The Pros & Cons of Dual-concentric/Coaxial drivers

[airvoid]

Hi Airvoid,
I don't get that point. And it goes against my own experience: i observed a 'gain in quality' each time i relieved a coax ( and -small- full range) from bass duty. I've played with a bunch of them till now ( with pa from 15" to 10", studio 15" to 5" coax, 5"/4" full range) and it was always the same, xover in the 200/300hz ( 500/600hz for 5" coax or full range) range and it sounds way cleaner to me.

The most obvious is with smaller size ( 8" and smaller): with my 8" Tannoy at high spl there is some 'gargling' happening, you can definitely hear the highs being modulated by the lows, it sound like no other distortions to me ( really special).

With bigger diameter it is less obvious but still hp gives a cleaner ( subjective i know) sound. I suspect the same gargling could be observed too but at unbearable SPL level so less encountered ( even on stage in wedge use).

I don't think it's doppler distortion ( i'm sceptical it can be heard too), more a kind of intermodulation distortion.


Could you explain more in depth your view on leting the woofer part run in the lows please? What are the benefits to you ( technical/theorical and subjective)?

Hi Krivium,

Firstly I am only talking about my experience with the 10”&12” BMS drivers we are using. Secondly it’s in conjunction with a BMS 12N630.
We have done extensive single- lind A/B listening tests over a year, including user groups of about 10-15 people each, and using pre-set active FIR filters this is quite easy to do and the preference has been for a shallower type filter and a about 80Hz crossing over a 150-250Hz cross. The sound is simply. more coherent and stable with the low cross. No effect on the treble (we cross asymmetric 6-8th order LWR at about 1.1k)

 

[fredygump]

I feel somewhat obligated to chime in. I'm using B&C 12FHX76 coaxial drivers in my build. The sound is pretty detailed, and they measure pretty well.

Their directivity is well controlled, as in there is a wide horizontal and vertical sweet spot. But still a fairly narrow directivity 60 degrees x 40 degrees.

At this moment it is crossed at 1,200hz and 100hz, but I'm working on an overly complicated plan that will allow me to cross to the front subwoofer @300hz, while maintaining a summed signal below 100hz with an independent delay for multi-sub tuning. (Each cabinet has 2 subwoofers, one ported and one sealed...like the Genelec W371A.)

I built one to see if it works as intended. It isn't "done"...but should give you the general idea.

 

[Mister Audio]

From YouTube - good to watch >

 

[Mister Audio]