True, PS-1220's are 3 ways... Maybe he didn't consider those "real ESS" without the Great Heil (mine have the little face mounted heil). I'm not sure I was speaking to Ricky this time, though I've talked to him before (when restoring the PS-1220's). I do like them, but they're not as airy as the AMT3s at all. Bass is lower, and yes, probably less defined than it should be. Great speakers, no doubt, even really loud, but they do start to distort if pushed too hard. They have the passive radiator in the back.
"Pro-Sound" to me is the sound of really efficient speakers. They can get really loud, and still be pretty clear, but typically don't have low end grunt and don't push as much air. Good for an auditorium, but aren't going to ruffle your pant legs with bass either, and usually less refined as a category than audiophile. Lack of bass sounds artificial to me. I'm not saying yours are in that class, but I'm cautious about the high SPL of the mid-bass from the woofers, and high Fs which will probably make deep lows near flat all but impossible. But as you mention, if you want low end grunt, you're not going to be able to drive them to very high SPL levels without distortion typically, which is just what the charts say. AMT3s were made to be the former, really loud, efficient speakers, I think... So my design goals might not be doable. The Heil is very efficient. The mid is too, and with 2x10" drivers, at probably 92dB each, (and maybe even originals were that efficient, I don't know), they're not going to reach low either. You can't have both it seems. Most woofers that have a low Fs will also be less efficient. If you want Fs to drop an octave, it seems you're going to give up 2 to 5dB everywhere. And tune everything else to fit (which may be OK on the AMT3 already, not sure). And then to drive them at high SPL is going to typically exceed xmax one way or another and introduce distortion, so maybe trying to match the original design goals and improve on them like you've done is the best course. I'm still trying to find a compromise that can get me some deeper low end than the ST-255-8 specs would indicate, but in the end maybe I should follow your advice and if I want 20Hz bass I should put a giant sonotube sub in the basement! That might be an interesting idea... Talk about group delay then, as the floor timbers come up to speed... I do think low bass is key, and I really like that octave, but getting that out of these cabinets may cause more trouble than it's worth, which is just what you're telling me (and the bass isn't lacking much anyway). And when the speakers were tested and charted, they probably weren't broken in either, and so maybe have lower frequency response than the chart would indicate.
Just gut feel, how would you rate the response of the Automojo version, as a guess, in dB at these frequencies (zero being flat):
25-50
50-100
100-200
200-400
400-800
This might be a big help. Is that with room gain?
Some reviews I've read also like the AMT1 towers a lot so I've been toying with the idea of seeing what would happen with one woofer, properly ported, that would be happy in a 75 liter box, and block the other hole. Those are TLs, so I wouldn't expect identical results, but it might be a good combination too, because the problem I'm seeing with using two low Fs woofers is that I'm very close to needing a sealed cabinet, which might be OK but quieter still. With two, there's just too much going on in too little space and driver choices are very limited. I'm also running into the issue that it's hard to predict what will happen because the different software I have gives different results (your bass box pro gives yet another answer!). The excel one has the formulas hidden so I can't even see why. One other issue is that mine is a first order for the woofers, while yours is a second order, so I may get breakup you don't hear, though it would be down probably 12dB or more... Wouldn't be a big deal to put a cap in parallel I suppose if that happens, I suspect it might.
They actually did sound really good with the mixed drivers but lacked bass. I didn't get to position them correctly or listen very loud because of the blown woofer. But the imaging blew me away which is why I want to be careful with the crossover.
