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11/29/14 at 08:53:53

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Placement Questions (Read 701 times)
Steve Deckert

If the 1st watt
sucks why continue?

Posts: 2441
Placement Questions
01/18/14 at 01:44:01
Hi Steve,

I ordered 8 of you pre-built diffusers. I have a few questions so I can start planning the installation:

1. In regard to my side walls, do you think it is necessary to go three high (thats the highest I can go) if I can only cover my first and second mirror reflection points (two panels wide)? If I go two high, I will have enough panels to go three or four wide. If I go two high and three wide, I can put four panels on my front wall. If I go four wide, I would leave my front wall with absorption until I can afford more panels for my front wall. In either scenario do I need to follow the barker code? I assume that is what you did in the photo of your room of three high and two wide? My preference is to stay two high because three high will cause me mounting problems due to a window cover.

2. Will my side wall diffusers direct sound to my front wall? My ceiling will be diffused but not my back wall. If the only way to get sound to my front wall is by diffusing my rear wall, there will be no need for me to treat the front wall at this time. I am having trouble understanding how non-specular reflections will travel.

3. If I only have enough sidewall diffusion to cover part of my sidewalls, should I extend the diffusion directly across the listening position or extend it further up toward the front wall to help excite front wall diffusion?

As you can tell, writing is not one of my strengths. If any / all the above is not clear enough, just let me know and I will draw the different scenarios.

Thanks so much for your help,

Such good questions, I thought I'd post the answer's here.

Here is how it works...

1) Direct energy from speakers hits your head and ears. You hear the sound.
2) What missed your head hits the back wall which reflects off and hits the side walls which in turn reflect the sound to the front wall located behind your speakers.
3) The reflection from the front wall goes past your speakers and hits your head and ears.
4) The fact that the same sound hit your head and ears twice spaced only a couple milliseconds apart is what causes poor imaging.  This second wavefront must be delayed in time and reduced in volume well outside of the 2.5 millisecond window for your brain to distinguish it from the original direct energy and categorize it as ambience.

With 8 diffusers your best bet is to place 6 of them on the front wall centered between your speakers in a 2 high x 3 wide pattern.  Place the remaining two panels on the side walls, one per wall. Have someone hold a mirror on the side wall and move it until you see the tweeter front he listening chair reflected in that mirror.  Center your panel on that exact spot.

The front wall cluster makes imaging possible and promotes depth that goes well past the wall itself.

The side wall units improve soundstage width, helping the image to float well outside the speakers location.

Adding rear wall units similar to the front wall cluster should square the performance of the front panels, in other words make them work 4 times better.

Of course any time you're just starting out with diffusion it is nice to make free standing panels by attaching legs so that you can move them around and experience the effects they make in different locations.

And remember that doing all four walls vs. a single wall would work not 4 times better but 64 times better.

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Re: Placement Questions
Reply #1 - 01/22/14 at 10:45:49
This is an excellent read Steve! Thanks!
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Lonely Raven
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Re: Placement Questions
Reply #2 - 01/22/14 at 19:06:45

And remember that doing all four walls vs. a single wall would work not 4 times better but 64 times better.

This line really resonates with me. I've heard rooms with all 4 walls treated with diffusers and also absorbers to handle the lower frequencies. It's pretty amazing - besides the precise imaging, the surround sound like reverb that's in most recordings is amazing. And if the recording actually includes the natural room reverb picked up during the session, your brain actually picks up on that and you're transported there.
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