The 2425Js Are SWEET!, but what Horn did I get?

[Zilch]

Unwindowed MLS and Sinusoidal:

[Which speaketh the truth? ]

[4313B]

Unwindowed MLS and Sinusoidal:

[Which speaketh the truth? ]

Whichever one looks the best.
I'll do some more 2425/2307/2308 measurements in a week or so and see what happens.

The pic below has another opinion.

Here's Greg's -

Keep in mind that a ground plane measurement does not give the correct midrange curve. (100 Hz to 400 or 500 Hz) This is due to the enclosure dimension being doubled by sitting on the ground. The baffle effects are presented at the wrong frequency. I figure if you try different distances between the ground plane and near field, you should be able to zero in on common ground in a splice region. Another possibility is to do curves outside and just put the speaker on a stand. Even 3 feet will help substantially at the 1 m mic distance. Any different measurements you can make will help to show what is real and what isn't.

That last sentence basically reiterates Doug's view on the subject.

[Zilch]

O.K., thank you, Giskard.

I updated the Sinusoidal to include gated and stepped.

Haven't used that enough to know what's optimum.

RTA says MLS and gated groundplane are correct.

[RTA's always my fallback frame of reference.... ]

[Zilch]

They're remarkably uniform considering varying age and indefinite provenance, I must say.

If it's real, there's an easy fix (bottom two)....

[boputnam]

What's the easy fix? I only see a graph.

"Blk = notched"...? (see top curve of bottom two). But it must be very low Q "notch" - it looks more like a gain structure issue...

[Zilch]

"Blk = notched"...? (see top curve of bottom two). But it must be very low Q "notch"....

Yup, Bo. 4-5 dB is a fairly major correction, actually. I'm reluctant to post the specifics until Giskard verifies this with his independent testing using 2425s, Todd's newly acquired driver type, as opposed to these LE85s. The "fix," if any, will likely be different. See the second graph here, 2426J on HL91:

http://audioheritage.org/vbulletin/s...5&postcount=15

Once running flat, the narrow (and collapsing) vertical beamwidth really becomes apparent. These need a tweeter, not so much for the VHF (13.5 kHz being plenty extended for some applications,) as for overcoming their beaminess.

David Smith documents the beamwidth as ~25° @ 10 kHz, and ~45° at 5 kHz. See Fig. 4 here:

http://audioheritage.org/vbulletin/s...ead.php?t=7852

Boosting the VHF would thus be a fruitless endeavor. Instead, I'm mating them with a 90° x 50° waveguide tweeter @ 6 kHz to see if that integrates well (bottom). Optimum might be somewhat lower, probably.

After that, I've gotta get back to doing my own stuff here. Todd always comes up with provocative subjects requiring empirical determinations....

[boputnam]

I simply have got to get over there and see this place for myself!