Nothing is wrong with the reference;
Let's start with:
"it has the lowest time delay for signals passing through it and it can be inverted."
The different times sound reaches microphone (ear) due to reflections is clearly not minimum phase in relation to direct sound, which is signal path with lowest delay. Such systems do not have proper Hilbert inverse.
Further at bottom of your reference:
This is Excess Group Delay plot typical to most modest sized domestic listening spaces. This clearly shows that addition of room reflections guarantees non minimum phase responses.
CBT delivers lateral reflections and lateral reflections add spaciousness.
CBT doesn't create floor and ceiling reflections. Virtually all other solutions do. Absorption for getting rid of the ceiling and floor reflection is required. Not very practical.
"Anywhere the excess group delay plot is flat is a minimum phase region of the response. [...] the plot is fairly flat in the region of the 28Hz and 60Hz peaks, which bodes well for attempts to apply EQ to them."
So something must be wrong with the reference because it states the opposite from what you're saying.
Markus,
Wouldn't the CBT enclosures have to actually reach the ceiling to not have a ceiling reflection? That doesn't see very practical but would seem to be a requirement to not reflect as you state. The in one hell of a large amount of devices to produce the cabinet as shown. That can't be cheap that many devices and I often wonder about the series component section of the arrays and how that affects the frequency response of those devices along the line.
Wouldn't the CBT enclosures have to actually reach the ceiling to not have a ceiling reflection? That doesn't see very practical but would seem to be a requirement to not reflect as you state. The in one hell of a large amount of devices to produce the cabinet as shown. That can't be cheap that many devices and I often wonder about the series component section of the arrays and how that affects the frequency response of those devices along the line.
I don't think anyone has made that claim, and they certainly don't need you putting words in their mouth.
And a degraded image - I choose to not compromise and have both, good image and good spaciousness. Perhaps my solution is not practical for everyone, but its not outrageous either - easily done in almost any room. Of course if you don't own the space then you are in a seriously compromised situation and I sympathize.
CBTs are very good at vertical control if you deem that essential. I'd rotate them 90 degrees.
Gedlee,
Personally I am not a big fan of that arrangement. I just keep thinking back to the original analysis of line arrays done years ago in the AES Journal and other sources and I imagine that most of that still holds true, but the spacing is much closer which should minimize some of the original objections. I also question the series parallel connection of the devices but have no first hand knowledge of the effect and what the crossovers look like in these systems.
Personally I am not a big fan of that arrangement. I just keep thinking back to the original analysis of line arrays done years ago in the AES Journal and other sources and I imagine that most of that still holds true, but the spacing is much closer which should minimize some of the original objections. I also question the series parallel connection of the devices but have no first hand knowledge of the effect and what the crossovers look like in these systems.
What don't you get about "anywhere" , "flat" , and "region". The statement also says: "Anywhere the excess group delay plot is not flat is a region of the response which is not minimum phase."
Take your blinders off!
Yes, for given measurement point and speaker location the IR may be decomposed into direct response and reflected responses, each with an excess phase component, and a minimum phase component.
This thread died a peaceful death many pages ago, until awakened by a fan of SL.
This thread was about auditory scene. A scene populated with elements such as human voices, and musical instruments. This scene could be in empty space, or could contain a diffuse reverberant sound element correlated to one or more of the primary elements in the auditory scene.
All information is in the recording and is used to illuminate the ears. No walls are required to decode this.
Spaciousness added by room is characteristic of the room, and will impart same spaciousness to all sound created in room. It's like looking through a kaleidoscope; a single element is used to generate a pleasing geometric pattern. Repeated viewing with different elements reveals the sameness of pattern imparted by reflectors within the kaleidoscope.
Imaging capability of speaker is function of speaker and not the room. Diffraction/reflection from speaker determines imaging performance. It's all about time frames shorter than involved with room reflections.
An example: A small full range driver without breakup images better than same driver when driven into breakup. Under breakup conditions the driver effectively becomes multiple sources with non-linear correlation. With two identical drivers with same breakup behavior the situation improves for mono source, but as two signals diverge with increasing stereo content the breakup conditions of the two drivers diverge, leading to loss of image detail, and unmasking of speaker location.
If moderators removed all posts from this thread pertaining to room reflections, this thread would clean up nicely.
Why would you say the image is degraded? Because of the side wall reflections? I'd think it's easier and therefore more practical to absorb those than mount absorbers to the ceiling and the floor, no?
What blinders? Did I claim that room responses are entirely minimum phase? No.
Go back to this post for example. I've said that "rooms do exhibit minimum phase regions". Which makes them correctable with equalization. This is by the way why the topic came up. Omholt claimed that it's per se not possible to correct room problems with EQ.
Furthermore I've linked the Mulcahy article multiple times. The article clearly shows that there are minimum phase regions and non-minimum phase regions. It even explains how adding two minimum phase responses creates large deviations from minimum phase behavior.
So what made you think I would claim room responses were completely minimum phase per se? I never did.
Is there a real sense of spaciousness (ASW, LEV, depth) when listening to a 2-channel stereo recording outside, i.e. under free field conditions?
There is no precise definition I know of. Bregman defines it as "complex auditory environment" or even "complex natural environment" in his definition of "Audio scene analysis (ASA)" Al Bregman's Website. Where "natural" is not "outdoor", but "out of laboratory"
.Rudolf
2-speaker stereo outside.
What is everybody else's experience? Is there a real sense of spaciousness under free field conditions with 2-speaker stereo (I'm NOT talking about live events)?
I have to admit it's been a long time when I dragged my speakers outside. From what I remember the image was pin-point but extremely near to my head, nearly headphone-like.
I get the same sensation with very high directivity speakers in a highly damped room.
So my conclusion is that stereo isn't capable of delivering a realistic sense of spaciousness where instruments seem to occupy a physical space in front of the listener. That has to be added in an additional effort.
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Really? Because you hold the truth? What you state is only true for very dry recordings, which sound awful anyway. As soon as there is some reverb, or spaciousness in the recording, the room is a carrier, not an offender, as long as we are not talking of bare walls and RT of a second or such. But hey, you must be one of these persons listening to "points" in space, not music..
the weather has been awful here every weekends..
logics, only logics.. music should come from everywhere, not only from two points in a room. unless we are talking ambiophonics here?