they have helped refine the soundstage, espcially for orchestral music, and they are doing a better job of isolating some rumble issues I have with a few recordings.

Foot tapper posted:

 

You are welcome to pop round one weekend to hear what they do for our system, though I strongly suspect that their effect is very dependant on the construction of the floor.

Best regards, FT 

I have used Townshend isolation pods under my speakers for about 5 years to great effect, During this time I changed floor covering from carpet (on concrete) to suspended wood flooring the pods were as equally effective on both interfaces.

This thread is really interesting. The thing I can't get my head around is the price of these products. Is £450+ really justifiable for 8 lumps of metal? I mean, what goes into them? I'm not downplaying their effectiveness, after all I am someone who will spend hundreds of Pounds on interconnects so I am a firm believer in improving one's system wherever possible.

So, for myself, I do suffer from a bass boom. I have a pair of Dynaudio Contours on stands which sit on a laminate laid floor which is the second floor in an apartment block, so the floor is basically sprung. I have spikes on the bottom of the stands and sorbothane feet between the speaker top plate and the speakers themselves. Willl using Gaira or Townsehand products in place of the spikes result in an audible improvement? Should I ditch the sorbothane? I was using blu-tac and that was not good. Thoughts/comments welcome!

Its a funny old game Hifi. I guess we are paying for lack of truly mass production, a perception that if we are spending thousands on Hifi, we will not flinch at a few hundreds here and there. Some of these parts are precision milled by skilled labour or expensive computer controlled equipment...... it all needs paying for.

Jonners posted:

I was using blu-tac and that was not good. Thoughts/comments welcome!

Jonners - before experimenting with expensive solutions, have you tried placing the stands on a concrete/stone slab (obviously on top of say a rug/carpet tile - latter is better IME as the rear rubbery side grips the floor) and/or can you fill the stands with kiln-dried (paving) sand. I have also had to try and tame a 'floating wood floor' (engineered wood over concrete, with usual damp-proof and comfort membrane between them). As others have said, I've found there is no universal solution, and I'm sure some floorstanding speakers didn't 'work' in my listening room due to the floor.