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Building An Extension - External Wall Construction

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Re: Building An Extension - External Wall Construction

Postby adamc » Fri Sep 03, 2004 8:47 pm

0VU - thanks for the detailed reply and for taking the time to look at my plan JPEGs - it will probably return to be a dining room if I ever move house. And besides, eating while recording - sounds a good combination to me :-)

Is HD block a name of a brand or just a generic term (e.g. High Density) ? I'll have a look into your suggestion of getting a heavier block and larger cavity. I was a bit put off doing this by Hugh's earlier reply which seemed to suggest that using heavier blocks might be less safe from a structural point of view.

At the moment I'm working out of two bedrooms in my 3 bed semi - one room with all the equipment and one room with mics in (and those duvets!) - most of my work is with singers and acoustic guitar players at them moment (plus monitoring at fairly low levels) and when I've talked to my neighbours in the other half of the semi they say they haven't really heard anything. So I'm expecting that with a standard construction (without room within a room) it should be as good as what I've got now.

Another reason for building the extension is just to get all the gear out of the bedrooms and turn them back into .. bedrooms. And new extension would give me quite a bit more space too.

What I was hoping to do was to build a fairly standard external wall construction (maybe with slightly heavier block) - which I think would be fine to continue the kind of work I'm currently doing (singers etc) and then add more soundproofing (room within a room) at a later date to be able to work with some louder music (drums etc) - the extension is going cost around 13-15K (pounds) and I've got about 20K to play with at the moment. I was hoping then to do more work soundproofing maybe a year or two down the line when some money has accumulated.

Yes I better think about some ventilation, it gets really hot upstairs in the house with all the windows closed and the PC on.

cheers

adam
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Re: Building An Extension - External Wall Construction

Postby Studio Support Gnome » Sat Sep 04, 2004 1:20 am

>As well as filling the cavity with Rockwool (or 2" polystyrene, its just as good) you could also batten out the internal wall and add more fibreglass or polystyrene in between before it is covered with plaster boards.

I just thought I’d mention that, for thermal insulation, polystyrene is better (cheaper too) than Rockwool ‘cos polystyrene doesn’t absorb water.

If any material used for thermal insulation absorbs water its thermal properties will be severely compromised (read no insulation at all); cavity walls can sometimes harbour damp.

Tim ;o)

Top Man Tim...
I never realised the intent was inside the cavity... I was thinking inside and inner Skin wall of Resilient bars and Plasterboard......

Must be too tired... think I'll go to bed earlier form now on :lol:

(Like hell I will..... but it's a noble intention anyway... )

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Re: Building An Extension - External Wall Construction

Postby Tim. » Sat Sep 04, 2004 6:26 am

Had a quick look at your plans Adam…0VU has admirably covered a lot of ground in his usual thorough style.

I’d just like to add a couple more thoughts:

You have lots of empty space above to make an interestingly shaped ceiling; interesting both visually and acoustically. At the very least I’d slope the ceiling so it’s not parallel to the floor. Also, by incorporating more of that empty space into the room you would increase its cubic capacity; usually a good thing acoustically and for air.

Re double glazing. Sorry if you already know this but I’ll mention it anyway…double glazed units with glass of the same thickness on both sides can produce sympathetic resonance problems at certain frequencies. Dissimilar thickness panes also help with attenuation.

Laminated glass is also slightly better acoustically because sound doesn’t like to travel through dissimilar materials (ie glass-plastic-glass sandwich) It is also better for safety and security too.

Re ventilation. If you go for a ducted ventilation/cooling system then the ducts do need to be of sufficient diameter to facilitate slow movement of air. The smaller the ducting, the faster the flow and hence noise at the inlets/outlets.

Also, silenced ducting (essential to stop noise transmission through the ducts) needs length to be effective; when building my latest studio I experimented and found at least two metres of 30cm silenced ducting was required for worthwhile attenuation.

Flexible sound attenuating ducting:

http://www.decinternational.com/

I have some details of my studio build on the Construction page at:

http://www.kymatasound.com/

Thanks Max… I’m tired too… fact of life in this business eh ;)

Tim ;o)
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Re: Building An Extension - External Wall Construction

Postby Driller » Sun Sep 05, 2004 11:22 am

Tim,

I've said nice studio before so I won't massage your ego ;)
There is mention of the accoustically treated live room on your site but no details. What kind of treatment do you have in there? Also in the control room aside from the two bass traps on the back wall and the absorber on the ceiling do you have any other treatment on the walls?

cheers
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Re: Building An Extension - External Wall Construction

Postby Tim. » Mon Sep 06, 2004 7:10 am

Thanks Driller :)

Before listing the live room treatments, a bit of background detail might help explain how I ended up with the final result:

The live room is (intentionally) rather an odd shape with two angled walls (one at 45 degs) and a stepped ceiling. The odd shape and angled walls made mode calculations pretty meaningless. In such a soundproofed room the bass would obviously be a problem so I first added a couple of large resonant panel bass traps at either end of the room.

I then set up the main monitors in there and listened to various tracks that I know well. The bass traps were doing there job but, with no HF treatments at all, it was not surprising to find that the room was overly bright and ringing at the higher frequencies. It was so bright that at high volumes the HFs were painful…

I used ETF5* to verify what my ears were telling me and got a picture of what was happening. ETF5 confirmed the much longer RT60s for the higher frequencies. I then started to temporarily fix one metre square acoustic foam panels to the bare walls, listening to the results and running ETF5 again to check the HF RT60s were moving closer to the lower frequencies.

So, the final treatments ended up as: 6 square metres of acoustic foam (mounted on 6 removable MDF panels), a 2.5 metre square wall of curtain (not that the curtain makes much difference acoustically, it’s more aesthetics) and the two resonant bass traps at either end of the room. Result… a nicely balanced sounding room. I’m very happy to report that most who have played in there say it’s a lovely sounding room

Moving on the control room: There are two large (I had to climb into them to fit the Rockwool) resonant panel bass traps on the angled front walls under the main monitors. Two slotted Helmholtz traps on the rear wall (which also absorb and diffuse HFs) shelves in between the traps for more diffusion and finally, the ceiling mounted HF/mid absorber. The left and right side walls are untreated because, being much further from the listening position than the distance to the monitors, they didn’t present a problem.

Again I used listening tests supplement with ETF5 to tune the room. Without wishing to blow my own trumpet too much…many have said it’s the best reproduction they’ve heard in their lives. I’m also extremely pleased with the results too :)

Tim ;o)

* http://www.etfacoustic.com/
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Re: Building An Extension - External Wall Construction

Postby Driller » Mon Sep 06, 2004 7:10 pm

Thanks for all that Tim! If I may though, the two resonant bass traps in the live room, are they a similar design to Ethan's panel traps or some other design. And is there a rear panel or are the frames simply pressed/sealed against the wall? Also, the Helmholtz's in the control room, did you just choose a "standard" frequency to have them made to absorb, or was it the software agin which told you? Finally, to realy push my luck, did you make the traps yourself or did you buy them (guessing you made them :))

Thanks for indulging me!

D
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Re: Building An Extension - External Wall Construction

Postby Tim. » Tue Sep 07, 2004 6:41 pm

>Thanks for all that Tim!

My pleasure Driller.

>If I may though, the two resonant bass traps in the live room, are they a similar design to Ethan's panel traps or some other design.

Mine are basically airtight sealed boxes (approx: 100 x 160 x 10cm deep) made of wood and filled with Rockwool with an air gap so the front resonant plywood panel doesn’t touch the Rockwool. They also have a larger frame around them that is dressed with a thin fabric to improve looks.

They have a fairly wide resonant centre frequency (approx 40 to 100Hz) and the overall response curve looks like a parabola, or bell curve, with the top of the curve slightly flattened.

Interestingly, the control room resonant panel traps, under the main monitors, use the same plywood fronts (albeit much smaller front panels but larger cubic capacity internally) but they exhibit a definite and much narrower centre frequency of approximately 48Hz and are –2dB at 96Hz, -8dB at 160 to 315Hz and –20dB at 500 to 800Hz. The response curve looks much more like a staircase.

>And is there a rear panel or are the frames simply pressed/sealed against the wall?

They are completely dismountable self-contained units hanging on the wall; don’t know how much they weigh but they are definitely a two-man job to lift. To maintain an airtight box all joints were: glued, screwed and covered with a generous quantity of flexible mastic.

Due to space limitations (depth) the Helmholz traps in the control room are fixed directly to the wall and sealed airtight to the wall with flexible mastic.

>Also, the Helmholtz's in the control room, did you just choose a "standard" frequency to have them made to absorb, or was it the software agin which told you?

No, not the software, I made ‘em before testing the room. My aim was to make traps that would respond to frequencies not covered by the other traps. The calculated frequencies they should be responding to are: 205,322,404,450 and 491Hz

I’d forgotten (memory error ;)) to say previously that I also used a DSP8024 RTA and ECM8000 test mic in the control room; a couple of very capable Behringer products; as a company, their products are frequently unfairly maligned.

>Finally, to realy push my luck, did you make the traps yourself or did you buy them (guessing you made them

Living on a fairly small and distant island, importing huge ready made traps would have cost a small fortune… so, the mother of invention lent me a hand in their construction ;)

>Thanks for indulging me!

You’re welcome sir. Now then, about those crowns… ;)

Tim ;o)
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Re: Building An Extension - External Wall Construction

Postby Driller » Tue Sep 07, 2004 10:57 pm

[quote You’re welcome sir. Now then, about those crowns… ;)

Tim ;o) [/quote]

Heh, heh. Tell you what, come and make my new basement look like your studio and I'll see what I can do ;)

cheers
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Re: Building An Extension - External Wall Construction

Postby Tim. » Wed Sep 08, 2004 7:24 am

>(approx: 100 x 160 x 10cm deep)

Ahem... sorry, user error... that should have read: approx: 100 x 160 x 18cm deep

I’d love to come and help Driller but I couldn’t find Paris on my map of Crete ;)

Tim ;o)
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