I have of pair of 2-way speakers, Jeff Bagby's Piccolos, on stands in a rather small room. They are set up in a near field arrangment in a roughly 6.5' equilateral triangle with my seating position. And I have been very pleased with the result. Excellent imaging and sound quality. Particularly with orchestras and opera. I can tell rather well where instruments and singers are located on the stage. There is a sense of 3 dimensional space.
Up to now the speakers have been located about 3 feet from the front wall and there has been nothing between them or on that wall at all. Just emptly space.
Now to please my wife I moved the equipment cabinet from where is was on a side wall to the front wall and centered between the speakers.
And I think that now I perceive a significant difference in the sound field with the equipment cabinet filling that previously empty space.
But before actually stating what that difference is I would like to ask for opinions on what to expect. In brief, if there is nothing on the front wall between the speakers and now you add a 3' high by 2' wide by 2' deep equipment cabinet what , if any, difference would you expect to hear.
Up to now the speakers have been located about 3 feet from the front wall and there has been nothing between them or on that wall at all. Just emptly space.
Now to please my wife I moved the equipment cabinet from where is was on a side wall to the front wall and centered between the speakers.
And I think that now I perceive a significant difference in the sound field with the equipment cabinet filling that previously empty space.
But before actually stating what that difference is I would like to ask for opinions on what to expect. In brief, if there is nothing on the front wall between the speakers and now you add a 3' high by 2' wide by 2' deep equipment cabinet what , if any, difference would you expect to hear.
Hi,
I've just experimented with controlled directivity speaker toe in few days ago. The speakers have rather high DI down to schroeder so I can reduce front wall reflection with toe-in, I've got television and other objects between the speakers. Initially I had great toe-in of 45 degrees the sound seemed fine, was experimenting with other perceived stuff so didn't pay particular attention to this.
However, when I toed the speakers out more, now perhaps only 30 degree toe-in or there abouts, I noticed peculiar thing happen. Phantom center suddenly got more height to it, high frequencies appear much higher up now, above the speaker height. What I think happens is that when there is objects in between the speakers and enough SPL is radiated towards it, ear can kind of detect and locate the phantom center to the stuff causing reflections. Now when the reflections are low enough in level brain has to figure out the direction to sound and best guess it can do is assume it to come from above as "there is nothing on the front".
Of course its all speculation but makes sense to me currently with the knowledge I have. Also side wall reflection intensity changes with toe-in but I'm quite sure it they would change apparent height, only width. Still, it could be this and not front wall, or mix of things. Anyway, something to listen to if you experiment with it, phantom center perceived "height" is what I noticed, perhaps its height for the whole sound stage. Brain making more of an illusion due to lack of physical location cues.
I've just experimented with controlled directivity speaker toe in few days ago. The speakers have rather high DI down to schroeder so I can reduce front wall reflection with toe-in, I've got television and other objects between the speakers. Initially I had great toe-in of 45 degrees the sound seemed fine, was experimenting with other perceived stuff so didn't pay particular attention to this.
However, when I toed the speakers out more, now perhaps only 30 degree toe-in or there abouts, I noticed peculiar thing happen. Phantom center suddenly got more height to it, high frequencies appear much higher up now, above the speaker height. What I think happens is that when there is objects in between the speakers and enough SPL is radiated towards it, ear can kind of detect and locate the phantom center to the stuff causing reflections. Now when the reflections are low enough in level brain has to figure out the direction to sound and best guess it can do is assume it to come from above as "there is nothing on the front".
Of course its all speculation but makes sense to me currently with the knowledge I have. Also side wall reflection intensity changes with toe-in but I'm quite sure it they would change apparent height, only width. Still, it could be this and not front wall, or mix of things. Anyway, something to listen to if you experiment with it, phantom center perceived "height" is what I noticed, perhaps its height for the whole sound stage. Brain making more of an illusion due to lack of physical location cues.
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It seems incredible to me, but I also have not only the system under the TV like so many others, but also a glass box (110x90x50cm) that "contains" my system (really, covers it) exactly at the center of the loudspeakers.
A few years ago, now I don't remember how many, I had a fairly different system, but the same loudspeakers that were positioned in a "slight" different way (I don't remember exactly how).
Well, in that particular positioning that I don't remember exactly how, but I remember exactly how the sound came out of them, then the voice of the singer of a certain track (and many others too) that I listen very often came from above which higher cannot be, I mean from above a lot and a lot to the left and the guitar from above a lot and a lot on the right just as if it had been listening to them in a cathedral (this is also a feeling that I remember very well).
I was no longer able to get that particular sound-image-effect and I always wondered what could have produced it.
Maybe thanks to your reply I've a significant clue to investigate and to experiment. Thank you very much!
I once had a 4' fish tank between a pair of conventional floorstanding box speakers and when I moved it, I could hear the absence of the 'shadow' of the tank, like an audible silouhette. It wasn't that it was objectionable, I was surprised that I could clearly hear it enough to 'see' it in my mind.
Also on the reflectivity of glass - https://www.diyaudio.com/community/threads/setting-up-the-nathan-10.130494/post-2477994
Thinking out loud there is another thing that happens with toe-in what could explain the perceived height. Reflection through ceiling (and floor) gets less or more highs depending toe-in. This vertical early reflection path is between me and speaker irrespective of speaker toe-in. What great toe-in does the top end rolls of to diagonal angles some, less high frequencies towards ceiling. Well, also just speculation at this point. Anyway
Nice report of a really singular experience!
Instead, it happened to me that I had to move the box and therefore place it a bit more advanced towards my listening point (so towards the center of the room) and at a distracted listening it seemed to me that it could hear a better arrangement of the "sound objects" inside the sound-scene...
Really I never poured out enough, but that feeling remained in my mind, or maybe in my body.
However I can't remove the box from the room because it is heavy and not small so I can't say about its "absence of the 'shadow'", but my guessing is that despite the opposite one could think it is not a (big) issue.
Probably my brain mapped it as part not only of the room, but also of the listening and then the resulting sound-image is very satisfactory for me (and not only for me).
Thank you for the linked page.
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I get a nice phantom center from placing my speakers close to each side of my flatscreen tv, so i would expect a cabinet might have the same effect due to diffraction (not quite as focused though)
It is a good idea to have a hard surface (e.g. wall) in between the speakers and if possible, even beyond, as this structure would (to a good extent) fix the radiation pattern to 180*, by preventing sounds from bending around the cabinets (edge diffraction). In fact, this is the basis behind the baffle wall concept often used behind cinema screens. The result is better imaging, smoother panning and louder midbass (4-6dB), that reduces amplifier power requirement, heat, distortion and cone excursion. However, in a home environment, having in-wall speakers appears to be the true solution, as baffles are usually difficult and expensive.
A TV is likely to incur a lot of vibrations (and sometimes rattling) due to the loudspeakers which, in my opinion, is not at all good for reliability of the LCD panel.
A TV is likely to incur a lot of vibrations (and sometimes rattling) due to the loudspeakers which, in my opinion, is not at all good for reliability of the LCD panel.
“ A TV is likely to incur a lot of vibrations (and sometimes rattling) due to the loudspeakers which, in my opinion, is not at all good for reliability of the LCD panel.”
Shout out for LG……..mines been rattlin’ for 3 years now! 😎
Shout out for LG……..mines been rattlin’ for 3 years now! 😎
Interesting, even if rather theoretical than very practical.
I'm not an engineer (although illo tempore I attended the 2 years preparatory to the Polytechnic Institute of my city...), but I think that the reliability of an LCD built nowadays is not affect (at all) by vibrations due to the sound of loudspeakers in the same room because their energy is not so huge as to damage it.
Certainly not as much as the vibrations and the shocks it suffers during its transport which have a different kind of energy and that are potentially much more harmful.
IMHO
This seems like a pretty good explanation for what is happening. In short, anything placed on the front wall between the speakers is going to produce edge diffraction to some extent. And an equipment cabinet can cause quite a bit of it, which in turn diffuses the image.
And that seems to be what I am experiencing. The difference, however, is much more than what I would have expected. It is rather significant and very easily heard.
Since I've just the feeling of not having fully understood your nice description would there be an image, a drawing, pics to show what Google Translate cannot explain? Thanks
I think the following should do. But this is from a cinema screen perspective.
https://blogs.qsc.com/cinema/2020/05/21/hows-and-whys-of-baffle-walls/?lang=nl
Vibrations do not kill the LCD panel instantly but mechanically stress them and this stress could accumulate to consume its useful lifetime, as these vibrations may not have been considered during the design phase.
https://focuslcds.com/journals/designing-lcds-for-use-in-high-vibration-environments/
https://blogs.qsc.com/cinema/2020/05/21/hows-and-whys-of-baffle-walls/?lang=nl
Vibrations do not kill the LCD panel instantly but mechanically stress them and this stress could accumulate to consume its useful lifetime, as these vibrations may not have been considered during the design phase.
https://focuslcds.com/journals/designing-lcds-for-use-in-high-vibration-environments/
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So I don't understand why people put disfussers on the front wall. It seems to me to be the exact opposite of what should be done if you want good imaging.
Dear classicanfan,
There are mainly two ways of dealing with the back reflections. However, for proper results these need to be done at the source, as far as possible.
1) Absorb / diffuse the back waves - This is what treatments do, as they dissipate (absorber) or spread and dissipate a little later (diffuser).
2) Project these back waves towards the front (listener) to improve efficiency - This is what baffles / baffle walls / horns do.
The latter improves efficiency by limiting the radiation angle to half-space, as opposed to the full-space radiation of a free standing speaker. Nevertheless, since the listener is seated in front of the speaker (and not the back), there seems to be no use for full-space radiation anyway, at least not for a main speaker.
To simplify things, a baffle wall may be thought of as a large horn with 180* coverage angle.
Hope that helps.
There are mainly two ways of dealing with the back reflections. However, for proper results these need to be done at the source, as far as possible.
1) Absorb / diffuse the back waves - This is what treatments do, as they dissipate (absorber) or spread and dissipate a little later (diffuser).
2) Project these back waves towards the front (listener) to improve efficiency - This is what baffles / baffle walls / horns do.
The latter improves efficiency by limiting the radiation angle to half-space, as opposed to the full-space radiation of a free standing speaker. Nevertheless, since the listener is seated in front of the speaker (and not the back), there seems to be no use for full-space radiation anyway, at least not for a main speaker.
To simplify things, a baffle wall may be thought of as a large horn with 180* coverage angle.
Hope that helps.
Yes. Better to control and/or absorb. Both make a worthwhile difference but controlling the sound is the better of the two.
It is much clearer now, thanks!
Well, no.
First of all, we should not be misleading what kind of vibrations we are referring to: perhaps we are referring to those of a Caterpillar truck on the move in a construction site?
I don't really think.
But please note that from your linked page you can read that. "Rugged LCD monitors are specialized devices designed to function in a variety of settings where harmful factors such as extreme heat or cold, dust, moisture, or water may be present. High vibration use-cases are often considered for such displays as components need to be able to withstand use in off-road vehicles, construction equipment, or wearable fitness devices."
Frankly it doesn't seem the topic we were talking about.
Also please note that a definition of vibration is "a mechanical oscillation about a fixed reference point".
But as far as I know an acoustic wave produced by loudspeakers driven by an audio system in a domestic environment propagated through the air is not able to move absolutely nothing even a sheet of paper not even a billion of a millimeter.
Please we do not mention the air that comes out of a door of a bass-reflex which is obviously a completely other story.
Different topic and concept is the resonance, but I would not like to deepen this specified topic just right now.
It would only be enough to remember that in any case a TV LCDisplay is made up of a wafer of many different matheres perfectly capable of resisting vibrations in a domestic environment and really very difficult to bring back to resonance.
No concern at all about LCD lifespan. IMO
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