Markus - only you would correct my spelling.
Did I mention that I now have a German son! He's 15 and living with us for a year. Maybe at the end of this I will better understand the German mentality!! (If that's at all possible
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Looks like Michigan is heavily contaminated by German ancestry:
http://upload.wikimedia.org/wikiped...2000-Data-Top-US-Ancestries-by-County.svg.png
Some of your neighbours should be able to introduce you to German mentality.
The pity about Markus is, that he is living in Switzerland now. The Swiss have a habit to tell the Germans how to lead a law-abiding life - and vice versa. May have rubbed off on poor Markus
Anyway, I really appreciate that you are giving a young German the opportunity to experience the USA for some time.
Rudolf
Earl,
I understand that the current information that you are sighting in the acoustic studies only goes down to 500hz but is this the true limit of our ability to discern directionality or is it still lower but on a sliding slope as we approach possibly 200hz? At this frequency and above I would say that you can identify the center of radiation when devices are separated by much distance in this region. That may not have much to do with room radiation patterns but what of fist primary waveform arrival? In nearfield listening I would think that we do hear to a better resolution than 500hz. Are we only using frequencies above 500hz with vocal Q's to localize directionality?
I understand that the current information that you are sighting in the acoustic studies only goes down to 500hz but is this the true limit of our ability to discern directionality or is it still lower but on a sliding slope as we approach possibly 200hz? At this frequency and above I would say that you can identify the center of radiation when devices are separated by much distance in this region. That may not have much to do with room radiation patterns but what of fist primary waveform arrival? In nearfield listening I would think that we do hear to a better resolution than 500hz. Are we only using frequencies above 500hz with vocal Q's to localize directionality?
Having worked with Bayer Corporation for many years there is a definite way of being that is different than an American way of doing things. Much more specific and usually more rigid in how things are done. I think that none of us can discount the intelligence of the German mentality it is a very learned society. Having grown up as an American on the Left coast I will say that even here we have so many ways of thinking that there is no real monolithic American thinking going on, that is what has made us so great as inventors and visionaries. Now taking that in context I do have 1/4 Dutch/German ancestry and also some Austrian to go alone with many other European backgrounds. A real mutt as I would call myself. I only wish that our education system would more parallel the German model, we would be turning out many more scientists and highly skilled tradesmen with that method of schooling. Just as we have freedom to be different here in America we also allow way to much failure prematurely to happen.
There is no "limit", its a sliding slope. You have to remember where this discussion started. Its not about the virtual source location played by two speakers, it about the image shift that results from reflections below 700 Hz. I maintain that this region is not a significant factor. I stand by that comment.
When I read post 333, that's not how I read it - even though a_tewinkel's post that you responded did concern reflections..
There is no real reference to image shift from reflections below 700 Hz.
333:
"We have talked about this a lot as well. Sure it would be great to have 90° control down to 200 Hz. but that is neither practical nor, IMO, necessary.
Frequencies below about 700 Hz do not have a strong influence on image perception.
In most of the literature, say from Blauert and the like, they do not even look below about 500 Hz. From 700 Hz and above then becomes the real target for controlling the directivity. The Abbey has very good control above about 700 Hz. When I say "spectraly nuetral" then I mean > 700 Hz.
24 dB between 100 and 5 kHz is not the issue, because it's likely only a few dB between 700 Hz and 5 kHz. It Rises rapidly below 700 Hz of course."
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On *this* topic I'd suggest an experiment with the loudspeakers moved significantly away from the "front wall" (or the wall behind the speakers as you face them). (..closer to the rear wall than the front.)
The sense of image "compression" (or images "bunching up") typically reduces, and the overall sense of depth and depth of image placement increases. In other words images tend to shift rearward toward the front wall.
You should note a resulting change with your speakers - specifically due to the front wall reflection at freq.s LOWER THAN 500 HZ.
My dipole speakers are at least 1.2 m from any wall. I listen at a distance from 1.8 m (reclined in the chair) to 1.2 m (leaning forward). While moving along that distance the direct/reverb ratio changes dramatically. This regards specifically "the sense of image "compression" (or images "bunching up") ... and the overall sense of depth and depth of image placement".
My woofers are crossed at 500 Hz to the midrange driver. I just pushed the low pass slope to but48 and shut off the mid/tweeter section. When I move my head forward and rearward, there is hardly any difference WRT spatial or tonal impression.
Next I switched off the woofer section and listened to mid/tweeter only. Now I could recognise the change in depth information better for sure. But it was still a long way from the combined response. All this tinkering with passbands, noises and clicks is nice for scientific reasons, but it surely doesn`t tell us the full truth about the acoustic scene as analysed by our brains.
Rudolf
I've not done this with loudspeakers that deliver dipole behavior, but have you tried it when the loudspeakers are 3+ meters away from the front wall?
See this person's setup for an idea of placement (..though the speakers are to close to the side-wall):
syst
Note I've also done this experiment with the loudspeakers in front of my garage (outside). Again though, "omni" <500 Hz monopoles were used.
This looks primarily like an exercise in initial time delay gap (ITDG). What if your speaker starts beaming above 500 Hz? Possibly already 12 dB down at 2 kHz in the rearward response? In this case the effect anyway will be more significant with the 500 Hz "omni" than with mid and tweeter mainly firing forward.
I don't want to prove anything special with my findings - just want to show how far we are from one-dimensional causes and easy explanations in this thread topic.
Rudolf
I used an equalizer to band-limit (Behringer digital eq.).
On Earl's speakers it shouldn't be an issue.I agree though, nothing truly definitive from such a simple experiment.
I should also note that this experiment was prompted specifically to try and "pin down" a reason why there was an alteration with some of my music with regard to drum-kit placement. It's perhaps the reason I eventually gravitated toward preferring a dipole in the mid-bass, it doesn't seem to be pushed forward in the mix (..something I noted from listening to SL's cheaper speakers at a retailer - deeper set-back for the drum kit in the mix). I don't know though if a dipole's radiation *reflections* had anything to do with that however.
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There is a difference between the hard and soft sciences. And for me, perhaps the attraction to hifi is that it's a conjunction between the hard and soft. In the hard sciences, we have absolutes, we can calibrate our measurements against a known standard, we can know that repeatable results will be repeated. In the softer sciences, everything is on a sliding scale. There are no absolutes, only averages, and if someone produces the exact same results, that is cause for suspicion, not certainty.
In acoustic testing with subjects, the subjects must be analyzed. The questions themselves must be tested. The environment must be neutral, and double blind. And finally, the results must be interpreted, not taken at face value. Engineers are ill-prepared for this sort of thing.
I don't mean to disparage the work done so far, I've been a fan of Dr. Toole for 20 years. But in truth, his results are merely a set of data points, the first of a much larger set that may come later, although it will require funding, and as music doesn't kill people or cure them, those dollars are hard to get.
Anyway, the discussion is interesting, but it's more applicable to Dr. Gedlee's work as he is marketing to a 'closer to average' section of the populace. For most of you, since DIY is your interest, then I humbly suggest DIY testing of these matters if they matter to you, as your appreciation of such subtleties is likely not near the centre of the curve.
And again, I propose that those of you who have built several systems have trained your hearing in the process, and are not necessarily subject to the constraints of statements about the perceptions of the general populace. You can all go pat yourselves on the back, unless you've reached the state of existential ennui that I have and wish you could go back to the days when a Wurlitzer made you want to get up and dance instead of sitting there, sucking your malted, and thinking about how you might improve the sound...
In some of the above posts there is speculation that sensitivity to localization cues (binaural diiferences) is somehow deficient for spectral regions at or below 500 Hz is simply incorrect.
Localization for narrow band signal signals (a round 500Hz) has thresholds around 1 degree. This corresponds to binaural differences in time of about 20 usec. That is pretty darn good. This is solid and robust finding that has been known for decades.
Localization for narrow band signal signals (a round 500Hz) has thresholds around 1 degree. This corresponds to binaural differences in time of about 20 usec. That is pretty darn good. This is solid and robust finding that has been known for decades.
A 500hz wavelength is about 4 times wider than an average human(Male) head. It seems to make mathematical sense that below this point, especially in a "normal living room" environment, that localization would start becoming practically very difficult and is therefore probably moot..
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"it seems" and "probably" .....
Feel free to speculate.
There are data and there are also speculations. However the fact remains that localization in this frequency region is not "very difficult and therefore probably moot"
Was this data you're speaking of derived in a normal living room?
Feel free to speculate..
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Using Laboratory conditions as points of contention? Everyone needs to go back and Read the OP(Including you, Greg). It looks like I have also not succeeded.
In retrospect, I guess that's not such a bad thing. This has been fun, informative and humbling..
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