The distance to an in-wall, on-wall speaker would be the same (or even greater) compared to a box speaker. The distance from left to right speaker will always determine the listening distance regardless of on/in-wall or before-wall.
Is the foam effective? Why the extra edge (see pic)?
An externally hosted image should be here but it was not working when we last tested it.
Reduces diffraction, apparently. That "wall" is 30 degrees from baffle plane instead of normally 90 degrees.
Correct, that MTM is canted inwards (they were made as left/right pairs). So the edge shown is the outter edge of its mounting surface. The inward edge is recessed within the cabinet (grille depth was an issue) so the foam absorbs the inward cavity reflections.
The inward angling, by the way, works primarily for the tweeter and its waveguide. A lot of drivers, when infinite baffle mounted, have very little directivity over much of their range. For example the 6 or 8 inch plastic inwalls that are mounted such that the woofer can be aimed, have almost no directivity to aim.
I ended up designing an angle firing tweeter for some of the other models including an inwall dipole surround.
David
Usually if you approach the system on an axis mid way between the drivers, the relative time alignment is constant and the integration is good. It may not be exactly the same curve as seen at 2 meters, but it should be close.
David S.
This morning I stumbled upon this paper by Jens Blauert about objectivity and subjectivity in psychoacoustics (and psychophysics in general) when I was browsing through the folder with papers on audio on my computer. I think it may be interesting in this discussion.
I was talking about the extra ridge on the right side. Doesn't that create unwanted additional diffraction? I guess a curved baffle would have been better?
An externally hosted image should be here but it was not working when we last tested it.
That is the outside edge of the angled baffle. The cross section of the baffle zig-zags up then down. The MTM is on the down slope. I think the lighting makes the contour hard to decipher.
A radiused edge might have been slightly better but my recollection was that the response was good (the waveguide directivity helps there).
David
One of the points made in this paper is that in psychophysics, subjectivity and objectivity are not separate, absolute measures but rather the end-point of a scale. I think this is important to keep in mind when using psychoacoustics as a basis for loudspeaker design.
Toole stresses that listeners tend to adapt and that preferences may vary between groups. I think that these are both very important points.
In this topic, there seems to be a group with a preference for allowing early reflections and (a majority it seems) that feels they should be eliminated. Both have provided reasons for their argument. Given the nature of the discussion, I doubt that psychoacoustics will provide a single "truth" for the design of a loudspeaker (or listening experience) that will apply to all listeners.
People listen differently, pay attention to different aspects of a sound stream and may develop a certain preference, different priorities (pin-point imaging or higher ASW) or sensitation for certain aspects of sound (such as early reflections).
Despite the opinion above, I think this thread has given great insight in the various aspects involved in designing a stereo loudspeaker.
Toole stresses that listeners tend to adapt and that preferences may vary between groups. I think that these are both very important points.
In this topic, there seems to be a group with a preference for allowing early reflections and (a majority it seems) that feels they should be eliminated. Both have provided reasons for their argument. Given the nature of the discussion, I doubt that psychoacoustics will provide a single "truth" for the design of a loudspeaker (or listening experience) that will apply to all listeners.
People listen differently, pay attention to different aspects of a sound stream and may develop a certain preference, different priorities (pin-point imaging or higher ASW) or sensitation for certain aspects of sound (such as early reflections).
Despite the opinion above, I think this thread has given great insight in the various aspects involved in designing a stereo loudspeaker.
If our speakers and our rooms are different, it may go on. If only we could get together in a controlled environment, I shouldn't be surprised if we all liked a similar thing.
I've been noticing more and more people deciding that early reflections are better eliminated. That being stated without taking sides, the point is smply that we are trying the ideas, the confusion is subsiding and the factions are reducing in numbers.
I've also noticed a revised attitude towards reverberation (too much of) in a listening room and that says to me that the concepts are maturing. Furthermore the peer acceptance encourages us to discuss the ideas further.
We can ask Terry-O about that as he tabulates the scores at the Puget Sound speaker contests. How close are the scores.
FWIW, when I was a judge at the Parts Express speaker competition along with Don Keele and Jerry McNutt I think our scores we all pretty close from speaker to speaker. We would certainly all three turn and comment to each other when we heard something above average.
Attachments
Siegfried Linkwitz has added a new section to his website concerning recording. He makes a good statement about a systems approach in the first paragraph. He also seems to mention the concepts of an Auditory Scene and Auditory Horizon more often lately.
Is anyone here familiar with the subject of Auditory Scene Analysis? It seems to me it might be relevant to this discussion, but I have not explored the subject myself (I bought the book by Albert Bregman a couple of months ago, but haven't had the time to read it).
Is anyone here familiar with the subject of Auditory Scene Analysis? It seems to me it might be relevant to this discussion, but I have not explored the subject myself (I bought the book by Albert Bregman a couple of months ago, but haven't had the time to read it).
I can't call myself "familiar with" and haven't read the book, but have read some papers related to ASA. To me the data processing beyond the cochlea is the much more important (and interesting) part of listening compared to the simple movement of air particles in the "outer" world.
But it could lead to some REALLY controversial discussions imho.
Rudolf
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