Speaker isolation - An eye (ear!) opener

Posted by: Alan Willby on 12 December 2017

When I extended my main living (listening) room last year I went for a stone floor over a thickly insulated suspended concrete floor with the screed layer containing a piped underfloor heating system. I previously had carpet over a standard suspended concrete floor and my PMC GB1i's were fixed with spikes as is the norm. I sort of expected that with this much harder and reflective floor the sound I was used to (and liked) would change. It was one of the reasons why I changed from my PMC's as I felt that with their bottom positioned front firing transmission line there might be some bass 'boom'. I went for Kef Reference 1's on their dedicated stands with spikes and floor protection cups. I have been delighted with them - but with a few bass heavy CD's (Neil Young's Prairie Wind being the worst offender for some reason) I was suffering 'boom' that had not been evident before. Now there is no doubt that the Kef's push out more bass - but I was on the look out for a solution. Anyway I have found it with IsoAcoustics Gaia isolation feet - the III model in my case. Not only have they cured the 'boom' but they have opened up the sound stage and increased the level of detail and separation (particularly in the bass registers) that can be heard. Can only think that the drivers are no longer being affected by energy bouncing back up through the stands from the floor and so are more able to perform as designed. Perhaps there is less energy finding its way into the equipment rack as well - who knows. Who cares - it's an ear opener. I was always convinced that speakers almost needed to be bolted to the floor so that the drivers could give their best - but these isolation feet suggest differently.

They might not work for all speakers or all floors/rooms - but from what I have heard I think an isolation solution is worthy of consideration. Mine are not going back.

Posted on: 12 December 2017 by Huge

It's not that, it's that the more compliant coupling doesn't hold the speakers in a precise position and the cabinets are moving in reaction to the lower frequency movements of the bass cones.  This means that the speaker system isn't so efficient at the bass frequencies and so the coupling to the fundamental room resonance modes isn't so pronounced.

It's a well know way of modifying the bass response at the expense of more colouration.

Posted on: 12 December 2017 by GerryMcg

I had the same experience a few years back, when I put Townshend isolation bars underneath my Ovators it removed bass bloom from various tracks. I had previously thought the problem tracks were the result of room dimensions.

Posted on: 12 December 2017 by Oldenbroke

I also have the GAIA IIIs under my PMC 20.23s on laminate flooring and agree with your comments re: bass taming. They have

dramatically improved the overall sound quality for far less than a new black box!

Posted on: 13 December 2017 by tonym

There's a very informative video regarding speaker isolation on the Townsend Audio website. They're a commercial company and in the business of selling their isolation platforms, but nevertheless, having recently put my speakers on Mana-type platforms, I agree with all the main points made in the video; the effectiveness of good speaker isolation is pretty obvious. I don't have a bass boom in my room, but the platforms improved bass response, plus music has become more focused and crisp. Certainly no colouration or decrease in bass response, quite the opposite. I even tried their seismometer test, using an IoS App.

Note that Naim, with SL2s and Ovators, built in suspension systems to their bases. I guess if you've these speakers then such isolation won't be so effective.

Posted on: 13 December 2017 by u77033103172058601

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.  

Posted on: 13 December 2017 by Huge
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!

Posted on: 13 December 2017 by Huge
tonym posted:

There's a very informative video regarding speaker isolation on the Townsend Audio website. They're a commercial company and in the business of selling their isolation platforms, but nevertheless, having recently put my speakers on Mana-type platforms, I agree with all the main points made in the video; the effectiveness of good speaker isolation is pretty obvious. I don't have a bass boom in my room, but the platforms improved bass response, plus music has become more focused and crisp. Certainly no colouration or decrease in bass response, quite the opposite. I even tried their seismometer test, using an IoS App.

Note that Naim, with SL2s and Ovators, built in suspension systems to their bases. I guess if you've these speakers then such isolation won't be so effective.

A number of Townsend's claims defy logic and are contrary to known physics (such as the laws of simple harmonic motion that control resonant vibrating structures).  Here are some examples...

"A movement-sensitive, air-resistance damper rapidly dissipates low frequency oscillation caused by disturbing the suspended equipment."
ALL dampers are movement sensitive - that's how they work.  Air resistance is very inefficient as a damper as it behaves as a variable force constant spring in series with a damper.  (The rubber surround on the other hand is more efficient as that behaves as a spring in parallel with a damper.)

"Seismic Load Cells™ are very ‘soft’ and allow free movement in all three dimensions; up/down, left/right and back/forth.
This unique solution blocks all deleterious vibration from 3Hz upwards and from all directions."
Really Free movement in the vertical?  i.e. they can't support any weight?  (They actually mean constrained movement, but that may give the wrong impression to people who initially don't understand the difference - don't 'talk down' to an intelligent audience!)

"This unique solution blocks all deleterious vibration from 3Hz upwards "
"Used in pairs under any speaker, be it floor standing, stand-mounted or sub-woofers."
"Designed as a range to accommodate any size and weight of speaker – standmount plus stand, floorstander or subwoofer – the Seismic Podium breaks the acoustic connection between the floor and the speaker, preventing the passage of deleterious vibrations both to and from the speaker cabinets."            (My emphasis)
This would require that the mass of the speaker has no effect on the value of the resonant frequency (i.e. it ALWAYS stays at 3Hz) - this defies the laws of simple harmonic motion.

Finally:
"So here’s the sobering fact. Every hi-fi system, from humble to high-end, has its performance ceiling set not by the cost and quality of its individual components but by how completely those components – the source, the amplification, the loudspeakers  – are isolated from the world around them. And when we say ‘world’ we mean that literally, as we’ll explain in a moment."
Well we also have a Denon D-M39DAB with Wharfedale Diamond 9.1s, so perhaps I should sell the 272+555DR / 300DR and Spendor SP2s, and by a few Townshend isolators for the Denon system.  The Denon will then have a higher performance ceiling than the Naim system ever can without the Townshend products.


If they weren't charging such high prices these statements would be laughable.


On the other hand vibration isolation can work in some circumstances (but it's not a universal 'fix').

Posted on: 13 December 2017 by tonym

I hope you noticed I did qualify my posting by noting this is essentially advertising, as I'm sure folks will appreciate. We can all easily pick holes in information produced with the main purpose of flogging kit. Even Naim...

Nevertheless, speaker isolation has worked very effectively on my DBLs. Bass response is better. Music is more focused. It's a very positive improvement. Their seismograph experiment worked. It's up to others if they wish to try this with their own speakers and form their own opinions.

Posted on: 13 December 2017 by GerryMcg
tonym posted:

There's a very informative video regarding speaker isolation on the Townsend Audio website. They're a commercial company and in the business of selling their isolation platforms, but nevertheless, having recently put my speakers on Mana-type platforms, I agree with all the main points made in the video; the effectiveness of good speaker isolation is pretty obvious. I don't have a bass boom in my room, but the platforms improved bass response, plus music has become more focused and crisp. Certainly no colouration or decrease in bass response, quite the opposite. I even tried their seismometer test, using an IoS App.

Note that Naim, with SL2s and Ovators, built in suspension systems to their bases. I guess if you've these speakers then such isolation won't be so effective.

In fact, I have then under my Ovator 600s and they have significantly improved the bass response. I also have placed their pods underneath my non-suspended turntable, on my non-audio rack, they work exceptionally well. Without the pods their is substantial feedback.

 

Posted on: 13 December 2017 by Huge
tonym posted:

I hope you noticed I did qualify my posting by noting this is essentially advertising, as I'm sure folks will appreciate. We can all easily pick holes in information produced with the main purpose of flogging kit. Even Naim...

Nevertheless, speaker isolation has worked very effectively on my DBLs. Bass response is better. Music is more focused. It's a very positive improvement. Their seismograph experiment worked. It's up to others if they wish to try this with their own speakers and form their own opinions.

Indeed, it's their marketing twaddle to which I strongly object (including the deeply flawed "seismograph" test - yes it shows what it measures, but their conclusion as to what that means for sound is fundamentally flawed).

Their products are actually pretty good (just incredibly overpriced for what they are).  In your case, your acoustic/mechanical environment seems to benefit considerably for the degree of mechanical isolation these devices provide.

Incidentally they are likely to work best with high mass speakers like DBLs!

Posted on: 13 December 2017 by Alan Willby
Huge posted:

It's not that, it's that the more compliant coupling doesn't hold the speakers in a precise position and the cabinets are moving in reaction to the lower frequency movements of the bass cones.  This means that the speaker system isn't so efficient at the bass frequencies and so the coupling to the fundamental room resonance modes isn't so pronounced.

It's a well know way of modifying the bass response at the expense of more colouration.

Agreed - but I am not hearing any colouration. I’ve now listened to many CD’s that I know really well and it is all sounding as normal but with the ‘improvements’ noted in my initial post depending on music type.  Something like choral music or solo acoustic guitar is as it was pre isolators. Rock and jazz though are sounding better to my ears. A couple of tracks that are sounding quite different (but not coloured) are Yes’s Yours Is No Disgrace and Dire Straits’ Telegraph Road. The extra definition in the bass guitar and it’s clear (now) separation from the bass drum is pretty impressive.

As I previously said - isolation may not work outside of particular room / floor / speaker combinations. There have been some favourable reviews in the press. I like to use my own ears - and in my case I recognise and agree with the printed findings.

Posted on: 13 December 2017 by Huge

In fact I'm thinking of putting some low hysteresis rubber supports under the sub I use.  But first I'll have to measure both the mechanical resonance of the room structure and it's interaction with an 11kg sub sitting on a 35kg plinth.  I'll then measure the resonance points with the rubber supports in place.  After that I'll re-measure the full in-room acoustic response of my whole system.

(I'll do the necessary measurements to ensure that I don't get the resonance points wrong and hence come to false conclusions when I listen to the result!)

Posted on: 13 December 2017 by Huge
Alan Willby posted:
Huge posted:

It's not that, it's that the more compliant coupling doesn't hold the speakers in a precise position and the cabinets are moving in reaction to the lower frequency movements of the bass cones.  This means that the speaker system isn't so efficient at the bass frequencies and so the coupling to the fundamental room resonance modes isn't so pronounced.

It's a well know way of modifying the bass response at the expense of more colouration.

Agreed - but I am not hearing any colouration. I’ve now listened to many CD’s that I know really well and it is all sounding as normal but with the ‘improvements’ noted in my initial post depending on music type.  Something like choral music or solo acoustic guitar is as it was pre isolators. Rock and jazz though are sounding better to my ears. A couple of tracks that are sounding quite different (but not coloured) are Yes’s Yours Is No Disgrace and Dire Straits’ Telegraph Road. The extra definition in the bass guitar and it’s clear (now) separation from the bass drum is pretty impressive.

As I previously said - isolation may not work outside of particular room / floor / speaker combinations. There have been some favourable reviews in the press. I like to use my own ears - and in my case I recognise and agree with the printed findings.

Ah, yes I should qualify my statement
"It's a well know way of modifying the bass response at the expense of more colouration."
that should be...
"It's a well know way of modifying the bass response at the expense of more colouration from the 'speaker."

Colouration components can arise from mechanical interaction of the speaker with the room or objects in the room; mechanical isolation can substantially reduce this.  Although colouration from the speaker increases, the reduction of colouration from the room can more than outweigh this.  Net result: the total level of colouration components CAN be reduced.

Posted on: 13 December 2017 by tonym

Mmm, that's an interesting thought. Might knock up a platform for under my sub too.

Posted on: 13 December 2017 by Huge

My sub sits on a sandwich...

No bread, just two 500mm sq ceramic tiles above and below four of the high density 'bricks' from inside a night storage heater (density = 4000kg/m3); all stuck together with modified silane adhesive.  The adhesive was chosen to provide just enough damping to kill the resonance of the ceramic tiles without adding enough energy absorbance to be of significance when considering the whole structure.  500mm x 500mm x 110mm, 35kg.

To do the isolation trick, I'll put another ceramic tile below this and position four chunks of low hysteresis rubber (maybe butyl rubber, but I haven't done the research yet) between the tile and the plinth.
Oooo, on second thoughts, how about a bicycle inner tube?


Incidentally I have the same type of plinths under my main speakers, with the plinths sitting on carpet (which itself is a slightly compliant 'suspension').

Posted on: 13 December 2017 by tonym

My sub's strictly for use in my home cinema system, but I've never bothered to do other than use its spikes. It weighs 42 kg, so those spikes are pretty well buried in the wooden floor... I'll try using the spare Fraim chips I reclaimed from under the speakers, see what effect they have.

Posted on: 13 December 2017 by DrMark

And TonyM has the strength of 10 average men, so he can pick the 42 kg sub up with one hand, whilst sliding the chips under with the other hand! It's not just his system that is impressive!

Posted on: 13 December 2017 by tonym

Yes, of course I could easily lift the whole thing up DrM, but maybe I'll just tilt it...with a lever...

Posted on: 13 December 2017 by Eoink
DrMark posted:

And TonyM has the strength of 10 average men, so he can pick the 42 kg sub up with one hand, whilst sliding the chips under with the other hand! It's not just his system that is impressive!

When I thought he was talking about a bouncy damper, I was thinking it'd end up like a Road Runner cartoon, you know the ones where a safe drops from a cliff, lands on a trampoline and bounces back up, so a 45Kg sub bouncing up and down.

Posted on: 13 December 2017 by Huge
tonym posted:

Yes, of course I could easily lift the whole thing up DrM, but maybe I'll just tilt it...with a lever...

Just make sure you're not playing "Tommy" at the same time!

Posted on: 13 December 2017 by Huge
Eoink posted:
DrMark posted:

And TonyM has the strength of 10 average men, so he can pick the 42 kg sub up with one hand, whilst sliding the chips under with the other hand! It's not just his system that is impressive!

When I thought he was talking about a bouncy damper, I was thinking it'd end up like a Road Runner cartoon, you know the ones where a safe drops from a cliff, lands on a trampoline and bounces back up, so a 45Kg sub bouncing up and down.

You mean like a 12.5kg sub standing on a 35kg ceramic plinth all suspended on a bicycle inner tube!

Posted on: 13 December 2017 by Eoink
Huge posted:
Eoink posted:
DrMark posted:

And TonyM has the strength of 10 average men, so he can pick the 42 kg sub up with one hand, whilst sliding the chips under with the other hand! It's not just his system that is impressive!

When I thought he was talking about a bouncy damper, I was thinking it'd end up like a Road Runner cartoon, you know the ones where a safe drops from a cliff, lands on a trampoline and bounces back up, so a 45Kg sub bouncing up and down.

You mean like a 12.5kg sub standing on a 35kg ceramic plinth all suspended on a bicycle inner tube!

Test it with DSOTM, the intro to Speak to me should tell you if you're getting resonance.

Posted on: 13 December 2017 by u77033103172058601
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.

Posted on: 13 December 2017 by DrMark

Sounds like you have the basics covered...anything else is overkill!

Posted on: 13 December 2017 by Jonas Olofsson

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