Speaker isolation - An eye (ear!) opener

Happy Listener posted:

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.

Nope, not yet but it's a good idea Happy Listener. I've been trying to tame my bass boom via the rear-firing port with some degree of success. The port bungs Dynaudio supply really kill the sound to my ears, I've got a sheet of loo roll gaffa taped over them and it's improved things no end, particularly when I chucked out the Blu-Tac and used some small sorbothane feet. Not sure about the slabs as that may be an aesthetic compromise but filling the stands with sand is a good, cheap solution. Cheers for that - any other suggestions welcome.

Jonners - many years back I had Contour 1.8mk II's - floorstanders, and they were incredibly amp-hungry. Supposedly a stable 4-ohm load. My Olive 250 controlled them far better than my previous 140 - and I didn't realise until I changed to the 250 just how untidy the bass was and how much untidy bass affects the whole soundscape. I also tried the bungs.

I think Dyn's in general nowadays are more tolerant power-wise?

Some more thoughts:

1- assume you have tried varying positions in the room  -  keep out of corners
2- have you tried listening further back in the room, if this is possible? 
3- try the sand/changing the Blu-Tac/foam interfacing etc. Don't forget that things like slabs can be painted to match in. I also spiked in to wood chopping boards at one point and others use granite slabs (as found in kitchen supplies).

Sadly, the trinity of the room/amp (pre/power) and speaker is the hardest puzzle to solve in a domestic environment. 

Foottapper wrote:

”..We know that our living room floor (a large concrete raft) does like to sing along when the volume is turned up a bit...”

Hi FT. really nice to meet you at the show. I’d love to get some more details of your floor construction and why you describe it as a concrete raft.

My reason for asking is that I’m about to specify a floor for my new listening room and would be very keen to avoid such issues.

My builder is recommending a screed at ground level, then 4” of Celotex, 4” of concrete poured onto that then carpet. Sounds OK to me, but now I’m wondering whether this will be solid and stable enough.

cheers,

Kevin

Happy Listener posted:

Jonners - many years back I had Contour 1.8mk II's - floorstanders, and they were incredibly amp-hungry. Supposedly a stable 4-ohm load. My Olive 250 controlled them far better than my previous 140 - and I didn't realise until I changed to the 250 just how untidy the bass was and how much untidy bass affects the whole soundscape. I also tried the bungs.

I think Dyn's in general nowadays are more tolerant power-wise?

Some more thoughts:

1- assume you have tried varying positions in the room  -  keep out of corners
2- have you tried listening further back in the room, if this is possible? 
3- try the sand/changing the Blu-Tac/foam interfacing etc. Don't forget that things like slabs can be painted to match in. I also spiked in to wood chopping boards at one point and others use granite slabs (as found in kitchen supplies).

Sadly, the trinity of the room/amp (pre/power) and speaker is the hardest puzzle to solve in a domestic environment. 

 

Thanks for this. I've got a it of an awkward setting having downsized from a house to a flat, the Dyns are now in an an small open-plan kitchen/lounge. This means a part alcove setting with about 4' of wall one side and 1' the other. They are about 10" out of the corners and slightly toed-in. The one with the 1' wall is clear, it's the other one which isn't and as mentioned I've a laminate floor which obviously doesn't help with reflections. I have a good sized rug, a sofa and an armchair to mitigate. The ceiling isn't high which obviously helps. 

I have experimented with different speakers recently (ProAc Tab 10 Sigs/ATC SCM 11's/PMC Twenty-5.21's) but none actually matched the Contours for dynamics, in fact the ProAc's were too bass-light and the ATC's weren't as revealing. The PMC's were great, similar sound to the Contours but more balanced - not enough of an improvement for £2k though. I think I may have to look at something further up the price scale to get the sort of sound I like with good bass but less fussy on position than Dyns are.

I'm driving mine with a 200/282 combo so plenty of grunt but I agree, Dyns like to be driven hard and that's a problem in a flat as I can't turn the wick up to really appreciate them! I'm going to do the sand thing and see what that does to the sound. A speaker cable change is also on the cards (I am thinking of replacing my 14 year old Chord Epic for Witch Hat Phantom).

Jonners posted:

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!

I was exactly where you appear to be in respect of occasional bass boom (see profile for kit detail). I loved, and still love, my speakers, but was keen to sort out the bass problem which occurred with perhaps 10-15% of my listening. The usual google searches turned up Townsend, Gaia and Stillpoints. I immediately discounted Townsend on aesthetic grounds and Stillpoints on cost. I bought a set of Gaia IIIs on a sale or return basis. They did make a difference, but a pretty negative one in my case. Bass was controlled better, but the Gaia’s sucked all the life out of most of my music. I kept them for 2 weeks, but in the end they had to go back. I replaced them with the Herbie’s Gliders I previously used with ProAc D20s, which worked in a fashion. 

When I mentioned all of this to my dealer he asked if I’d considered Stillpoints. To cut a long story short I was given  sets of Ultra SS and Ultra 5s to trial. The Ultra 5s were disappointing, but the Ultra SS - Wow, wow and wow again!! I’m now hearing bass as it’s meant to sound, and the overall sound is just more incisive and balanced. The effect has been very similar to that experienced when adding a 555PS to the 272. Yes, they are expensive (£1,800), but that’s still less than a black box or a Superlumina interconnect. 

Im sure they won’t work in everybody’s system, but if you can get either a free trial or a sale or return offer they are well worth trying.

Jonners - 

Re speaker cable, I never found favour with Chord's lesser cables due to bass aspects (too much). Can you try some NACA5?

I empathise with your challenge. 

Happy Listener posted:

Jonners - 

Re speaker cable, I never found favour with Chord's lesser cables due to bass aspects (too much). Can you try some NACA5?

I empathise with your challenge. 

I can probably try anything that's out to there to be honest, I've got several dealers within striking distance which all do home demos of various stuff so NACA5 would be fine, I don't need to go round corners either. I think it's extremely likely I will change the speaker cable anyway.

Other options could be to swap out the Dynaudio stands themselves, say for some Torlyte ones from Russ Andrews which have had some rave reviews. Thing is that we're fundamentally talking about spending hundreds (and in the case of timmo1341 thousands), of Pounds on achieving relatively small incrementals in improvement but I guess that's what we're into at our sort of level guys. I'm open to anything but keen to avoid the snake oil salesmen!

Jonners posted:

Nope, not yet but it's a good idea Happy Listener. I've been trying to tame my bass boom via the rear-firing port with some degree of success. The port bungs Dynaudio supply really kill the sound to my ears, I've got a sheet of loo roll gaffa taped over them and it's improved things no end, particularly when I chucked out the Blu-Tac and used some small sorbothane feet. Not sure about the slabs as that may be an aesthetic compromise but filling the stands with sand is a good, cheap solution. Cheers for that - any other suggestions welcome.

If you can’t make aesthetically pleasing, you can always regard cheap concrete slabs as a ‘throwaway’ trial, to be replaced if they work with something like a slab of granite - whether cut to size and polished by a local granite supplier, or bought as a specialist ‘hifi’ item. (However, as characteristics could vary with the density, thickness, mass and ‘deadness’ of the specific material as well as what it is coupled with, a bit of experimenting may be dictated.)

BTW, re blu-tack, I think it is only ever meant to be the thinnest possible amount, not as damping but more to stick together and fill surface imperfections, preventing movement between soeaker and stand if not spiked together.

Innocent Bystander posted:

If you can’t make aesthetically pleasing, you can always regard cheap concrete slabs as a ‘throwaway’ trial, to be replaced if they work with something like a slab of granite - whether cut to size and polished by a local granite supplier, or bought as a specialist ‘hifi’ item. (However, as characteristics could vary with the density, thickness, mass and ‘deadness’ of the specific material as well as what it is coupled with, a bit of experimenting may be dictated.)

BTW, re blu-tack, I think it is only ever meant to be the thinnest possible amount, not as damping but more to stick together and fill surface imperfections, preventing movement between soeaker and stand if not spiked together.

Thanks Innocent Bystander. Question - if going for a granite slab, what should I do about the spiked feet on the stands? Is conventional wisdom to fit spike shoes underneath or remove the spikes altogether? If removing altogether I guess I'd still need something between the slab and the bit the spike screws into. 

Jonners posted:

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!

I think it is a nicely designed and manufactured product - it looks and feels classy. The III model is good value in my mind

Timmo1341 posted:

Jonners posted:

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!

I was exactly where you appear to be in respect of occasional bass boom (see profile for kit detail). I loved, and still love, my speakers, but was keen to sort out the bass problem which occurred with perhaps 10-15% of my listening. The usual google searches turned up Townsend, Gaia and Stillpoints. I immediately discounted Townsend on aesthetic grounds and Stillpoints on cost. I bought a set of Gaia IIIs on a sale or return basis. They did make a difference, but a pretty negative one in my case. Bass was controlled better, but the Gaia’s sucked all the life out of most of my music. I kept them for 2 weeks, but in the end they had to go back. I replaced them with the Herbie’s Gliders I previously used with ProAc D20s, which worked in a fashion. 

When I mentioned all of this to my dealer he asked if I’d considered Stillpoints. To cut a long story short I was given  sets of Ultra SS and Ultra 5s to trial. The Ultra 5s were disappointing, but the Ultra SS - Wow, wow and wow again!! I’m now hearing bass as it’s meant to sound, and the overall sound is just more incisive and balanced. The effect has been very similar to that experienced when adding a 555PS to the 272. Yes, they are expensive (£1,800), but that’s still less than a black box or a Superlumina interconnect. 

Im sure they won’t work in everybody’s system, but if you can get either a free trial or a sale or return offer they are well worth trying.

 

 

 

finite elemente cerabases have the nearly same construction as the stillpoints ultra ss, but less cost effective.  I could say « whaouh » too when i got them and placed them on my wood suspended floor, under my speakers.  The sound opened, the bass was not booming anymore, the highs very softer, the sound more fluent, with more details too.

Probably the stillpoints ultra ss are better, but too expensive for my 6 k speakers.

Jonners posted:

Thanks Innocent Bystander. Question - if going for a granite slab, what should I do about the spiked feet on the stands? Is conventional wisdom to fit spike shoes underneath or remove the spikes altogether? If removing altogether I guess I'd still need something between the slab and the bit the spike screws into. 

There is different thinking as to whether a masdy slab should be firmly coupled to the floor and decoupled from the speakers, or vice versa. Options include all manner of approaches - possibly something resilient, from sorbothane to piece of carpet tile to Huge’s idea of a bicycle pneumatic inner tube (I wonder hiw that went - could be good - or might not be). All these you can play with easily (though not so cheaply with  Sorbothane). At the other wnd of the rigidity scale you can buy spiked granite platforms - or drill yourslf, or get the supplier to drill a suitable hole, e,g oversize to take a threaded insert embedded in epoxy resin.  

Hopefully others will contribute their experiences and preferences...

IIRC, there is (was?) a marketed product which involves a turntable/kit support in the form of an inflatable rubber tube, much akin to a bicycle tyre tube.

Alan Willby posted:

Jonners posted:

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!

I think it is a nicely designed and manufactured product - it looks and feels classy. The III model is good value in my mind

I think you have to try some of the solutions out there. I reckon it is very speaker / floor construction / positioning dependant. I might have been lucky first time  - but it really did sort out 95% of my bass boom ( I now think the other 5% is just poor recording quality as it is nothing to do with volume or how low the bass is). I am sure you I’ll find a solution.

kevin J Carden posted:

Foottapper wrote:

”..We know that our living room floor (a large concrete raft) does like to sing along when the volume is turned up a bit...”

Hi FT. really nice to meet you at the show. I’d love to get some more details of your floor construction and why you describe it as a concrete raft.

My reason for asking is that I’m about to specify a floor for my new listening room and would be very keen to avoid such issues.

My builder is recommending a screed at ground level, then 4” of Celotex, 4” of concrete poured onto that then carpet. Sounds OK to me, but now I’m wondering whether this will be solid and stable enough.

cheers,

Kevin

In my case, an area of predominately clay soil, grandfather in law was a builder and was not happy that we had bought a 1960s house. Jerry built, it'll fall down...

He then described how he was taught to build and avoid instability through drought sink and heave. Remove any topsoil, about 18 inches or so deep to the external dimensions of the building. Rake on 4 to 6 inches of cinders, in his case the waste from a local clay pipe works. Fix shuttering about 6 inches above ground level and lay concrete to fill it. Therefore effectively a solid block that with the house built on it floated on the cinders and was not subjected to the movement of the clay, hence a raft.

Jonners posted:

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?

So, for myself, I do suffer from a bass boom.... Will using Gaira or Townsehand products in place of the spikes result in an audible improvement? Thoughts/comments welcome!

Hi Jonners,

I commend your scepticism and shared it until this weekend. Should they cost £450+? Of course not, even though they are not lumps of metal. Each is made up of an upper and lower steel housing but with  a directionally springy mechanism inside. Their orientation affects their performance, according to the installation manual and to reviews. The ARTs used to be rigid but now have a damped slow rock to them if nudged.

If the floor is being excited to sing along at certain bass frequencies, thereby causing room boom, the yes, these should help. As far as I can tell, their job is to isolate the floor from speaker vibration, leaving the mass of the speaker cabinet to provide the platform for the drive units.

At this price, they are available on a home trial basis, so why not ask a dealer to let you try a set?

Best regards, FT

kevin J Carden posted:

Hi FT. really nice to meet you at the show. I’d love to get some more details of your floor construction and why you describe it as a concrete raft.

My reason for asking is that I’m about to specify a floor for my new listening room and would be very keen to avoid such issues.

My builder is recommending a screed at ground level, then 4” of Celotex, 4” of concrete poured onto that then carpet. Sounds OK to me, but now I’m wondering whether this will be solid and stable enough.

cheers,

Kevin

Hi Kevin, great to finally catch up with you too. Re floors, there used to be two types of concrete floor. The first was made by compacting a bed of crushed hardcore into the ground before pouring a concrete layer on top to form a level surface.  

The second, or raft construction, was made by building the walls to above ground level, then resting a series of steel reinforced concrete beams across the inner walls before pouring a final screed on top to form a level floor. This is the method used for our living room. The floor effectively rests on the walls and does not touch the ground so is not damped in the middle. It is free to bounce or “sing along”,badly out of time.  Alastair kindly suggested at one point to jack hammer a 1m2 hole in the centre of our living room floor, before casting a large, ground based supporting pillar to dampen the whole thing. I’m sure that it would have been highly effective from an acoustic perspective but the thought of even mentioning such an idea to my wife caused minor palpitations, so I decided perhaps not...

best regards, FT

I'm rather tempted to try these replacement feet - my 20.23 have no obvious flaws (no bass boom in particular), but there's always the niggling thought that I may get a better sense of space with those feet. I'm using the original spikes, on small granite slabs (or is it marble?) with bluetack (underneath the slab) to stop them sliding on the floor.

Has anyone tried Gaia III on a late-nineteenth century wooden floor, laid on conventional beams - slightly springy?

Foot tapper posted

Hi Jonners,

I commend your scepticism and shared it until this weekend. Should they cost £450+? Of course not, even though they are not lumps of metal. Each is made up of an upper and lower steel housing but with  a directionally springy mechanism inside. Their orientation affects their performance, according to the installation manual and to reviews. The ARTs used to be rigid but now have a damped slow rock to them if nudged.

If the floor is being excited to sing along at certain bass frequencies, thereby causing room boom, the yes, these should help. As far as I can tell, their job is to isolate the floor from speaker vibration, leaving the mass of the speaker cabinet to provide the platform for the drive units.

At this price, they are available on a home trial basis, so why not ask a dealer to let you try a set?

Best regards, FT

It's tempting FT, I am a bit of a sucker for these relatively easy to implement products but still, its a lot of dosh. Then again, if the results really are that dramatic these Gaios could actually be a bargain!

SamClaus posted:

I'm rather tempted to try these replacement feet - my 20.23 have no obvious flaws (no bass boom in particular), but there's always the niggling thought that I may get a better sense of space with those feet. I'm using the original spikes, on small granite slabs (or is it marble?) with bluetack (underneath the slab) to stop them sliding on the floor.

Has anyone tried Gaia III on a late-nineteenth century wooden floor, laid on conventional beams - slightly springy?

I am using Gaia II (I need the larger size) on springy wood floors, on the second floor of a brick two-story built in 1928. They have made an improvement in staging and resolving detail. I am running two subs so I think they help keep the speakers isolated from their output too.

If only.....My raft has heaved a great deal due to either poor groundworks on construction and/or large water-sucking trees being left in situ which were ~8 metres from the house. When these were removed in the early 1970s, I suspect the heavy clay was once again 'moisturised' with obvious effect. Instead of cinders, I have a bed of shingle.

Back on topic:

Always very interesting these threads, given there's never a universal solution.

Like Foot tapper I've ARTs which are very heavy (IIRC ~60kg each) and I'm going to try using large ball bearings which sit in a recess under the feet and sit the balls on Fraim chips. The bass is already good but wonder if it could be better.

SamClaus posted:

I'm rather tempted to try these replacement feet - my 20.23 have no obvious flaws (no bass boom in particular), but there's always the niggling thought that I may get a better sense of space with those feet. I'm using the original spikes, on small granite slabs (or is it marble?) with bluetack (underneath the slab) to stop them sliding on the floor.

Has anyone tried Gaia III on a late-nineteenth century wooden floor, laid on conventional beams - slightly springy?

I think it’s worth considering the condition of the floor, and whether anything can be done to improve it, before spending money on fancy plinths, paving slabs, etc. etc. Old floorboards often come slightly loose, and it’s not unusual to find all sorts of stuff underneath that can rattle around and vibrate. Unsecured wires and pipes and associated debris chucked in the void by electricians, can vibrate with the sound from your speakers. (This might also be the case with the ceiling above.)

Last year I moved the HiFi from a ground floor, concrete floored room to a first floor room with old floorboards and was concerned that the room wouldn’t sound too good, but actually it’s much better than the old room. I had to lift a lot of the floorboards, so I took the opportunity to clean out the mess, secure cables to joists, etc. I also also made sure the boards were very securely fixed with fully threaded headless screws so that they don’t bounce around on the joists. 

Also, there is generally less bounce in the floor next to the wall(s) into which the joists are fixed, so positioning the speakers against this wall might be best. 

ChrisSU posted:

SamClaus posted:

I'm rather tempted to try these replacement feet - my 20.23 have no obvious flaws (no bass boom in particular), but there's always the niggling thought that I may get a better sense of space with those feet. I'm using the original spikes, on small granite slabs (or is it marble?) with bluetack (underneath the slab) to stop them sliding on the floor.

Has anyone tried Gaia III on a late-nineteenth century wooden floor, laid on conventional beams - slightly springy?

I think it’s worth considering the condition of the floor, and whether anything can be done to improve it, before spending money on fancy plinths, paving slabs, etc. etc. Old floorboards often come slightly loose, and it’s not unusual to find all sorts of stuff underneath that can rattle around and vibrate. Unsecured wires and pipes and associated debris chucked in the void by electricians, can vibrate with the sound from your speakers. (This might also be the case with the ceiling above.)

Last year I moved the HiFi from a ground floor, concrete floored room to a first floor room with old floorboards and was concerned that the room wouldn’t sound too good, but actually it’s much better than the old room. I had to lift a lot of the floorboards, so I took the opportunity to clean out the mess, secure cables to joists, etc. I also also made sure the boards were very securely fixed with fully threaded headless screws so that they don’t bounce around on the joists. 

Also, there is generally less bounce in the floor next to the wall(s) into which the joists are fixed, so positioning the speakers against this wall might be best. 

Very useful advice, but this means major work, which I'm not quite prepared to do right now - I will keep in mind your suggestions anyway. As I said, there are no major flaws, and I would tend to agree that an older room might sound better than a recent one, with concrete walls, concrete floor, etc.

SamClaus posted:

ChrisSU posted:

SamClaus posted:

I'm rather tempted to try these replacement feet - my 20.23 have no obvious flaws (no bass boom in particular), but there's always the niggling thought that I may get a better sense of space with those feet. I'm using the original spikes, on small granite slabs (or is it marble?) with bluetack (underneath the slab) to stop them sliding on the floor.

Has anyone tried Gaia III on a late-nineteenth century wooden floor, laid on conventional beams - slightly springy?

I think it’s worth considering the condition of the floor, and whether anything can be done to improve it, before spending money on fancy plinths, paving slabs, etc. etc. Old floorboards often come slightly loose, and it’s not unusual to find all sorts of stuff underneath that can rattle around and vibrate. Unsecured wires and pipes and associated debris chucked in the void by electricians, can vibrate with the sound from your speakers. (This might also be the case with the ceiling above.)

Last year I moved the HiFi from a ground floor, concrete floored room to a first floor room with old floorboards and was concerned that the room wouldn’t sound too good, but actually it’s much better than the old room. I had to lift a lot of the floorboards, so I took the opportunity to clean out the mess, secure cables to joists, etc. I also also made sure the boards were very securely fixed with fully threaded headless screws so that they don’t bounce around on the joists. 

Also, there is generally less bounce in the floor next to the wall(s) into which the joists are fixed, so positioning the speakers against this wall might be best. 

Very useful advice, but this means major work, which I'm not quite prepared to do right now - I will keep in mind your suggestions anyway. As I said, there are no major flaws, and I would tend to agree that an older room might sound better than a recent one, with concrete walls, concrete floor, etc.

Yes, this is all quite disruptive although in my case I was refurbishing the house anyway. I was quite surprised how much things seemed to improve having done before and after tests in both rooms. 

Foot tapper posted:

kevin J Carden posted:

Hi FT. really nice to meet you at the show. I’d love to get some more details of your floor construction and why you describe it as a concrete raft.

My reason for asking is that I’m about to specify a floor for my new listening room and would be very keen to avoid such issues.

My builder is recommending a screed at ground level, then 4” of Celotex, 4” of concrete poured onto that then carpet. Sounds OK to me, but now I’m wondering whether this will be solid and stable enough.

cheers,

Kevin

Hi Kevin, great to finally catch up with you too. Re floors, there used to be two types of concrete floor. The first was made by compacting a bed of crushed hardcore into the ground before pouring a concrete layer on top to form a level surface.  

The second, or raft construction, was made by building the walls to above ground level, then resting a series of steel reinforced concrete beams across the inner walls before pouring a final screed on top to form a level floor. This is the method used for our living room. The floor effectively rests on the walls and does not touch the ground so is not damped in the middle. It is free to bounce or “sing along”,badly out of time.  Alastair kindly suggested at one point to jack hammer a 1m2 hole in the centre of our living room floor, before casting a large, ground based supporting pillar to dampen the whole thing. I’m sure that it would have been highly effective from an acoustic perspective but the thought of even mentioning such an idea to my wife caused minor palpitations, so I decided perhaps not...

best regards, FT

Thanks FT. Clear and helpful. Mine will be more like the first type you describe, just with an extra layer of Celotex in the middle, so I’m thinking should approach the solidity of type 1 more than your suspended floor.

Additionally, I’m now thinking of having just solid concrete all the way through in the areas where the HiFi racks and the speakers will be standing and Celotex/concrete everywhere else  just to be sure that the system itself has solid support right down to ground level. 

Kevin