Hey Omholt You know the saying about throwing out the baby with the bath water? 😀
for my part - the Beveridge side-wall placement remains an option:
line source is not needed, elimination of floor reflection can be achieved with the use of a flooder speaker which can be effectively integrated into the side wall just as the tweeter was effectively integrated into the floor in Snell "Type 1"
in that way floor and ipsilateral 1st order reflections are out, ceiling reflection seems to be quite unproblematic
there is still strong 1st order contralateral reflection but even in a moderately sized room it can be delayed by more than 10 ms depending on angle of stereo triangle
but such reflection perhaps - at least some studies to which Toole refers in his book suggest so - has good potential of low IACC and thus of increasing spaciousness
front and rear wall reflections coming from relatively wide angles (relatively wide for such reflections) could be delayed even more
I can only imagine one solution with better pattern of early lateral reflections - true CD narrow directivity in a corner speaker, the floor reflection would be back in that case though
for my part - the Beveridge side-wall placement remains an option:
line source is not needed, elimination of floor reflection can be achieved with the use of a flooder speaker which can be effectively integrated into the side wall just as the tweeter was effectively integrated into the floor in Snell "Type 1"
in that way floor and ipsilateral 1st order reflections are out, ceiling reflection seems to be quite unproblematic
there is still strong 1st order contralateral reflection but even in a moderately sized room it can be delayed by more than 10 ms depending on angle of stereo triangle
but such reflection perhaps - at least some studies to which Toole refers in his book suggest so - has good potential of low IACC and thus of increasing spaciousness
front and rear wall reflections coming from relatively wide angles (relatively wide for such reflections) could be delayed even more
I can only imagine one solution with better pattern of early lateral reflections - true CD narrow directivity in a corner speaker, the floor reflection would be back in that case though
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It is black and white if the reflections impede on the ISD-gap and as long as we're talking about accuracy.
Preferences are something else.
Have you experienced many small rooms and setups when this is not case? Reflections need to be attenuated by -20-30dB to be considered effectively anechoic.
Remember that late arriving reflections with high gain isn't a good thing either. They are just less negative then early ones.Hey Omholt You know the saying about throwing out the baby with the bath water? 😀
for my part - the Beveridge side-wall placement remains an option:
line source is not needed, elimination of floor reflection can be achieved with the use of a flooder speaker which can be effectively integrated into the side wall just as the tweeter was effectively integrated into the floor in Snell "Type 1"
in that way floor and ipsilateral 1st order reflections are out, ceiling reflection seems to be quite unproblematic
there is still strong 1st order contralateral reflection but even in a moderately sized room it can be delayed by more than 10 ms depending on angle of stereo triangle
but such reflection perhaps - at least some studies to which Toole refers in his book suggest so - has good potential of low IACC and thus of increasing spaciousness
front and rear wall reflections coming from relatively wide angles (relatively wide for such reflections) could be delayed even more
I can only imagine one solution with better pattern of early lateral reflections - true CD narrow directivity in a corner speaker, the floor reflection would be back in that case though
If you can't treat the room at all, buy headphones. 😀
If you can do some treatment of sidewalls (and possibly back wall), I would get a pair of CBT speakers by Don Keele. No need for vertical treatment there and a better polar response then anything I've seen.
I'd like to see those studies that deny "a strong influence on image perception" for frequencies below 700Hz. I can't remember reading any of that in Blauert's publications.
Even a simple minimum phase filter applied around the Schröder frequency can improve image localization to a great degrees.
Why don't you let the consumer decide? What do you have to loose? You produce "on demand" anyway so you don't have to invest in production, "just" the prototypes.
Gedlee
Is this the type of speaker you're talking about? Emerald Physics - almost live - speakers
It seems that your waveguide in a configuration like this wouldn't be that expensive(relatively speaking)
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Waveguide with cardiode bass section might be a better commecial idea. More output then dipole and possibly less sensitive to placement.
Guys
Just send me the deposit checks and I'll get right on it! Until then I'll make the business decisions as I see fit.
Just remember "The customer is always right" except that they would gladly have you go bankrupt if it gets them what they want.
I got a lot of requests to make the Summa again, but then when I could, I got no orders - too expensive. The dipole/cardiod would be on the same order as the Summa maybe more.
Just send me the deposit checks and I'll get right on it! Until then I'll make the business decisions as I see fit.
Just remember "The customer is always right" except that they would gladly have you go bankrupt if it gets them what they want.
I got a lot of requests to make the Summa again, but then when I could, I got no orders - too expensive. The dipole/cardiod would be on the same order as the Summa maybe more.
If you see things like that then we are not on the same page. Something is either "perfect" or its not is that the choice?
Are you suggesting that the influences on "image" are greater for frequencies below 700 Hz than they are above? Because that is what you are suggesting. That's what a "strong influence" means.
I can't think of anywhere in Blauert where he even discusses frequencies below 500 Hz. Why do you think that is? Because its so dominate?
How the heck do they figure these things out, anyway? Pure tones? Music that is high passed or low passed? Do you have to point to where the sound is coming from?
Most of the testing is done with headphones and altering channel balance/intensity and/or timing. Pure tones, speech, and even mixed media are used.
Intensity difference owing to the *lateral* portion of localization are largely missing in action above 500 Hz because of head-shading. However, with respect to lateral intensity differences, our perception really only starts to get "good" at freq.s above 3 kHz (with a "notch" like exception generally occurring around 7.5 kHz).
Timing differences are generally used in testing below 500 Hz for localization cues (..though timing is still a factor up to around 4 kHz).
Both intensity and time relate to the perception of depth localization, but time seems to have a greater relationship. Ex. say you hear someone shouting to your left, you recognize that it's coming from your left, but you turn to that "source" to get a better sense of distance (and for a visual cue, though a blind person does the same thing).
Of course "image perception" is a broad topic, and certainly includes freq.s below 500 Hz, particularly with respect to time as it relates to intensity. Even Lord Rayleigh was aware of this at the turn of the *last* century.
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We must have read a different book. It's well known that interchannel phase differences can shift an intensity-based phantom source (and vice versa).
If interchannel level and time differences don't correspond with each other, the phantom image also gets blurry.
The room tranfer function can create such differences even if they are not present in the recording (most recordings are intensity-based). I believe that these room effects below and within the transition region are the main cause for blurred phantom image focus.
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I've always wondered if the desire for a sloping power response is simply the result of mixing/mastering environments and the speakers they use.
Flat power response might actually be more desirable in a general sense but such speakers will always sound bright if the record creators don't use similar speakers as well.
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phase? headphones?
can we go back to the topic of this thread and a normal living room environment please?
phase ITD is useless with music under reverberant conditions, only cues from onset ITD are working
can we go back to the topic of this thread and a normal living room environment please?
phase ITD is useless with music under reverberant conditions, only cues from onset ITD are working
I'm with you there Markus. Although is fair to say that a larger percentage of image location comes from high frequencies, unequal lower midrange response from left and right speakers at the listening location (both amplitude and phase) that are due to room assymetry do blur and confuse the phantom image location or tear it apart partially.
In a room where speakers are less than a metre from side walls but its impossible to position them symmetrically (eg my room) I've found it helpful to apply a small bit of EQ in the lower midrange that is tailored to each speaker to give a better lower midrange left right balance at the listening position - small changes in the region of around 250-400Hz seem to make quite a difference in image focus.
Having the speakers unequal distances from the side walls is obviously suboptimal (I was amused to see Earl say he has never tested this configuration and thus doesn't know what the effects on imaging might be) but sometimes we're stuck with where speakers have to be and have to make the most of it.
As long as you have good directivity at high frequencies a bit of differential lower midrange EQ to partially compensate the different comb filtering of the two sidewall reflections seems to help quite a bit in restoring good imaging and phantom image focus...
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Simon, an asymmetric setup is one cause but another is the room's modal behavior. The smaller the room the worse the problems even in the mid-range. Those problems go just gradually away around the Schroeder frequency.
By the way, the Litovsky papers on precedence (Earl, written with an "e") are available for download on her homepage at Binaural Hearing & Speech Lab: About - Publications
By the way, the Litovsky papers on precedence (Earl, written with an "e") are available for download on her homepage at Binaural Hearing & Speech Lab: About - Publications
Markus
I have no idea what you are talking about - I am talking about the frequency ranges which dominate these effects, not the effects, which clearly exist, themselves. You don't even mention what frequency range you are talking about.
Take Fig 2.81 in Blauert for example - the chapter on nonidentical ear signals. The data stops at 500 Hz, nothing below that is even evaluated. Figure 2.83 has only single point below 500 Hz, 3 at 500 Hz, and all the rest above. In the Table 2.4 above it, there is only a single test out of 11 that does any testing below 500 Hz. Why do you think that is? It's because the two ear signals are becoming identical below 500 Hz and any location cues from ear signal differences are vanishing.
Check Fig 3.8 in Blauert and see how much difference there is in the phasor diagrams at the two ears for 300 Hz and 3 kHz. The 3 kHz changes are much larger than the 300 Hz changes, which of course only makes sense. The head at frequencies below 500 Hz is simply not big enough to generate large signal differences between the ears so there are no differences for the cognitive aspects of localization to work with. The spatial resolution of our hearing below 500 Hz MUST be getting worse - so no one studies it.
Pan
The paper that I refered to discusses the signals used and how they can dramtically affect the test results. They also discuss how the questions asked have a strong influence. Like "When can you hear a second signal for a reflection" and not "When is the image shifted" or "When is the signal colored". All of these different questions will yield different results.
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