Warning
Treble panels/front of bass panels
Rear
bass Danel dust cover
Final
task -shrinking the polymer
One Thing Audio
Quad
Instructions, New dustcovers for ESL 57
WARNING: Electrostatic loudspeakers can remain charged up for anything up to two hours after being unplugged from the mains. If possible, leave them overnight to discharge. But if a 'quick' discharge is required, short the HT (any connection on the HT line central rear) down to speaker chasis (ie. metal frame or spring grille contacts, bottom of speaker). NEVER work on a speaker while it is plugged into an amplifier, even if the amplifier is assumed to be switched off. Basic electronic skills and technical competence are assumed for anyone reading these notes.
Treble panels/front of bass panels 
With a Stanley knife, cut off the old dust cover complete with its wooden frame. Note: if paint has been sprayed over the edge of the periphery tape, remove a few inches of this with cellulose thinners, Acetone etc. so you can clearly see where to insert the blade of the Stanley knife.
Remove old dust cover and clean remnants of dust cover/glue from the frame with a coarse piece of glass paper or similar. To affix new dust cover material, apply contact adhesive (Bostik, Evostik or similar) to surface of frame and allow to 'go tacky' for 5 minutes or so. Lay an oversized piece of the new dust cover material on to a flat surface (tabletop etc.) and sellotape the four comers to take up the 'slack'. Then simply lay the glued frame on top of it. Lift, and cut off the excess overlapping material.
Note: In the latest kits, a small quantity of 3 micron PET film has been included for use on the FRONT of the treble panel, this offering more 'transparency' for the critical mid and high frequencies.
This is slightly more complicated, as it is necessary to deal with the connecting wires and terminal block. The 3 wires (panel front drive, rear drive & HT) pass through 3 holes in the terminal block and are soldered to the appropriate terminal post, to which the speaker's internal wiring is also soldered.
First, unwind the remnants of the old wires from the terminal posts -a pair of pointed-nose pliers or tweezers will do the job while heat is being applied to the terminal. If the speaker's wires have already been removed from the terminals, proceed to 'unwind' the 3 wires feeding into the panel. You should now have 3 clean (but tinned) solder terminals at the head of each post. Cut round the dust cover frame to free it from the drive panel, but DO NOT allow the center rear-drive wire to 'tug' on its solder tag. Unfortunately, in the de-soldering process the wire insulation will have swelled making it impossible to pull the wire through the holes. There are two solutions: either cut away about 5 mm of insulation from the 3 wires just below the soldered ends -in which case the wires should now pull through -or simply snip off the wires above (or below if you can reach them) the terminal block. This will, of course, leave the wires short when you come to reconnect -but it is an easy matter to extend the 3 wires with 3 short and neat thin wire extensions, ideally finishing off with short lengths of heat-shrink tubing (but this is not important: it won't matter if the thin wires are exposed).
Before re-mounting the solder terminal onto the rear frame, place a length of the special polythene tape provided across the bottom of the frame (see illustration). This will prevent melting the new dust cover when a heat gun Is applied to the heat-shrink tubing over the HT terminal when the panel is finally reinstalled. Affix the terminal block to the frame with the old screws, or if they are in poor condition, use 2 x 12 mm M3 nuts and screws. With a soldering iron, burn 3 holes through the dust cover in line with the terminal block holes through which the wires can pass.
The above method of using the 'old' wires is favoured by DIYers because it avoids soldering new wires direct to the electrode solder tags. But for those with a little more courage (or experience) the following tips are given which will make a more 'professional' job.
Pre-cut lengths of each coloured wire are supplied with the kit (more can be ordered if required -see entry on site). Black is for the front electrode connection, white for the rear, and red for the HT.
The black wire (front electrode) passes through a hole in the panel. Place a length of heat-shrink tubing (provided) over the part of the wire which passes through the panel -extra insulation is needed here. It is perfectly straightforward to solder new wires directly to the electrode solder tags if sensible precautions are taken.
First, to avoid splashing solder onto the diaphragm (beads of hot solder can easily pass through the holes) place a sheet of paper -or better still, a square of cardboard -over the bottom six inches or so of the panel through which a small hole has been cut for the panel's solder tag to pass through. Find some flat metal object you can press against the solder tag's rivet to drain away any excessive heat. THIS IS IMPORTANT: without the use of such a heat sink the electrode plastic will melt and 'shed' the solder tag. (Oh -if we had £1 for every bass panel which has passed our way -minus one or both electrode solder tags!) The heat sink will be copper or aluminium (both goodish heat absorbers) and the surface which is pressed against the tag rivet should be cleaned with wire wool. A smear of heat sink compound on one (or both) surfaces will help further.
It is suggested -to keep the heat application to a minimum -that the old wires are closely snipped off the terminal. The soldering iron should be at its hottest temperature. If desired, get another person to press the heat sink down firmly onto the rivet and hold it still while you do the soldering. DO NOT try to solder in the conventional manner- i.e., applying multicore solder to the tip of the iron whilst applying both to the joint. It is desirable to work quicker than this. Rather, smear some resin flux onto the panel's solder tag. Prepare a length of wire (already pre-cut in the package) by removing 3 mm of insulation and tinning the end. Now simply hold the tinned end against the panel's flux-treated solder tag and apply the iron. Don't be apprehensive or hesitant at this stage -if you have taken the above precautions, you can make a perfectly normal soldered joint. The heat sink will absorb any excessive heat. BUT -if you are unhappy with the joint (or think it looks 'dry') don't have another go immediately. Leave for a minute or so for all the heat to drain away -then try again.
Now simply pass the wires through the 3 holes and re-solder onto the terminal posts. Hold the front and rear covers in place by sticking short lengths of ordinary sellotape from front to rear, pulling the 'sandwich' as tightly together as possible. Then use the thick polythene tape provided to tape round the frame periphery -twice round is advised. A short length of the colourless heat-shrink tubing should be placed over the HT terminal once the panel is reinstalled.
Final task -shrinking the polymer
A hair-dryer will do the job if run at its highest temperature. A heat-gun is quicker and more effective, but as these run at higher temperatures, care must be taken. Excessive concentration of heat in one spot will melt the material. Hold the nozzle about 7/8 inches away from the cover and always keep the gun moving. You will see the material shrink -don't dwell on a spot once this has happened, but keep moving across the area of the cover until the entire cover is under tension. (Note: if care is exercised, it is possible to gently 'coax' the cover -eliminating any creases still visible -into greater tension without damaging the material). Have a go: the worst that can happen is that you will have to do the job all over again, but we have deliberately supplied enough material to cope with several pairs of 57s. What have you got to lose?
