Quad ESL-63 loudspeaker Follow-Up November 1983
Our full report on the Quad ESL-63 electrostatic loudspeaker last month was inconclusive because (1) our first two samples of it broke down and started arcing, protection circuit or not, and (2) 1 had the feeling that there must be amplifiers which would them sound better than I had them sound to date.
Since then, we obtained two more of the speakers; here's what we found:
On most program material, the '63s would play cleanly at levels up to 98dB SPL, measured at 1 meter on-axis. Above that, one speaker's protection started closing down; the other's did not. This was the same condition we had experienced with the first pair, followed by the diaphragm breakdown of the "ailing" speaker, and shortly thereafter by breakdown of the non-ailing one.
On material with deep, heavy bass, which included many Compact Discs, that same speaker's protection circuitry shut down at levels measured at around 86dB, which isn't exactly soft but it won't blow you out of the room either. With Telarc's CD of the Firebird, shutdown in that speaker occurred on deep bass at the same measured level, but because that recording has much more dynamic range and bass on it than anything else we have on CD, the 86dB figure put the rest of the program at a level lower than most people are going to want to listen at.
Our conclusion: Regardless of the sonic merits it may possess, this system simply does not have the power-handling capability needed to cope with some of the program material available now on both CD and the better analog discs, let alone what tomorrow may bring. And our experience indicated that the protection circuits cannot always be relied on to protect the speakers from permanent damage due to momentary overload. Crossing over to an external subwoofer would improve the '63s' ability to handle high signal levels, but not by much more than 4 to 6dB. Without a subwoofer, we can recommend this system only to those people who listen to symphonic music at significantly lower than live-music levels, or to people whose tastes run to chamber or small-group music. With a subwoofer, the speakers do significantly better, but still will not reproduce an orchestra at close to a live-music level.
In the light of the foregoing, our experience with '63s and the EAR amplifiers may seem irrelevant, but we'll relate them anyway.
Because the EAR amplifiers had to be returned to the manufacturer (who needed them for CES) at the very time we set up our second pair of '63s, we were not able to audition this combination for more than a couple of hours. This was, however, long enough to confirm my suspicions that the "right" amplifier would make these speakers take off and fly! The sound was simply superb, in every respect. Which is all the more frustrating in view of our findings about the speaker's maximum-output limitations.
Damn! I had such high hopes for the '63s.—J. Gordon Holt