We both know from experience that one can get both, and that those "horrible" front wall reflections not only don't eat babies but they don't compromise "clarity" or "timber" either. We also know that it's difficult to explain that to someone who listens to ray diagrams and impulse charts that don't much, if at all, reflect what happens in real rooms. Of course our experience also comes from "point source" dipoles in adequate spaces rather than "planar" dipoles (with their myriad other problems) in too-small spaces. That may make some difference . . .
We seat antiphonal, which makes it (a bit) easier. Up close, anyway, or outdoors. It's still sometimes difficult "out in the hall" . . .Maybe when you go at the hall, you can pinpoint the 1st and 2nd violins from the string section..
Sitting one meter from the frontwall? That's not a potential situation. I don't know if what you're saying is correct either.
Anyway, I've the speakers and listening postion very close to the frontwall and I have measured with and without absorption. The reflections are attenuated in the area of -20/-25 dB with no treatment.
I meant that the speakers are less than 1 meter from the front wall with a listening distance of, let's say, 3 meters from the speakers. A narrow baffled speaker would be nearly omnidirectional in the lower midrange, so one could expect irregularities between 5 and 10 dB due to constructive and destructive interference.
I believe your assumption is wrong. A tall CBT will not become omni that early. But that's something Don Keele would have to confirm. The polar I presented was of a small prototype by the way.
Other designs will however become omni quite early.
The room will of course decide where the schoeder frequency is. I don't believe in controlled directivity in the modal region.
I would be interested in listening to a pair of CBT's. To my understanding and experience, more drivers used always sort of makes the sound fuzzier, and is only a matter of what part of the music it is more pronounced at which involved what spectrum each driver covers. The same happens when you operate in the modal range of diaphragms.
I have always found more quiet and non-reflective rooms to reveal the original ambiance of the recording much better. Of course, if you record in a pretty dead room, the you sort of can use the listening room to create the room ambiance you want. It just seems like two difference approaches. The problem comes when you listen to live performance recordings in a room designed to create certain ambiance characteristics, or when you listening to a dead studio recording in a dead room. This is when you get the worst of both worlds regardless what kind of speakers you have.
I have always found more quiet and non-reflective rooms to reveal the original ambiance of the recording much better. Of course, if you record in a pretty dead room, the you sort of can use the listening room to create the room ambiance you want. It just seems like two difference approaches. The problem comes when you listen to live performance recordings in a room designed to create certain ambiance characteristics, or when you listening to a dead studio recording in a dead room. This is when you get the worst of both worlds regardless what kind of speakers you have.
You see it the same way that I do - do what works for the least cost and effort.
I have done designs with narrow vertical response and fairly narrow horizontal, its not impossible, but they get very big and are hard to make. treating the room for the vertical is far more effective and practical.
Isn't it difficult to generalize on the merits of a particular technology with data from specific examples. I mean the dipoles could be poorly designed, or the narrow directivity design is poor. You simply cannot generalize the technology based on specific examples of a design - there are too many confounding variables.
I have found and agree with Toole that the wall behind the speakers should be well damped. This is the only damping in my rooms at all, except for a small patch on the floor between the speakers and the listener.
This is consistent with what I heard when I auditioned the CBTs. In a lot of respects they're virtually the opposite of my Summas. Instead of a big dynamic sound, they're very diffuse.
If I had to guess, I think that this is related to their behavior in the time domain. For instance, picture a big drum hit that's produced by a Gedlee Summa. In the time domain, you're going to see a big 'spike', with a quick decay. The CBT won't have this; by creating the 'spike' with thirty six drivers, the 'spike' in the time domain is going to be 'smeared' over time. I think this has the effect of dampening dynamics, IMHO.
I really really wanted to like the CBTs, and it was the ONE speaker that I went to CES to hear. (If you don't believe me, just email the people at Parts Express, I was practically hounding them to get a demo, because they kept doing meetings in their exhibition room, precluding the demo.)
But I couldn't live with that type of speaker; I'll take my Summa over it any day. Obviously, this is a subjective opinion and some may find the assets of the CBT to appeal to their room or their listening preferences.
An Open Letter
Continuing on with the original topic of this thread, I have decided to issue an open letter to Linkwitz Labs addressing the discrepancies between AES Convention Paper 7959 and Paper 8307.
I will be returning this letter, along with all of my construction manuals, directly to Linkwitz Labs. A redacted version (addresses and contact information) of the letter has been posted publicly on my Google Drive.
I sincerely hope that this message is considered on topic.
Continuing on with the original topic of this thread, I have decided to issue an open letter to Linkwitz Labs addressing the discrepancies between AES Convention Paper 7959 and Paper 8307.
I will be returning this letter, along with all of my construction manuals, directly to Linkwitz Labs. A redacted version (addresses and contact information) of the letter has been posted publicly on my Google Drive.
I sincerely hope that this message is considered on topic.
I do not recall whether I have this these papers or not, but I have to agree that the speakers can disappear. However, the system needs to be considered as whole, and every link counts. You never know what is preventing such experienced unless you have taken care to look into the VERY detail, which is pretty much beyond the capability of most DIYers. Lot's of things probably would not be accepted by many professionals simply because of the education process, for example, the concept of circuit ground. When you start connecting all equipment together, you quickly find that there are ground loops, and although you do not hear hum, current do flow interactively throughout the connections, and do degrade sound.
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I know this is not a CBT thread, but I want to comment this.
The dynamics of the CBTs are encredible. Subjectively, much better then Abbey. The CBTs tolerate very high peaks.
You cannot dismiss a speaker based simply on an experience from a show. Gedlee speakers have also received poor reviews from demos like that. But the fact is that they are both great speakers.
There's absolutely no truth to the fact that the sound is smearing with a proper setup CBTs. They are crystal clear whith an amazing openness. This isn't simply a speaker with many stacked drivers. If that was the case, what you said would be true. The speaker looks great in the time domain.
I do believe I can say this, since I after all have both speakers in position. I have done measurements too of course.
With all due respect, many of you do not seem to understand the importance of a uniform response over a broad passband, and think that a speaker this is beaming is without flaws. You are overly concern with some sidewall reflections while you overlook the coloration it brings. A speaker that is beaming and has a polar that is collapsing is in totally need of broadband treatment to sound correct. Both at sidewalls and at the ceiling!
Having heard the Geddes, the CBT and the Danley horns (even once the CBT and Synergy in the same room) I have to say that the horn designs still take the dynamics trophy, by far. They also take the sustained clean high volume prize.
I don't think that's a fault of the CBT concept, but of the driver and passive shading used in the present CBT build. It still plays very loud, tho, and is more dynamic than many other speakers.
I don't think that's a fault of the CBT concept, but of the driver and passive shading used in the present CBT build. It still plays very loud, tho, and is more dynamic than many other speakers.
Sounds like alot of people need to get out and build some speakers...
CBT is nothing more than a curved linesource, the first one i heard was back in the eighties, curved like the letter C towards the listener as opposed to curving away from the listener as the ones I'm seeing today, the issues they represent are immense, IMO a flat linesource with correct height to width dimension is superior.
CBT is nothing more than a curved linesource, the first one i heard was back in the eighties, curved like the letter C towards the listener as opposed to curving away from the listener as the ones I'm seeing today, the issues they represent are immense, IMO a flat linesource with correct height to width dimension is superior.
I would expect loud , i would expect dynamic if done right , i would also expect alot of smearing , has anyone post impulse or step response on the CBT
My home theatre speakers are not true CBTs. The outer 6 drivers have the most restricted bandwidth (and largely make up diffraction loss), the center three have more extended bandwidth (to about 6 khz), and only the center driver extends full bandwidth (to approximately 20khz). I wanted a vertically spread out 'sound' to match my large screen TV, but didn't want to have strobing effects or exaggerated floor or ceiling cancellation effects.
There's something about the sound of 72 Lexicon style 3 1/2" drivers all pumping from 8 channels at the same time
There's something about the sound of 72 Lexicon style 3 1/2" drivers all pumping from 8 channels at the same time
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Those two measurements are horrific on a straight array. I've done measurements on mine.