OK, I think it's finally time to get my 57s worked on. After 40 years of ownership, one no longer powers up and there's some buzzing in one of the panels. I run them on a pair of Dynaco kit monos and a Spectral preamp from Richard Fryer decades ago. With a sub, I've loved these Quads.
I do plan on having a professional do the refurbishment, but am wondering what updates or modifications would good to do while we're at it.
I do plan on having a professional do the refurbishment, but am wondering what updates or modifications would good to do while we're at it.
I would first contact Sheldon Stokes in NH, who repairs Quads.
He is a member here as stokessd
His web site is:
https://www.quadesl.com/index.shtml
He is a member here as stokessd
His web site is:
https://www.quadesl.com/index.shtml
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Rayma, thanks for the kind words and reference.
I don't do any modifications to the quads beyond using modern materials and arguably higher precision build techniques. I have the luxury of taking my time and really getting panels to match because I'm producing one pair in two weeks, unlike the factory originally. I use 6 uM mylar for the treble panels and the dust covers like the originals, but I use a different conductive coating, which is formulated to have the same surface resistivity as the original quads had before it started to evaporate over time. I don't use metal rivets for the panels, I use nylon fasteners which eliminates one possible leak and corrosion path in the panels. I use a thinner mylar in the bass panel diaphragms instead of the saran material, it will last a lot longer than the saran and the thinner mylar has the same modulus and thus the same resonant frequency when properly tensioned. I use a similar saran material as the originals for the bass panel dust covers.
I wouldn't call these upgrades, just proper modern parts: I keep the EHT circuits the same but I replace the very early sketchy diodes with modern 3000PIV diodes. I replace the dead neon power indicators on the power supplies with little LED boards that fit inside the neon bulb holders. On the input side, I replace the sketchy banana jacks that quad used with Hirshman gold plated banana jacks (used on Naim equipment), no metal modifications needed. I replace the ancient and always drifted carbon comp resistors with Vishay VR68 high voltage resistors. I leave the capacitors unless they are bad (very rare), because I think they are a part of the voicing and thus charm of the speaker.
One thing that IS an upgrade is that I add a treble clamp board (see: https://getinthewoodchipper.com/?p=597) under the input transformer (unless the customer explicitly says not to). The vast majority of these speakers have no treble panel protection. This board is electrically identical to the quad clamp board installed in some later ESL's, but uses surface mount diodes and is small enough to tuck under the input transformer.
This quad fixing thing is just a hobby for me, so I'm glad to chat about this stuff at length. Ask questions...
Sheldon
I don't do any modifications to the quads beyond using modern materials and arguably higher precision build techniques. I have the luxury of taking my time and really getting panels to match because I'm producing one pair in two weeks, unlike the factory originally. I use 6 uM mylar for the treble panels and the dust covers like the originals, but I use a different conductive coating, which is formulated to have the same surface resistivity as the original quads had before it started to evaporate over time. I don't use metal rivets for the panels, I use nylon fasteners which eliminates one possible leak and corrosion path in the panels. I use a thinner mylar in the bass panel diaphragms instead of the saran material, it will last a lot longer than the saran and the thinner mylar has the same modulus and thus the same resonant frequency when properly tensioned. I use a similar saran material as the originals for the bass panel dust covers.
I wouldn't call these upgrades, just proper modern parts: I keep the EHT circuits the same but I replace the very early sketchy diodes with modern 3000PIV diodes. I replace the dead neon power indicators on the power supplies with little LED boards that fit inside the neon bulb holders. On the input side, I replace the sketchy banana jacks that quad used with Hirshman gold plated banana jacks (used on Naim equipment), no metal modifications needed. I replace the ancient and always drifted carbon comp resistors with Vishay VR68 high voltage resistors. I leave the capacitors unless they are bad (very rare), because I think they are a part of the voicing and thus charm of the speaker.
One thing that IS an upgrade is that I add a treble clamp board (see: https://getinthewoodchipper.com/?p=597) under the input transformer (unless the customer explicitly says not to). The vast majority of these speakers have no treble panel protection. This board is electrically identical to the quad clamp board installed in some later ESL's, but uses surface mount diodes and is small enough to tuck under the input transformer.
This quad fixing thing is just a hobby for me, so I'm glad to chat about this stuff at length. Ask questions...
Sheldon
