this far from the front-wall and next to side-walls positioning is quite similar to Beveridge placement only Beveridge means that the speakers are effectively integrated into side-walls so there is no 1st order ipsilateral reflection at all
Well, to go back to this...
For comfortable conversation as well as listening to music a room should have adequate damping. Neither too little nor too much. Reverberation time should be around 400 ms.
Wide dispersion speakers, in my experience, tend to overload a room quickly if it's too live. If treatment of the room is not an option, then a narrow directivity speaker can help, especially for better tolerance of higher playback levels and music with lots of mid/high frequency energy, such as pianos.
that is also my experience
I think that thicker carpet, thicker curtains, softer upholstery and some bigger plants in the corners rarely are unnegotiably "not an option"
I believe that a serious "decor" advantage of wide uniform dispersion is that such speakers need only a matching average absorption coefficient of the room - not any special treatments of areas of 1st order reflections
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There are some "if" and "when" to consider when making such a bold statement. http://www2.pa.msu.edu/acoustics/rooms2.pdf gives a nice summary, how things change under different experiment conditions.
CBT speaker? the one that requires 36 midwoofers, and 144 tweeters and some superhuman woodworking skills? indeed very practical, especially DIY-wise
and what is the horizontal directivity of it? No side wall treatments are necessary really?
less treatment with a CD waveguides? Gedlee uses a lot of treatment in His room IIRC
You mean anechoic or quasi-anechoic in room?
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You can buy a kit from partsexpress and only sanding and finish needs to be applied. A car garage could take care of that for you. Drivers needs to be assembled and you need to solder quite a bit.CBT speaker? the one that requires 36 midwoofers, and 144 tweeters and some superhuman woodworking skills? indeed very practical, especially DIY-wise
They do have controlled horizontal directivity. They disperse more then a waveguide in the horizontal, but have no collapsing polar response.
Unless you want lateral contribution, sidewalls needs to be treated some. Not much more then waveguide/horn though if they are toed in.
Since they don't need any treatment on the floor or ceiling however, you end up with a total of less treatment. And if you can't treat the room, some sidewall reflections (with very little coloration) would be better in most cases then a waveguide/horn that will not sound that good without vertical treatment. You were the one referring to Toole, weren't you?
I mean generally. Even in a small and narrow room with little or no treatment. The CBT is flatter.
To me it looks like waveguide/horn are basically dead in regards to sound quality with the introduction of CBT. The advantage I see with horns are more output. Which may be of course needed for concerts and such, but not in a home.
The CBT is a nice speaker but it's complex, expensive, 1,5 meters tall and not really visually attractive. It will also need to be at least 1 meter away from the front wall (and probably more, with such a narrow baffle and high baffle step frequency). Horizontal directivity may be reasonably smooth but not state of the art since it will have lots of diffraction problems. A waveguide speaker will have less diffraction and thus a smoother frequency response and smoother horizontal directivity.
The CBT addresses some problems but still has some issues of its own.
The CBT addresses some problems but still has some issues of its own.
From that paper:
"It is almost impossible to localize a tone in a room in the absence of transients because he ongoing sound field provides no reliable information concerning the source location."
"transients" = frequencies > 700 Hz.
I can't comment to depth, but I believe you're mistaken.
First of all it's not expensive if you buy the kit and build it yourself. A complete kit costs $2000.
Looks are a matter of taste but personally I think a slim and tall speaker looks better then a very wide speaker.
I don't think they need much distance to frontwall and I'm quite sure you're mistaken about diffraction problems. And I can assure you that the frecuency response is more even then a waveguide speaker. I have compared.
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This is simply not true. They have a finite width and the polar pattern will collapse according to this width. The idea is to keep this width as small as possible such that the collapse is out of band. But that leaves a 360 degree horizontal pattern which is not at all what one wants. "No directivity" is not "controlled directivity" So they do not have a "controlled horizontal directivity" anymore than any small omni speaker does. "Controlled" means something less than 180 degrees. They are "constant horizontal directivity" in the same sense that as any monopole.
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That's not correct! It's a_tewinkel, actually
.I thought I'd join Markus in correcting your spelling. Just kidding of course.
Earl, why do you say "transients" = frequencies > 700 Hz?
They are not omnis. We also need to remember that the full range horizontal disperson will result in lateral reflections that are more nearly identical to the direct sound, thus resulting in less superpositionally created coloration.
Whether one wants to deal with sidewall reflections or not depends if one desires best imaging or more spaciousness. And it doesn't take much treatment on sidewalls anyway. I know this from experience. It's easier with overall treatment with the CBTs then it is with a waveguide/horn speaker.
When it comes to diffractal problems, all I can say is that I've seen the impulse response and it was very clean. But obviously someone would have to measure both and compare. Maybe a waveguide is better in this regard, I don't know.
Here are some comments by Don Keele.
An externally hosted image should be here but it was not working when we last tested it.
With a good waveguide speaker, the only treatment necessary may be a thick carpet to reduce the floor reflection. Sidewall reflections will be below the image shift threshold and the front wall reflection will also be minimal to non-existent.
I'd rather have relatively compact speaker and a thick carpet than a tall CBT and absorbers on the side walls, for aesthetic reasons.
yeah, not sure you can say that those huge 2K accidents waiting to happen could possibly displace all WG speakers and make them a thing of the past (stability doesnt look too flash, one bump from a dog...). Given CD based WG tech has penetration at all levels these days, they are not going away any time soon. these things will never get that kind of acceptance, WAF is also exceedingly low
You will need treatment of the ceiling as well with a waveguide. They don't measure that well vertically. And in most cases you need to treat the opposite sidewall reflection. The only difference with the sidewalls is that you need to treat the mirror image of the closest speaker with the CBTs. I haven't seen anything that indicates need for absorption on the front wall. Of course other then bass, but that's the case with all speakers.
I've never encountered a speaker that is so easy when it comes to treatment as CBTs. I have and have had both waveguide and cardoide speakers and they needed more treatment.
And like mentioned before, the reflected energy is closer to the direct signal with CBT speakers. So you have less coloration. CBTs are the first speakers I've heard that still sounded good with sidewall reflections. I still prefer treating them for a sharper image, but I could live ok without it. This has not been the case with neither waveguide speakers or others.
You know, CBT speakers take up less space on the floor as well. I think mine look good, but we may have different taste. I have wide and big waveguides too and they much more obtrusive looking. Perhaps more masculine though, haha.
So no bias here for your "new" speakers.
I have yet to see a good presentation of the CBT frequency response, ala a polar map, to see how well they actually do what's claimed. Don's discussion is theoretical not real data. Shaded curved line arrays are far from new, why all-of-a-sudden are they of such interest?
If you toe-in the speakers, yes. If you do not, this is not a problem because of the directivity.
The CBT, with its narrow, closed baffle will radiate lots of sound towards the front wall. That will either require damping or moving the speakers away from the wall to improve imaging and reducing colouration (also see "Sound Reproduction" by Toole). A good wide-baffled speaker or gradient source can minimize this, making treatment or lots of space behind the speaker unnecessary.
A good waveguide speaker with a gradient mid/woofer can have far better constant directivity in the horizontal plane than a closed baffle CBT with it's baffle step and diffraction problems.
The largest advantage I see for a CBT is the reduced floor and ceiling reflection. In the Bech study, using a standard, moderately wide dispersing KEF loudspeaker, only the floor reflection proved to be a problem. The simulated floor was rather reflective and detection was mainly based upon the 500-2000 Hz range, so a thick carpet would probably fix this. A moderately directional waveguide speaker may also (partly) alleviate this problem. Note that the ceiling reflection did not cause colouration with the simulated speaker (although it did with a simulated cardioid); moderate vertical directivity would thus probably eliminate colouration from the ceiling reflection. However, the simulated speaker was rather far away from the front and side wall. Especially the former is an important factor in colouration and bad (mid)bass performance and therefore would have priority to address, for me.
All things considered, I think a well engineered waveguide speaker will perform better with minimal treatment when space is an issue. If you have lots of space around the speaker, a CBT may be a better choice. You may disagree, of course. It will certainly depend on room size and possibly on personal preference.
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