Welcome! Need support, you got it. Or share your ideas and experiences.
Return to Planar Speaker Asylum
71.141.146.68
In Reply to: What to look for when buying a pair of ESL-57s posted by arend-jan on December 5, 2006 at 06:30:37:
I'll give you 3 points in order of difficulty:1. The speakers need to have been plugged in for a few hours. This insures all the panels are properly charged. Move the two speakers as close to each other as possible without touching. They should be in the same plane. Then, with no amplifier hooked up, put your best ear (!) close to each grill. You should hear nothing. No pops, no ticks, no spitting, no hum—silence.
2. Connect amplification, including an fm tuner. Disable the tuner's muting & turn to interstation noise. Settle back & listen (normal volume or lower will do nicely) to each speaker—1st one than the other—using the balance control on the preamplifier. Dissimilar sensitivity & frequency response are what to listen for. Takes only a few seconds so repeat the drill several times until you get the hang of it.
3. Remove the back screen of each ESL. Look for torn dust covers (mainly bass panels) & arced spots on the backs of the treble panels. This last task takes a little practice because the dust covers are so reflective. Lift up the felt strips as far as you can & take your time looking for a tell-tale burned spot. If you think you see one (or more) but you aren't sure, the next step is to take off the front grills. It's a pain but there is really no substitute for a complete visual assessment. BTW, only t. panels arc so don't waste time trying to glean something by looking at the bass panels. After listening for hum, the b. panels are best assessed by determining whether they load down the EHT block (high voltage probe & meter required) more than they should. At this point you should also take measurements of the block itself. If you don't understand these last procedures have a qualified person comfortable around high voltages do the work. If any of this stuff isn't clear you can email me privately.
Sandro Boccara
Follow Ups:
Thank you Sandro for these very helpfull tips!I understand completely and feel more confident in making a proper assessment now. The seller told me one was playing a little louder than the other. Could this be because of the large difference in serial numbers or is it likely to be something that can be cured?
Thanks again,
Serial numbers are a deversion from the real issues. At this point I'd want to open up the back of the reduced output speaker to check the EHT block & panels with my meter/probe (see my previous post). Sorry but it's the best way to diagnose that problem. Frankly, these are the likely possibilities: a bad EHT block ($125.00) and/or one or more of the 3 panels requires rebuilding (approx. $275-300 per panel).Sandro
Hello,The age difference of the panels could have quite a marked impact...it's documented on the one thing audio site that that the panels performance deteriorates gradually for a few years initially (losing the diaphragm coating, I think). That said, I have heard a non-matched pair that definitely had treble panels of widely differing vintages that still sounded pretty good in a stereo set.
If you can make a visual inspection with grilles off, definitely check closely for signs of arcing on treble panels...one arced treble panel out of the pair would make for a big difference in output.
A severely leaky panel (or set of panels) could drain the EHT a lot, and cause some loss of output...in that case you'd hear some funny noises rather than the silence described in another earlier post.
It is possible that there is a weak-ish EHT cascade on one speaker, which would be relatively easy (and cheap) to fix. But in my experience leaky bass panels and weak EHT cascades often go hand in hand (I guess the EHT cascade is worked that much harder by a leaky set of panels).
Probably best to go for a matching pair that meet the criteria set out by Dr Quad, unless you can get them cheap enough to make it worthwhile having them rebuilt OR if you fancy rebuilding them yourself. If you think about rebuilding yourself there is plenty of info around, but do not underestimate the amount of time it takes to get to grips with everything, and then to put it into practise successfully.
Hope that is helpful, good luck! 57's are definitely worth the effort.
...These are sooooo old that the drop in efficiency that one does indeed observer in "older" panels has happened long ago whether the panels have been in use or not. It's caused by inevitable oxidation of the nylon coating over the years. Accelerated, albeit, byt exposure to low levels of ozone if the speaker has been in use.I'd be betting that the EHT units have gone bye-byes and you should negotiate the price down accordingly.
Yes, the ESL when well and fully rebuilt is a treasure you will not want to let go.
One thing to consider is that although the serial numbers differ widely, it is possible that both speakers might have had repairs done as a stereo pair at some point. The last pair I bought a pair (sn 5## and 11,### or so) had matching treble panels, clamp boards and EHT blocks. This was a pleasant surprise....the bass panels all required rebuilds though.I was lucky on that occasion - but only a detailed examination could reveal that sort of good fortune, unless the seller can provide more information.
This post is made possible by the generous support of people like you and our sponsors: