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Need some advice from those in the know........i have a platerboard wall behind my fairly hefty Sonor Audio Capellas, due to the room use i cant move them more than obout 40 cm from the wall, slightly toe in. I can feel the rsonance in the wall and do believe there is a bitt too much bass masking higher frequencies. The room is definitely less than ideal, but its the only place i have for stereo.

My question is, would bass traps/aqoustic panels placed behind the speakers have any benefit ?

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I remember some one on another forum telling me how when  he moved from an old Georgian house (in the UK) with pretty solid walls into a modern house with wooden stud and plaster board walls how they sucked out the bass dramatically so it looks like acoustic panels or something similar will definitely be needed.

 

It seems that bad building products are everywhere. I remember very well on a UK audio forum someone was asking what materials to use for some internal walls in their home and I advised against using the out of date stud and plaster board method and to use aircrete blocks, much faster and really easy for someone without construction knowledge to do - they blanked the idea and went for the old way, stupid but not surprised.

 

Here in France I'm surprised that anyone listens to music other than via h/phones because the houses are built using 3" clay block walls for internal walls, not only no privacy but awful acoustic effects, coupled with an obsession with tiled floors the resulting noise is terrible.

 

 

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  • 2 weeks later...
On 03/02/2020 at 6:56 AM, Balvenie said:

I can feel the rsonance in the wall and do believe there is a bitt too much bass masking higher frequencies.

if the walls rattle, that's an issue, but if the walls are vibrating but not rattling, that means they're absorbing energy (which is good) - is there insulation in the walls? that would be ideal.

 

On 03/02/2020 at 6:56 AM, Balvenie said:

My question is, would bass traps/aqoustic panels placed behind the speakers have any benefit ?

if looking to absorb bass energy in the room below about 250Hz or so (this is roughly the transition frequency of most domestic rooms, where below this frequency the modal region dominates) - it won't matter where in the room the absorption is placed - the bass is bouncing around the room like a pebble dropped into a fish tank.

Place as much absorption, as big and deep as you can get away with, straddling as many corners as you can get away with...always straddling corners - the air gap behind helps them to work absorbing lower frequencies.

 

By all means put absorption behind the speakers (straddling corners) - but other corners will work the same.

 

The air gap is important - absorption flat on walls won't be that effective for lower frequencies for the material close to the wall - gapping is free, but takes up space...200mm of absorption will work way lower with a 200mm airgap...and if you want absorption to work down to 150Hz, then 200mm thick and at least 1000mm wide straddling multiple corners (say floor to ceiling) would provide good bass absorption >150Hz

 

For room issues below 150Hz or so, absorption needs to be too big/deep to be practical, but IME it works wonders >150Hz and can clean up the mid bass region very well.

 

Below 150Hz, IMO speaker/sub placement and EQ is key.

 

IMHO every room can benefit from absorption cleaning up the mid/upper bass 150Hz - 500Hz, and a few bands of EQ cut below 150Hz tames the rest in lightly constructed rooms (ie gyprock on studs), which lets most low bass pass through the walls (great for the "in room" sound, not so great for other house occupants/neighbours).

 

IME cleaning up the mid bass with room treatment makes a massive difference to the "in room" sound, and I add EQ cut below 150Hz or so based on measurements where the absorption is reducing in effectiveness.

 

I would say I have the bass in my room "reasonably under control".

A room with the bass under control is amazing - I have tone controls on my remote, and I usually can't help dialing up the bass on well recorded tracks with great bass.

 

Mike

Edited by almikel
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On 09/02/2020 at 9:35 AM, Southerly said:

I remember some one on another forum telling me how when  he moved from an old Georgian house (in the UK) with pretty solid walls into a modern house with wooden stud and plaster board walls how they sucked out the bass dramatically

to me this is ideal (but bad for other house occupants and neighbours) as it means the bass is not bouncing around the room needing to be dealt with (increasing reverb times and ringing).

Rooms keeping bass in is always bad - rooms letting bass out, or absorbing the bass is good for the "in room" sound.

On 09/02/2020 at 9:35 AM, Southerly said:

I remember very well on a UK audio forum someone was asking what materials to use for some internal walls in their home and I advised against using the out of date stud and plaster board method and to use aircrete blocks,

Perhaps aircrete blocks have an acoustic benefit over stud/gyprock construction?...I couldn't find reference data.

The acoustic properties of stud/gyprock construction is well understood from an isolation perspective at least (eg here https://www.soundproofingcompany.com/soundproofing-101)

 

I have tolerant family members and neighbours - so I'm less interested in isolation, and more interested in bass control within the room - lightweight gyprock/stud construction is good for "in room" bass, as none of the low bass stays in the room to bounce around (because it passes through, or is absorbed in multi layer gyprock/greenglue) - does aircrete either absorb or transmit the low bass, or is it reflected back into the room?

 

mike

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On 09/02/2020 at 9:35 AM, Southerly said:

Here in France I'm surprised that anyone listens to music other than via h/phones because the houses are built using 3" clay block walls for internal walls, not only no privacy but awful acoustic effects, coupled with an obsession with tiled floors the resulting noise is terrible.

here in Australia, multi dwelling buildings (eg units/flats etc) typically have brick or besser block wall construction between dwellings which have quite good isolation properties from a privacy perspective (ignoring flanking paths).

Being rigid, they don't have good acoustic properties inside the room, and we have the same obsession with tiled floors and generally rigid surfaces to make the "in room" sound typically awful.

 

Mike

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On 09/02/2020 at 9:35 AM, Southerly said:

It seems that bad building products are everywhere.

I don't deem gyprock/plasterboard on studs with insulation to be a "bad" building approach - I'd be happy to look at other products, but it works very well on a cost/performance basis.

If you require additional isolation then the standard methods of multi layers of gyprock with green glue and double studs/isolation clips etc aren't prohibitively expensive with documented results.

Building a room using the guidelines from here  https://www.soundproofingcompany.com/soundproofing-101 will achieve isolation and reasonable bass management as the boundaries will have some compliance, requiring less treatment within the room.

 

Mike

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15 minutes ago, almikel said:

to me this is ideal (but bad for other house occupants and neighbours) as it means the bass is not bouncing around the room needing to be dealt with (increasing reverb times and ringing).

Rooms keeping bass in is always bad - rooms letting bass out, or absorbing the bass is good for the "in room" sound.

Perhaps aircrete blocks have an acoustic benefit over stud/gyprock construction?...I couldn't find reference data.

The acoustic properties of stud/gyprock construction is well understood from an isolation perspective at least (eg here https://www.soundproofingcompany.com/soundproofing-101)

 

I have tolerant family members and neighbours - so I'm less interested in isolation, and more interested in bass control within the room - lightweight gyprock/stud construction is good for "in room" bass, as none of the low bass stays in the room to bounce around (because it passes through, or is absorbed in multi layer gyprock/greenglue) - does aircrete either absorb or transmit the low bass, or is it reflected back into the room?

 

mike

Sorry to say but your post doesn't make any sense. First - stud and plasterboard, even with rockwool will absorb all sound and transfer it to the other side of the construction and indeed will/can cause domestic problems.

 

Bass or indeed all sound will be reflected by walls constructed of hard  reflective material. Here in France and in Spain they use 3" red clay blocks that do just that. Neither the Spanish or the French use a bonding plaster, just a single coat of finish plaster - the result, their homes ring like a bell. The Regs. in both France and Spain are a joke. The last place we lived in Spain, an apartment block built just a few years before (2000) was typical, the flat next door had their bathroom/toilet next to our lounge - it was easy to tell whether a man or woman was using the toilet and as for rumpy pumpy - noisy beds a no-no, silent sex, no thank you.

 

The old Georgian houses used very soft bricks for internal walls then a thick bonding plaster which contained a lot of horse hair and finally finish plaster nothing like the hard type used today.

 

You can easily find info on aercrete blocks - www.xella.com. aercrete blocks have some excellent properties (1) environmentally friendly materials (2) fireproof (3) insect proof (4) thermally very efficient, so creating an efficient barrier between an internal and external environment (5) acoustically superb why? each precise block contains millions of air bubbles. The surface is soft so they need to be handled carefully but are structurally strong unlike the overpriced hemp blocks aka they are not reflective but sound is initially absorbed but not passed on/through, so privacy is another desirable point. I wouldn't dream of building my own home using anything else.

 

I cannot believe that anyone in Oz who lost their home to the fires would consider using combustible materials in a rebuild but I'm sure that builders will try to persuade them to use the same old, same old, just plain crazy to even contemplate this.

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On 21/02/2020 at 12:01 AM, Southerly said:

Sorry to say but your post doesn't make any sense.

You'll have to be more specific on which parts of my post don't make sense.

 

On 21/02/2020 at 12:01 AM, Southerly said:

First - stud and plasterboard, even with rockwool will absorb all sound and transfer it to the other side of the construction and indeed will/can cause domestic problems.

No it won't - higher frequencies will be reflected back into the room, some mid frequencies will be absorbed, and some low frequencies will be transmitted through the wall - and I agree, the transmitted frequencies may cause domestic issues.

 

On 21/02/2020 at 12:01 AM, Southerly said:

Bass or indeed all sound will be reflected by walls constructed of hard  reflective material.

agreed

On 21/02/2020 at 12:01 AM, Southerly said:

the result, their homes ring like a bell.

agreed - rigid walls are terrible for the "in room" sound

 

On 21/02/2020 at 12:01 AM, Southerly said:

The last place we lived in Spain, an apartment block built just a few years before (2000) was typical, the flat next door had their bathroom/toilet next to our lounge - it was easy to tell whether a man or woman was using the toilet and as for rumpy pumpy - noisy beds a no-no, silent sex, no thank you.

I understand your point, but you're confusing isolation with achieving good "in room" sound, and contradicting yourself in the process....

On 21/02/2020 at 12:01 AM, Southerly said:

Bass or indeed all sound will be reflected by walls constructed of hard  reflective material.

if the sound is reflected it won't be transmitted - but I get that your saying some sound is reflected and some is transmitted...and with the building practises used in your part of the world, rigid walls don't provide very good isolation.

 

On 20/02/2020 at 11:31 PM, almikel said:

here in Australia, multi dwelling buildings (eg units/flats etc) typically have brick or besser block wall construction between dwellings which have quite good isolation properties from a privacy perspective (ignoring flanking paths).

In our part of the world, rigid walls do provide good isolation (ignoring flanking paths), but also reflect more sound back into the room, making it harder to achieve good "in room" sound

 

On 21/02/2020 at 12:01 AM, Southerly said:

The old Georgian houses used very soft bricks for internal walls then a thick bonding plaster which contained a lot of horse hair and finally finish plaster nothing like the hard type used today.

I can't comment on the acoustic properties of old Georgian houses - I was commenting on the acoustic properties of modern Gyprock/stud construction vs the Australian version of a "rigid" wall, ie a brick/besser block wall that has very good isolation - apparently very unlike the version of a "rigid" wall you're used to that has very poor isolation.

 

On 21/02/2020 at 12:01 AM, Southerly said:

I cannot believe that anyone in Oz who lost their home to the fires would consider using combustible materials in a rebuild

I wasn't commenting on the combustibility of the materials, just their acoustic properties.

 

cheers

Mike

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Mike,

insolation and isolation are two completely different things. Rigid walls - if walls were flexible then any weight placed upon them would make them collapse. Even internal walls have to be able to support their own weight or collapse, so walls have to be rigid or collapse,irrespective of the materials used.

 

Using stud and plasterboard for internal walls is completely outdated both from a construction and cost base and most definitely from an acoustic point - I speak as some one who has worked in construction in 4 different countries and over time. There used to be a concert hall in East Anglia built using wood for the walls and ceiling - the sound was wonderful and so organic -the morons forgot to add smoke and heat detectors and it burnt down.

 

The Germans spent huge amounts of money (€870 million) creating the new concert hall in Hamburg. Take a look online at the construction methods and materials they used. Via two TV channels Mezzo and Brava I have listened to concerts from there and the sound is wonderful. I have also, when living in the Netherlands experienced wonderful concerts in the Concertgebouw in A'dam, definitely not neutral but also wonderful.

 

Long ago in the Netherlands  a Dutch friend was converting an old salmon cannery into a recording studio using - the soft fibrous cardboard egg boxes - it worked a treat.

 

The question has to be, have you listened to music in anything other than stud and plasterboard walled rooms and what was/is the construction of the ceilings. Cowboys use only one plasterboard skin, instead of two.  I would choose to use t&g softwood and ideally oak for the floor - not neutral but a lovely organic sound.

 

 

 

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Hi Stuart,

On 26/02/2020 at 4:09 AM, Southerly said:

insolation and isolation are two completely different things.

I assume you mean (thermal) insulation and (acoustic) isolation are two different things??? if that's what you meant, then I get that...

...there was nothing in any of my posts regarding thermal insulation - I was only discussing the acoustic properties of wall construction and the acoustic isolation/transmission/absorption of Gyprock and stud construction compared to rigid wall (brick/besser) construction in Australia

 

On 26/02/2020 at 4:09 AM, Southerly said:

if walls were flexible then any weight placed upon them would make them collapse. Even internal walls have to be able to support their own weight or collapse, so walls have to be rigid or collapse,irrespective of the materials used.

From an acoustics perspective this is not so, as per your examples...

 

On 21/02/2020 at 12:01 AM, Southerly said:

The old Georgian houses used very soft bricks for internal walls then a thick bonding plaster which contained a lot of horse hair and finally finish plaster nothing like the hard type used today.

 

On 09/02/2020 at 9:35 AM, Southerly said:

someone was asking what materials to use for some internal walls in their home and I advised against using the out of date stud and plaster board method and to use aircrete blocks,

neither are rigid from an acoustics perspective - nor is standard Gyprock and stud construction as rigid acoustically as brick/besser construction...

 

On 26/02/2020 at 4:09 AM, Southerly said:

Even internal walls have to be able to support their own weight or collapse, so walls have to be rigid or collapse,irrespective of the materials used.

Of course walls have to support their own weight, but that doesn't make them rigid from an acoustic perspective.

A tent frame easily supports the walls of the tent - does that make the tent walls rigid?

 

On 26/02/2020 at 4:09 AM, Southerly said:

I would choose to use t&g softwood and ideally oak for the floor

I have personal experience in how bad a tongue and groove softwood constructed room can sound - my lounge room has tongue and groove pine walls and floors - but it's poor sound is far more related to the room dimensions than the construction...and I don't think swapping my pine T&G floor to an oak floor would make any real acoustic difference...

...you are deluded if you think tongue and groove softwood construction is superior to Gyprock from an acoustic perspective - every board in T&G having it's own resonance, and the potential for rattles between boards is enormous.

 

On 26/02/2020 at 4:09 AM, Southerly said:

Using stud and plasterboard for internal walls is completely outdated ....and most definitely from an acoustic point

when you say your preference is for T&G softwood but "using stud and plasterboard for internal walls is completely outdated" you lose me...Gyprock on studs is a tried and tested construction method with "dial your own" isolation based on published metrics, but I accept that the "in room" metrics for Gyprock aren't understood or published - nor is T&G, but Gyprock will be vastly superior to T&G from an "in room" acoustics perspective.

 

Gyprock/plasterboard is more compliant/flexible than T&G softwood, and many times more compliant than a "rigid" boundary such as a concrete slab floor or brick/besser walls - Gyprock/plasterboard will absorb bass, as will T&G boards, but Gyprock/plasterboard will absorb bass more predictably than T&G boards.

 

On 26/02/2020 at 4:09 AM, Southerly said:

Cowboys use only one plasterboard skin, instead of two. 

that completely depends on isolation requirements.

If it was an external brick veneer or double brick wall, I'd likely be happy with a single skin of Gyprock/plasterboard, as the brick will provide the isolation (assuming flanking paths were managed) - and the compliance of the single layer of Gyprock/plasterboard will soak up bass (better again with fluffy insulation behind the Gyprock).

 

Gyprock/stud internal walls should be constructed based on isolation requirements - guidance here https://www.soundproofingcompany.com/soundproofing-101

 

Products such as Greenglue are always recommended between layers of Gyprock/plasterboard - this increases compliance of the boundary, making them more acoustically less rigid.

On 26/02/2020 at 4:09 AM, Southerly said:

The question has to be, have you listened to music in anything other than stud and plasterboard walled rooms

Of course I have - from concert halls to pub gigs to outdoor...I question your understanding of acoustics and the engineering behind construction techniques...best demonstrated by your comment :

On 26/02/2020 at 4:09 AM, Southerly said:

Rigid walls - if walls were flexible then any weight placed upon them would make them collapse. Even internal walls have to be able to support their own weight or collapse, so walls have to be rigid or collapse,irrespective of the materials used.

your comment demonstrates a lack of understanding between the acoustic properties and the structural properties of a boundary/wall.

 

cheers

Mike

 

Edited by almikel
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Just put a couple of these bad boys in,

 

Problem solved and much less headache in the process for you!!

 

Extremely unique product, and they work wonders 

 

https://www.psiaudio.swiss/avaa-c20-active-bass-trap/

 

They basically simulate punching a large hole in your wall to allow the problematic low frequency to escape.

 

I dont work for PSI Audio btw, just love their products 👍

Edited by PSI Audio
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  • 1 month later...

almikel,

what an hilarious post from you - comparing in any way a tent wall with that of a house😀.

 

Why are you quoting an American company when you live in Australia? Not only that but failing to mention that when fire encounters these  materials they give off a toxic smoke. 

 

Everyone check out exactly the fire retardant materials used in furniture now. You may well find that companies have used the cheapest types which, in contact with fire will kill you with toxic smoke - the poor sods in the notorious Grenfell Tower debacle were killed by just this toxic smoke rather than by the toxic smoke of the cladding.

 

Your whole post smacks of  theory, I get this very strong feeling that your profession begins with the letter A. 

 

Just what experience do you have in construction, you certainly have no experience of aercrete blocks but you do seem to have a barely hidden agenda or vested interest - what is it. Hvae you ever listened to music in a room constructed using aercrete blocks - I don't think so, which means your talking from theory - all  theory should come from practice.

 

I mentioned not only the undoubted (from experience) acoustic properties of aercrete blocks but very relevant to Australians  their inflammability and insect proof qualities. To prove my point take a look at the properties totally consumed by fire - all that's left is twisted metal roofs (nothing wrong with this roofing material) and stone or brick chimney stacks - that was all that was left - there was nothing left of wooden stud and plasterboard walls.

 

So now tell us all what your occupation is and what actual experience in construction do you have. 

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Ah, I read the "Stereophile" report on them and they gave the price at US $2k per unit - not sure if this would be the same today and it seems like using 3 units was better - the ferq response didn't change all that much but no mention of change in the room Rt.

It looks like a diaphragmatic absorber or BAD panel would be better value for money.

 

Sorry for intruding on your discussion, guys.

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I just found that results are not always predictable and can be downright counter-intuitive.

 

While slowly progressing the acoustic treatment of my listening room I came across a couple of spare 1200x600x100 polyester batts. I'm eventually going to hang them as clouds behind the listening position (because the rear part of the room is still quite reverberant), but until I got there I thought I stand them up against the front wall, where I currently just have a curtain. So, behind the curtain they go, and suddenly there is a peak in the upper midrange, somewhere between 1500 and 2500Hz. I thought, how is that possible, but it was definitely there. Some string notes and some vocals came across ear piercing, something I'd never had in this room before. I remove the batts and the peak is gone.

 

I'm still not sure what was going on there, but my confidence in well-planned room treatment has been shaken somewhat. 

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have you measured the response with the panels in and out?

I'm not sure how a couple of relatively small panels cause such a noticeable  peak in the response

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No, I didn't measure the response with the two panels up, since they were going to be just temporary anyway. Within a couple of days they were out again anyway ;)

 

I'm not sure either how a polyester batt can do that.

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On 03/02/2020 at 6:56 AM, Balvenie said:

Need some advice from those in the know........i have a platerboard wall behind my fairly hefty Sonor Audio Capellas, due to the room use i cant move them more than obout 40 cm from the wall, slightly toe in. I can feel the rsonance in the wall and do believe there is a bitt too much bass masking higher frequencies. The room is definitely less than ideal, but its the only place i have for stereo.

My question is, would bass traps/aqoustic panels placed behind the speakers have any benefit ?

It sounds like you are talking about two problems:

 

1. Excessive bass

2. A wall that appears to be vibrating

 

Where you have plasterboard vibrating enough that you can hear it, plaster against framing, bass traps won't help.

 

If you have too much bass for your taste, bass traps typically also won't help. Generally bass traps in the front corners won't sufficiently change the frequency response enough that you would reduce excessive bass. From your description you most likely have some peaks caused by room modes.

 

When you treat a room with bass traps with full range absorption, you get three changes:

 

1. Bass becomes tighter, with improved decay characteristics

2. The low midrange region becomes cleaner - less muddy

3. The overall reflection levels in the room are reduced - the brighter the room, the most obvious the change

 

Acoustic panels on the front wall can have an impact on the sound stage, especially with regards to depth.

 

It's fairly safe to add bass traps to any room. It's virtually always beneficial, the exceptions being only rooms that are already too dead. However, with full range acoustic panels, not every step is in the forwards direction.

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On 07/04/2020 at 10:46 PM, Southerly said:

what an hilarious post from you - comparing in any way a tent wall with that of a house😀.

it's an analogy used quite commonly in audio, popularised by Ethan Winer (Realtraps), but I've read it in other texts also, to describe the continuum of the acoustic rigidity of boundaries from free space through to tents through to garden sheds through to lightweight wall construction (eg Gyprock/stud) through to acoustically rigid walls (eg cored besser block) etc

My tent example was trying to explain to you that structural rigidity does not equate to acoustic rigidity - they are different.

 

On 07/04/2020 at 10:46 PM, Southerly said:

Why are you quoting an American company when you live in Australia?

Are you referring to Greenglue? it's the most well known product available in Australia for acoustic isolation between Gyprock layers - there are others - I've only used Greenglue.

 

On 07/04/2020 at 10:46 PM, Southerly said:

Not only that but failing to mention that when fire encounters these  materials they give off a toxic smoke. 

None of my posts above consider fire safety, only their acoustic properties. Following the recent fires in Australia, most of us would consider more "fire safe" products, like a switch back to fiberglass batts compared to poly, even though fiberglass is horrible to deal with.

 

On 07/04/2020 at 10:46 PM, Southerly said:

you certainly have no experience of aercrete blocks

Nil experience - I've not seen them used in Australia 

On 07/04/2020 at 10:46 PM, Southerly said:

Hvae you ever listened to music in a room constructed using aercrete blocks

No - I've not seen them used in Australia 

 

On 07/04/2020 at 10:46 PM, Southerly said:

but you do seem to have a barely hidden agenda or vested interest

I have no hidden agenda or vested interest - audio is a hobby for me, and I like the science

On 07/04/2020 at 10:46 PM, Southerly said:

Your whole post smacks of  theory,

On 07/04/2020 at 10:46 PM, Southerly said:

Just what experience do you have in construction

I like the theory but I also have experience in construction/room treatment in Australia - including multiple dedicated listening spaces - but it's not my day job, just a hobby.

 

In a post ages ago I asked you for references for the acoustic properties of aercrete and all you provided was the link to www.xella.com - I couldn't find any acoustic properties on their site.

The closest product I could find in Australia is Hebel - still not widely used in Australia - but I accept it looks like a good construction product, but I couldn't comment on its acoustic properties without better data. 

 

On 07/04/2020 at 10:46 PM, Southerly said:

I mentioned not only the undoubted (from experience) acoustic properties of aercrete blocks

umm - "undoubted" acoustic properties of aercrete from experience - with you unable to direct us to better data...after you saying tongue and groove construction is your preference for audio...
...with your demonstrated lack of understanding between structural rigidity and acoustic rigidity? ...we should just take your word for it? without even 1 room measurement?

 

On 07/04/2020 at 10:46 PM, Southerly said:

I get this very strong feeling that your profession begins with the letter A. 

On 07/04/2020 at 10:46 PM, Southerly said:

So now tell us all what your occupation is and what actual experience in construction do you have. 

...I'm not an astronaut, or an astrophysicist, or an artist, or an architect...which A word did you have in mind?

 

Everything I've said has a good grounding in science, theory and experience, (edit) and measurements.

 

Mike

Edited by almikel
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On 21/02/2020 at 1:01 AM, Southerly said:

 

Sorry to say but your post doesn't make any sense. First - stud and plasterboard, even with rockwool will absorb all sound and transfer it to the other side of the construction and indeed will/can cause domestic problems.

Sorry, but this isn't correct. 

 

The walls used between residences here in Australia using this construction have higher transmission loss ratings than the rendered clay brick you are comparing it with.

 

The first panel of gyprock will however absorb more sound at lower frequency than the brick wall. This is taken into account in acoustic architectural design and is usually a benefit as others have described. 22% is lost below 125Hz compared to 1% for brick, ie 78% reflected vs 99%. By 1000Hz the difference is lower, depending on brick surface its the same or 91-96% reflected vs 99%. Gyprock spec affects it too, 25mm is often used between residences in the first layer which increases reflectivity. 

 

Punch this into decibels, about 1dB difference in loss on reflection at low frequency and 0.3dB or less at higher frequencies. 

 

Quote

 

Bass or indeed all sound will be reflected by walls constructed of hard  reflective material.

The base more so than the lightweight constructions above. 

 

Quote

 

Here in France and in Spain they use 3" red clay blocks that do just that. Neither the Spanish or the French use a bonding plaster, just a single coat of finish plaster - the result, their homes ring like a bell. The Regs. in both France and Spain are a joke. The last place we lived in Spain, an apartment block built just a few years before (2000) was typical, the flat next door had their bathroom/toilet next to our lounge - it was easy to tell whether a man or woman was using the toilet and as for rumpy pumpy - noisy beds a no-no, silent sex, no thank you.

Thankfully not legal here. Not by a long way. 

 

Quote

The old Georgian houses used very soft bricks for internal walls then a thick bonding plaster which contained a lot of horse hair and finally finish plaster nothing like the hard type used today.

 

You can easily find info on aercrete blocks - www.xella.com. aercrete blocks have some excellent properties (1) environmentally friendly materials (2) fireproof (3) insect proof (4) thermally very efficient, so creating an efficient barrier between an internal and external environment (5) acoustically superb why? each precise block contains millions of air bubbles. The surface is soft so they need to be handled carefully but are structurally strong unlike the overpriced hemp blocks aka they are not reflective but sound is initially absorbed but not passed on/through, so privacy is another desirable point. I wouldn't dream of building my own home using anything else.

In terms of speech privacy their 125mm internal wall systems are comparable to standard Gyprock construction with insulation. They do have better low frequency performance but need additional studwork and Gyprock to get an impact rating.  This rating is still way too low between residences, normally Gyprock on studwork is also required. 

 

I'm also trying to remember, but I'm not sure whether aerated concrete has a cracking issue in bush fires. Can't remember the outcome when that came up on a project. Standard concrete can anyway when hot enough, one way to get water in for concrete cancer. 

 

A consideration is this form of concrete is soft and normally needs protection. While Gyprock is also soft it is easy to repair. Aerated concrete when used in residential normally has Gyprock added as a protective layer. 

 

I can't find any data for absorption, only their claim it does. Typical aerated concrete still has poor absorption as an absorber. 

 

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I cannot believe that anyone in Oz who lost their home to the fires would consider using combustible materials in a rebuild but I'm sure that builders will try to persuade them to use the same old, same old, just plain crazy to even contemplate this.

Improved fire protection drives up costs significantly.  Affordabilty relates to insurance pay outs and being able to rebuild depends on if any new requirements are affordable. 

 

Another added expense with concrete walls is wiring all light switches and power points. And expensive to change them later. I know from a few of our internal brick walls. The previously mentioned layer of Gyprock when on stud work is often used to solve this issue too. I did this at home in key areas and usually specify it as a given for architectural projects. 

Edited by DrSK
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DrSK,

Improved fire protection drives up costs - not if you use aercrete blocks. All the methods you use in Oz are by your own definition  labour intensive. If you include timber then very nasty chemicals have to be used to protect against woodworm and termites. Consider an aercrete block, it's U value is impressive and most importantly it's fireproof and no it doesn't crack when hot from a fire. Only an idiot would use ordinary mortar, when used with the correct aercrete adhesive - the thin joint method and a good quality crepi finish will withstand any fire. 

 

Exterior walls - 15 cm blocks  bonded through to create  a 35/40  cm depth infilled with blown insulation. Or use a single 30 cm block. I prefer to use 15 cm blocks (better for a brickie's back). With walls using this type of 'cavity' it's so easy to introduce cabling before using the blown insulation. The blocks are easy to cut accurately, so work is fast. No manufacturer produces half blocks, same for bricks no one makes bats - why not?.  So, for the exterior just (2) operations. Internally, the blocks present a very smooth finish with only minor faults to be skim coated. Wiring - is a doddle because of the soft nature - chisel out (very easy) the perp on one course and drill out the centre of the block above. On the bench cut out for the wiring box on the bed of top and bottom of two blocks and coat with a 5-1 Unibond. Introduce the cable as you build.  Your comments about concrete are about standard 'dense' concrete, not aercrete. Size the walls and line/cross line or use patterned paper. 

 

Why would you need to 'protect' the aercrete wall, who's going to 'attack' it? ergo no need for a plaster finish. If you want to hang something on the wall which is heavy, use  longer screws. I guarantee that I can build an aercrete wall far faster than using any of the traditional methods. I re-iterate again that a house built using these blocks will go up far faster, cheaper and will be fire and insect proof and if you want you can build a house that is earthquake proof as well using additional re-inforcement materials.

 

For those affected by the horrendous fires  - research and then more research and don't be bullied into accepting the views of those with vested interests or those trapped in the past. Having worked in various countries I can say that builders in all countries are reluctant to change, the exception is cordless tools. You will find that you can build or have built a house that will withstand any fire. There are other things like having a house built off the ground using factory made reinforced concrete flooring plates, way better than making concrete floors in situ, adding waterproofing compounds to concrete foundations, protecting windows from solar energy. Indeed it's not difficult  to design a house that doesn't need a/c, all it requires is an open  mind and borrow ideas from different cultures - the Arabs a long time ago learned how to build comfortable cool homes. 

 

 

 

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