FWIW I agree that to evaluate *the sound* of a speaker at a show is hit or miss at best. But to document a situation wherein a driver bottoms out once a certain combination of frequency and amplitude are met- that is a different matter. The room they had was not that large- we were not playing that loud a volume (leastwise not in my book anyway), yet the midrange driver buzzed loudly as it bottomed out repeatedly during the duration of the bass note.
I think the design path was: no crossover capacitor in series with the midrange, instead limit its excursion via an airtight box on the backside of the driver. The advantage of this approach is that crossover cap isn't there to mess up the sound of the mids and highs.
The downside is threefold: the midrange is electrically in parallel with the woofer, making this an inappropriate load for a tube amp (8 ohms in the mids and highs, 4 ohms in the bass; no tube amp will play the bass right on it as a result), no crossover on the midrange means that with enough bass excursion the driver can bottom out (which could damage the driver), and finally doppler-effect distortion from the midrange driver due to excessive excursion.
I don't recall the amp being used (it was transistor) but the speaker sounded good when otherwise within its limits.
I think the design path was: no crossover capacitor in series with the midrange, instead limit its excursion via an airtight box on the backside of the driver. The advantage of this approach is that crossover cap isn't there to mess up the sound of the mids and highs.
The downside is threefold: the midrange is electrically in parallel with the woofer, making this an inappropriate load for a tube amp (8 ohms in the mids and highs, 4 ohms in the bass; no tube amp will play the bass right on it as a result), no crossover on the midrange means that with enough bass excursion the driver can bottom out (which could damage the driver), and finally doppler-effect distortion from the midrange driver due to excessive excursion.
I don't recall the amp being used (it was transistor) but the speaker sounded good when otherwise within its limits.