# Thoughts on Sept '10 S+V Budget Acoustics article?



## MarkMac (Jan 5, 2008)

Has anyone read the DIY Room Tune-Up article in the September 2010 issue of Sound & Vision? I was surprised by some (not all) of the suggestions in the article. Dr. Floyd Toole was referenced a number of times, which, I suppose, gives some credence to the suggestions. I guess I was just very surprised by the recommendation against 1st reflection treatments on the side walls. Also, the DIY Diffuser instructions were different than what I have seen in the past. Would any of you acoustic experts be willing to weigh in?


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## bpape (Sep 14, 2006)

Just remember that that recommendation assumes a lot, and I mean a lot. It assumes that the reflections are at least of a certain length and also assumes that the off axis response of the speakers is very close to the on axis response. Very very few speakers fit that last criteria.

Also, there is a difference between not treating and not absorbing. I believe he did offer the option of diffusion at the reflection points as opposed to absorption in the cases where the timing and the off axis response were acceptable.

Bryan


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## MarkMac (Jan 5, 2008)

Thanks Bryan.

I'm not sure that the article suggested diffusion at the first reflection points (I'll have to go back and check). I do remember that diffusion was suggested on either side of the surrounds. Absorption was suggested behind the mains and in the middle of the rear wall.


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## Stele (Jul 3, 2010)

I've attended classes by people in the 'know' and done some listening test myself with the first order reflections, and the results I have come up with that vary on a case by case basis. Generally reflections are a good thing assuming they are not time delayed too long (about 70-80ms max) and that the reflections are of a similar response to the direct sound (they don't have to be exact - and will likely never been as the reflection surface will do something to the sound).

All too often I see people placing the thin egg shell foam where the first order reflection on the side walls would be, which would absorb high freqs but not the lower (depending on the foam/absorber used of course), so they are actually making the reflections sound worse then if they left them alone.

If you get a very wide dispersion pattern that the off axis response is similar to the direct (on-axis) then leave them be is the best bet as it aids in making the sound stage wider and to speech intelligibility, most people would agree that they are highly desirable things.

In saying all that I haven't had a read of the article in question yet, best I go read it before I input further.

Pete


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