Hi all, very interesting thread....I've been trying to achieve lowering frequency of directivity control for some time.
Directiva R2 looks very cool...following this (and similar efforts on DIY).
My path for lowering the control frequency has been with large Danley style conicals.
I thought i'd throw in a few anecdotal impressions, after trying to give an intro to maybe gather some credibility.
I've made various sized horns, with various H-V patterns. They have all ranged between roughly 30" to 48" wide.
Horizontal patterns have ranged from 50 to 90 degrees, and vertical patterns from 50 to 60 degrees.
They have all used the same compression drivers reaching down to 500-700Hz, with various sized cone compliments picking up duty down to 100Hz, .......all for use with subs.
Two particular versions have removable secondary flares, which takes their width from about 34" without the flares, to 48" with them.
Using Keele's classic formula for a 90 degree horizontal, that gives about 270Hz control without the flares, vs 190Hz with.
My smallest 30" builds were 60 deg @ 410Hz; and 90 degrees @ 310 Hz.
Just trying to impart i've had a good range of 'lowest frequency of control' to listen to, from about 190Hz to 410Hz.
All the builds were tuned exactly the same way, getting the best on-ax and off-axis set possible, out to pattern control edges.
Used a spinorama outdoors off a deck, with mic about 9ft away. Muti-way FIR processing. Good flat mag and phase traces were pretty much a given.
Anyway, after that longwinded intro....i really only have two rather small observations to offer. (Sorry, sigh).
First, there has been a downward shift in tonality, when adding secondary flares (this was after retuning with the flares on to the same previous flat mag and phase, with only the polar widths varying some).
The same flat magnitude traces sound a little more downward sloping with increased horn width and lower pattern control, like a little HF/VHF high-shelf attenuation was added.
I observed this both indoors and out. My room is fairly large, maybe 6000 cu ft with Schroeder down close to 100Hz. I guess this probably accounts for much of the sameness, indoors vs out.
Second, after hearing the downward shift in tonality and liking it, I've tried to EQ the smaller horn without secondary flares to the same tonality.
It's easy to get very close, but I've never made cigar. There's a richness to the lower frequency control, even outdoors, that can't quite be duplicated via processing....so i dunno what's going on really.
I'm lucky to have a partner such that the WAF doesn't even enter the picture, We divided up the house where we each have our "free to do as please zones". She and I both love it
