History on ohm A's and F's.

Spiked,

IIRC, the doppler effect is the pitch shift that results when a sound source moves toward (or away) from you (at relatively low speed). A train whistle is the usual example. If a speaker's driver produced this problem, I'd think that you would get a slight "quiver" around a vocalist's pitch. Given the short distance (and oscillating path) that a driver travels, it would be barely audible at worst.

I wonder why you are ascribing the "gargling" vocal problem you heard specifically to this? There are surely other possible wayward behaviors that would cause what you heard - a flaw in the surround comes to mind. I'm not sure that this is ever audible in loudspeakers, even if the drivers are pointed at you and "qualify" for doppler shift. However, since the Walsh driver moves vertically, it would seem even less applicable. The horizontal "travel" on a Walsh driver is virtually nil. What's your thinking on this one?

Marty

Sure sounds like IM distortion to me!

Yes, However I believe that the IM distortion is the end result which is preceded by doppler frequency shifts of midrange audio frequencies produced by the cone that is also producing low audio frequencies. Wonder how this is mitigated in Mr. Harder's updated designs? I noted this issue with both older F's and in a brand spankin' new pair straight outta Taffe Place. I have wondered if insufficient wave termination might also add to this effect. The newer F style versions appear to have the same surface pattern and termination materials as the original (an assumption). I wonder if other patterns have been used or if there is a way to calculate them. Anyone applied Bud Purvines's enABL process? Does this work?

Spike,

Which Marley live recording?

Were the Fs possibly being over-driven? It was not hard to do this with Fs from what I have heard.

If the source was vinyl in particular, was it possible that low frequency noise (rumble, etc.) was present? That might contribute significantly to a problem as you describe if so.

Hi Mapman,
It is the Babylon by Bus album, specifically remembering "Punky Reggae Party" as the worst offender, which I had recorded to maxell XLII tape with an Akai glass head tape deck using DBX NR. Shouldn't have been any appreciable rumble since it went straight from Technics SL series TT, w/ Ortofon Concorde cartridge through an Apt-Holman preamp with subsonic filter on, into the deck. I had a pair of Dynaco ST-400 bridged amps driving the F's, so probably (definitely) no clipping. I am sure the soft spider contributed to the excessive cone movements, but when the bass notes hit, you could see those cones really dance, and that's when the distortion set in.