This is a cut/paste from a follow up posting I made in the Helkion SL thread. It is sufficiently off topic to deserve relabeling as a seperate thread.
Its the room... stupid
quote:
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Ron,
How are the DBLs sounding now that you have insulated your walls?
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Simply put... DBLs have entirely no business being in a room with flimsy and acoustically translucent walls...they act as a low pass filter to suck out all of the visceral heft the extra $10,000 is supposed to provide you with.
I approached this task in two phases. Firstly the room flooring was just plyboard on top of sheetrock with a nice hollow cavity between. In its native state the music was almost as loud in the room beneath (actually a 3 car garage) than in the main music room- and had far more bass as well. In comparison the music room had an emasculated unbalanced sound that could not be corrected with the Snaxo trim pots. There was also a peaky dysphonic tonal quality to the midrange. Oh, and no imaging whatsoever.
Following packing of this cavity with cellulose insulation things improved by greater a Hicaps worth... the long absent bass was back.. and tuneful to boot. There was a vast reduction in the hashy untimely sound with a far more natural and unforced presentation. The volume pot on the 52 also needed to be rotated 2-3 o'clocks less- a fact which cost me a pair of tweeters in the earlier days (listening at 3 oclock position with a sixpack the achieve the same volume levels that I can now have at 12 o'clock). All in all... well worth the $750-ish-bear in mind this is quite a large room with lots of sq. footage.
After several months of wondering what the effects of the internal walls would be (they too are uninsulated sheetrock/drywall with hollow central cavities)I had them blown with the same cellulose stuff as was in the flooring. This required 2 holes to be punched between every stud, and is somewhat of a messy chore. The insulator guy replaced those sheetrock divots with plugs of styrofoam which he then smoothed over with joint compound- they are yet to be repainted. Interenstingly enough during this process he found there WAS some in-wall insulation to the right of the right speaker (as this then became an outside wall), but none between the speakers and to the left of them. There was also none in the side walls or in the walls of the walk in closet in which I house all the electronics.
The immediately noticeable result is that the sound no longer has the right-side heavy skew.. before that I had to run the balance control in the 11 o-clock position to maintain a dead-center image. No doubt a result of inwall insulation existing only to the right of the right DBL. Further listening again shows an increase in clarity, tunefullness and purity- although it is no louder on any given volume setting. Given that this additional stage cost less than $300, it too was well worthwhile.
Finally the 20A circuit breaker was replaced with a 70A one, that straddles two of the circuits. This then allows me 4 duplex plugs all being fed of this high-current, common earthed feed- giving me the opportunity to electrically connect all 14 powered boxes into it (the Wiremould strip only allows 9). There was the expected improvement in bass extension and upper register articulation.
There is really only one final coup de grace left. When the floor insulation was installed, he had to cut a strip out of the sheetrock beneath.. about a food wide, and spanning the entire width of the room. This has not yet been patched and probably is letting some unwanted sound vent through instead of being contained internally. Eventually I will have that repaired and expect some additional incremental improvements.
To put it into perspective.. I am sure an 82 in the 'treated room' would handily outperform a 52 in the untreated one. That is the level of souring that uncomplimentary room acoustics can inject upon sound.
My ultimate tweak would be to maybe put the DBLs on granite blocks, and to screw sheets of 12-ply onto the walls directly behind each DBL, to further reinforce them. Those will eventually happen.
Any other DBL user out there with suspended wooden floors using masonry beneath the speakers??
Ron
Dum spiro audio
Dum audio vivo
Posted on: 11 March 2002 by ken c
To put it into perspective.. I am sure an 82 in the 'treated room' would handily outperform a 52 in the untreated one. That is the level of souring that uncomplimentary room acoustics can inject upon sound. ron, it sounds like your music was so handicapped that ANY good and balanaced system would sound better in the treated room? yes?
it is amazing how things outside the equipment itself can affect the sound so negatively as to make the investment not worthwhile. might this explain the diversity of views on a number of naim components, e.g. SBL? 500? etc etc
long may you continue to enjoy what is in fact a really fabulous system...
ken
Posted on: 12 March 2002 by P
Interesting points raised here.
I've experimented with mass loading behind my SBLs. An extra layer of MDF board directly behind the speakers really helped to decrease the wooliness and tightened up the Bass considerably.
Placing the MDF also reduces the recess depth from the speakers to the fire surround (Due to the room layout I have my speakers either side of a dense and heavy portland stone fireplace)
I've been toying with the idea of cavity wall insulation too. Anyone done this in the UK in a new build style house?
P
Posted on: 12 March 2002 by Ron Toolsie
The large missing strip of sheetrock beneath the flooring (probably some 20-30 square feet) is being added today, effectively sealing the now-filled cavity between the floor of the music room and the ceiling of the underlying room. Observations to follow.
I should either do the ply-behind-DBLs or the extra layer of sheetrock sometime in the next couple weeks. Its always nice to get Hicap-level improvements for Snaic prices 
Ron
Dum spiro audio
Dum audio vivo
Posted on: 12 March 2002 by P
Derek I was referring specifically to the type of house currently being built enmasse all over this country ie brick and block cavity wall with dot and dab plasterboard walls and concrete floor.
Builders always state that the thermal insulation is quite adequate within the building envelope itself and there's no need for anything extra within the cavity. They generally say this because it's quite expensive to install and can highlight problems with the quality of the build too.
I might add that we're currently in our third brand new house within 5 years that have all been of a similar size and design and we've never had cavity wall insulation installed. It's something I'm quite keen to try and would be interested to know if anyone here has done it. I know it helps with external sound transmission levels but how does it affect the room Q in general?
Anyone?
P
Posted on: 12 March 2002 by P
Derek
I won't go there regarding the Rigid Sandwich thing, as much as I'm tempted (reminds me of the old joke about Ben Doon and Phil Mcavity - ooh err)
Having said that, the bond between the block and board could and really should have a fair amount of integrity although this does depend on the skill of the installer and the level of quality expected.
Double skinning a wall is a good idea and, I think, the sonic benefits can prove that.
The large void between the brick and block is another issue. I'm thinking in terms of total mass damping and sonic integrity.
Did you notice any improvement after having your cavity filled?
P
Feeling like Ken Dodd
Posted on: 12 March 2002 by Derek Wright
I had the cavity wall unsulation done in 1974 during one of the great coal strikes, at the time I had a leak Stereo 70, a pair of Spendor BC1s and a Thorens TD125 mk ii with a Shure V15 cartridge.
The improvement to the sound is not a thing I remember <g>
I now live in a timber frame house (again chosen for heat insulation reasons) but it does require that the speakers are free standing and not dependant on wall space. Hence Naim speakers are out of the selection list.
Derek
Posted on: 12 March 2002 by Martin Clark
Short answer: if your listening room has brick and block walls then adding insulation to the cavity will do nothing for the sound in-room because the leaves have great mass, and contrary to popular belief are fairly stiffly coupled by things called wall ties. Attention elsewhere such as sealing doors / acoustic treatment / stiffening floors or ceilings will give
far higher return on investment
Long answer and shameless plug: see here under 'soundproofing'
MC
Posted on: 12 March 2002 by Ron Toolsie
Pursuant to my above postings, this afternoon I had the missing strip of sheetrock replaced (about 1 ft wide and 20 feet in length) spanning the entire width of the listening room. This may have only accounted for less than 10% of the square footage, and was at the listening rather than speaker side of the room...BUT.....
The audible improvements are very obvious. Firt up the volum pot needed yet one less o'clock advancement. So now the 11 oclock position sounds as loud as the 3:00 did previously. Colouration has been greatly reduced, most noticeable in the vital midrange. Low frequency extension is subjectively half an octave deeper with a *far* more effortless feel to it. Somewhat suprisingly there is now a real center image and soundstage, that while admittedly is not that deep, is anchored pretty tightly in the lateral plane. Yes folks, the DBLs can cast in image.
The overall effects of (most importantantly) filling the flooring and then the cavities of the side walls has been (I swear) a Supercap-level improvement. Although the electronics and the layout of the room is identical to the way it used to be... this system now plays music with great finesse and tune. In retrospect the uninsulated walls and flooring made everything sound like a very big boombox stereo- power without responsibility.
As far as the effects of finally sealing up the flooring with the final sheetrock strip, the moral is that is is far better to tightly fill one small hole, than to turn a very large hole into a small hole.
No doubts these can all be physically explained by changes in Q's. But whatever the reason, anybody using an upper level suspended wooden floor with new-style sheetrock walls can make enormous improvements for a price of roughly 1/2 a Hicap.
Oh, did I mention that one of the DBLs gaskets became unseated during moving the speakers around to patch the sheetrock, and all the changes I've noted today were with one suboptimally performing DBL. Tomorrow after the room gets repainted (and the speakers moved again) I'll reseal the gaskets and let 'er RIP.
Yes, life is good.
Ron
Dum spiro audio
Dum audio vivo
Posted on: 13 March 2002 by Rico
Ron
great posts, and congrats on your changes.
quote:
(they too are uninsulated sheetrock/drywall with hollow central cavities)I had them blown with the same cellulose stuff as was in the flooring.
Could you give a little more detail on this Cellulose insulation, please?
I have a timber floor, which I had been planning to insulate underneath with fibreglass insulation (I think this is rockwool?) and building foil, from a warmth/energy saving perspective. Will be very interesting to note changes/improvements to the sound - if it works as well as I might now expect, I will certainly consider ply or sheetrock under the foil (it's a basement workshop).
The cavity walls in the room have already been insulated with fibreglass insulation. .
All this after the separate spur is installed, of course
Rico - SM/Mullet Audio
Posted on: 14 March 2002 by Ron Toolsie
quote:
Could you give a little more detail on this Cellulose insulation, please?
From what (little) I understand cellulose is somewhat more expensive, somewhat denser and somewhat less likely to act as an irritant as compared to fiberglass. Regardless, the biggest difference is to replace empty space with something..... about anything would be better than nothing.
I'll leave it up to architects/acoustic engineers to debate the applicational differences between fiberglass and cellulose.
Ron
Dum spiro audio
Dum audio vivo
Posted on: 14 March 2002 by Martin Clark
Rico - mineral wool and glass fibre aren't quite the same (different source material), with the mineral wool being considerably less of an irritant since the fibres are larger. Keep away from glass fibre if it might get disturbed, it's is nasty stuff and the fibres easily migrate. Oh, and your foil layer should go on the 'warm' side - the top, if your basement is unheated.
Ron is right on the money, cellulose is probably good for your application; in the UK 'Warmcel' is one tradename - made from recyled newspaper. There's also a sheep's wool insulation available - comes in small bales, very nice to handle!
MC
Posted on: 14 March 2002 by P
Is Warmcell the stuff that looks a bit and certainly smells, a lot, like SugarPuffs (the blown wheat breakfast cereal)?
I'd have the munchies all day long if I had that stuff in my walls.
Big Thanks to the Acoustica boys BTW. Great site!
P
Counting the days before I start work again boohoo.
Posted on: 14 March 2002 by Rico
Thanks for the replies, guys.
Down here there is (as you'd expect) sheep's wool insulation available. Not so sure I'd care to have such organic material in an exterior cavity wall (most of our houses are timber clad) - water leaks and rot spring to mind, although I'll admit this is backed up by no scientific thought.
Not sure we have mineral wool-based insulation down here?
In NZ the biggest selling brand is "Pink Batts"Pink Batts - natrually you'd expect such lines as "MORE COMFORTABLE
Advances in fibre and binding technology mean very low levels of irritation. In-house tests show dust levels less than half that of competing products. Blind tests confirm that PinkTM Batts® is the softest glasswool insulation available. ", and there are a few other competed fibreglass insulation products available.
Best I talk with an architect mate, and indeed with our own resident forum architectural specification enthusiast for further info on the cellulose insulation.
Unfortunately I will be unable to foil-line the floor before installing insulation. My workshop is "virtually heated" - that is, the large heating ducts from the exterior gas central heating heat-exchanger pass through and around the workshop.
Will follow the recommendation and ensure the space is filled.
Cheers!
Rico - SM/Mullet Audio
