Tweakers' Asylum

RE: It is possible not to be satisfied but there's a reason for that�

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AudioDwebe

In Reply to: RE: It is possible not to be satisfied but there's a reason for that� posted by David Aiken on October 13, 2009 at 19:52:05

I am looking to get the widest, deepest and tallest soundstage my room/system will allow while maintaining image precision.

Yep, that'd be about it.

I hope "dream on" didn't enter your mind when reading the above.

Cheers.

Follow Ups:

RE: It is possible not to be satisfied but there's a reason for that� - David Aiken 13:37:30 10/14/09 (0)
Then I would recommend the following things:

1- make the setup (speaker location, listening position) as symmetrical as possible within the room. Also take a look at the Audio Physic speaker setup method in the FAQ and experiment with the ideas in that document, especially maximising the difference in length between the direct sound path and the first reflection sound paths by placing speakers and listening position some distance from the walls. That's easier in large rooms than in small rooms but read the document several times and then start experimenting with the approach described in it. Like all setup documents it assumes a symmetrical room but you can apply the same principles of keeping the direct path short relative to the length of the first reflection paths in asymmetrical rooms and that, on it's own, will help to reduce the soundstage and imaging anomalies that occur in such rooms.

2- keep a clear space around each speaker for at least 3 to 4 feet if possible, more is better.

3- clear anything that you don't regard as necessary out of the room in order to minimise the objects that can create unpaired reflections.

Then to treatment:

- bass traps in corners,

- absorption at side wall and front wall (behind the speaker) reflection points. There is some evidence that some/most people prefer no absorption at the side wall points but I definitely prefer absorption there. If you opt for absorption you may also want to try treating the opposite wall first reflection point for each speaker�this can be done by using a wider panel on each side or adding a second panel on each side a little closer to you than the panels for the same wall first reflection points.

- either absorption or diffusion at rear wall reflection points. In a small room I'd go for absorption because you want at least 10' or so between you and a diffuser if it's going to work optimally for you.

- since height of soundstage is important to you I'd also consider absorption at ceiling first reflection points which is something I haven't tried yet since I don't want to have to drill into the ceiling to mount anything.

The absorption used should be good quality, broad band absorption and the material used at first reflection points should not have a limp membrane facing the room. Limp membranes improve bass absorption but also reduce mid and high frequency absorption by reflecting those frequencies back into the room. At first reflection points absorption of mid and high frequencies is more important than a bit more bass absorption.

If you want to understand a bit about these recommendations, then read Floyd Toole's recent book "Sound Reproduction". He explains how these absorption locations improve imaging.

If you have a room with left/right asymmetry or the speakers are different distances from the side walls, then you're probably going to have to do some experimentation in order to eliminate the pull of the centre image to one side that usually occurs as a result of asymmetrical side reflections. I've never seen a nice, neat set of rules for dealing with asymmetry but you can get there with experimentation. I know that because I have an L-shaped room and I've got there.

I'd also confine the use of absorption to bass traps in corners and treatment of the first reflection points mentioned, plus a floor rug between you and the speakers if you have a hard, reflective floor. Keeping the rest of the room reflective helps keep the sound dynamically lively in my view. Provided the absorption used is broad band with a relatively smooth absorption spectrum you should not have to worry about making the sound tonally dead since broad band absorption should have minimal effect on the tonal balance of the reflected sound. If you use absorption which is not broad band, such as fairly thin foam, you tend to end up with the absorption skewed towards the high frequencies and upper mids, and not enough absorption at lower frequencies to keep the reflected sound tonally neutral. The effect of that is dead sound and many people cite that kind of experience as proof that acoustic treatment is not a good idea. There's a big difference in quality of results between using absorption properly and not using it properly, and you don't want to not use it properly because you won't like the sound you'll get as a result.

David Aiken

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