Refurbing Quad ESL-57....Some Queries!

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Hello,

I am in the processs of refrubising my Quad ESL-57 electrostatic speakers.

I have fitted new EHT boards and devices to them (plus corona lacquer due to HV), as the components on the old boards are not so hot anyway and degrade over 20 years!

The treble panels look fine and also the bass. No arcing etc. But I am worried about the dust covers in particular. Have ordered new dust covers.

Couple of things.

Have noticed wrinkles on the treble panel dust covers though no holes and it ain't that bad being honest. May try a hair dryer first, then a heatgun after if needed. Have read the that the treble panal dust covers are the most important to get smooth otherwise yiou will get rattles at HF.

One one of the ELS57's there is no dust covers for the bass panels!. So this needs sorted out asap. Have also noticed that around the rivets on the bass panel it looks like some leakage etc
Almost like fluid. Wondering whether to use isoprop alcohol (IPA)to clean these up before fitting the dust covers.

Any advice/help appreciatted!

Kevin
 
Fanuc said:
I have fitted new EHT boards and devices to them (plus corona lacquer due to HV), as the components on the old boards are not so hot anyway and degrade over 20 years!
Make sure you leave no sharp points on the solder joints (like pieces of wire and such). Round and smooth is what you're looking for.

Have noticed wrinkles on the treble panel dust covers though no holes and it ain't that bad being honest. May try a hair dryer first, then a heatgun after if needed.

A hair dryer won't do much, you need a heatgun to shrink the mylar. Can you post a pic? If it's not too bad I would not risk burning a hole in it. A couple of small wrinkels around the edge is not necessarily a problem.

One one of the ELS57's there is no dust covers for the bass panels!. So this needs sorted out asap. Have also noticed that around the rivets on the bass panel it looks like some leakage etc
Almost like fluid. Wondering whether to use isoprop alcohol (IPA)to clean these up before fitting the dust covers.

You can use IPA safely on the panels but in my experience it does not help you much. Don't use aceton here unless you want to remove the paint (which it will for sure).
Thoroughly vacuum the panels and hook them up. Let them charge for a couple of hours and then carefully listen for strange noises like plops, hissing or ticking. If it's silent then you're probably in the clear.

When you replace the dustcovers, don't tension them untill you have repositioned the panels in the frame. What materials did you order?
 
Hello,

Have attached an image of the back of the els57. What I am concerned about is there is no dust covers on the bass panels, but also look at the rivets. Doesn't appear to be bad corrosion but there is some leakage I suspect.

Was wondering if IPA would clean this up. With new EHT boards being installed I guess there is some leakage from the diaphragm to the grounded rivets!.

In the treble panel, the picture does not show the small ripples in the centre of the panel, but I may try a heatgun to smooth it off. Just start with low temperature at first. PS. there isn't any holes etc in the treble panel dust covers.

Advice appreciatted.

Kevin
 
Hello,

Have attached an image of the back of the els57. What I am concerned about is there is no dust covers on the bass panels, but also look at the rivets. Doesn't appear to be bad corrosion but there is some leakage I suspect.

Was wondering if IPA would clean this up. With new EHT boards being installed I guess there is some leakage from the diaphragm to the grounded rivets!.

In the treble panel, the picture does not show the small ripples in the centre of the panel, but I may try a heatgun to smooth it off. Just start with low temperature at first. PS. there isn't any holes etc in the treble panel dust covers.

Advice appreciatted.
 
Hello,

Have attached an image of the back of the els57. What I am concerned about is there is no dust covers on the bass panels, but also look at the rivets. Doesn't appear to be bad corrosion but there is some leakage I suspect.

Was wondering if IPA would clean this up. With new EHT boards being installed I guess there is some leakage from the diaphragm to the grounded rivets!.

In the treble panel, the picture does not show the small ripples in the centre of the panel, but I may try a heatgun to smooth it off. Just start with low temperature at first. PS. there isn't any holes etc in the treble panel dust covers.

Advice appreciatted.

Kevin
 
Hello,

Have attached an image of the back of the els57. What I am concerned about is there is no dust covers on the bass panels, but also look at the rivets. Doesn't appear to be bad corrosion but there is some leakage I suspect.

Was wondering if IPA would clean this up. With new EHT boards being installed I guess there is some leakage from the diaphragm to the grounded rivets!.

In the treble panel, the picture does not show the small ripples in the centre of the panel, but I may try a heatgun to smooth it off. Just start with low temperature at first. PS. there isn't any holes etc in the treble panel dust covers.

Advice appreciatted.

Kevin
 

Attachments

  • dscf0003.jpg
    dscf0003.jpg
    97.2 KB · Views: 396
Seraph said:
Hello

Reading your posts with interest contemplating delving into my own 57's at some point. Thought I'd bring to your attention that the image referenced in your previous post appears to have been inadvertently left off.

Regards

seraph

Hi,

Sorry about that. I am using an "erratic" wireless internet link at the moment (at least until tomorrow) and it kept bombing out when uploading the image. Just noticed there is a duplicate post also! :)

Kevin
 
What concerns me for people in the know about refurbing Quad ELS57's etc is the liquid like substance around the rivets on the bass panel, if you look closely.

Clean it off with Isoprop Alcohol ? and get the hoover out etc?

In fact some people think the Quads sound better without the dust covers ( higher SPL I think? ) or more transparent sound etc. Though I have no opinion to offer on this personally and would prefer to put the dust covers back on. £32 for a kit (rolls) - apparently it could do 10 - 20 quads!
 
Hi Fanuc,

Looks like a bit of coloration around the rivets, I've seen it before and it's not necessarily a problem. I've seen much much worse.

First you need to find out if you have a problem. Vacuum it out, hook it up and listen for strange noises. If you have a high voltage probe check that the HT is up to where it should be.

Those rivets are not grounded, in fact there is a very high chance of them being connected to the bass panel HT which is +6KV.

The foto is too low quality to say anything about the treble panel dustcover. I do notice a small black spot on the the treble panel right in the middle which could be caused by arcing. Perhaps you can make some close-up pictures?

What material did you buy for the dustcovers?
 
Hi Fanuc,

I also restored some Quad ESLs myself. As arend-jan suggested, have a closer look (and smell!) at the middle of the treble panel. Trebles go wrong frequently by arcing. Bass panels never. This is because the metallization of the treble stators is inside, so the diaphragm may touch the stator when it is overdriven. The metallization of the bass stators is outside.

If the treble has a burnt diaphragm, the only cure is to replace it.

Never use the bass panels without dust cover. A dust bridge will build up very soon (or invisible soot particles from the air), it will arc, and it is nearly impossible to clean the inner side of the stators and the diphragm.

A simple method for checking the leaking is to insert a small neon lamp in series at the HV supply. I use separate lamps for both bass panels and one for the treble panel. If there is any leaking, the lamp will glow or blink. Some 80 Volt is falling on the lamp, which is negligible to 6 kV or 1.5 kV. I installed the lamps permanently - they improve the sound.

Laszlo
 

Attachments

  • neon_lamp.jpg
    neon_lamp.jpg
    40.3 KB · Views: 272
oshifis said:
A simple method for checking the leaking is to insert a small neon lamp in series at the HV supply.

This is indeed a cheap and fine working leakage indicator, thanks for bringing that up!

I installed the lamps permanently - they improve the sound.

Personally I have never noticed any change in sound with or without the bulb. Nor can I find a reason that it should. Some have argued that the bulb would 'disconnect' the HT from the panel which IMO is not happening. But I don't think it will hurt to leave the bulb in either.
 
It is best to use three neon bulbs. Connect one in series with each HT wire that is going to the center binding post of each panel. I soldered one leg of the bulbs on the HT pins on the rectifier block, and the HT wires are attached to the other leg of the bulbs. If you wish, add some binding posts, becase the legs stretched by the HT wires break easily.
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.