How low can we really take this 2426/2370 horn combo? The JBL literature shows loading down to 500 hz. with a 630 hz. minumum crossover(20 watt maximum cont.) At 20 watts we're close to 130 db, so shouldn't be a factor. Want to mate with a pair of 2226 J woofers per channel. I assume that 12 db low pass, 18 db high pass with Wayne's rc network would be the best implementation? Are there programs available to determine proper crossover components by simply plugging the numbers? Also, anyone used the JBL 2426 with the Altec 511 B horn? Any comparisons? Would the rc network still be appropriate? Thanks to all! Jerrod

The 2426/2370 combo is usable down to 800Hz, which is the low frequency cutoff of the horn. You might be able to reach 500Hz on a larger horn, but below that, diaphragm excursion is too great on any horn except at very low power levels.

It turns out that when welded, lots of internal stress must occur. When the recip saw blade was cutting thru, it would be "pinched" by the horn trying to close where the blade had passed, and as the blade exited, the first gap snapped shut like "snap". The gap the width of the metal saw blade had closed almost completely. So about a 1/8 inch section needed to be removed from each sectoral fin.

Black tape was used to keep the rtv from dripping out the bottom of the cuts, once dry, it was removed. The horns then went "clunk" when struck...no further mods needed for now...even decided BBQ black was a more fitting finish than bare aluminum...lets the speakers "go away" in a darkened room...Sam

2035 update...levels match pretty well using "12 dB Pi pad", 1.0mH/10uF LP w/ 4.4 ohm/10uF zobel...average LF level from 100 to 1000 Hz. was flat +/- 1 dB; from 2 to 11 kHz. the HF averaged about 1/2 dB lower than the LF, and from 8 to 16 kHz, HF averaged 1.5 to 2 dB hotter than from 2 to 11 kHz., and varied +/- 2.3 dB's average. HF F10 estimated somewhat more than 17 kHz...these were measured with the 4 Pi on the floor, and the mike about 2 meters away...mike height adjusted to put it in the "line of hearing" from the middle of the two drivers to the listening position, 12 feet away. hf readings averaged for the 8 to 16 Khz. response were "corrected" per data from a net posting.
Since I need to go in and replace the port tubes with shorter ones, I will "boost" the overall HF by about 1 dB, getting it 1/2 dB hotter, rather than cooler than the LF. And seal the HF horn flares to the front baffle...did not see puffs of air, but the newspaper slid under one end of each H-290, gotta be a leak there! a machinist straight edge says the H-290's are not flat...at least the fronts aren't! Drivers are sealed to the rear of the horns with a "certainteed" elastomer plumbing gasket...about 2.75 od, they just fit in between the two bolts. These are "done", and sound great...I'm just putting on the "auction wax" for that last 1% of "shine". Sam

• Emilar bowtie