Talk but not walk?

My 5’/10ms figure was suggested as the minimum distance a planar should be expected to need for anyone contemplating such a speaker. Of course reflections are more than a single line from the back of the speaker to the wall behind the speaker, and then theoretically back to the speaker, and then theoretically to the listener. The fact remains, however, that if you position a planar closer than 5’ from the wall behind it, there will be the very real possibility of negative consequences. If you have ten feet to spare, all the better! If you have less than five feet, you have been warned. I have had Maggies and QUADs 3’ from the wall, and have found 5’ to provide a definite improvement. I have never had 10’, but would sure like to!

But remember, it is the 10ms delay between the front and rear waves that is important, not the 5’ distance. You can create that 10ms delay by any means you choose; if heavy tow-in causes the rear wave to reflect off more surfaces, thereby delaying its arrival at your ears to 10ms or more in relation to the front wave, great! By the way, that 5’/10ms figure was not pulled out of thin air, it is the inevitable consequence of the behavior of sound---physics, and the brains processing of sound arriving at the ears from the same direction but at different times. "Toeing-in" a planar speaker provides benefits in a couple of ways, one of which is to decrease the direct reflection off the wall coming straight back at the speaker; toe-in scatters the rear wave, but not as effectively and predictably as do properly designed and built true diffusers (RPG, ASC, GIK, DIY, etc.).

Your almost there dbp24. 5 or 6 more years and you might be to the point of adding me to your list, lol. It’s tough isn’t it when you have this idea of someone in your head and your finding out they aren’t what you thought :) You’ll get there we all do.

I want to ask you guys something and I don’t want you to answer with audiophile-isms.

Instead of thinking about acoustics in such general terms why don’t you get more specific? The cool thing about acoustical, mechanical and electrical is how they are all part of each other. HEA has tried to make cookie cutters to make things easier to sell but in doing so they fail to cover the variables. Let me give you a few examples.

In 1989 when I designed and built my testing facility we did several different structures with the same measurements so we could study the surface effect among many other topics. The first rooms were built on the same slab inches apart from each other. Same construction materials and even the drywall screw patterns were the same, and using the same tension per screw. We measured the rooms to try to get them as close as possible from a starting point.

As a point of reference I used long time pals at Audio-Technica to do my anechoic measuring at their place in Akron Ohio in exchange for them visiting my tunes, plus 2 of them owned speakers I made for them. (nice to have friends) We tested many different variables in the audio chain and quickly came to the conclusion that at best testing is a snap shot approach to a continuum. This was nothing new as I came to the same conclusions in Atlanta in the early 80’s and further back in Miami and Europe in the 70’s. Audio is not a tape measurer and the more you experience audio the more you want to throw out the rule book and cut to the listening chase.

back to the 2 rooms

When we did surfaces testing in the two rooms we chose, there are a few things we did that might help you guys understand some variables.

1) when changing paint types the rooms performed differently

2) when changing temps and or humidity different sound

3) adding objects to the room, different again

4) different flooring, different sound

5) how long the signal played, different

6) changing the wall surface type (dry wall to wood to plaster) all different

7) diffusion, different

8) trapping, different

9) dampening, different

10) tuning, different

The list goes on, but lets get to speaker placement.

With any of the changes above (except for tuning) we found there was no two speaker locations that were the same. With any change, such as hard wood to carpet, the speakers’ locations changed. Even different brands of carpet and padding required speaker placement changes. We found that any and all speaker placement suggestions by the manufacturers to be completely off. We even went to the manufacturers facilities and found the recommended placements were not accurate.

In the case of panel speakers, the difference in setup in a plaster walled house and drywalled house are completely different. We also found there is no such thing as "first wall reflection", the way the audio folks describe it. Rooms are mostly made up of Pressure Zones not Reflecting Points. Reflecting points usually stay within a paralleled echo pattern. Remember when I introduced the clap test.

there’s more

mg

Here's a little bit of the more (you can do all these tests yourselves).

Do your echo tests.

Did you know that a first reflection test only works if you are outside in a flat open area with one single wall set up? The size of the wall and frequency played at the wall will show you which frequencies actual reflect and reflect intact. As soon as a second wall is put up (attached to the first wall) the reflection is altered. Add a third wall and you will have the development of pressure zones as opposed to reflections. By the time you have 6 walls the frequencies that will reflect in the room are. Mid to high frequencies in an echoslap and selective high frequencies in a wall reflection pattern.

Think about how far you can go, when you get out from underneath these audiophile prescribed myths. Keep in mind that the folks making these myths are folks who themselves are only theorizing. If they haven't gone and done they are doing the same thing that the "talkers" here are. I remember when Harry took his flashlight and came up with the first reflection thing. Cute, but it wasn't real. There's a big difference between drawing drawings and talking theory vs actually doing.

mg