@erik_squires wrote:
The efficiency of a driver in a cabinet is determined by the driver, not the box.
Except with horns. The cabinet/horn does the heavy lifting, not the driver - very neat. When the driver has the sole burden to carry, you hear the effort, but it requires of one to have experienced the difference to assess its impact, and react on it. The next step, if one ever gets this far, is actually implementing horn sub variants in your home, but most would be intimidated by the sheer size demand of such solutions.
@gdaddy1 --
Different ways to skin you cat. Implementation is key for whatever route is taken here, and being I favor active configuration from a DIY-approach setting filter values of both the mains and subs, high-passing the mains lends itself even more naturally; although housed in different boxes, each sub and corresponding main speaker channel is treated as a single L/R system. The important thing is we're happy with whatever path we're choosing. It seems you are, as am I.
@sfgak wrote:
Agree completely with @erik_squires, @audiokinesis and others regarding treating the peaks with EQ, but not trying to boost nulls. Multiple subs helps with that (not wading into the swarm debate).
My point was that with a limited amount of bass sources both nulls and peaks are unavoidable, and not boosting the nulls here can certainly be an issue - just like failing to address peaks.
Another issue comes from the lauded flexibility of placing, say, two bass sources diagonally to try and address room modes, which I've tried several times with countless filter permutations and room treatments without ever getting to a satisfying result (even with a fairly low XO-point). It may look good "on paper," but I far and away prefer symmetry of subs-to-the-mains placement with all that it entails. Sidewall placement, symmetrically, has proved is viable solution as well.
So, up to a point, the higher you can cross over, the better, up until where you can start hearing the directionality of the subs.
Unless the subs are placed fairly close to and symmetrically to the mains.
The other issue sort of mentioned so far that could be stated more explicitly is phase-matching the mains and the subs at the point of crossover. This requires two things: (1) a continuous phase adjustment on the subs (like on those by Rythmik) or digital PEQ; and (2) a very steep and symmetrical crossover, typically implying an active crossover. That means both low-passing the sub and high-passing the mains are important.
This is of course a cardinal point. I would never do with a built-in DSP/filter of a sub, instead using a Xilica DSP for both the mains and subs, actively, with elaborate filter settings and finely scaled adjustments.
Because the wavelengths change quite a bit from 20 Hz (56 feet) to 80 Hz (14 feet), the mains and subs can only be in phase at a small range of frequencies. That is why the steep crossover is needed. Otherwise, even if the mains and subs are in phase at 70 Hz, with 6 dB/octave sloped filters there will be audible overlapping of the subs and mains from the lower audible limits all the way up to ~250 Hz or so. Because all filters have a frequency-dependent phase shift, most of that overlap is out of phase and contributing to "smudging" that translates to "slow bass."
FIR-filter would be helpful here, but using IIR-filters of the Xilica with 36dB/octave L-R slopes produces very good results. 48dB/octave slopes didn't fare as well sonically in my setup context.
@tomic601 wrote:
... building an inert cabinet for those massive low THD but high IMD woofers is not trivial…. but then cabinet movement = trash = output = “ efficiency “….. funny how systems engineering just creeps in…..
Forest for trees, as they say; engineering only gets you so far when the physical framework is stunted as an outset.