Room coupling

[vitalstates]

This is prompted by a conversation on Saturday evening at eggfest:

In my experience it is possible to transform speakers into a completely new/different sound by experimenting with the room coupling. I have found that by sound treating the listening room the speakers change their characteristics completely.

The real mcCoy is auralex:

http://www.auralex.com/

and it can be obtained in the uk at:

http://www.dolphinmusic.co.uk/d2/?pa...FUiAEAod-GcNvg

a cheap version for experimenting can be found here:

http://www.bandmlatexupholstery.co.u...d/11/index.htm

I know that in normal circumstances the WAF is about 0.1 on a scale 1 to 100 but for those with a dedicated room it might be worth an experiment.

The most obvious changes I have found come about by identifying the reflection spots and obliterating them. There are further gains however by putting in bass-traps.

Regards

Ed

[Paul Barker]

Thanks Ed, I take it the idea is to face the rippled surface out into the room. My head hurts!

[vitalstates]

Doh!

I hope the headache isnt caused by thinking about auralex...

yeah the bumpy surface points out to break up the reflections. From what I can gather thickness is not such an issue, its just to scatter the reflections and stop them blurring the image. There are long discussions about this on some of the studio sound treatment vendor sites.

There are also articles in the SOS(sound on sound) archive but you'll need to google for them as I've lost all the links I had.

Regards

Ed

[petercom]

The 'bumpy' surface will only break up reflections where the height of the bump is greater than the half wavelength of the incident wave. I would guess, therefore, that the bumpiness has little effect under 3 to 5kHz. Below that you are relying on the thickness of foam to act as an 'absorber'. Again this follows the half wavelength rule. Have a look at the Auralex bass traps to see the tall wedge principle, then compare them to the size of the wedges in an anechoic chamber.

As Auralex say the main use of foam is to cut down high frequency 'flutter' echo. This isn't usually a problem in domestic living rooms due to the amount of soft furnishing, carpeting and curtains. You can hear if you have a problem just by clapping your hands and listening for an echo. If you can hear more than one echo then you need some room damping.

IMO the best reducer of room reflections that is also domestically friendly is a tall bookcase stuffed full of books, magazines or LPs. The bookcase also has the advantage that it can be moved around to stop unwanted reflections as you hear them. Personally I like speakers to be at the 'live' end of a room and the seating to be at the 'dead' absorbent end. This also fits in well with using sofas and armchairs as room absorbers (because of their thickness they work well at low frequencies).

[johnlncstr]

I have followed with interest the discussion so far and gleaned a lot of useful info. I have a listening room 10ft.6ins x 11ft.6ins and if I put in too much furniture and record shelves etc I will reduce the effective size of the room, does this matter? Some of you may recall I was hoping to move and build a listening room from scratch but this idea has had to be scrapped as BA have indicated that my son in law may be required to move should an anticipated promotion come to pass. We are far from chuffed as you may imagine.

Regards
John Lancaster.