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forbesaw

Room acoustic help needed in Perth

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Hi there.  I've had my home theatre room for few years now. It's was my first attempt and and now need to improve on what I've got. I'm seriously considering floor to ceiling bass traps on at least two side of the room. I originally put some wavewod at the back and has made a marked difference. I don't profess to know about low frequencies other than that after reading up on it I suspect my room needs them.

 

Can I get polymax in Perth 100mm thick?

 

How is easy is it to do diy for this type of job. 

 

Your thoughts are appreciated.

 

Adrian

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Hi Adrian,

With the listening position hard against the side/rear wall,  the Vicoustic panels 'save the day' and the open door nearest this end (in the photo, that is) and the louvres (windows) on the far wall will reduce the bass energy buildup to a certain extent but you'd really benefit from obtaining a room measurement to avoid purchasing unnecessary bass traps, or the incorrect operating range ones like the Vicoustic 'Varitraps' for example

 

I'm pretty sure this room measuring service is available in Perth and should be in the vicinity of $300 -500 which may seem expensive but room acoustics quickly adds up in cost, especially with mistakes and knowing exactly what areas need attention, actually saves money and effort

 

There is, or was, a recent group buy in Perth for that same 100mm Polymax, not sure what colour - check the threads here a couple weeks ago 

The 4" thick Polymax is relatively easy to use - you can simply wrap it in a choice fabric if positioned in/across a corner but support frames can be quite lightweight and simple to build - suggest you lookup the mentions about partly covering the front surface with reflective material to avoid too much midrange absorbtion - the 4" polymax operating range across a corner with an 800mm polymax front surface width (floor to ceiling) is about 200Hz upwards and, unfortunately, the frequencies below this are often the 'more problematic' and hence the suggestion to get a room measurement first

 

I'm guessing a bit but I think each 2400 x 1200mm sheet of 100mm thich Poly XHD will cost well over A$100 ea - the idea of a Group Buy is that you have to buy a pack that has a minimum number of sheets/pieces (I think it's 3 off for the 100mm ones) so you could share a pack  

 

Another 'thought' is to maybe see if you can lift those panels further off the wall - maybe another 100mm or more, or at least at the bottom edge even tho it may look weird - you might be able to simply add a spacer under the bottom edge and see if it makes a difference to the sound at the listening position - they're actually rather effective units and it's worth 'playing around' with them a bit   

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Hi Adrian,

 

All rooms benefit from bass traps but it's a decision best made after considering how the room performs acoustically. When you can see the decay performance then you are better positioned to weigh up whether or not you want to add traps. Some rooms have major problems making it a clear choice. Others are already fairly well behaved and won't see significant improvement without adding traps larger than you may accept.
 

Quote


Can I get polymax in Perth 100mm thick?

 

 

You will need to check with your local dealers. Consider 50mm Polymax which is easier to cut and you can simply add two sheets. It also comes in black, which provides extra options when it comes to building your own.

 

Quote

How is easy is it to do diy for this type of job. 

 

DIY acoustic panels are a great DIY project. How easy depends on your DIY skillset and your expectations.

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What are the room dimensions?

 

Depending on the use of the room...if it were mine, I'd build some window plugs, mount the center in that cabinet with your gear, get an AT screen and have the L and R slightly forward (you'd need to treat the wall immediately next to them....well.....I'd panel the whole thing in a variety of styles....but that's me :D

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Hi Adrian

 

I am in a similar position to you. I'm located in Perth and have a dedicated theatre room (solid brick construction) in need of treatment. I think we can probably help each other out with a group buy, but I'll get to that later.  

 

I should preface this post by saying I'm still a complete rookie at room acoustics, but my experience to this point may help others who are starting from scratch. 

 

To give you a background, I started my journey by reading various forums and literature (Sound Reproduction By Floyd Toole), and whilst they helped understand some of the broad principles of acoustics, I wasn't really any closer to understanding my specific problem and how to solve it.

 

What did become evident from this reading is that room acoustics is seriously complicated, and you're flying blind unless you have the ability to take measurements. Sure you could whack a few panels up and you may perceive there to be improvement, but that's akin to a GP prescribing you with meds before listening to your symptoms. 

 

So I set about purchasing a Mini DSP UMIK-1 microphone and downloaded Room EQ Wizard (REW) for free. All up it cost well under $100 delivered and arrived in about a week. The microphone connects to your laptop via USB, and your laptop connects to your receiver via a 3.5mm to stereo RCA cable. A little calibration of the software and away you go. The process is all documented on the Mini DSP site.  


So once you obtain some basic measurements you'll have a baseline of what your room is doing to the sound. If you're like me, your next question will likely be, "OK, now what?". In other words, I've got some pretty graphs in front of me, but how do I know where my problem areas are? This is Paul Spencer's Bass Integration Guide comes in handy (kindly referred to me by @almikel). The document outlines some key benchmarks you should aim for with respect to frequency response and decay, and provides a tutorial on some strategies to achieve these marks (e.g. bass traps, multiple subs, crossover and EQ). 

 

If you reach this point, congratulations! You've just passed med school and you now know your symptoms. The bad news is, you now need your PHD in rocket science to fix them! Ok, it's not quite that bad, but low frequencies are notoriously difficult to tame in small rooms.

 

In my case I know that I require some broadband absorption to reduce mid and high frequency decay. This is where the Polymax will be beneficial. As far as bass control goes, I'm going to try and tame things down using DIY corner chunk bass traps made with fluffy style insulation. At that point I'm expecting I'll need an additional subwoofer (or two) to smooth out the frequency response at multiple listening positions.

 

The beauty of it all is, once you have the ability to take measurements, it becomes an enjoyable, informed process.

 

Hopefully this information assists and if you're interested in doing a group buy of Polymax then I'm happy to organise it. The minimum order is three packs, with each pack containing 3 sheets measuring 2400x1200mm. I'd probably only need one pack.  

 

Cheers

 

Steve

 

Edited by iversons13

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Thank you for all your responses.

 

Steve.

 

i will look into the Rew this week. 

 

Regard Adrian

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Just out of interest can I use a av receiver microphone for the measurements?

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Possibly. But my understanding is you'll need an external sound card and be able to get your hands on a calibration file for the mic. USB mics simplify the process for us casuals. 

 

Cheers

 

Steve

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 Quick question again .  I am predominantly an Apple user however I do have a older style laptop that's about eight years old and still works though. Would this still be effective  in your opinion with the minidsp

 

 

 

A

Edited by forbesaw
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From what I can see you won't have an issue on either platforms, but check out the UMIK-1 and REW sites to confirm compatibility.

 

Cheers

 

Steve

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Ok.

 

once i have the microphone and the rew results. What is it i exactly do with them?

 

can you tell what bass traps or acoustical treatments can be placed from the data extacted? 

 

This is all very good in theory but looking at the demonstrated analysis gives me a headache already ( and I have a science degree!)

 

Thanks in advance

 

Adrian

 

 

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I believe the UMIK-1 needs a USB 2.0 connection as a minimum.

 

Yes, you can identify where to place reflection point treatments with the data you collect in REW using the impulse response data.

 

 

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