Dutch & Dutch 8C

[Bjorn]

Could it be that the main subjective improvement of the beolabs or the Kiis doesn't lie in the directionality of the very deep bass, but rather that they're directional down to the midbass? Say to 120-150-200 hz? To be directional that far down is nevertheless vastly better than almost all other commercial loudspeakers.

I think so, or rather down to 200-300 Hz. While there may be some benefit below 200-300 Hz in some rooms with certain placements, the directivity is gradually lost and swamped by room modes, dependent on the room (size and materials).

I've measured a horn that has a certain controlled (cd) directvity down to approximately 90 Hz with a few placements and compared it to a direct woofer. While I generally see a flatter response with the horn it's by no means independent of the room and modes. The lower you get, the less benefit there is. If cd really worked great for low frequencies, we should be able to move the speaker and sitting position around and not see much change. If that was the case with Kii and Beolab 90, you have to wonder why in room measurements aren't showed as it would be very convincing and great marketing.

 

[Cosmik]

Could it be that the main subjective improvement of the beolabs or the Kiis doesn't lie in the directionality of the very deep bass, but rather that they're directional down to the midbass? Say to 120-150-200 hz? To be directional that far down is nevertheless vastly better than almost all other commercial loudspeakers.

Not to mention the fact that they are DSP-active with time & phase alignment, sealed bass and so on - which makes them unusual even without the directivity control. Most people have still not heard such speakers - or messed up demos of them with 'misguided' attempts at room correction or whatever. I have certainly heard one demo of an expensive DSP-based system (not any that we've discussed here) that was appalling, and I got the impression that despite what he does for a living, the sales rep couldn't even tell there was anything wrong.

When it's right, it's robustly right - and all those thoughts you have that vinyl might just contain magic, or that expensive cables might just improve what you're hearing, go out of the window.

 

[Purité Audio]

The controlled directivity of the Beolabs goes down to 60Hz I believe the measurements are on the B&O website, subjectively it is immediately apparent, everything is just so much better defined.
Keith

 

[Bjorn]

B&O can obviously update the software and alter the response, but the measurements of Beolab 90 below would be anything than defined and tight bass. A waterfall would show this better though.

 

[Thomas savage]

B&O can obviously update the software and alter the response, but the measurements of Beolab 90 below would be anything than defined and tight bass. A waterfall would show this better though.

View attachment 5751

All they need to do is take room measurements in a few different stores to show how consistent the frequency response is in different acoustic environments. can't believe they have not don't that, weird.

 

[oivavoi]

Not to mention the fact that they are DSP-active with time & phase alignment, sealed bass and so on - which makes them unusual even without the directivity control. Most people have still not heard such speakers - or messed up demos of them with 'misguided' attempts at room correction or whatever. I have certainly heard one demo of an expensive DSP-based system (not any that we've discussed here) that was appalling, and I got the impression that despite what he does for a living, the sales rep couldn't even tell there was anything wrong.

When it's right, it's robustly right - and all those thoughts you have that vinyl might just contain magic, or that expensive cables might just improve what you're hearing, go out of the window.

Yap. I heard the Grimm LS1 demoed with and without room correction with Trinnov. Amazing without room eq, and just ghastly when trinnov was turned on.

 

[Bjorn]

Here's another measurement of Beolab 90 in a room. I think this is with room correction in the lows but I'm not certain.

 

[Purité Audio]

All they need to do is take room measurements in a few different stores to show how consistent the frequency response is in different acoustic environments. can't believe they have not don't that, weird.

Just look at the 90' polar plot, they are the finest loudspeakers available, at the moment at least.
Keith

 

[Bjorn]

But where's the vertical polar plot of Beolab 90? How have they overcome classic vertical phase issues in the sensitive range?

I agree they are good speakers, but first of all they sound like good hifi and aren't able to give an illusion of real music. There are better designs.

 

[Purité Audio]

Live music shouldn't be confused with its reproduction.
Keith

 

[Bjorn]

Live music shouldn't be confused with its reproduction.
Keith

It's not about that. It's about weaknesses in the design which leads to a result where instruments and vocals never will sound like the real deal. It has to do with the vertical issues, too high distortion, and lack of dynamic capabilities also contribute some.

It's possible to get a speaker with much higher quality in this areas at a much lower price, but it will not have beamwidth control and electronics built in. Very few though have heard such speakers. It's not something you buy at your local hifi shop.

 

[Cosmik]

But where's the vertical polar plot of Beolab 90? How have they overcome classic vertical phase issues in the sensitive range?

Through multiple small drivers mounted close together being driven with independent phase and time alignment..?

 

[Bjorn]

Through multiple small drivers mounted close together being driven with independent phase and time alignment..?

Nope. The multiple drivers actually makes the vertical response worse. Time alignment and a possible linear phase filter (if they use one) only minimizes the problem some, but not very much.

 

[Cosmik]

Nope. The multiple drivers actually makes the vertical response worse. Time alignment and a possible linear phase filter (if they use one) only minimizes the problem some, but not very much.

Which is better for lobing? A two-way, a three-way or a four-way - assuming the drivers are as vertically close to each other as possible?

I would say that it is obvious that the four way is best because it allows the drivers to get closer to each other, particularly at the higher frequencies. If I cross over a 10" driver to a 1", I will get serious lobing (and other problems). If I cross a 10" to a 5" to a 2.5" to a 1" the situation will be much better. If I make an array of multiple small drivers I have the flexibility to get the best of all worlds.

 

[Bjorn]

Which is better for lobing? A two-way, a three-way or a four-way - assuming the drivers are as vertically close to each other as possible?

I would say that it is obvious that the four way is best because it allows the drivers to get closer to each other, particularly at the higher frequencies. If I cross over a 10" driver to a 1", I will get serious lobing (and other problems). If I cross a 10" to a 5" to a 2.5" to a 1" the situation will be much better. If I make an array of multiple small drivers I have the flexibility to get the best of all worlds.

Is it a question or a statement?
Either way, your presumption is wrong. I don't mean this in a rude way; but you haven't understood the basics.

 

[oivavoi]

Is it a question or a statement?
Either way, your presumption is wrong. I don't mean this in a rude way; but you haven't understood the basics.

Could you try to explain why you think Cosmik is wrong, Bjorn? I'm interested in rational exchanges of opinion on these issues.

 

[Purité Audio]

Rival manufacturer rubbishes more advanced design, of which he is not capable nothing new here!
Keith

 

[Cosmik]

Is it a question or a statement?
Either way, your presumption is wrong. I don't mean this in a rude way; but you haven't understood the basics.

Quite possibly! Here's how I see it:

Acoustic lobing is a comb filtering effect related to multiple acoustic sources and the physical distance between them compared to wavelength being reproduced. If I reproduce a frequency f from two drivers simultaneously (such as through a crossover region), they will interfere and cancel each other out to differing degrees in three dimensional space due to differing path lengths causing phase cancellation. If the drivers are small, and as close together as possible, this effect is reduced compared to the situation when one driver is large, and the other small i.e. their centres are further apart.

I get the feeling that that there is an audiophile 'rule' that says that a single driver is best, and multiple drivers bad. But of course a single driver 'lobes' too - it is called beaming. There may also be an audiophile rule of thumb that says the phase effects of (traditional passive) crossover filters are always a problem and should be avoided by using as few drivers as possible, but of course with DSP the crossovers can be optimised in phase and time, too. By using multiple drivers (and DSP), it is possible to get the best of all worlds: at any particular frequency, the acoustic centres of the two drivers being blended acoustically are as close to each other as possible.

 

[Bjorn]

With the exception of lobes being the same as beaming you are correct Cosmik. Phase issues is also related to crossover frequency and wavelength. But bottom line is that no crossover is perfect in regards to summation. More xovers and increased spacing with multiple drivers causes more superposition. A line array is really bad here.

I'm sorry for coming out a bit forward. And while I should have said B when I said A I simply don't have the time to go into further explanations.

 

[Cosmik]

With the exception of lobes being the same as beaming you are correct Cosmik. Phase issues is also related to crossover frequency and wavelength. But bottom line is that no crossover is perfect in regards to summation. More xovers and increased spacing with multiple drivers causes more superposition. A line array is really bad here.

I'm sorry for coming out a bit forward. And while I should have said B when I said A I simply don't have the time to go into further explanations.

Don't worry. Far worse gets said on other forums!

I still think a single driver can 'lobe' - by the common dictionary definition of "lobe" (except for the noun versus verb aspect). See the following drawings of a single piston's acoustic output at different wavelengths relative to its diameter.