Posted by GM [ 68.158.247.177 ] on September 16, 2006 at 15:15:34:
In Reply to: Re: Really Front-Loaded posted by PointSource on September 15, 2006 at 22:42:38:
Greets!
You're welcome!
No, it means a lower HF corner (IOW less BW for a given Fc), less acoustic power, ergo lower throat distortion which can actually increase efficiency down around Fc because it's not being 'squeezed' hard. Choosing XO point/slopes is a balancing act of trade-offs of which the horn's mass corner can be one of them. Not being familiar with MSL-4 beyond its published data, it's 800 Hz XO point doesn't seem all that low considering its 65 Hz F4.
Not sure what you mean by 'smoothing guide' since with a <1.0 CR there's nothing to impede the driver's beaming BW, but if you mean a phase plug to improve its power response, then I've experimented quite a bit, though it was back when we only used our ears and minimal measuring equipment. Anyway, other's more current efforts have proven that what seems intuitively correct, isn't necessarily, and our ears can fool us, so who knows how good or bad the results really were without replicating/measuring them.
Coaxes in general and putting the HF in the phase plug didn't sound 'right' to me, no doubt mainly due to the huge phasing error, though in either case it wasn't as bad as when mounted outside the horn unless it was XO'd very high (above our acute hearing BW), so we preferred using drivers with enough BW that allowed EQing them ~flat and accepted the narrow 'sweet spot'. To gain back the dynamics we lost in the midbass/lower mids, multiple drivers or horns were used. Not a cheap solution, but one does the best one can when trying to satisfy our desires. 
Later, I experimented with huge conical horns to maybe 'have my cake and eat it too', but being higher math challenged and not having today's computer modeling capability I had to learn the hard way that it has to be way too big for a typical listening room. With today's ~cheap digital time delay capability though, this isn't an issue anymore if you're not a 'minimalist'/'purist'/whatever.
GM
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