The ESL-63, ESL-988 and ESL-989 use identical and interchangeable stator panels. An ESL-989 costs about $13,000 Cdn, and has two panels fewer than a stacked ESL-63. Two pairs of ESL-63's can be bought for about about $4,000 Cdn, and as these images show, building your own stacked ESL-63's may be complicated, but it is not rocket science. Used Quad ESL 57 Floorstanding speakers for sale on 300+ second hand hifi sites & shops. Use Hifi Shark to monitor pricing and global availability "The Quad ESL-63 sets new standards in three important areas of loudspeaker technology, low distortion, low colouration and controlled directivity, resulting in a a level of performance limited solely by the quality of programme source.With Quad Esl-63's and a CD player less than 0,1% THD intrudes between the listener and the studio master tape, reproducing Quad ESL-63 Life is good sometimes Got them home, plugged them in, gave them an hour to warm up. Sadly there was some slight popping from one but I had to push on and hear what these could do. I had a Sansui BA-2000 hanging around so I used this to test them, I also used my Creek CD60 as a One only (not a pair) QUAD electrostatic ESL-63. Perfect exterior aspect. Perfect sound. No original box so a would prefer listening in my music room and pick-up if satisfied. If desire I can leave for free the other speaker which need repair. Included custom made bases. Avec le Quad ESL-63, l'excitation des deux modes horizontaux de resonnance de la piece est de 3 db inferieure a l'excitation d'une source omnidirectionnelle alors que les modes verticaux ne sont pas excites. Le rapport du son direct et du son reflechi est beaucoup plus grand avec une source en dipole. Quad ESL-63 Surface Resistivity. Below you see the ideal value of surface resistivity of a well coated diaphragm, measured with a calibrated DR.THIEDIG Milli-TO 2 with standardized VERMASON high resistance concentric ring electrode probe at V_M =1000V. The resistivity