We have found the best Quad is the one in the listening room!
For the original ESL best performance is achieved by leaving them energized all the time. The high surface resistance of the conductive coating on the diaphragm causes a long charge time. In dry environments, this can take a day or more to fully charge. Leaving the original ESL energized continuously assures the speaker is at optimum performance at all times. The ESL63 may be turned off when not in use. The low surface resistance of the conductive coating on the diaphragm allows the ESL63 to energize and fully stabilize in less than 10 seconds. During power outages or electrical storms both speakers should be de-energized and the power cord removed from the wall outlet.
Both speakers require an amplifier that is highly stable into reactive loads and has a large, stable power supply. We have found that amplifiers in the 50-100 watt range are ideal for either speaker. Protection circuitry in the speaker will allow the user to choose amplifiers of any output without fear of damage. Dual mono designs will perform the best with both speakers.
Both Quads sound best in a near-field listening set-up. Spread the speakers as wide apart as possible; placing them near the sidewalls is no problem. Make sure they are at least 2-3' from the rear wall, adjust toe-in so the speaker is on axis to your ears, sit back and enjoy. Minor adjustments to toe-in should be made to "lock-in" the soundstage.
Yes, both speakers will sound better with the protective screens and dust covers removed. There is a price to be paid for such modifications to either speaker. Removal of the protective screens exposes the users to potentially LETHAL voltages. Removal of the dust covers will dramatically shorten element life. We do not feel the performance improvement is worth the potential danger of damage to the speaker or killing the user!
The Quad ESL98 and ESL05 series speakers are near clones of the original ESL63. Electrostatic elements, audio transformers, electronics are identical. The frame of the ESL98 series is virtually the same as the ESL63 frame. The ESL05 series does have a much improved frame structure versus either the ESL63 or 98 series. The major difference is in the directivity achieved with the delay line. ESL98 and ESL05 series speakers have altered the frequency response pattern, increasing the high frequency energy of the speaker. While the ESL63 is essentially flat to 18kHz; both the ESL98 and ESL05 speakers have a rising top end. Build quality between all the speakers is essentially the same. The ESL63 electronics layout is modular in nature versus the single motherboard approach of the ESL98 and ESL05 speakers.
No. Power cords have no sonic effect on a properly functioning Quad.

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