Re: So this almost never happens...
Stuart, unfortunately, it is hard. I would maintain that the KF650 is not at all a simple box - it has 3 passbands with the drivers being quite physically separated. I would challenge you to design the tuning for this box with just your ear and have it come anywhere close to what EAW provided.
Crossover points take into consideration many, many other things than sound. In fact, sound is probably the least concern of selecting proper crossover points of a box. The main concern of selecting crossover points, in my opinion, is polar response. The crossover points should be located where the patterns of adjacent drivers combine well, where the drivers are still operating in their comfortable range, and loading whatever horn/box they are placed in correctly.
Another huge component of building a DSP tuning is phase alignment between passbands. This is hard, because with the exception of a coaxial speaker, there is no one setting that is correct; they are all a compromise depending on listening position. Even if there was one setting that was correct, it's still not that easy. Different crossover types and different drivers will create instances of varying phase slope. I dare anyone to phase align drivers by ear when their phase slopes are not identical, if you could phase align anything by ear at all.
Without making complete polar measurements in an anechoic chamber, it's really quite doubtful that you'd come anywhere close to what EAW's engineering team could come up with. I have built DSP settings from scratch, using up entire days trying to do it. There is really no way to get it done without lifting a speaker far enough into the air that ground bounce is not a concern, or using ground plane, which is only semi-functional with the upper end of things, because it changes the loading from full space to half space. When doing this myself, I do multiple measurements off-axis and on-axis to confirm pattern and crossover compatibility, and still feel like I only get halfway there.
The EQ of the box is probably the easiest part to do by ear, but it's still hard. When doing my own tunings, I usually set the EQ such that each passband is flat beyond an octave past its expected bandpass. This ensures crossovers are consistent. Still, even simple things that exist in the EAW tunings, like 2dB cuts with a Q of 10, are so subtle that I bet most people couldn't hear them, even doing an A/B comparison with and without that filter. This is why a controlled measurement environment is so critical.
There's more to it than just getting the crossovers, phase alignment, and overall magnitude response correct. As I hinted above, phase is a big deal, and it directly corresponds to impulse response. If the tuning is done, the crossovers are set, the pattern is good, it's nice and flat, guess what? It could still be just OK from a time perspective. I did a quick measurement with an Audix TM1 when I was done with the KF650 - the magnitude response was pretty decent (given the terrible measuring conditions), but the phase trace showed a few thousand degrees of phase wrap. This not only shows the bad measuring conditions, but it shows that the KF650 impulse response is going to be terrible. As I mentioned in my OP, I'm planning to implement all-pass filters to flatten the phase of the box as soon as I get a chance. This will drastically improve the impulse response and subjective sound quality of the box without affecting magnitude response at all.
I've challenged you to design crossover settings by ear, which is one thing. Let's see someone design a flat-phase tuning with all-pass filters by ear alone.
And after all this basic IIR stuff is done, then the really hard stuff comes into play. Think about horn resonances or throat distortion or all those other things that cannot be corrected with any amount of EQ or phase adjustment. Most notably, Dave Gunness can build FIR tunings that combat as much of this as possible. The average magnitude/phase FFT measurement doesn't even show things like throat distortion, so where would you even start building an FIR (truely, even I don't know) if you aren't Dave Gunness?
EAW provides tunings as a baseline that takes the environment out of the equation. They are designed to be flat out of the box, and the engineer is expected to EQ to taste at each show.
PS- I hate the EP series speaker connectors.
PPS- consider also that these factory-provided tunings are as good as they may have gotten with the technology available at the time (and with the ears they had at the time :lol
, but with the advent of Dave Gunness, it got even better. From everyone I have talked to, the processing that he created for EAW with Gunness Focusing makes a dramatic improvement to the sound quality of the box. Guess what? I bet they both measure flat!
PPPS- Black Box systems exist because 'engineers' almost always make the system sound worse when they are allowed to change things themselves. The Black Box locks the system down so it can't be ruined by incompetent wannabes (or anyone else)...
