Rented concrete apartment and a newbie to boot

**jasonmac** · **03-28-09, 06:48 AM**

I'm new to room acoustics so please bear with me!

I've just moved into a rented apartment. The living room is a narrow room about 5750mm x 3300mm and 2500mm high ceiling. There is an open doorway that leads to a hallway (as marked), a glass door and window looking onto the balcony at the rear and another hallway leading to the front door on the left of the diagram. There are two leather sofas but currently no other furniture until I've worked out some of the acoustics first. I've omitted the south wall from the diagram.

The floor is carpeted but the walls and ceiling feel like concrete (maybe some type of render??).

I was thinking of initially treating the first reflection points with a set of four of the following panels:

Company: Sound Acoustics
SA600/75 Broadband Acoustic Panel
Frequency Range: 200Hz and above
Dimensions: 600 x 600 x 75mm

I was also going to install a bass trap in the corner near the front right speaker, one from the same company.

Are there any other locations that I should consider? Like the rear wall for example? Will the products I've listed (easily available to me in Australia) be satisfactory or are there better options?

I have some spare cash at the moment so I feel compelled to spend it to ensure that I do my bit for the economy

. Function is more important than looks - any yes you've guessed it, I'm single

Thanks for any help.

**bpape** · **03-28-09, 08:32 AM**

Hi Jason

I'd try to trap the 3 available corners.

Reflection control on the right wall directly next to the right speaker is going to be very important due to the proximity and potential for boundary related bass anomolies (SBIR).

The product you showed would be OK for general reflection control. I'm not sure what's up with it. 75mm should have a decent amount of control significantly below 200Hz.

Bryan

**jasonmac** · **03-29-09, 05:49 PM**

Thanks Bryan

Just wondering, how do the foam based bass traps perform? The product I was thinking of using has the following dimensions: 600 x 600 x 150mm

I understand that DIY rockwool type traps are better performers, but I'm assuming I would get some benefit from the foam based ones right?

Thanks,
Jason

**bpape** · **03-29-09, 08:49 PM**

Foam in general is very poor for bass control. Rockwool/mineral wool is MUCH better per inch of thickness and per dollar/euro

Bryan

**jasonmac** · **03-29-09, 10:21 PM**

Great, thanks Bryan. A couple more questions I'm afraid:

1. Given my 2500mm celing height, how high would DIY rockwool bass traps need to be? Floor to ceiling is ok, I just need to plan it.

2. Anyone know a suitable brand name and product for the rockwool in Australia?

Cheers,
Jason

**bpape** · **03-30-09, 07:31 AM**

These guys don't have anything terribly dense listed but it's worth a call

http://www.insulco.com.au/index.htm

These guys seem to have a nice variety of denser insulation products.

http://www.bradfordinsulation.com.au/home.aspx

Bryan

**jasonmac** · **03-31-09, 06:08 AM**

How does this product rate:

- Bradford Rockwool Partition Batt. 38 kg/m3

I'm very excited about doing some DIY. I've made some aquarium stands in the past so these should not be too difficult.

**bpape** · **03-31-09, 07:16 AM**

The density is very light but you can either use extra thickness or compress it to double the density. You'd like to find something in the 80kg range at least.

Bryan

**jasonmac** · **08-09-09, 06:23 PM**

I'm just getting back to this after being slack for ages

I've found a product that is rated 80kg.

As the right speaker is in the corner where I am going to bass trap do I need to worry about reflections from that speaker? I plan to make a solid triangle bass trap.

If I understand correctly the material you would use for reflection control should be less dense than you would use for a corner bass trap.

Thanks,
Jason

**bpape** · **08-09-09, 07:50 PM**

In general, yes. For reflections, anywhere between a 2.5 and 4lb/cu ft density is usually desirable.

Bryan

**jasonmac** · **08-09-09, 08:37 PM**

Thanks Bryan.

Re-reading my post I may not have made myself clear.

What is the ideal density for the base trap given that it will extend behind the speaker?

Thanks,
Jason

**Prof.** · **08-09-09, 08:45 PM**

Hi Jason,

The fibreglass material you need for bass traps and reflection points is Bradfords "Ultratel"..
It comes in 1200x2400x50mm sheets, in a pack of three..

You just use 1 layer for the first and second reflection points..and if you're doing bass trap chunks, just cut it into triangular sections and stack it to the ceiling..

**jasonmac** · **08-09-09, 09:42 PM**

Thanks Prof. That's great.

Cheers,
Jason

**bpape** · **08-09-09, 11:27 PM**

The 'ideal' density depends on the thickness you're using. As you get thicker, the density can be less (and less expensive) to accomplish the same thing.

Behind the speakers, the 'reflections' are primarily lower in frequency and also more direct.

The place where lighter material is better for reflections is on side walls where angles of incidence can be shallow and there can be some 'skipping' off the surface like a rock across water at shallow angles.

Bryan

**cinema mad** · **08-10-09, 07:28 AM**

Quote:

bpape wrote:

In general, yes. For reflections, anywhere between a 2.5 and 4lb/cu ft density is usually desirable.

Bryan

Hi Bryan, The CSR Bradfords Ultratel (48Kg m3) is the same as owens corning 703 3lb/cu ft, Supertel is only 32Kg m3 and Quietel is around 6.0 pcf (100 kg/m3) close to Owens corning 705, But Bradfords Quietel only comes as thick as 25mm/1" ...

Cheers....

**bpape** · **08-10-09, 09:09 AM**

The Ultratel will work fine for everything provided your bass absorbers are over 4" thick.

Bryan

**jasonmac** · **08-10-09, 05:16 PM**

A big thank you to Bryan, Prof & cinema mad for your help with my project. I have measured up and I'm ready to order

**bpape** · **08-10-09, 05:50 PM**

Glad to help. Post if you have any more questions along the way.

Bryan

**Prof.** · **08-10-09, 08:16 PM**

Let us know how it works out..

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