That's an easy fix for high frequency problems but I think lower frequency problems are way more severe and hard to fix.
Not everybody has a highly damped room at lower frequencies like you do. In fact most people don't and there's also no practical way for them to change anything other than searching for a different solution.
Markus
What does that have to do with my comment? I didn't even think that we were talking about damping the front wall (thats not what I was refering to), but about the importance of directivity control below 500 Hz.
All I am saying about the front wall is the more its damped the better. If you can't do it you can't do it. I also completly agree that if you can't dampen it then you should be able to diffuse it. But I, again in agreement with Toole, do not see any reflections coming from behind the speakers as advantageous. Certainly directivity helps. But there are not too many feasible directivity controls for below 500 Hz., so good luck with that.
What does that have to do with my comment? I didn't even think that we were talking about damping the front wall (thats not what I was refering to), but about the importance of directivity control below 500 Hz.
All I am saying about the front wall is the more its damped the better. If you can't do it you can't do it. I also completly agree that if you can't dampen it then you should be able to diffuse it. But I, again in agreement with Toole, do not see any reflections coming from behind the speakers as advantageous. Certainly directivity helps. But there are not too many feasible directivity controls for below 500 Hz., so good luck with that.
"Way more severe"? Markus really? Hard to fix yes, but "way more severe". I don't buy it.
How many here have actually heard a speaker with directivity down to 200 or 300 Hz? I have and it makes a profound difference in imaging and localization. Talking about Pano's VOTT system. I wouldn't mind betting on this increased directivity in the nether regions being the main reason why Tom's horns image so well.
So, hard to achieve? Yes. Does it improve localization? Yes.
Again, this is law of small numbers, so I need to be careful (Thanks to the doc for recommending the book).
So, hard to achieve? Yes. Does it improve localization? Yes.
Again, this is law of small numbers, so I need to be careful (Thanks to the doc for recommending the book).
The VOTT may image very well. How do you know that it is the 200-300 Hz range that accounts for that? There are way to many variables to draw such a conclusion. And I am not sure how much directivity effect the small waveguide would actually have over a direct radiating 15" speaker. I'd like to actually see some data. Many have said that my speakers image exceedingly well and they have no big directivity control at 200 Hz. All of these speakers have "good" directivity control where it counts and this is the difference, not 200-300 Hz.
I'm not sure what your specific problems are. What range is "lower"? And do those lower frequency problems affect the spatial or the tonal qualities in your room?
The opposing walls in my room are hard/soft in both directions: Front wall is drywall, rear wall is brick (with a wall high diffusing storage rack in front of it). Left side wall is drywall with a large window, right side wall is plastered brick again. I have no big issues with reverberation time or room modes above 50 Hz.
Rudolf
You've set the marker at 1kHz, so I was talking about anything below. And yes, lower frequency problems do affect spatial and tonal qualities.
Could you post a in-room IR from your listening position as a sound file?
I have to admit that his conclusions are the exact opposite of what I think. I'd have to read more about his experiment to make sure that I agreed with it. It is very easy to miss a confounding variable in tests like this end up with a null experiment (kind of like the one referenced in this thread.) It seems surprising that in the ten years since this was published that it has not been widely quoted or replicated. Normally such a radical departure is either quickly supported, or something went wrong and others just let it lie.
Have there been any follow-up studies that confirm his conclusions?
WAV, ASCII or CSV format?
Microphone vertical or horizontal (my calibration is for 0° only)?
One speaker, both speakers together and/or each speaker?
Rudolf
It would seem rather intuitively that as frequency rises directivity and the ability to localize sounds increases. As we go lower into the band room modes are going to contribute much more in a steady state condition no matter what room treatment you may use in a normally constructed home situation. Now in a large space, an auditorium or concert venue things are much easier to manipulate when it comes to directivity, dynamic response and other issues if these are originally considered in the construction of the space. Now when it comes to a loudspeaker alone in a room we again have limitation of what will normally be acceptable. Most of us are not going to have large bass horns in rooms, anything that is going to control wavelengths down below 200hz is just to large typically unless you have a man cave or such. So we are really stuck with control above these frequencies at best. I agree that a horn loaded system will always be the easiest type reproducer to control dispersion into the room, but then you will have much stronger rear wall reflection and depending on the depth vs width of the room this can be a fairly short time frame or in a larger room of say 25 foot depth a longer reflective time that we would probably discount. Again, are we only to look at directivity as regards the term dynamic response, or do we have to look at the overall combined room response across the entire bandwidth of the devices in question. I guess if you had an omni directional device places very close to the front wall or even in the corners that would be another case. There are just so many variables here, it seems you really have to chose two real models to have any real discussion of the differences rather than whole categories that have so much variation in implementation.
Do you believe that the perception would turn into something completely opposite like day to night when we add few reflections ?
The room influences frequencies below 1kHz much more than freqs above 1kHz. Also the perception below 1kHz is influenced more by the room response.
It does not make sense to neglect this and focus only on the remainder high freqs that are being left mocked more gently by the room. I think correct first thing to do is to avoid room reflections influencing the precious freqs below 1kHz in the first place.
By the way, I think Toole is a rather bad reference here because while he talks about room reflections a lot in his book he does not make any differentiation between frequencies of those reflections and what perceptual effects different freq bands may have. His comments on room reflections are way too general to draw any conclusions.
- Elias
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To get over this conventional blockage of thinking, one must understand the music signal in the room is not in a steady state. The envelope is not constant. Music is dynamic process, constantly chancing.
ITD perception is a possible below 1kHz, since the leading part of each tone/note/sound carries the information for ITD to be extracted.
More directional speakers below 1kHz allow longer part of each tone to reach to the listening position before reflections arrive. It is clear that more directional speakers at low-mid freqs are desirable for improved stereo reproduction.
- Elias
No, steady state has nothing to do with it. The phase of the signal changes as soon as a reflection gets summed on it, from the very beginning the phase start to shift. This phase shift causes ITD to be what ever.
Exactly but that is a steady state process. Wavelengths are largish, direct sound and reflections superimpose which shifts phase hence interchannel time differences change from what can be found on the recording.
Elias,
The question in my eye is whether the reflections actually cause a phase shift at all or if this is just a complex overlay of one signal on top of the other? Why would the delayed signal shift the original, why would it not just add a second source as all music does with complex signal?
The question in my eye is whether the reflections actually cause a phase shift at all or if this is just a complex overlay of one signal on top of the other? Why would the delayed signal shift the original, why would it not just add a second source as all music does with complex signal?
Left speaker from listening position microphone horizontal:
www.dipolplus.de/assets2/Hoerp_links_waag.wav
Left speaker from listening position microphone vertical:
www.dipolplus.de/assets2/Hoerpl_links_senk.wav
Have fun
Rudolf