Constant Beamwidth Transducer (CBT) Speakers

[j_j]

Above about 2kHz ILD ques dominate the apparent source direction.

That depends entirely on the signal. If you have a signal with a strong attack, then ITD will dominate even above 2kHz. This leads, among other things, directly to the "xylophone problem" where the attacks do not localize where the ring-notes are. With a strong attack, and then a ring, ITD rules first, then ILD. And weird away it goes.

 

[j_j]

Probably @j_j has psychoacoustically most elegant way doing it with 'THX Neural' / 'DTS Neural X', but we like some adjustability, 'season to taste' if I may.

I am not in any fashion associated with that any more. For reference, look to mixcubed.com, although the full array of tools is anything but out there yet.

 

[dannut]

I am not in any fashion associated with that any more. For reference, look to mixcubed.com, although the full array of tools is anything but out there yet.

I am seriously looking forward to the developments on that front. As I understand, it is a new, novel way of making new mixes/renders from stems. What about the vast majority of 2 channel 'pre made' recordings, that will probably never get remastered to multichannel using 'modern' techniques?

PS I apologise. Edited previous post, hope it is now factually correct.

 

[Rick Sykora]

I had enormous interest in the early days of the tech. I even bought a full set of drivers in 2009 for a DIY design I had in mind. Yes, I was excited.

But something was bugging me. I eventually realized what it was (duh, slow). The constant beamwidth is only in the vertical plane. In the horizontal plane, the beamwidth behaves just like a small 2-way turned on its side. NOT GOOD. There are good reasons why small 2-ways are designed to be used in the vertical position.

Once I realized this, I went a bit cold on the idea. I also reviewed all Keele's talks and papers to see how I missed the obvious, and you know what? It isn't very clearly stated at all, that the 'width' in the name is vertical. I think DBK is really talking to more educated professionals than typical self-taught hobbyists like me, and it probably never occurred to him how easily I (we?) could mis-read the word 'width'.

Of course with a single full-range driver for the line, instead of a separate tweeter, the horizontal interference issue is avoided, but then the CBT has horizontal dispersion the same as the single driver, ie narrowing (beaming) in the treble. That is still an issue for me.

JBL seem to have handled this conundrum best with their CBT 70J speaker, having the tweeter and woofer lines coaxial. But the 70J appears to have a lot of engineering development behind it, and I would rather just buy it than try to go a similar path with a DIY effort.

cheers

Was wondering if you have ever had the opportunity to hear CBTs?

My whole family can verify how much improved the widened sweet spot is over typical monopoles. Mine are as close the front wall as the arc allows. Couches are along the sidewalls so the speakers are closer in.

The only time the speakers have struggled to present well is in our owner bedroom. In this case, the bed blocked the lower part of the speakers. This was a temporary problem as my wife wanted them out of our family room for the holidays.

 

[Newman]

No luck so far

 

[Da cynics]

I posted it in a different thread, but this may be more appropriate・・・

DaS AuReality — 3D Loudspeaker Technology

A fully patented 3D loudspeaker technology resulted from a multi-year effort of Diffusion at Source (DaS) and elliptical soundfield speaker design approaches. DaS AuReality has evolved out of work known as “Acoustic3D” from an Australian-based company and is now being commercialized by Vastigo...

audioxpress.com

 

[j_j]

I posted it in a different thread, but this may be more appropriate・・・

DaS AuReality — 3D Loudspeaker Technology

A fully patented 3D loudspeaker technology resulted from a multi-year effort of Diffusion at Source (DaS) and elliptical soundfield speaker design approaches. DaS AuReality has evolved out of work known as “Acoustic3D” from an Australian-based company and is now being commercialized by Vastigo...

audioxpress.com

Much like these guys, I think. This is a solution to half (and only half) of the realism problem.

Home

www.tectonicaudiolabs.com

Neither a customer nor anything else, and strictly FYI. Neither recommendation nor dislike.

 

[markus]

I posted it in a different thread, but this may be more appropriate・・・

DaS AuReality — 3D Loudspeaker Technology

A fully patented 3D loudspeaker technology resulted from a multi-year effort of Diffusion at Source (DaS) and elliptical soundfield speaker design approaches. DaS AuReality has evolved out of work known as “Acoustic3D” from an Australian-based company and is now being commercialized by Vastigo...

audioxpress.com

Are they saying that the off-axis response of the driver array is purposely decorrelated to the listening axis? So basically something approaching Blackbird Studio C without actually treating the room? Is this really what we want from a speaker with each and every recording regardless how it was recorded, whether it's stereo or multichannel?

 

[Da cynics]

Much like these guys, I think. This is a solution to half (and only half) of the realism problem.

I don't really understand this technology in the first place, but could you tell me a little more about it?

 

[Newman]

Me too please.

Especially how a pretty large number of drivers driven by quite a few amps and signal processing, is, in the words of the article, a “very simple but far more efficient way to achieve the same listening result” as putting a ring of absorptive pads around the room at head height.

 

[youngho]

Especially how a pretty large number of drivers driven by quite a few amps and signal processing, is, in the words of the article, a “very simple but far more efficient way to achieve the same listening result” as putting a ring of absorptive pads around the room at head height.

If you're talking about the DaS Aureality link, those aren't absorptive pads at listener head height. Interestingly, the Corsini link in references has incorrect information about the type of diffusion used, although the manufacturer's is correct. I had recently seen the same diffusion modules used in an immersive audio studio linked in another thread: https://www.genelec.com/-/press/genelec-the-ones-power-morten-lindberg-s-stunning-immersive-studio

The approach described by DaS made me think more of the Early Sound Scattering studio approach but miniaturized to the driver itself. It looks like the only commercial product thus far is rather modest in size and frequency response: https://shop.newaudio.com.au/produc...red-by-rotorsonics-red?variant=15390815158336

 

[Newman]

Yes I should have said diffuser panels…then made the same point.

 

[Da cynics]

 

[Bjorn]

Seems like part of what Das AuReality does it to create a lot of lobes (=mess) at the source, so you can't hear individual reflections well anymore. Same principle if one would use diffusion for early specular reflections. That hinders our ability to detect individual reflections.

But here's the drawback with it. Everything you're listening to is being altered and you are not hearing the recorded signal or how it was mixed/mastered accurate anymore. The speaker will add it's own flavour or signature to everything.

While I haven't heard these speakers, I personally don't like to diffuse early reflections for the above reason and the fact that everything sounds live and with loss of clarity, intelligibility and localization compared to attenuating those reflections. While very "diffuse" sound can be fun, always impresses at first and can work well with especially classic music, adding oregano to everything get's kind of borrowing in the long run. It's nice with variation and let the music producers have a say in how it's going to sound.

 

[markus]

Thanks, so that speaker driver exhibits frequency-dependent lobing at higher frequencies. Not sure this is what we want though. Just another solution to a problem that doesn't exist?
We'd hear the original on-axis signal (which by the way will still create "correlated" reflections) and decorrelated reflected energy based on the direct signal. What does the latter add perceptionally? Noise? Envelopment?
Lower frequency content (up to 1-2kHz?) will still produce "correlated" but spectrally altered reflections that might change timbre perception (for the worse?).

 

[Da cynics]

https://vastigo.com/wp-content/uploads/2021/02/Automotive-Audio.A3D-versus-Piston-Loudspeakers-3.pdf

 

[pozz]

I don't think his comments on loudness hold. Likely, driver distortion is the culprit. That and directivity would probably explain his other comments.

Probably a good design for cellphones and VR headsets, like he said, but probably not cars or speakers.

 

[dziemian]

Does anybody have an idea how to measure CBT36k (or any other cbt design) to be used with Dirac / Audiolense/ Acourate dsp/drc software? All of this software is based on an impulse measurement from a single driver. How to measure several drivers at once playing the same frequency, each delayed by some ms? Is that possible at all? Is the measurement not going to be flawed in general?

 

[j_j]

Does anybody have an idea how to measure CBT36k (or any other cbt design) to be used with Dirac / Audiolense/ Acourate dsp/drc software? All of this software is based on an impulse measurement from a single driver. How to measure several drivers at once playing the same frequency, each delayed by some ms? Is that possible at all? Is the measurement not going to be flawed in general?

What are you trying to measure? let's start with that.

 

[dziemian]

I want to improve speaker's behaviour both in time and frequency domain. All three software correct timing errors of the room and the speakers by a phase correction. In a diffrent way.