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Perceptual Effects of Room Reflections

Joined
Feb 18, 2021
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Here's a crude drawing of my room and what I believe are the direct speaker reflections. I believe this works mainly due to speaker design but do not know for sure. And I think it may work in a larger room provided speakers have reflector panels in place at an optimal distance. This however would require experimentation which I am not able to do.

View attachment 127542
Very interesting, and brave. How does it sound? And have you ever just once done a spectrum analysis in there?
 
Joined
Mar 18, 2021
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Very interesting, and brave. How does it sound? And have you ever just once done a spectrum analysis in there?
I've been sitting on this discovery for 7 years and I'm not going to live forever. This maybe an alternative method of listening to stereo rather than the typical stereo setup. Have not done a spectrum analysis.
Your typical stereo setup has IMO a narrow stereo image it can range from practically non-existence to perhaps 8' depending on the room and the image seems to be behind the speaker plane. Also proponents of typical stereo setup emphasis elimination of first reflection points.

With some experimentation I think my setup could be adapted to bigger rooms using reflective panels replacing backwall which maybe much further back than optimal distance from speaker, to create a good reflected image. Allows for wider sweet spot listening, further back into a room.

Pros:
15' wide phantom stereo image/soundstage (could be expanded given more room space).
Image seems to project off of front wall, giving an accurate forward presentation.
can't locate speaker position.
enveloping nearfield wall of sound.
phantom image can be easily moved left or right to center image just by adjusting speaker toe-in.
don't have to worry about reflection cause you using the reflection to create stereo image.
works in long narrow room.
full range speakers
obstacles or junk in room does not interfere with the reflected image.

Cons:
may require specific speaker design and brand name for optimal imaging as well as being an accurate speaker.
some people may not like a forward presentation or accurate sound.
requires a long wall or wide wall in a room.

That's all I can think of for now.
 

josh358

Senior Member
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Jun 13, 2017
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Thanks! Credit to my partner James Romeyn for using the vertical plane like that. Based on various things I've read I would have said that keeping the reflections in the horizontal plane was the higher priority, but Jim didn't know any better so he just tried it, and the additional time delay made a big improvement. I went from designing bipolar speakers to designing polydirectionals which deliberately use the ceiling.

We can get within a foot or so of the front wall and still hit our ten milliseconds backwave delay target in most rooms, without electronic delay. The spatial impression (including the sense of depth) changes significantly from one recording to the next so I think it is dominated by the recording rather than the playback room. I think this is because the "playback room" cues are rendered inconsistent by early reflections off some of the walls and the ceiling arriving considerably later than they "should", thereby weakening the "small room signature" package of cues, which in turn offers the recording's package of "venue cues" (whether real or engineered or both) a window of opportunity, assuming they are effectively presented. The later-arriving room reflections have the job of effectively presenting the venue cues which are on the recording (in particular the reverberation tails), so imo we don't want an overdamped room.

The claimed theoretical benefit of this approach is good imaging because the early reflections have been minimized, AND good spaciousness because we have a lot of relatively late-arrival reflections. Like a well-set-up pair of dipoles, our approach arguably offers both qualities at the same time, though with less real estate required because the backwave energy uses the room's vertical dimension.
It's a good idea!
 
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