Quad ESL 57 most common repairs

Arced treble panel

Symptoms: sparks visible in the dark at high volume, faint ticking or whistling noises. Bad distortion on high volume.

Be careful not to turn up the wick too far especially with big amplifiers. A clamp (protection) board will prevent the treble panel from blowing up. Once lightning strikes there is no other option but to refurbish the treble panel completely.

Read more about the Quad ESL treble panel

Weak high tension power supply

Symptoms: low sensitivity (amplifier has to be turned up), uneven loudness between left and right, no sound production at all.

A deteriorating power supply will make you turn up the amplifier further and further over time, until eventually the treble panel blows up. This phenomenon can sneak up on you unnoticed, so have them checked regularly.

Leaking bass panel, aged bass panel

Symptoms: low sensitivity, no deep bass, humming panel.

The very high operational voltage of the bass panel causes corrosion. Eventually this will lead to bad contacts and charge leakage. Another problem is aging of the diaphragm. This causes the resonance frequency of the bass panel to rise, and as a result the low bass production deteriorates. Some panels have almost no output below 100Hz, while a proper functioning Quad ESL will go down to about 40Hz.

Read more about the Quad ESL bass panel

Torn or slack dust covers

Symptoms: lowered sensitivity, slight buzzing from the panel, buzzing or other weird sounds during playback.

The dust cover protects the panel against dirt. Once dirt gets inside the panel it will build up a leakage path which causes the speaker to lose sensitivity. A slack dust cover can be the cause of buzzing or rattling noises during playback.