This is a private website that will help you refurbish or repair your Quad ESL 57 electrostatic speakers. Or at least understand what is behind. Please read disclaimer first.
About 53150 Quad ESL 57 were produced over 26 years. Find the year of production for your Quad ESL 57 here below:
Source: http://www.audiocircuit.com/Home-Audio/Quad/ESL-57
Second source for serial number vs production year: https://www.lencoheaven.net/forum/index.php?topic=15705.0 (copied here just for archiving purpose, in case this becomes a broken link)
Need to repair your Quad ESL 57 ? You will find essential information in this document: