That is naturally the goal of controlled directivity speakers. Might as well use headphones though. Same effect.
That is indeed the point. When you start to control horizontal directivity to avoid reflections. You ultimately end at the road with headphones. And in that respect you might have spent a fortune on speakers, amps, room treatment etc etc to get a listening experience you essentially could have gotten even better from the start with a set of reasonably priced headphones.
And with that, we are essentially back to the theory behind it all. There are 2 "perfect" horizontal dispersion patterns. Virtually 0 degree dispersion which are essentially headphones, or 360 degree dispersion which are essentially omni-polar speakers. Anything in between is a compromise.
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Interesting that they concluded that damping on the front wall improved image localization, (something I knew already) given that apart from reflections which have bounced around the room before returning to reflect from the front wall, (by definition being late reflections) the only sound that might be getting attenuated is the lower midrange which is near or below the baffle step frequency of the speaker, which according to some shouldn't have any significant effect on image localization...
So improvement in image localisation from front wall damping is either reduction in the lower midrange reflection which causes comb filtering, (showing low midrange does affect imaging) or its just an overall reduction in the level of reverberant field in the room, (and a consequent increase in direct to reflected ratio) or a combination of both.
Neither involve full spectrum early reflections.
Very interesting indeed.
I think it suggests that although the lower midrange is less important than high frequencies for imaging, early reflections in the lower midrange do contribute negatively to imaging.
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the only sound that might be getting attenuated is the lower midrange which is near or below the baffle step frequency of the speaker, which according to some shouldn't have any significant effect on image localization...
I'm sure Earl will comment
or rather a reduction of a spurious spectrally unrelated (to the original one) transient - You seem to ignore the temporal aspect
musical signal is of a transient nature and in a reflective environment our spatial hearing depends on comparison of time arrival of wavefronts at the ears
comb filtering may affect timbre but doesn't explain spatial effects
I didn't exclude the possibility that the delay of the lower midrange reflection is part of the problem.
I know that the comb filtering from the reflection is definitely audible, however I agree that the fact that the lower midrange wall reflection is delayed may also be a contributing factor.
However if the sum of the two is still minimum phase, how can we prove that what we hear is not simply the spectral imbalance that results ?
Like it or not, spectral balance / imbalance at various different frequencies is a key factor that makes or breaks good imaging...
but only 360 degress horizontally - not a point source!
and 180 degrees boundary coupled is a reasonable option too
You seem to underestimate time domain problems, time domain is not just about phase relationships just as music is not a steady state signal
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The aim of controlled dispersion has never been to simulate headphones, only to reduce colouration and/or image shift. Dispersion which is more narrow than needed to achieve these goals is of no use since it will make the presentation too dead and aggravate the audibility of the crosstalk comb filter.
The other extreme suggestion, 360 degree dispersion, will suffer from colouration from front wall reflections. If you want wide dispersion and lots of image broadening, 180 degrees would be more than adequate. Anything wider than that has no added advantage.
...or maybe we want just the lateral but not the contralateral reflections. In that case even narrower dispersion would be desirable
VERY important observation, and the crosstalk comb filter seems to be the most serious flaw of stereo reproduction over loudspeakers
...or maybe we want just the lateral but not the contralateral reflections. In that case even narrower dispersion would be desirable
are there any research studies suggesting that contralateral reflections are bad?
Indeed and it also makes a comparison with headphones invalid. Unless you would use crosstalk cancellation.
Yes; the first experiment of Bech, which simulated the pure cardioid source, suggested the contralateral reflection may cause colouration (but not the ipsilateral reflection, which is interesting). The second experiment, with a more typical 2-way KEF speaker and a slightly more realistic room simulation, did not find this. It may wel depend on the situation.
thanks again for the information
but problem is how 1st order contralateral reflection can be eliminated?
it seems that only "Stereolith-like" stereo bipole with direct sound blocked can do it, perhaps it is part of magic of this arrangement
ps. but then the ipsilateral reflection is itself perceived as the source of sound and 1st contralateal reflection is back again
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And amplifiers with no distortion will make the music too cold...
You guys need to admit you're talking about euphonics, which are a matter of taste.
And amplifiers with no distortion will make the music too cold...
You guys need to admit you're talking about euphonics, which are a matter of taste.
...too dead and aggravate the audibility of the crosstalk comb filter
we are rather talking about how to make stereo sound more realistic despite its flaws
more realistic sound is exactly what HiFi is all about, it is not about perfectly reproducing errors
although I agree that all this can be a matter of taste ...in a sense
I can't stand typical audiophile euphonics - I like it cold and "ruler flat" but not flat soundstage-wise
I like it realistic
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And amplifiers with no distortion will make the music too cold...
You guys need to admit you're talking about euphonics, which are a matter of taste.
You need to distinguish between obvious errors, neutral or possibly beneficial effects, and yes, matters of taste. Neutral or beneficial effects are not always simply a matter of taste and may cover up some flaws inherent in stereo. Look at the science.
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Wow. Really? You sure about that? I have controlled directivity speakers in my room and they sound nothing like headphones (apart from tonal balance). They just don't compare.
I've also heard Geddes and Danley's speakers and they don't sound like headphones either.
I have to completely disagree with your statement, Saturnus.
Interesting that they concluded that damping on the front wall improved image localization, (something I knew already) given that apart from reflections which have bounced around the room before returning to reflect from the front wall, (by definition being late reflections) the only sound that might be getting attenuated is the lower midrange which is near or below the baffle step frequency of the speaker, which according to some shouldn't have any significant effect on image localization...
So improvement in image localisation from front wall damping is either reduction in the lower midrange reflection which causes comb filtering, (showing low midrange does affect imaging) or its just an overall reduction in the level of reverberant field in the room, (and a consequent increase in direct to reflected ratio) or a combination of both.
Neither involve full spectrum early reflections.
Hi Simon
Your logic is respectable and I agree with most of it. But, and I understand that this does contradict my position in many respects, I have found that high levels of damping on the front wall behind the speakers - even very directional ones like mine - is an improvment in sound quality. I won't jump to what it is that is improved precisely, but the effect is notable. And I have measured the bounce off of the front wall - it has more HF content than I expected.
But I have to caution here that we are talking about small perceptual changes in a system that already has a great deal of VER surpression. Hence the effect is "minimal" in the total landscape, not dramatic. This may be the "rocks at the bottom of the river" effect where as you improve all other disturbing reflections the front wall rises up to become the "main" degradation even though it is in fact small compared to all the other reflection effects. Is just that all those other ones have already been fixed.
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