I was doing some experiments with increased speaker toe-in. At 56° I get a pretty spacious presentation. The ETC shows two strong contralateral reflections after about 11ms and 13ms:
When putting thick porous absorption next to the speaker, the reflections are gone:
Now the image is more detailed and localization is improved but all spaciousness and depth is gone.
In earlier tests I didn't get the spacious image with a 45° toe-in. My assumption was that a contralateral reflection couldn't contribute to spaciousness. It probably simply had to pass a certain level to become a contributor to perceived spaciousness.
Speculating on what's going on, in case when you have delayed large reflection where the ear can distinguish, then the room presents artificial spaciousness. This may also be why people prefer this. If this reflection damps out quickly, then you will have less effects of reduced detail and focus.
I like for the room influence to come in at as low frequency as possible and enough to supplement the low end roll off of the speaker.
I do plan to experiment with the concept of using absorbent material to sort of control directivity of the speakers to see what happens the next time we get something into a show. I recall that Earl mentioned the idea of an absorbent wave guide; althoughn I don' like the idea foe higher frequencies, but the idea is great for lower frequencies.
Yes, I'm fully aware of that fact.
I believe that stereo itself isn't capable of delivering any spaciousness that is perceived as real or natural.
In two-speaker stereo all reflections that could carry information about spaciousness are lumped together in two locations, namely the left and right speaker location. This can't create a sense natural spaciousness. Reflections have to arrive from different locations for that to happen.
I'm talking here about "real" stereo recordings (level panned) and not about binaural(ish) recordings and/or crosstalk cancellation playback.
Did you test your Pluto clone outside? Does it still sound spacious?
Basically, the room always messes up the original recording. But since the speaker is also far from perfect, we can only figure out the best match which fits into our lives. Since the effect is gradual in terms of absolute value, so different people will draw a different line of compromise. I don't think there is a universally quantifiable criteria.
Yes, but the two reflections you see are from the other side of the room. They are caused by the extreme toe-in of 56°. The speakers are firing at the first reflection point of the far wall.
One reflection is directly from the side wall, the other is a ceiling to wall reflection.
But what we don't know is how to add spaciousness while maintaining good localization.
Is a single, loud and maximally delayed reflection best? Or is a specific reflection pattern made of multiple reflections better?
The former would suggest a high directivity (on-wall?) speaker firing at the opposite wall. This would maximize the reflection free time.
That is very true. I think Rudolf provided the answer a few pages back about the different effect it makes.
I would tend to think, just by imagination that a large room, with maybe 2m from any boundary would be the ideal, and a pattern of reflexions that goes in order from lateral, contralateral, ceiling and rear wall might work best. Unfortunately for us it's not often the case..
Spaciousness is perceived by either delay arrival plus out of phase signals between the left and right. These ques are generally in the original recording if done in a normal performance environment. Some systems create ques electronically by generating some low level out of phase signal either intentionally or unintentionally. These can also be done as Markus as experienced, by introducing reflections from the wall of the opposite side. It becomes a problem when the reflection and the continuous reverbant energy level is too high, and is why a combination of diffusion, diffraction, and absorption is more favorable.
Now people may question, if the spaciousness ques are in the original recording, why would we not here spaciousness if we listen to the speakers in an open environment. This is because most speakers mask the ques with their own delayed release of stored energy as shown in CSD plots. The ques are of much lower level than the main sound, and if the level of delayed release of stored energy is too high, it dominates and masks the ques.
Now people may question, if the spaciousness ques are in the original recording, why would we not here spaciousness if we listen to the speakers in an open environment. This is because most speakers mask the ques with their own delayed release of stored energy as shown in CSD plots. The ques are of much lower level than the main sound, and if the level of delayed release of stored energy is too high, it dominates and masks the ques.
mmm. CSD? No. Play a violin outside, same effect, small sound no spaciousness. We need a room, a good room, which then carries the space info, not destroy it. Some people even talk about "deverberation".
When it comes to spatial cues, they are indeed lower in level, but how low? What are the usual recorded dynamics on redbook? 60db? You can't hear them because you can't put the sound high enough in level as it "crashes" on the high SPL passages. This usually means too high room reverb and too close boundaries. At least this is my experience.
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You're mixing up concepts here. "Out of phase" does not equal "spaciousness". Please read the Lipshitz paper "Stereo Microphone Techniques - Are the Purists Wrong?", J. Audio Engineering Society, vol. 34, no. 9, pp. 716-744 (Sept. 1986)
Reflections in a recording can be pretty loud. Of course in most rooms chances are high that cues in the recording get masked but not in the example I've shown. There is no realistic sounding spaciousness once all reflections are suppressed below a certain level.
It can be different with binaural techniques but I'm talking about two-speaker stereo and 99,9% of all recordings which are based solely on interchannel level differences.
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Oh, dear ...
Trouble is, until one hears what can be achieved, then this is probably a reasonable conclusion.
Yes, you should hear the recorded spaciousness, but if it doesn't happen then it is not the fault of the speaker, but rather the electronics. Having gone from normal loudspeaker sound to spacious sound, over and over again, by improving the electrical signal driving the speakers vs. fiddling with the speakers or room this is 100% fact as far as I'm concerned ...
of course, but you have tried it and did not seem too happy with the result, so?
I can actually recall another thing I read last night, a comment from the Amsterdam Concertgebouw manager about halls that do surround, and halls that just give a window into an even. Again, I believe this also applies to us, not new stuff though..
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Oh, dear ...
Trouble is, until one hears what can be achieved, then this is probably a reasonable conclusion.
Yes, you should hear the recorded spaciousness, but if it doesn't happen then it is not the fault of the speaker, but rather the electronics. Having gone from normal loudspeaker sound to spacious sound, over and over again, by improving the electrical signal driving the speakers vs. fiddling with the speakers or room this is 100% fact as far as I'm concerned ...
I accept your opinion (without using a roll eyes icon btw) but strongly disagree.
Fair enough ...
- it's just a bit frustrating for me watching this discussion, which assumes that stereo is inherently so limited. From my perspective I see a bunch of people doing this, 
, when there is a very clear solution, a straightforward way of moving forward and achieving more satisfactory sound Sorry ...
First of all, "spaciousness" is a descriptive expression, when people use it, they are just expressing a personal impression, which differ quite significantly.
I cannot speaker for other people, but it is my experience, with the same driver, if I treat it so that the CSD is greatly improved, then the spaciousness and details both improve concurrently. If I move the speakers to a more dead room, then the spaciousness improves, and if there is a problem, it becomes more evident. My expression of spaciousness is that the reflective ques seem more separated from the performer, and the room seems larger than it really is if the room is relatively small (less than 20 cubic meters).
I listen to a great variety of music as well, some recordings of which were done at the same time I was listening in the hall, and I know exactly where the mics were.
Oh, dear ...
Trouble is, until one hears what can be achieved, then this is probably a reasonable conclusion.
Yes, you should hear the recorded spaciousness, but if it doesn't happen then it is not the fault of the speaker, but rather the electronics. Having gone from normal loudspeaker sound to spacious sound, over and over again, by improving the electrical signal driving the speakers vs. fiddling with the speakers or room this is 100% fact as far as I'm concerned ...
I think if one just plugs one ear up for a week, go to different locations to experience "spaciousness", then maybe they will start to understand rather than just memorize what the books say. I kicked a few people off some projects in my early years of engineering because of that.
You know, I just listen to the sound and try to figure out where to start. Everything in the link counts, sometimes when you know you should hear an improvement, but it does not happen, it's just necessary to move on to the next thing you suspect until the improvement shows up. I have faith in technology, but never believe all that has been reported is unconditionally true.
Right on the money. Once you 'know' what the system should do, then sheer persistence will reward you with good results. I shake my head at times at how terrible expensive systems sound - it's like a Ferrari with half the spark plugs missing, two flat tyres and the hand brake full on all the time ...