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  Does speaker toe-in affect reflection points?
I recently used the "mirror method" mentioned elsewhere in the forums to verify the location of the 1st and 2d reflection points along my side walls.

Then I realized that as I play with speaker placement further, I may go back to angling my speakers in. That made me wonder if the toe-in would cause the reflection points on the side walls to move toward the listener and rendering the mirror method unreliable.

Anyone with thoughts on this?
Aggielaw  (System | Reviews | Threads | Answers | This Thread)

02-26-09
  Responses
02-26-09: Tvad
That's a good question.

I would think toeing the speakers in moves the first reflection point up the wall closer to the listening position, whereas toeing them out moves the first reflection point away from the listening position.

However, the speaker's physical relationship to the wall doesn't change, as one can tell by using the mirror method.

So, the question is, how much does the reflection point change, and how audible is it? Perhaps the only way to know is to shift the acoustical treatments and listen for a difference.

Tvad  (Threads | Answers | This Thread)


02-26-09: Newbee
It certainly changes the critical part of the reflection point, not only on the side walls but on the ceiling and the floor as well. Not a small thing, BTW, but often overlooked.

Remember when you are thinking about side wall reflections that the 'balance' of the radiation pattern is critical. Often the signal is hot on axis and more balanced off axis. Those speakers sound best either pointed straight ahead or having the axis cross in an identical degree of angle beyond the listening position. Only with the latter you will also minimize side wall reflection induced distortion, and lose some of the sense of artificially (room) created sound stage which relies on the side wall reflections for its presence. You might gain a very defined, pin point image, at least to the extent that your speakers allow.

With typical dynamic speakers in a small to medium size room I've found having the axis cross in front of the listeners head, to some degree, is preferable. Of course that is my sonic preference.

Newbee  (System | Reviews | Threads | Answers | This Thread)


02-26-09: Zargon
The first reflection location to the listener is always determined by the mirror. It a function only of the locations of the speaker driver, the wall, and your ear. For small changes in toe in, it essentially stays in the same location.

What changes as you adjust toe in is the intensity of the first reflection. It gets greater with toe out and less with toe in and has a maximum when the drivers are pointed directly at the reflection point.

What also changes with toe in is the direction of the speakers maximum intensity (generally perpendiclar to the drivers) and thus the locations of the resulting reflections as they travel around the room.

These changes can be significant and explain why such small adjustments can cause such a large change in the sound stage.

Zargon  (System | Threads | Answers | This Thread)


02-26-09: Beavis
See: www.realtraps
Scroll down to Figure 4.

Beavis  (Answers | This Thread)


02-26-09: Shadorne
Zargon is right - it makes no difference in the reflection point. However, if your speaker has a fall off in response off axis (such as a horn) then the energy being reflected may be lower by as much as 3 to 6 db when toed-in.
Shadorne  (System | Reviews | Threads | Answers | This Thread)


02-26-09: Tvad
02-26-09: Shadorne
...if your speaker has a fall off in response off axis (such as a horn) then the energy being reflected may be lower by as much as 3 to 6 db when toed-in.

That indicates to me that the reflection point is indeed affected by toe-in. If the reflection point is moved farther up the wall to the listener (and the angle of reflection becoming more oblique), then wouldn't the trajectory of the sound wave reflect farther behind the listener, thereby measuring down a few dB?

Tvad  (Threads | Answers | This Thread)


02-26-09: Mrjstark
Shadorne,
take the speaker's horizontal dispersion into consideration. ;)
I am sure that Martin Logan with very narrow dispersion will be less affected by 1st reflection points and closer to side wall placement then ................... lets say DALI speakers.

Mrjstark  (Threads | Answers | This Thread)


02-27-09: Zargon
Be careful not to confuse sound from the first reflection with the direction of maximum reflected sound or the direction of maximum sound. They are all different.

Speakers generate sound waves in all directions and every driver/enclosure combination has a different pattern (dispersion). The first reflection on the side wall is that point which reflects whatever sound waves from the speaker are hitting it directly back to the listeners ear. This can be determined geometrically on paper or with a mirror and is independent of the speaker's dispersion or its toe in.

As soon as you begin to toe a speaker in (assuming you do not change the position of the driver), the level of the sound hitting the first reflection point is reduced (assuming as is true for most speakers that the horizontal dispersion falls off to both sides of the driver). So, the effect is that you will hear a less intense first reflection and hear a more intense direct level of sound from the speaker. Also, as you toe in, the level of sound directly hitting the entire wall is reduced, and more of this energy now reflects off the back wall.

Zargon  (System | Threads | Answers | This Thread)


02-27-09: Audioblazer
If u read up from real trap website on first reflection , based on the mathematically formula on how to calculate first reflection, shifting the speaking forward by 1 ft and toe in by few inches hardly change the first reflection point. Happy listening
Audioblazer  (Threads | Answers | This Thread)


02-27-09: Markphd
Two additional points to complicate your considerations.

First, the first reflection point to your ear is the floor in front of the speaker (it's closer). So changing wall reflections points cannot be considered in isolation. Any effect may be lost or amplified by the interaction with other reflection points, particularly closer, stronger ones.

Second, different frequencies are bounced, absorbed or partly abosorbed depending upon what it is hitting. So the composition of the reflection point is as significant as its location.

So in other words, just fiddle around with it and see what you like. Speaker manufacturers are also a good source of information as whether their speakers should be toed in or not, and by how much.

Markphd  (Answers | This Thread)


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