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Old 16th February 2010, 12:18 AM   #391
Key is offline Key  United States
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I think the reflection off of the opposing speaker will beat the ceiling reflection in most cases. Anyway I was concentrating on horizontal. For this example I am assuming a 2 dimensional room. I know how ridiculous this model is but still I am looking at a pattern I see with loudspeakers and the offaxis response target and seeing if the reflections might have something to do with why speakers use this pattern.

I personally don't think it's the reflections so much at a certain point but more the way off axis response effects phantom imagery or imaging in general.
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Old 16th February 2010, 12:57 AM   #392
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Seems you first need to educate yourself on the basic physical principles of diffraction and reflection. Then look at some real world data.

Here's some data (reported) by Olive for reflection detection thresholds:

Click the image to open in full size.

Last edited by markus76; 16th February 2010 at 01:05 AM.
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Old 16th February 2010, 01:24 AM   #393
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Can you explain that chart? I don't get what exactly it's trying to tell me.
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Old 16th February 2010, 03:42 AM   #394
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I guess that's too broad of a question but still that chart doesn't tell me much without some background. What speakers were they using? What does the degree off to the side represent?
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Old 16th February 2010, 04:58 AM   #395
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Default CD or at least CONTROLLED directivity....?

surely, the nearest we can hope to get to a perfect soundstage would be CD or, as above, at least controlled directivity; coupled to a near as perfectly 'sound dead' listening room as possible???

Gedlee, i understand the drive towards CD repro.

Since in nature sounds below a couple of k's arent all that directive; an ON AXIS, CD(if possible/due to limitations) audio system operatind from 2k upwards, and delivered in an acoustically absorbent listening space is the key.

ANY reflections, VER, or spatially, subjectively unoffensive reflection is unfaithful to the recording, and is hence colouration. Its just a more favourable colouration, to the ear at least; in the same way 1% 2nd harmonic THD is nicer to the ear than 1% 3rd harmonic THD.

It doesnt change the fact that is is distortion, which is why ill still with SS amps, and (unfortunately) stick with my 'normal' speakers, and await the day when i have room to house something bigger and more CD.
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Old 16th February 2010, 05:59 AM   #396
Key is offline Key  United States
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Quote:
Originally Posted by mondogenerator View Post
ANY reflections, VER, or spatially, subjectively unoffensive reflection is unfaithful to the recording, and is hence colouration.
I don't think this is true. My experience with loudspeakers is that in contrast to other situations where I am not in the path of the direct sound, with a stereo system I tend to ignore most all of the reflections that are present in a room.

A simple example is to take a set of competent bookshelf speakers that are tightly calibrated and matched and play something mono. For me the more the speakers match and the more controlled the off axis response is the more the sound just seems extremely dry and coming from the center. Unnaturally dry. Even if the recording has reflections embedded on the recording they seem to be unnaturally dry because they are coming at you only from one isolated angle.

It seems obvious to me that if the speakers are good enough (whatever that is) that you will just ignore late reflections unless they are an embedded part of the direct sound firing at you from some angle. I couldn't tell you why but it seems very obvious to me from mixing and controlling reverb on recordings that I can hear the recorded reflections clear as day but the reflections in the room seem totally absent.
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Old 16th February 2010, 09:57 AM   #397
graaf is offline graaf  Poland
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Quote:
Originally Posted by Key View Post
I don't think this is true. My experience with loudspeakers is that in contrast to other situations where I am not in the path of the direct sound, with a stereo system I tend to ignore most all of the reflections that are present in a room.
(...)
I couldn't tell you why but it seems very obvious to me from mixing and controlling reverb on recordings that I can hear the recorded reflections clear as day but the reflections in the room seem totally absent.
such is also my experience

the subject is VERY controversial and our adversaries would keep persuading us to death that we have impaired sense of hearing and/or have no grip of what hi-fi is all about

fortunately for us (or perhaps rather unfortunately?) there are some informed people (of course wheter they are truly informed and/or morally integral is subject to an ongoing controversy) who are not only sharing our experience but who are also trying to give explanations:

Quote:
Originally Posted by graaf View Post
Moulton suggests that if we supress the reverb of the listening room after 50 ms the listening room becomes just a carrier of information about acoustics of the recording space:
He says:
>>But if you take a look at what's really going on in recordings, playback rooms are generally small and the early reflections happen very quickly-whereas in a recording space (or simulation of a recording space that we do with artificial reverb), those reflections are much, much later in time.
What happens is that the early reflections of the playback room carry information about the recording room quite well<<
see:
Moulton's Takes

Quote:
Simple Dereverberation Experiment

Last Summer, I visited Michigan State professor William Hartmann who is a well known psychoacoustics researcher. I ran my dereverberation theory by him and he noted that some aspects had been confirmed by published experiments. He suggested we do a little experiment right there. His anechoic chamber and reverberation chambers are separated by a large and quite reverberant work area. (I had noted my usual adaptation and dereverberation to this room when I entered.) We made recordings of the professor reading text at a distance of one meter in the work area, then again in the anechoic chamber.
When we played the workroom recording back in the anechoic chamber (over a Minimus 7 speaker on a stand placing it at head height), we heard excess workroom reverberation that was not present when we listened to his voice live in the workroom. The voice sounded artificial and distant even though there was no added reverberation from our anechoic playback room.
Next was playback of the anechoic recording in the workroom (and comparison to the real Dr. Hartmann). The Minimus 7 was identifiable as a loudspeaker source, but all seemed quite natural with no excess reverberation. Far more natural than the same amount of reverberation heard in the anechoic chamber.
Experimentís conclusion: recorded reverberation is far more audible than live reverberation, at least for a simple recording technique.
see:
http://home.provide.net/~djcarlst/SLCBI.htm

Quote:
Originally Posted by graaf View Post
>>"A certain amount of the right kind of reflected sound appears to enhance the music listening experience and, interestingly enough, to improve speech intelligibility."
Toole has concluded that normal reflections in a typical small living room seem not to interfere with perception of the recorded space. He has also determined that early lateral reflections (<50ms) have a beneficial effect on intelligibility similar to raising the dialog level, and that the reflection pattern is more important than reverberation.<<
see:
http://www.linkwitzlab.com/Acoustics...ll%20Rooms.doc
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Old 16th February 2010, 02:27 PM   #398
gedlee is offline gedlee  United States
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Quote:
Originally Posted by mondogenerator View Post
surely, the nearest we can hope to get to a perfect soundstage would be CD or, as above, at least controlled directivity; coupled to a near as perfectly 'sound dead' listening room as possible???

Gedlee, i understand the drive towards CD repro.
I don't think that the room should be acousticaly dead, not at all. In fact all my designs are the exact opposite - very live. (Except at LFs of course).
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Old 16th February 2010, 02:52 PM   #399
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Quote:
Originally Posted by Key View Post
Can you explain that chart? I don't get what exactly it's trying to tell me.
You still did not read Toole's book?!
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Old 16th February 2010, 03:02 PM   #400
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Quote:
Originally Posted by graaf View Post
"In actual fact, loudspeakers themselves are perceived in stereo as early reflections of a sound whose direct version we missed."
Did he or anybody else ever prove this to be true??
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