OK, count me as one of the many that just love - love these speakers! I have the Quad ESL-63 and the ESL-988...and are my favorites!
And I trust what I am about to say is not to be taken as Quad Blasphemy!
Yeah, all those that say the removal of the dustcover does not change its sound at all.... and I agree. And understand I am not advocating the removal of the Dustcover as it will not improve the SQ....
But, that only can mean one thing - ready?
That because what you are really hearing is the DUSTCOVER, not the actual panels thru the Dustcover. The sound cannot pass thru the mylar Dustcover. The Dustcover is a measly 3um for this reason. Its Supersensitive Acoustic Coupling, not unlike a passive radiator in a box speaker.
So, if some agree that we are hearing the Dustcover only, the delay rings on the panel - how the sound propagation of these delay rings can somehow superimpose onto their exact locations on the Dustcover to do as they are designed to do... huh?
I have always wanted to build an infinite baffle type speaker (w/ tweeter, bass drivers, etc), and put a "box" around the baffle edge to be able to pull a 3um mylar on both sides to see if this speakers separate (front / back) airtight "Dustcovers" Acoustically couples all the low, mid, and high frequencies and and allows all the frequencies to emanate off one (well, two) common surface, just like the Quad or any other Electrostatic speaker...all with basic "box" drivers...
Go ahead, call me crazy.
And I trust what I am about to say is not to be taken as Quad Blasphemy!
Yeah, all those that say the removal of the dustcover does not change its sound at all.... and I agree. And understand I am not advocating the removal of the Dustcover as it will not improve the SQ....
But, that only can mean one thing - ready?
That because what you are really hearing is the DUSTCOVER, not the actual panels thru the Dustcover. The sound cannot pass thru the mylar Dustcover. The Dustcover is a measly 3um for this reason. Its Supersensitive Acoustic Coupling, not unlike a passive radiator in a box speaker.
So, if some agree that we are hearing the Dustcover only, the delay rings on the panel - how the sound propagation of these delay rings can somehow superimpose onto their exact locations on the Dustcover to do as they are designed to do... huh?
I have always wanted to build an infinite baffle type speaker (w/ tweeter, bass drivers, etc), and put a "box" around the baffle edge to be able to pull a 3um mylar on both sides to see if this speakers separate (front / back) airtight "Dustcovers" Acoustically couples all the low, mid, and high frequencies and and allows all the frequencies to emanate off one (well, two) common surface, just like the Quad or any other Electrostatic speaker...all with basic "box" drivers...
Go ahead, call me crazy.
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You may be sane 
Dali Dacapo was made that way: A 8’’ woofer push/ pull the foil. But: dust cover do not block the sound. That would be big business in a sound isolation context. I really dislike the dustcover as it add noise to music when aged / un- tensioned. Why do Quad need them when ML and others do not?
Dali Dacapo was made that way: A 8’’ woofer push/ pull the foil. But: dust cover do not block the sound. That would be big business in a sound isolation context. I really dislike the dustcover as it add noise to music when aged / un- tensioned. Why do Quad need them when ML and others do not?
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Do this , remove one speaker dust cover and listen for a change in the stereo image to see if it’s worth doing
I picked up some Soundlab R-1,s that had no dust covers other than a spandex black typical
Fabric and after what , 40 years since new , had zero dust on the surface of the mylar.
They looked like new so I don’t see why you couldn’t get rid of one layer although running them naked might lead to neuroses
I picked up some Soundlab R-1,s that had no dust covers other than a spandex black typical
Fabric and after what , 40 years since new , had zero dust on the surface of the mylar.
They looked like new so I don’t see why you couldn’t get rid of one layer although running them naked might lead to neuroses
Hello Sheldon!! I was hoping to snag you into this... you know these speakers better than anyone...
Your example reminds me of those Styrofoam panel speakers - a MacGyver'ed Electrostatic / Magneplanar type - Bertagni Speakers? Speakers only Helen Keller would love.
AVWERK - yeah Quads are the only Electrostatic speakers with Dustcovers as far as I know, and the only ones that have bare metal exposed stators to shock you with 72 x the voltage off your amp speaker leads (driven with all that added amperage)! Forget the dangerous bias voltages, the stator voltages will do far more damage! And that is most likely one of the main reasons for the Dustcovers - one more safety stop-gap...
Your example reminds me of those Styrofoam panel speakers - a MacGyver'ed Electrostatic / Magneplanar type - Bertagni Speakers? Speakers only Helen Keller would love.
AVWERK - yeah Quads are the only Electrostatic speakers with Dustcovers as far as I know, and the only ones that have bare metal exposed stators to shock you with 72 x the voltage off your amp speaker leads (driven with all that added amperage)! Forget the dangerous bias voltages, the stator voltages will do far more damage! And that is most likely one of the main reasons for the Dustcovers - one more safety stop-gap...
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For me, there is a contradiction within the Quad ESL 63 construction, and I understand everybody taking their's ESL 63 dust protective membranes away:
To my knowledge, the membrane of an ESL should be decdently stretched, and should moreover be damped very nearby on one side of it, to damp it's mid-frequencies resonances like standing waves and the like (artefacts which generates the so-called parasitic "mylar sound"). For this reason, inside the ESL63 there is a mesh attached to one of the stators side, providing this damping. So, well done, Quad ... But if this holds true as a generalization, then the same would go for any other potenially resonating membrane also, such as a (mylar or whatever) dustcover. The two dustcovers inside the ESL63 however are not provided with any damping. So these two dustcovers might indeed add theirs own acustic signatures.
I run my ESL63's without the original dustcovers. But for another reason than the suspictious and eventual, clandestine acoustic life of these membranes: I simply messed up two of them as I was disassembling my ESL's for the first time, for repairs/revision's sake. So I stripped away the two others also. And I replaced them by another dust brake: A very thin texile felt made of polywhatsoever. This material has a high internal damping, muffling, turning any possible resonance into heat. No mylar sound for shure.
The objection against this modification is evident. But this is ok for me, and I generously give away some 0.5 ... 1.0, and even 3 dB SPL @ 20kHz for the sake of the best of all worlds. My hearing actually decays at 12.5kHz. So for me, this might be some kind of hopefully successful bionic mod ...
To my knowledge, the membrane of an ESL should be decdently stretched, and should moreover be damped very nearby on one side of it, to damp it's mid-frequencies resonances like standing waves and the like (artefacts which generates the so-called parasitic "mylar sound"). For this reason, inside the ESL63 there is a mesh attached to one of the stators side, providing this damping. So, well done, Quad ... But if this holds true as a generalization, then the same would go for any other potenially resonating membrane also, such as a (mylar or whatever) dustcover. The two dustcovers inside the ESL63 however are not provided with any damping. So these two dustcovers might indeed add theirs own acustic signatures.
I run my ESL63's without the original dustcovers. But for another reason than the suspictious and eventual, clandestine acoustic life of these membranes: I simply messed up two of them as I was disassembling my ESL's for the first time, for repairs/revision's sake. So I stripped away the two others also. And I replaced them by another dust brake: A very thin texile felt made of polywhatsoever. This material has a high internal damping, muffling, turning any possible resonance into heat. No mylar sound for shure.
The objection against this modification is evident. But this is ok for me, and I generously give away some 0.5 ... 1.0, and even 3 dB SPL @ 20kHz for the sake of the best of all worlds. My hearing actually decays at 12.5kHz. So for me, this might be some kind of hopefully successful bionic mod ...
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Amazes me that people tie themselves in knots over which bit of the fairly-delicate Quads to excise in the pursuit of something ..else / ' a tad more' - when they could keep all the factory -protective thoughts (that few other ESls manufactures ever bothered with) - and merely add a dab of a dB here of there in the signal input to fix instead.
It's desperately easy these days, if that's what you think/measure/convince yourself that is what you want. And even easier to change or revert, if not!
It's desperately easy these days, if that's what you think/measure/convince yourself that is what you want. And even easier to change or revert, if not!
One thing there hasn't been much discussion of, is the short-lived damping of the dust covers. I've only seen these on a few ESL-63's, and I don't have a good feel for when they started or stopped supplying them. There is one of these on the front and back of each dust cover between the mid-panels and the bass-panels. All the grill support rods have cutouts for these dampers but only a few speakers had them.
http://quadesl.com/diyaudio/IMG_1061.JPG
Sheldon
http://quadesl.com/diyaudio/IMG_1061.JPG
Sheldon
This is interesting. So this is an add-on which would provide a damped mechanical junction between the outer, passive and protective parts (such as the two aluminium rods, the metal grid, the textile sock) and the inner, driven unit, and also between the two vertical rods. Not shure then which part(s) then was aimed at to damp/stiffen with this bracing? These vertical rods do not seem very stable by themselves either, and are wildly "singing" theirs own tune when naked (without the grid/sock) and e.g. when knocked with a screwdriver.
There must be an obvious reason why Quad fitted these additional devices later on within a limited series. So which flaw was that these devices were aiming at? A flaw known by Quad, which obviously seems persistent, after these connecting/damping devices were omitted again? So do you know more about the reason for this damped bracing, and about the reason of theirs removal? My ESL63's e.g. do not include these braces.
Maybe you also know something about further experiments to better damp and stiffen the inner assembly? I had the impression, that this assembly could indeed deserve some better, decently damped stiffening.
There must be an obvious reason why Quad fitted these additional devices later on within a limited series. So which flaw was that these devices were aiming at? A flaw known by Quad, which obviously seems persistent, after these connecting/damping devices were omitted again? So do you know more about the reason for this damped bracing, and about the reason of theirs removal? My ESL63's e.g. do not include these braces.
Maybe you also know something about further experiments to better damp and stiffen the inner assembly? I had the impression, that this assembly could indeed deserve some better, decently damped stiffening.
There is some amount of air (with its mass that can be calculated from the volume and specific density of air) captured between the diaphragm and the dust covers. That means the dust covers and the captured air move together with the diaphragm, at least at low frequencies. Does it mean the virtual mass of the diaphragm is increased by the mass of the captured air and by the mass of the dust covers themselves?
Or it doesn't matter, because air is moving anyway, whether there is dustcover present or it is not?
Or it doesn't matter, because air is moving anyway, whether there is dustcover present or it is not?
Practically it IS the dustcover that radiates the sound!
However is there a measurable difference on the polar plot?
If the cover is stretched with no wrinkles and do not rattle, I doubt there is.
Me myself has used them for 40years with no covers.. but I also do refurbish with new membranes and new coating. Not often though...
However is there a measurable difference on the polar plot?
If the cover is stretched with no wrinkles and do not rattle, I doubt there is.
Me myself has used them for 40years with no covers.. but I also do refurbish with new membranes and new coating. Not often though...
Foolling around last night with REW, for some fool reason, I lifted the paisley synthetic very light cloth that surrounds my ESL panels (just the front drape)... but didn't bother saving the plots.
The loss was about .7 to .9 dB across maybe 200 to 10kHz and beyond. In other words, noticeable but very small and not too freq dependant, at least as far as viewing FR plots by eye.
The Dayton-Wrights were enclosed in a heavy mylar sheet and gas. The result was pretty good, eh.
B.
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Hi
Membranes like the dustcovers behave as first-order low pass filters due to their mass - as a rough approximation the cutoff frequency is about 95 kHz divided by the thickness in microns - so about 30 kHz - well above audio range.
Walker famously performed an experiment with a large sheet - moving the membrane in front of his face when he was speaking and defying anyone to hear the difference.
Membranes like the dustcovers behave as first-order low pass filters due to their mass - as a rough approximation the cutoff frequency is about 95 kHz divided by the thickness in microns - so about 30 kHz - well above audio range.
Walker famously performed an experiment with a large sheet - moving the membrane in front of his face when he was speaking and defying anyone to hear the difference.
I think that is, with respect, far too simplistic.
A thin-enough lamella adds so little impedance that it is effectively 'not there' up to the break frequency @golfnut indicates. Note also - since that membrane isn't porous - it essentially adds lttle-or-no frictional damping/loss to sound propagating through it (where a thin fabric would!). That's the more interesting point.
A thin-enough lamella adds so little impedance that it is effectively 'not there' up to the break frequency @golfnut indicates. Note also - since that membrane isn't porous - it essentially adds lttle-or-no frictional damping/loss to sound propagating through it (where a thin fabric would!). That's the more interesting point.