Ribbed vs Smooth diaphragms

[stevem]

Has anyone ever listened to and compared the sound of the ribbed versus smooth versions of a diaphragm? Are there any differences in the way they sound at moderate volume levels?

[duaneage]

THe main advantage or difference to the concentric ribs seems to be the suppression of breakup nodes. You would notice this on sine waves at high levels. The breakups are raise to higher frequencies and dispersion is improved.

[MJC]

I've got 7 L212s, 3 have the original ribbed cones and 4 have been reconed with smooth cones, done by JBL authorized service center.

I listen to music, quite often, in 7 channel stereo and I can't tell much, if any, difference between them. Producing much more of a difference is having a pair, I built, that are mirrored image. The drivers are offset 2" from the centerline of the baffle. Those produce a much better soundstage for stereo than the originals.

[toddalin]

And here, I had always thought that the "ribs" were for her pleasure, but these are usually on prophylactics, not diaphrams.

Sorry, couldn't resist.

[stevem]

Thanks all for your responses (even yours, toddalin ). I suppose the ribs are really there for high output applications to prevent break-up. They probably won't make a difference at typical home listening levels.