I am willing to be that that speaker manufacturer was not manufacturing planar dipoles.
If I were actually building a new room from scratch, and space and cost were not relevant, I would use golden ratio dimensions of about 25' wide and 40' long; the front and rear walls would be parallel; the side walls would form gentle convex ovals, and the ceiling would incline. It goes against the golden ratio calculation but, subjectively, I have always liked the "sound" of high ceilings (it seems somehow to have the acoustic effect of allowing the system to "breathe" bretter).
Symmetry is a mixed blessing. It can help ensure predictable pressurization (low freq), matching L/R levels and more accurate spacial cues in all dimensions but it can also result in nasty room modes especially at lower frequencies (as we all know). The trick IMO is to employ symmetry for key reflection points for mids / highs implemented via treatment (diffusion preferably) augmented with low freq diffusion (often employed non - symmetrically) and / or absorption + subs (DSP can help, but for me its detriment outweighed the benefits). Unless you have a very large room, there is no other way IME.
This is such a simple point and you guys keep talking past each other. sbo6: Which walls are you intending to be talking about when you write "symmetry is a mixed blessing"?
Symmetry of front and rear walls is not a mixed blessing (it is a complete blessing, in my opinion).
Who advocates asymmetrical front and real walls as being good acoustically?
Does one absolutely need a dedicated room for reference-level sound? How close can one get to the ultimate potential of their system if they are not fortunate enough to have a dedicated room?
It is amazing how quickly these discussions can get away from the OP. I assume the was talking trying to get reference level sound from say the family entertainment room A shared space that has to accommodate AV,WAF and limited options for speaker placement. Indeed room treatment may totally violate WAF. in some cases asymmetry may actually be a benefit.
Yes Ron a trapezoid may actually have two parallel sides.
This is such a simple point and you guys keep talking past each other. sbo6: Which walls are you intending to be talking about when you write "symmetry is a mixed blessing"?
Symmetry of front and rear walls is not a mixed blessing (it is a complete blessing, in my opinion).
Who advocates asymmetrical front and real walls as being good acoustically?
It's not that the point is simple - it's multi - faceted and depends on symmetry to do what? sound staging / cues? bass response?
In general, any and all walls with symmetry (parallel let's say) ensure equal amplitude across the mid and high frequencies assuming mirror image treatment for L and R walls but also is important for front and back walls. Parallel wall symmetry for bass is bad, again, unless your room is quite large.
The most symmetric room possible is either a cube or a sphere and neither of these would result in a good sounding listening room. The cube would be horrible as it would have standing wave nodes and peaks.
I think the point Mike is making is that the room should be symmetrical. Of course a sphere or cube would be bad, but a rectangle would be better. Another advantage of a symmetrical room is that it is easier for the acoustician to calculate room nodes, peaks and nulls for proper placement and design of room treatments. It is much more of a crap shoot to treat an asymmetrical room. Of course, good sound can be heard in many different scenarios, but the question here is "reference-level-sound", which still has not been defined by the OP.
With the right speakers with the right dispersion pattern, one can achieve reference SQ in a non-optimal room, but probably only optimal for a smaller sweet-spot. If you are okay with that, then go for it. Acoustic treatments for the first sidewall HF reflections and some kind of scattering diffuser between and behind the speakers will usually do the trick. If this was not possible, you would never hear anything decent at hotel shows. I am usually able to get excellent width, depth and focus by using two tube-traps and a couple of Sonex panels in a hotel room. This will not deal with the room bass resonances, but if you can angle the speakers in the space, this will mostly take care of that.
Another option is to use dipole radiating speakers like full-range ribbons. These disperse so evenly that a pretty good image can be achieved almost everywhere in the room.
With the right speakers with the right dispersion pattern, one can achieve reference SQ in a non-optimal room, but probably only optimal for a smaller sweet-spot. If you are okay with that, then go for it.
Another option is to use dipole radiating speakers like full-range ribbons. These disperse so evenly that a pretty good image can be achieved almost everywhere in the room.
Why can’t dynamic cone speakers dispersion pattern disperse evenly? They can and if they disappear then they can be improved tremendously. Throwing a holographic and multi dimensional image is very possible,making the room seem to be non existent. That should be the goal first. If that is achieved then the sweet spot expands to a point that in good recordings is much less of a factor.
Why can’t dynamic cone speakers dispersion pattern disperse evenly? They can and if they disappear then they can be improved tremendously. Throwing a holographic and multi dimensional image is very possible,making the room seem to be non existent. That should be the goal first. If that is achieved then the sweet spot expands to a point that in good recordings is much less of a factor.
The problem with a wide dispersion speaker, even if that dispersion is completely equal at all frequencies, is that you are at the mercy of the reflective surfaces for what frequencies come off that surface. In effect your walls, floor and ceiling become frequency filters.
A speaker with a well controlled dispersion, like a line source dipole minimizes floor and ceiling reflections and virtually eliminates the first sidewall reflection. You do get a back wall (behind the speaker) reflection that is mostly perceived as an increase in spaciousness. Horns will also have controlled directivity and this can allow them to fit ok in a room where a wide dispersion speaker would be a disaster.
It is possible to build direct radiating speakers with controlled directivity. Legacy Audio does just this in models like the Whisper, which would probably excel in a "tough" room.
With the right speakers with the right dispersion pattern, one can achieve reference SQ in a non-optimal room, but probably only optimal for a smaller sweet-spot. If you are okay with that, then go for it. Acoustic treatments for the first sidewall HF reflections and some kind of scattering diffuser between and behind the speakers will usually do the trick. If this was not possible, you would never hear anything decent at hotel shows. I am usually able to get excellent width, depth and focus by using two tube-traps and a couple of Sonex panels in a hotel room. This will not deal with the room bass resonances, but if you can angle the speakers in the space, this will mostly take care of that.
Another option is to use dipole radiating speakers like full-range ribbons. These disperse so evenly that a pretty good image can be achieved almost everywhere in the room.
. . . A speaker with a well controlled dispersion, like a line source dipole minimizes floor and ceiling reflections and virtually eliminates the first sidewall reflection. You do get a back wall (behind the speaker) reflection that is mostly perceived as an increase in spaciousness. . . .
Why not a curved wall behind the speakers? I would think a convex wall would have some potential advantages. Minimizing standing waves (the biggest problem I have found in most rooms are bass issues) should be a top priority.
One can also eliminate too much symmetry with a slanted ceiling. In my listening room, which is otherwise small and rectangular, I have a sloped ceiling that goes from over 4 meters high at the highest point down to only about 80 cm at the shortest. The ceiling is wood beams and probably has some natural diffusion power in addition to breaking up a lot of standing waves. When you couple this with a relatively narrow dispersion speaker, carefully placed and toed-in, and I get sound without most of the issues one might expect putting a speaker that size in a room that small (about 18 square meters).
My previous apartment (actually 3 apartments ago but the last time I had a dedicated space) was basically a rectangular room with a 2.4 meter high ceiling; however, the room walls, floor and ceiling were all concrete and with Dipole electrostats the sound was very good in that room other than bass mode issues. I had a large hump at 62Hz that I tamed, in digital only, with a digital equalizer sucking that down by 8db or so. From 200hz to 14Khz I was flat, in-room, +-2db, with a gentle downward curve from there (about -2-3db at 20Khz). This is actually pretty normal for a speaker with controlled directivity. Actually though, the room had a very small dog-leg on the righ side where the speakers were set up. Did this help or hurt? Probably neither with the figure 8 dispersion pattern of a dipole. I got pretty much reference sound from that room ONCE I went with dipole speakers. Before dipoles the sound was so-so and probably needed more treatment than I was willing to go with. With tall dipole speakers (starting with AudioStatic RS100s then Infinity IRS Betas, then Apogee Caliper signatures, then Acoustat 1+1 and STAX ELS-F81, then finally Acoustat Spectra 2200 and 4400) most of those problems evaporated and I got intense 3d imaging and huge soundstage...also heavily electronics dependent.
In an apartment in between then and now I was unable to get really good sound from a pair of Genesis VI, which when I once took them to a friend's dedicated room, sounded phenomenal, and I almost regretted selling them...almost. That is the most fullrange mid-size speaker I have ever heard... 3 active woofers made it so.
Why can’t dynamic cone speakers dispersion pattern disperse evenly? They can and if they disappear then they can be improved tremendously. Throwing a holographic and multi dimensional image is very possible,making the room seem to be non existent. That should be the goal first. If that is achieved then the sweet spot expands to a point that in good recordings is much less of a factor.
Maybe with line sources, but most cone drivers do not disperse that well. Physics.
Some rooms do not respond well to wide polar responses because of reflective surfaces like floor to ceiling windows. For these rooms, the small sweet spot is probably more optimum.
I am willing to be that that speaker manufacturer was not manufacturing planar dipoles.
If I were actually building a new room from scratch, and space and cost were not relevant, I would use golden ratio dimensions of about 25' wide and 40' long; the front and rear walls would be parallel; the side walls would form gentle convex ovals, and the ceiling would incline. It goes against the golden ratio calculation but, subjectively, I have always liked the "sound" of high ceilings (it seems somehow to have the acoustic effect of allowing the system to "breathe" bretter).
Hi Ron, does my room fit the majority of your "likes" here?
18' wide, 38' deep one half, 48' deep the other half (to incl the 10' deep alcove), not quite a curved ceiling, but eaves at 30°.
Despite my curiosity in treating it, so much feels (sounds) "right" in its basic state.
Brad, I've had so many comments that my sloping eaves by definition cannot be anything other than a negative, and yet nothing further from the truth.
Now you mention yr ceiling has beams that break up standing waves, and that's precisely what I have, in effect 9" deep steels at 6' centres, meaning a half dozen members acting to obviate nodes.
I'm sure this is why my eaves aren't the issue one would think they'd be in principle.
