It's been a half a year since I posted my original questions about these drivers. And now I have some experience with a particular variety of them, the CGN-1808, with the dual-layer honeycomb reinforced fiberglass cones.
I purchased some previously owned demo units, which have been through the gamut of power levels over an extended period.
Now that the units are here, I have had an opportunity to disassemble them and inspect the construction, glues, materials and overall design quality of the drivers.
They are utilitarian in design--that is to say, their form follows function and there is no cosmetic frill in the design of the driver.
I have tested the sensitivity at 1W against the EVX-180Bs that I also utilize as midbass drivers, and they straddle the line +/-1dB of the 180Bs, so I'd say they are roughly the same sensitivity, or slightly more sensitive at the lower frequencies.
The first two inches are linear, such that no audible harmonics are heard. Even in free air testing, the driver produces a 20Hz fundamental and little else, something I have not seen from any driver I tested in the past. I've been able to get more than 3" of excursion out of them without much audible distortion in this particular version of the driver.
In cabinets, the 1808s have a useful upper crossover of around 50-60Hz. The start to roll off pretty much above 80Hz. That's kind of a blessing, for those who run their amps to clipping because it masks the clipping to a degree.
At normal levels, there is noticeably more subsonic thump than with the 180Bs. But when the power levels get crazy, the CGN-1808s keep getting louder, while the 180Bs start to produce all sorts of out-of-band junk.
The 180Bs have more top end, and so carry the hard edge of a kick drum, but the 1808s carry the very low end much better.
In fact, one dual 1808 cabinet can basically put my original ten 18-inch woofer system to shame.
I'm putting four of these drivers in service this month. I have two installed on the right side already. Even two against the other 8 conventional commercial drivers is noticeable. The low end is stronger and much cleaner. The only distortion I note now is building structural-related. The ceilings, the walls, and everything in the studio auditorium vibrate so much that if the tone is pure, with no other sound to mask, these annoyances are very audible and disconcerting.
I have some cabinet work to do, as these drivers easily exceed the mach speed at vent velocity when excursion approaches 2" around vent tuning frequency (18Hz).
This version was built to address the high compression stress issues with horn-loaded systems. The cones are 1/4" thick honeycombed fiberglass. They're so tough that you could take a baseball bat to it without doing much if any damage. The surrounds are a butyl rubber half round with lots of movement range. The rubber on those surrounds is 1/4" thick in places. These are not your dad's acoustic-suspension surrounds!
Overall, a strictly-business design, no frilly cosmetic stuff, all around rugged subwoofer driver.
I tested these with four times the sine wave power that I've used in testing some earlier E-V drivers and the coils didn't even get warm, while the E-V 18BX fractured and had to be RMA'd.
I love how these drivers sound/feel. They add the tactile sensation to the music that was almost there with the 180Bs, but now is really there in almost overbearing quantities with the CGN-1808s.
In a few days, I'll have the other two installed on the left side of the array, and then the difference should become even more obvious. I'm very pleased so far with the drivers and the results. And that with only 2060W per dual 18 cabinet. Throwing a larger amplifier at it in the near future will realize more of their potential.
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Topic: LAB-sub based on 18” seismic driver. (Read 13915 times)