Mouth termination issues we would see off axis, stored energy can be EQ'ed away if its minimum phase. Here we don't have enough data to be sure (we would need waterfall) but certinaly in other speakers with simlar short horn phenomen they can be correct with EQ where if you measure the speaker post EQ you cannot see any artifact of the resonance. I would contend that as there is no diectivty anomaly at 600Hz its likley that EQ is fully effective for this particular speaker.
I concede that's possible. But we'd need to see proof.
Be that as it may, I still vastly prefer better-behaved waveguides/horns to begin with.
Smooth unequalized response is always the preferred acoustic design goal, imo.
Additional smoothing with EQ works fine when it holds up consistently and smoothly over the entire intended coverage pattern.
Ime, when EQ does hold up like that, it has shown no time domain problems in waterfalls, burst decays, etc.
John, may i also respectively say....something looks very amiss between the 15 deg and 0 deg traces.
Like you did, i generally use 10-15 degrees off axis as the tuning reference.
I've found the more axisymmetric the horn is (Hor vs Ver), the more likely 15 deg works best,
whereas if the horn has an aspect ratio to it say 3:2, 10 deg might be best.
(I think i've heard even the vaunted OS horns, being axisymmetric, have a problem with 0 deg ?)
Anyway, by best I mean having the least variance across all angles, including 0 deg.
I don't think I've ever seen a variance as large as between the 15 deg and 0 deg, you're showing.
But the rest of the angles are looking sweet !
I don't follow your logic about the mid-range between 100-600Hz....can't see how there should be polar variance there due to horn loading, or not.
Seems to me something funky is going on with mouth termination, or port interplays, etc...
Response at zero degrees
Response at 15 degrees off axis
What's "very amiss?"
Here's the polars from last night, but restricted to zero to 15 degrees in 7.5 degree increments
Here's the spec sheet for the SB26ADC tweeter I'm using
1) phase plug
2) acts as a support during print time, so the throat comes out perfectly circular. (Cooling and gravity will sometimes make waveguide throats slightly elliptical, because if they're unsupported. Not the end of the world if you're using a compression driver, but I'm using a dome tweeter so the shape has to be perfect or stuff will rub
2) acts as a support during print time, so the throat comes out perfectly circular. (Cooling and gravity will sometimes make waveguide throats slightly elliptical, because if they're unsupported. Not the end of the world if you're using a compression driver, but I'm using a dome tweeter so the shape has to be perfect or stuff will rub