The speakers are Carver ALS Silver Editions pushed by a Carver PT-2400.
During an extended high volume session I witnessed a bright flash from behind one of the ALS Silvers immediately followed by loss of ribbon output from both speakers.
The fuses are intact so not sure what caused the bright flash.
No visible burn marks on or near the crossovers.
All 6 woofers still functioning but at a seemingly greatly reduced sound level. Have never heard the ALS Silvers without the ribbons so my idea of "reduced" woofer output may be the normal/correct output. Have done the 9v battery test on the woofers and they each push out.
By-passed the largest of the two black capacitors, but still nothing from the ribbons. This cap by-pass test also resulted in no output from the woofersd during the test. Woofers were responsive after the by-pass was removed.
Tried other amps, preamps and cables with the damaged ALS Silvers and still have the same problem.
Most likely the ribbons are fried but I'd appreciate being able to confirm this with something other than my ears.