Not a mixture but the ability to move proportionally from one to another. 

Fansastic wrote:

Hi Geoff,

- as the 90’s have all the magic programmed in them, how big a step down are the acoustical enhancements of the 50’s and then again the 28’s?

Fansastic wrote:

Hi Geoff,

- my brother in law happens to be a professional music producer and he is actually understanding all of this. I was discussing with him the working principals of room compensation capability of the BL’s. He was impressed but still a bit sceptical (and here comes my question); he mentioned that no matter how you enhance the sound beam, it will bounce back on the back wall of the room and still have impact of the sound beam. How does this apply for the 90’s for instance?

Geoff Martin wrote:

This is almost-as-complicated a question, however: In principle, the difference between the 90s, the 50s, and the 28s is the frequency range of the directivity control that I describe above. The 50s control the directivity of the high frequency band using the movable sides of the lens instead. This actually means that, at 20 kHz, the beam width of the 50s is more like the other bands than in the 90s, where the 1" tweeter has started beaming. This is noticeable in the measurements published in the Technical Sound Guides for the two loudspeakers. The 28s only have a single woofer, so it's impossible to do directivity control in the frequency band covered by that driver. However, the method of controlling the directivity is, in principle, the same. Of course, the filters that are calculated and implemented are completely different.

Your brother in law is completely correct. However, the back wall reflection will have a primary impact on the timbre instead of the imaging. So, we use the beam width control (directivity) to reduce the side wall reflections, and the ARC (Adaptive Room Compensation) to look after the timbral effects of the back wall reflection. Tell your brother in law that the primary analysis and processing for the ARC is correcting the frequency-dependent phase, not the magnitude response, of the loudspeakers. So, we're not just attenuating the symptoms - we're trying to correct the problem. Cheers -geoff

Mikipidia wrote:

Btw maybe silly question, but could one sort of make one of these half way filters by measuring widely (like how the manual tells you to do for wide mode) in the narrow mode and vice versa or taking a bunch of narrow measurements and combining them in to a filter while the speakers play in wide mode?

It’s still somewhat static, but could that be a half way between both modes?

Hi,

I'm not sure that I understand the question, but you seem to be mixing up the ARC measurements that are done in the listening room with the individual loudspeaker driver measurements that we do in the Cube.

We only check the "total" output of the loudspeaker (using all 18 drivers at once, for example) to verify that the sum of the individual measurements produces the directivity result we expect.

However, the 18 individual driver measurements are done one at a time - they have to be. We don't even assume that the loudspeaker is symmetrical - we measure the left and the right drivers to make sure that this is, in fact, true.

Does that answer your question? Or have I misunderstood?

Cheers

-geoff

A big thank you to Geoff for such a detailed response. I did not expect that. Whilst I love your analagy with gearboxes I immediately thought of the DAF Variomatic. That didn't help.

So my understanding is that a proportional variance would not be possible but many many "inbetween" positions would, in theory, bar the fact every one would need a new filter? 

That does make sense to me and my original "simple software update" comment does seem a tad ignorant now. 

But I'll stick my neck on the line and predict that in time B&O do something akin to this is the future? 

I'll be 1st in the line for the royalties? :)