RaZorTT's Theatre Build

**Prof.** · **07-26-09, 11:19 PM**

Quote:

raZorTT wrote:

Based on what I could find going through the various threads, Bradfords Ultratel is the most suitable insulation for treatments on the sidewall and rear walls. The rear walls (slightly different colour) should have an FSK or equivalent facing to keep the rear a little lively (thanks bpape!). I had planned for the sides and rear to be 25mm (1") thick.

When I was making my rear window plug, I asked Bradfords about FSK and they informed me that they don't have that product..
The only facing they have with Supertel or Ultratel is a BPF facing (Black Paper Face) and it's a lot more expensive than the plain fibreglass..

I bought it and used it in the window plug, but have always wondered whether it was as effective as the FSK..
It's only a very thin membrane on the face of the fibreglass..

Just recently I've been doing some experimenting, placing different material in front of the window plug, to see if there is any improvement in reflecting the highs..

The different paper based materials I tried didn't seem to make much difference, so in desperation I whacked up a piece of 3mm. MDF in front!!

Wow!!.. did that change things dramatically!!..
Surround sounds were much more detailed and seemed to project more coherently to locations in the room, where you would expect to hear them in respect of the action on the screen..
Interestingly enough..bass extension seemed to be even better, but I don't know if that was just my imagination..

I'm doing further tests at the moment using Mylar as the high frequency reflector..
I'll let you know the outcome of that..

**raZorTT** · **07-27-09, 12:13 AM**

Quote:

bpape wrote:

The front wall can be 1" or 2". I prefer 2" to help deeper with SBIR issues as well as surround reflections.

On the side walls, do the first 5' or so floor to ceiling. 1" is OK if space is at a premium.

On the rear wall, use something thicker and do full wall coverage - but use an FSK facing on it to keep the surround lively while still being able to help with nulls off the rear wall in the bass range.

Bryan

Thanks Bryan!

Space isn't a huge issue so i'll look to go 2" everywhere and i'll update my model so the first part of the side walls and the rear wall are floor to ceiling.

Do you have any preference on the superchunk versus hanging for bass traps?

Cheers,
Simon

**raZorTT** · **07-27-09, 12:22 AM**

Quote:

Prof. wrote:

Well if you were going to use two different thicknesses, then that's the way I would do it..But using 2" thick all round would be better..

2" it is

Quote:

Prof. wrote:

I was originally going to use chunks, but then I heard about the effectiveness of spaced flat corner panels for traps..
So I decided to try the panels first ( much less work..

) and see how they performed..I could always do the chunks later if need be..
I was so impressed with the bass performance that I decided to leave it as they were.

The only thing is the bottom of my soffit is about 2.7m off the ground and the sheets are only 2.4m long :-\

Quote:

Prof. wrote:

That's a nasty little corner..
It doesn't look to be much corner wall area with the door open..but with the door closed, you then have a large empty corner again..
There's probably not much you can do about it...Possibly placing a vertical panel on the side wall above your existing insulation..and a panel on the door, might help a bit..

Yeah nasty is right! do you think a chunk with a 300mm face (1/2 normal) would be worth it?

I'll definitely put some panels on the door. Actually, have been thinking maybe I need to switch it from opening out to opening in so the panels will be a bit more seamless.

Quote:

Prof. wrote:

I would still fill any soffits with insulation..

Would you pack them completely? Or leave a bit of a gap at the top?

Cheers,
Simon

**raZorTT** · **07-27-09, 12:28 AM**

Quote:

Prof. wrote:

When I was making my rear window plug, I asked Bradfords about FSK and they informed me that they don't have that product..
The only facing they have with Supertel or Ultratel is a BPF facing (Black Paper Face) and it's a lot more expensive than the plain fibreglass..

I bought it and used it in the window plug, but have always wondered whether it was as effective as the FSK..
It's only a very thin membrane on the face of the fibreglass..

Just recently I've been doing some experimenting, placing different material in front of the window plug, to see if there is any improvement in reflecting the highs..

The different paper based materials I tried didn't seem to make much difference, so in desperation I whacked up a piece of 3mm. MDF in front!!

Wow!!.. did that change things dramatically!!..
Surround sounds were much more detailed and seemed to project more coherently to locations in the room, where you would expect to hear them in respect of the action on the screen..
Interestingly enough..bass extension seemed to be even better, but I don't know if that was just my imagination..

I'm doing further tests at the moment using Mylar as the high frequency reflector..
I'll let you know the outcome of that..

Wow that sounds promising! Definitely keep us posted! Sounds like I should look at buying some ultratel in bulk then for the rear wall building in either thin mdf or the mylar in the panels!

Have you tried some 6mm gyprock? wondering if that would work like the MDF?

Thanks Prof!

Simon

**raZorTT** · **07-27-09, 04:23 AM**

Ok I did up the changes in sketchup.

Treatments

All the treatments are 2" thick now and the first 1.5m (5ft) and rear wall are from floor to ceiling.

Do you think I should stick the insulation in the columns too? seeing as they're only covered with GOM. Probably wouldn't hurt.

Prof. for your bass traps did you cut a 1200mm sheet into two and sandwich them together? so you have a 600mm face?

Cheers,
Simon

**bpape** · **07-27-09, 07:23 AM**

Well sure. Something 3mm thick and stiff like that is going to reflect pretty much everything. As for bass, it'll still probably pass most of it. It's also likely acting as a membrane tuned to who knows what.

Bryan

**bpape** · **07-27-09, 07:24 AM**

Simon,

Please explain a bit more (or link) to exactly what you're talking about for the other than chunks

Bryan

**raZorTT** · **07-27-09, 08:15 AM**

Quote:

bpape wrote:

Simon,

Please explain a bit more (or link) to exactly what you're talking about for the other than chunks

Bryan

Hi Bryan,

This is my understanding (which is obviously quite limited

) of what I've read/seen used as a bass trap.

alt bass trap

The 3 sheets of insulation would be a total of 6" thick. Put in the corner with an air gap behind them.

I'm not sure if the corners of the front sheet should be touching walls or the rear corners. I suspect probably the front.

Cheers,
Simon

**bpape** · **07-27-09, 09:54 AM**

OK. Just wanted to make sure. There are things in the studio world called 'hangers' which are a different animal. What you showed will work just fine - it just takes up a lot more space in the room. If it were me and I could have that much space, I'd make 24x24x34" chunks (4 triangles per 2'x4' sheet as opposed to 8 triangles per).

Bryan

**raZorTT** · **07-27-09, 05:22 PM**

Quote:

bpape wrote:

OK. Just wanted to make sure. There are things in the studio world called 'hangers' which are a different animal. What you showed will work just fine - it just takes up a lot more space in the room. If it were me and I could have that much space, I'd make 24x24x34" chunks (4 triangles per 2'x4' sheet as opposed to 8 triangles per).

Bryan

Thanks Bryan,

I Appreciate your advice!

Do you think it's worth making a small trap in each of the rear corners? With a face of about 300mm ( 1ft)?

Or will making larger ones like you mention above and isulation in the soffits be enough?

Cheers,
Simon

**Prof.** · **07-27-09, 08:05 PM**

Quote:

raZorTT wrote:

The only thing is the bottom of my soffit is about 2.7m off the ground and the sheets are only 2.4m long :-\

I wouldn't be overly concerned about that..
You could just build the mounting frame to the full height between the floor and the soffits, and have the trap at 2.4M.high..or alternatively, if you have any Ultratel left over, just add a bit on top..

Quote:

Yeah nasty is right! do you think a chunk with a 300mm face (1/2 normal) would be worth it?

I don't think small chunks are going to do very much..
If you made up some panels.. say 2' x 6' and 4" thick for the side wall right next to the door opening and at floor level..and the same on the door, I think that would be more effective..

Quote:

Would you pack them completely? Or leave a bit of a gap at the top?

I would loosely fill them completely..to stop any ringing..
It's quite amazing the effect they have when filled, in deadening the acoustics in the room..

**Prof.** · **07-27-09, 08:15 PM**

Quote:

raZorTT wrote:

Wow that sounds promising! Definitely keep us posted! Sounds like I should look at buying some ultratel in bulk then for the rear wall building in either thin mdf or the mylar in the panels!

Have you tried some 6mm gyprock? wondering if that would work like the MDF?

Thanks Prof!

Simon

I haven't tried gyprock but that could be very effective since it's not as hard a surface as the MDF..
Thanks Simon, I'll give that a try..

**Prof.** · **07-27-09, 08:25 PM**

Quote:

raZorTT wrote:

Do you think I should stick the insulation in the columns too? seeing as they're only covered with GOM. Probably wouldn't hurt.

Definitely fill the columns with insulation..just something like "Pink bats" will be fine..

Quote:

Prof. for your bass traps did you cut a 1200mm sheet into two and sandwich them together? so you have a 600mm face?

Actually I had to cut the sheets into three 450mm. wide strips..
I didn't have enough room behind the screenwall to make them 600 wide..

**Prof.** · **07-27-09, 08:33 PM**

Quote:

bpape wrote:

Well sure. Something 3mm thick and stiff like that is going to reflect pretty much everything. As for bass, it'll still probably pass most of it. It's also likely acting as a membrane tuned to who knows what.

Bryan

I used the 3mm. MDF as an extreme change from the paper faced panel, to see how much difference there would be..
It did show a big difference, but not necessarily ideal..that's why I'm now trying the Mylar film..which is a bit softer but still reflective..and I'll also now try the gyprock (drywall)..

**bpape** · **07-28-09, 09:39 AM**

Quote:

raZorTT wrote:

Thanks Bryan,

I Appreciate your advice!

Do you think it's worth making a small trap in each of the rear corners? With a face of about 300mm ( 1ft)?

Or will making larger ones like you mention above and isulation in the soffits be enough?

Cheers,
Simon

Rear corners would be nice. 1 ft will be fine.

Having it spread in different areas will only make it more efficient.

Bryan

**cinema mad** · **07-28-09, 12:47 PM**

Quote:

Prof. wrote:

When I was making my rear window plug, I asked Bradfords about FSK and they informed me that they don't have that product..
The only facing they have with Supertel or Ultratel is a BPF facing (Black Paper Face) and it's a lot more expensive than the plain fibreglass..

I bought it and used it in the window plug, but have always wondered whether it was as effective as the FSK..
It's only a very thin membrane on the face of the fibreglass..

Just recently I've been doing some experimenting, placing different material in front of the window plug, to see if there is any improvement in reflecting the highs..

The different paper based materials I tried didn't seem to make much difference, so in desperation I whacked up a piece of 3mm. MDF in front!!

Wow!!.. did that change things dramatically!!..
Surround sounds were much more detailed and seemed to project more coherently to locations in the room, where you would expect to hear them in respect of the action on the screen..
Interestingly enough..bass extension seemed to be even better, but I don't know if that was just my imagination..

I'm doing further tests at the moment using Mylar as the high frequency reflector..
I'll let you know the outcome of that..

Hi all,
You can get 50mm Ultratel with A facing called Acoustistuff, its A thin foil lining which appears to be A close match to the Owens corning FRK (foil reinforced kraft). These facings are used as A vapor barrier but as Bryan Pape has pointed out will reflect the higher frequency's when used as acoustic treatments...

Here is A link to A PDF of the different facings avalible for the CSR Bradfords semi rigid fiberglass boards, See Page 7

http://www.bradfordinsulation.com.au...6585a4d55c.pdf

Hope this helps,
Cheers....

**raZorTT** · **07-28-09, 06:39 PM**

Quote:

bpape wrote:

Rear corners would be nice. 1 ft will be fine.

Having it spread in different areas will only make it more efficient.

Bryan

Thanks Bryan,

I think the ultratel comes in packs of three so based on my calculations ill have at least 1 sheet spare, which will be more than enough to make the rear traps

Quote:

cinema mad wrote:

Hi all,
You can get 50mm Ultratel with A facing called Acoustistuff, its A thin foil lining which appears to be A close match to the Owens corning FRK (foil reinforced kraft). These facings are used as A vapor barrier but as Bryan Pape has pointed out will reflect the higher frequency's when used as acoustic treatments...

Here is A link to A PDF of the different facings avalible for the CSR Bradfords semi rigid fiberglass boards, See Page 7

http://www.bradfordinsulation.com.au...6585a4d55c.pdf

Hope this helps,
Cheers....

Hey cinema mad,

Thanks for the heads up on Acoustistuff. I found out yesterday that the place my dad gets all his building supplies can get their hands on ultratel

I'll have to find out if it costs extra for the Acoustistuff facing.

Am trying to accumulate as much as I can before we really kick into construction

Cheers,
Simon

**Prof.** · **07-28-09, 08:44 PM**

Quote:

cinema mad wrote:

Hi all,
You can get 50mm Ultratel with A facing called Acoustistuff, its A thin foil lining which appears to be A close match to the Owens corning FRK (foil reinforced kraft). These facings are used as A vapor barrier but as Bryan Pape has pointed out will reflect the higher frequency's when used as acoustic treatments...

Here is A link to A PDF of the different facings avalible for the CSR Bradfords semi rigid fiberglass boards, See Page 7

http://www.bradfordinsulation.com.au...6585a4d55c.pdf

Hope this helps,
Cheers....

Hi Jason,

I did see that alum. faced fibreglass at the time I bought my 50mm. BMF (not BPF) sheet..
I decided against it because I was under the impression (at that time) that the FSK was more like our normal brown kraft paper..
The aluminium face was thicker than the BMF and I felt it would be too reflective..

Looking at that chart you linked to, I can see now that the BMF absorption rate is much higher than the Acoustituff material and that would have been the better choice..
It also is confirmed by recent experiments using different facing materials, that the BMF has very little reflective qualities..

I think the Mylar film I'm currently testing will most likely come close to the alum. Acoustituff..

**raZorTT** · **07-28-09, 10:31 PM**

Quote:

Prof. wrote:

Hi Jason,

I did see that alum. faced fibreglass at the time I bought my 50mm. BMF (not BPF) sheet..
I decided against it because I was under the impression (at that time) that the FSK was more like our normal brown kraft paper..
The aluminium face was thicker than the BMF and I felt it would be too reflective..

Looking at that chart you linked to, I can see now that the BMF absorption rate is much higher than the Acoustituff material and that would have been the better choice..
It also is confirmed by recent experiments using different facing materials, that the BMF has very little reflective qualities..

I think the Mylar film I'm currently testing will most likely come close to the alum. Acoustituff..

Hey guys,

So are there three types of ultratel? unfaced, BMF and acoustituff?

Or is the BMF the "normal"?

I think i'll order 3 or 4 sheets of the acoustituff to use on the rear wall.

Looks like the place my dad gets most of his building supplies from can supply us with ultratel

Cheers,
Simon

**Prof.** · **07-28-09, 10:46 PM**

Half your luck Simon..
I just priced the 50mm. unfaced Ultratel 3 pack and they want $200.00/pack!!

Edit..I should add that I only need 1 sheet and they won't break the packs..

**raZorTT** · **07-28-09, 10:54 PM**

Quote:

Prof. wrote:

Half your luck Simon..
I just priced the 50mm. unfaced Ultratel 3 pack and they want $200.00/pack!!

Unfortunately the price looks like it's fairly standard :-\ But the bonus is I won't have to buy it elsewhere and then get it shipped to me.

So looks like there are 3 in the range then. wonder how much they'll whack on for the acoustituff facing

Cheers,
Simon

**Prof.** · **07-28-09, 11:05 PM**

When I bought my Supertel, they were $68.00/sheet..
The same sheets with BMF were $94.00/ sheet!..The Acoustituff facing might be even more..

**cinema mad** · **07-28-09, 11:34 PM**

Hi,
Yes the UltraTel comes as 1200x2400 x3 only, I must have A good Rep at my CSR Bradfords outlet because I get it for under $200

Simon, Acoustistuff is close to the FSK, there is A thiker foil avalible but it is not the same as FSK...

Cheers...

**cinema mad** · **07-28-09, 11:40 PM**

Prof, You Know Kraft paper works to reflect the Higher freq Why not just use that?..
I used it to make Membrane based and posted the build on my thread...

**Prof.** · **07-29-09, 08:01 PM**

Quote:

cinema mad wrote:

Prof, You Know Kraft paper works to reflect the Higher freq Why not just use that?..
I used it to make Membrane based and posted the build on my thread...

Jason,

I used the Mylar film initially because I had a roll of it on hand..and thought it would be very similar to very thin aluminium foil in it's reflective qualities..

For the tests, I've just placed the Mylar between the cloth covering and the fibreglass on the window plug..but I'm beginning wonder whether it would make any difference to the reflectivity if it was actually bonded to the fibreglass!..I can't see that it really would..it's not flexing because it's very firmly pressed against the cloth..but you never know..
Any thoughts on that?

I can't find Kraft paper online anywhere, other than buying a large roll of it..and for just a try out it's not worth it.. No shops locally use Kraft paper where I might just be able to get a few feet of it..
It seems the days of a counter top having a roll of brown paper for wrapping purposes, have gone!

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