[wilsonj]

Hi,

I'm wanting to build some acoustic panels to dampen down the first reflection points in my room.

I went down to my local hardware shop and bought the only insulation they had. These were standard wall and ceiling pink bats r1.5 and are approx 70mm (3") thick. They are also very soft and only just stand up on their own if placed against a wall.

I have 20 of the things all over the back wall and down the sides, but only leaning against the walls.

I did notice a difference straight away. Vocals seemed clearer, imaging improved and bass sounded stronger. I assume the latter was due to the reduced higher freq. reflections.

Anyway, back to my question.

I can't find any info on these panels acoustically. Are they even suitable? Or could I find a much better solution? Actually I think I can, looking at the industrial section...

Eventually I want to use these in my HT/music room. So before I make em look all pretty, I want to make sure I have the right product.

What density should I be looking at? ~50kg/m^3?

What acoustic coefficients should I be after?

There are just soooo many choices, it gets confusing!

Regards
Jamie

 

[wilsonj]

this is what I have
http://www.insulation.com.au/content/upload/FI_DS_PinkBatts(3).pdf

this is what I think I should get.
http://www.insulation.com.au/content/upload/FI_DS_FI48 Rigid(1).pdf

I have also looked here http://www.bobgolds.com/AbsorptionCoefficients.htm
But I think the products have changed, at least the names of them have.

One last link to the manufacturer's website.
http://www.insulation.com.au/products-range.aspx

 

[robbo266317]

Bunnies occasionally has acoustic bats on special here in Newcastle

 

[wilsonj]

So you are saying use tha acoustic pink batts?

Sonobatts or the silencer range?

 

[robbo266317]

I haven't made any myself yet. Llike you, I have been doing a bit of research online.
A lot of the panels use either the 50mm (2") acoustic bats or squash ordinary bats down to 2".
I'm sure someone stateside will give you more info when they are online.

 

[Prof.]

Hi Jamie,

Bradford Ultratel semi-rigid fibreglass sheets is what you need..
The sheet size is 1200 x 2400 x 50..and they come in a pack of 3..

You won't find them in any Hardware store..You might have to contact Bradfords and ask them for your nearest Insulation supplier..

 

[wilsonj]

Thanks Prof,

Where abouts are you? I'm North of Adelaide! Waikerie.

I assume you have these sheets? where did you get yours?

Cheers
Jamie

 

[Prof.]

Waikerie on the Murray..right!
I'm about 15K.inland from Goolwa..down South..at Finniss.

I bought my fibreglass sheets in Adelaide, from Southern Insulations..on South Road..
They have a big ad. in the yellow pages..
Bernie is the Manager there, and he'll be able to help you..

 

[Mika75]

Howdy Mr.Wilson

The pink batts u purchased are different in that they aren't as dense and haven't been compressed and glued to become rigid (extra costs involved)

The Fletcher Insulation 48 Rigid Glasswool u linked to is almost identical in acoustic performance to the Bradford Ultratel suggested by Prof...buy direct from the wholesaler and don't deal with retail outlets like Bunning's who will rip u off

The link below is probably the best forum ur ever going to read about Acoustic Insulation Q and A

Bass Traps Network Insulation FAQ

Readyacoustics.com is another great site which although wants to sell u something, give some very good advice free :T

 

[wilsonj]

Thanks Mika75

In reading the first link, they suggest doubling the thickness to 4". Looking at the acoustic coefficients I wonder how much is to be gained. Basically any frequency above 250hz is at 1 or above already. So I would think you would only gain bass absorption performance ? As I am trying to tame reflection points first, is this going to be needed? I would rather build dedicated corner traps.

 

[Mika75]

Readyacoustics / Early Reflections Explained

Smaller rooms typically need a significant amount of low frequency absorption. So if you room is approximately 5,000 cubic feet [on the order of 20' x 25' x 10'] or smaller, then you should probably use 4" RT424 Bass Trap panels for all your treatment including early reflection control. If your room is larger the +/- 3,000 cubic feet, and/or you already have enough Bass Traps or other form of low frequency absorption such as lots of heavily padded furniture in the room but still need to treat for early reflections, then your circumstances suggest you should consider the use the less expensive 2" thick RT422 panels instead of broadband 4" RT424 Bass Traps for your early reflection treatment.

BassTraps.net / The Broadband Approach

The tendency to over absorb rooms is exacerbated when people use thin absorbers such as 2” thick panels for all their acoustic treatments. Thin absorbers will absorb high frequencies effectively, but have little beneficial effect for low frequency control. If all thin absorbers are used in a small room [less than 7,000 cubic feet – smaller than a room on the order of 35’x20’x10’], then one can remove all the high frequency sparkle from a room and still have a muddy low end having done nothing to relieve the boominess that arises from low modal density.

By using all thick panels [at least 4” thick], one may be assured all of the absorptive panels will contribute to controlling the low frequencies, and as a result you can balance the negative of low modal density while addressing other issues such as early reflections. In essence all of your panels are doing double duty, and thus you will end up using fewer panels overall.

 

[wilsonj]

Waikerie on the Murray..right!
I'm about 15K.inland from Goolwa..down South..at Finniss.

I bought my fibreglass sheets in Adelaide, from Southern Insulations..on South Road..
They have a big ad. in the yellow pages..
Bernie is the Manager there, and he'll be able to help you..

Hi Prof,

Nice area down there. I'm sure it was much cooler than up here last week!
Thanks for the link, I'll give them a call.

Cheers
Jamie

 

[wilsonj]

Mika75,

Thanks for the quotes. Makes sense. But there are no coefficients given for freqs below 125hz. I can only assume that the performance of the insulation reduces as you go lower. Hence the need still for dedicated bass traps.

If I was to build a superchunk corner bass trap, would I want to use the same material? Given the amount of material required would there be a more economical alternative?

Lastly, would thick curtains in front of a bass trap reduce its performance?

 

[Prof.]

Hi Prof,

Nice area down there. I'm sure it was much cooler than up here last week!
Thanks for the link, I'll give them a call.

Cheers
Jamie

Actually Jamie, we did hit 42C. down here...Nasty!!

If you're planning on building reflection panels and bass traps, you can use the Ultratel for both..
Super chunks or layered panels for the traps..and just 2" thick panels for the reflection points...

Placing thick curtains in front of the traps won't have much affect on the lower frequencies, but may affect the absorption ability of the upper bass frequencies..

 

[wilsonj]

Hi Prof,

Ouch. thats not much better than us! We got up to 46.

Rang Bernie, just waiting for him to call me back.

Cheers
Jamie

 

[wilsonj]

OK, I've organised some panels with Bernie. thanks.

These aren't particularly cheap, and I would estimate that if I was to build a super chunk bass trap it would cost ~$500 each!! Surely I could use a cheaper product??

 

[Mika75]

What did u end up with, and how much we talkin ? :gulp:

 

[scottrichardson]

Hi guys..

Hoping you can help.. I just got 3 packs of 2400 x 1200 ultratel. I was thinking of literally slicing each pack down the middle.. making enough for 6 6" thick corner traps (I only need 4). The remaining 2 I could cut in half and make reflection panels. Perhaps even go 4" thick and make 6 panels.

Anyways.. either that.... or.. make superchunks.

What I wanna know.... which is better? Superchunk, or corner traps with airgap?

 

[scottrichardson]

hmm.. looking at my calculations.... I'd need 2 packs (6 sheets) per corner. That is way beyond my budget! Cost me $850 AUD for 3 packs already!

 

[wilsonj]

Well I got quoted $223 per 3 pack ultratel 2400 x 1200 x 50 un-backed.

Scott, $850 sounds a little high. I was told I could get another 5% if I bought 3 packs (9 panels) So roughly $210 per 3 pack.

Still it is very expensive if we build super chunks. Hence my question.