Box speakers with very wide and very even dispersion?

[oivavoi]

Seems like there's more people online now, so bumping this: Nobody who wants to chime in on the reason for choosing a TM over a MT configuration in a threeway, trade-offs etc?

Btw, I'm looking a bit a pair of cheap second hand infinity primus 360. Not perfect speakers by any means, but they do a lot of things right when it comes to even and broad dispersion - horizontally at least. What I wonder is about the tweeter/mid alignment. On many classical three-ways the tweeter is located at the top, above the mid woofer. Here it is located below the mid. Does anybody have a qualified opinion as to why it's so, and how this affects dispersion, FR etc? I have read some stuff on the MTM arrangement, but can't recall reading much on MT vs TM arrangements on speakers.

View attachment 37244

 

[MZKM]

Seems like there's more people online now, so bumping this: Nobody who wants to chime in on the reason for choosing a TM over a MT configuration in a threeway, trade-offs etc?

Most design the tweeter to be the reference axis, so ear level. If building a tall speaker, going MTW would still allow the tweeter to be ear level.

 

[MZKM]

Looking just at towers measured by Stereophile:

JBL Stage A170 ($600):

Thiel TT1 ($7000, defunct):

 

[oivavoi]

Most design the tweeter to be the reference axis, so ear level. If building a tall speaker, going MTW would still allow the tweeter to be ear level.

Thanks! That's the easiest explanation. I was just wondering whether it affects the broader dispersion of the speaker as well, particularly vertically. Depending on the crossover slope there has got to be some interference between the mid and the tweeter I guess?

 

[fredoamigo]

I am very interested in this subject even if I am not a specialist in directivities far from it! but humbly I find that your specifications are heavy (without horns).
maybe the new dynaudio confidence 20 with ddc (Dynaudio Directivity Control) technology would be in line with your research?

 

[oivavoi]

I am very interested in this subject even if I am not a specialist in directivities far from it! but humbly I find that your specifications are heavy (without horns).
maybe the new dynaudio confidence 20 with ddc (Dynaudio Directivity Control) technology would be in line with your research?

That's interesting! Read a bit about their technology here: https://www.dynaudio.com/home-audio/confidence

The idea seems to be to restrict vertical dispersion, but get wider horizontal dispersion. That may be a good thing if one thinks - as has been discussed in this thread - that vertical reflections are more harmful than lateral/horizontal reflections. But the directivity pattern of the smaller Confidence 20 is almost certainly much worse than that of its bigger brothers. This is because the Confidence 20 is a two-way, so the tweeter gets crossed over to a larger bass driver, instead of the smaller midrange drivers in the larger models. This means that the tweeter and the woofer get different directivities at the crossover region. The Confidence 30 looks good though. But would like to see proper measurements of it!

 

[Bjorn]

Mentioned this before. A circular CBT with beam width control would be able to meet every horizontal dispersion desire. One would be able to choose between a multitude of beam width options combined with a uniform vertical directivity, avoidance of the troublesome floor reflections, and minimization of ceiling reflections.

But it's not going to be cheap and require a heck of a lot of amps! But still, would be fun to offer something like it one day. We've labeled it "The Matrix".

 

[MZKM]

Thanks! That's the easiest explanation. I was just wondering whether it affects the broader dispersion of the speaker as well, particularly vertically. Depending on the crossover slope there has got to be some interference between the mid and the tweeter I guess?

Depends on how well designed it is. Not an MTW, but if you look at some D’Appolito designs, some have large suckouts vertically in the crossover region, but the KEF R700’s do not (well, it’s a W-coaxial-W). You have to take into account the baffle step in the vertical plane and not just the horizontal, so the distance from the top, if the edges are chamfered/rounded, etc. are all in play.

 

[Bjorn]

Lexicon SL-1 is of course another speaker that should offer wide horizontal dispersion.
https://www.audioxpress.com/news/ha...agship-lexicon-sl-1-high-end-adaptive-speaker

If you can afford it......
"The Lexicon SL-1 floorstanding system will become available during the fourth quarter of this year, with its recommended retail price set at £40,000 in the UK, €43,000 across Europe and $40,000 in the United States."

 

[oivavoi]

Mentioned this before. A circular CBT with beam width control would be able to meet every horizontal dispersion desire. One would be able to choose between a multitude of beam width options combined with a uniform vertical directivity, avoidance of the troublesome floor reflections, and minimization of ceiling reflections.

But it's not going to be cheap and require a heck of a lot of amps! But still, would be fun to offer something like it one day. We've labeled it "The Matrix".

View attachment 37332

If I was able to like this post twice, I would!

 

[Bjorn]

If I was able to like this post twice, I would!

Hehe. I'm afraid it's going to be difficult to a system like that under 200 000 NOK. Perhaps with very low cost chip amps, but they don't necessarily have the desired watts.

 

[maty]

Yesterday new video: Acoustic Center Spacing and Why it Matters! -> ceiling, floor, time alignment, phase shift, coaxial / concentric speakers...

I had made a capture and cleared the speaker front to see the drivers.

Vertical axis of these DIY speakers:

The speaker is the GR Research N2X kit: http://gr-research.com/n2x.aspx

GR Research N1 kit: http://gr-research.com/n1.aspx


https://en.wikipedia.org/wiki/Loudspeaker_time_alignment

 

[maty]

BTW, about MTM: https://en.wikipedia.org/wiki/Midwoofer-tweeter-midwoofer

Another problem with the MTM configuration is the interaction between the two midwoofers. For any frequency (over the operating range of the midwoofers), the off-axis response exhibits different lobing patterns because of the vertical distance between the midwoofers, and as a function of the frequency and horizontal distance from the speaker. At any off-axis listening position, although both midwoofers operate in phase (are time-aligned), the waves from each reach the listening position at different times (and therefore have a relative phase difference) - at frequencies where the time displacement between the two midwoofers corresponds to one-half of one wavelength, the outputs of the two midwoofers will null.[4] However, the time displacement itself is a function of the distance from the speaker and frequency, which means that the lobing for a given listening distance and off-axis position will be different at different frequencies. Since the basic reason for this is the distance between the midwoofers, again the solution is to use as small drivers as possible, placed as close as possible. With this, for listening distances much greater than the distance between the drivers the lobing effects are much less obvious...

 

[cookiefactory]

How about the Energy Veritas?
http://soundstagenetwork.com/measurements/energy_veritas_v24i/

 

[LTig]

That's interesting! Read a bit about their technology here: https://www.dynaudio.com/home-audio/confidence

The idea seems to be to restrict vertical dispersion, but get wider horizontal dispersion. That may be a good thing if one thinks - as has been discussed in this thread - that vertical reflections are more harmful than lateral/horizontal reflections.

Did it took Dynaudio really 18 years to detect this problem and its solution? The K&H O500C was released in 2000 and sported wave guides for mids and highs. Other companies might have released similar speakers even earlier...

 

[Absolute]

The Confidence-series from Dynaudio is the biggest disappointment I've personally come across. Always liked Dynaudio and expected much from these beautiful speakers, but the new Confidence is not good to my ears.

 

[Bjorn]

@oivavoi
How do you like the B&O Beolab 50 or 90 in wide mode? Assuming you have heard them in a decent room.

 

[oivavoi]

@oivavoi
How do you like the B&O Beolab 50 or 90 in wide mode? Assuming you have heard them in a decent room.

I've heard both of them in both modes, but only at a B&O dealer where setup was not ideal. With the Beolab 90 I handily preferred the wide mode on classical, but the narrow mode on electronic studio music. The Beolab 50 I heard were standing in room corners, and in that setup I - unsurprisingly, perhaps - much preferred the narrow mode on all kinds of music.

 

[Kal Rubinson]

I've heard both of them in both modes, but only at a B&O dealer where setup was not ideal. With the Beolab 90 I handily preferred the wide mode on classical, but the narrow mode on electronic studio music.

Interesting. I've heard the Beolab 90 in my own room and much preferred the narrow mode. Wide was more diffusely focused.

 

[oivavoi]

Interesting. I've heard the Beolab 90 in my own room and much preferred the narrow mode. Wide was more diffusely focused.

Well, it was a short listening and informal listening session, so I won't discard the possibility that I would have thought otherwise given more time etc... The polar plots indicate that the response is much smoother in narrow than in wide mode.