I think about some comparative testing of different materials for the ESL63 dust protection purpose.
Background: Quite many posts in different threads are related to the dust protection film and it's potential impact on the impulse response of the assembled ESL63 speaker. Some advocate to omit this dust protection altogether, some claim no influence of the two film sheets, some fit them hands down for practical reasons while trading in a potential slight sonic drawback. I therefore would like to perform some comparative, more theoretical, yet systematic testing of some standard and also of some non-standard materials for dust protection. If the test succeeds, then a more precise weighting/compromizing might become possible for every of the tested materials.
For my refitted ESL63, I used Vliesseline stich n tear, which showed some quite pleasing results while measuring. I do not claim that it is the best compromize, and I don't know how it performs against other options. So I would like to test this product against some experimantal 100% PET felt sheets/panels and of course also against different brands and strengths of standard film ("standard" == routinely used as dust protection). It would also be interesting to test some, say 3 different brands and strengths of standardly fitted films one against the other.
To perform these tests, I need some samples. So my question/request to the pro ESL63 rebuilders here in this forum is: Are some of you experts willing to send me 1.5m of yours preferred and routinely fitted dust protection film? Of course I would pay for the material and shipping. Please contact me per PM for my shipping address and for the mode of payment. I will perform this test if I can get 2 or 3 samples.
Test setup would include the absorbtive and the reflective property of each dust protector candidate (DPC) under test. I imagine to place everything into a line:
Sound source - Mic - DPC - Flat/plane surface as near-perfect acoustic reflector. The mic would therefore catch first the wavefront of the direct sound, then the wavefront reflected by the DPC, then the reflected and twice partly absorbed wavefront. Reflected by the acoustic reflecting plane, absorbed by the DPC.
Any comments welcome.
Background: Quite many posts in different threads are related to the dust protection film and it's potential impact on the impulse response of the assembled ESL63 speaker. Some advocate to omit this dust protection altogether, some claim no influence of the two film sheets, some fit them hands down for practical reasons while trading in a potential slight sonic drawback. I therefore would like to perform some comparative, more theoretical, yet systematic testing of some standard and also of some non-standard materials for dust protection. If the test succeeds, then a more precise weighting/compromizing might become possible for every of the tested materials.
For my refitted ESL63, I used Vliesseline stich n tear, which showed some quite pleasing results while measuring. I do not claim that it is the best compromize, and I don't know how it performs against other options. So I would like to test this product against some experimantal 100% PET felt sheets/panels and of course also against different brands and strengths of standard film ("standard" == routinely used as dust protection). It would also be interesting to test some, say 3 different brands and strengths of standardly fitted films one against the other.
To perform these tests, I need some samples. So my question/request to the pro ESL63 rebuilders here in this forum is: Are some of you experts willing to send me 1.5m of yours preferred and routinely fitted dust protection film? Of course I would pay for the material and shipping. Please contact me per PM for my shipping address and for the mode of payment. I will perform this test if I can get 2 or 3 samples.
Test setup would include the absorbtive and the reflective property of each dust protector candidate (DPC) under test. I imagine to place everything into a line:
Sound source - Mic - DPC - Flat/plane surface as near-perfect acoustic reflector. The mic would therefore catch first the wavefront of the direct sound, then the wavefront reflected by the DPC, then the reflected and twice partly absorbed wavefront. Reflected by the acoustic reflecting plane, absorbed by the DPC.
Any comments welcome.
I had 63's for many years - rebuilt a slew of panels to keep them going. One thing NOT mentioned in discussion was that ti me it's MANDATORY to have them in an air-conditioned environment, AND turn them off if your not going to listen for a while. The conductive coatings are hydroscopic and will accumulate charge hot spots if left on in a humid environment.
That said, if you are in a relatively dry environment and don't smoke, you can easily get by WITHOUT the dust covers. If need be, brush the surface every so often with a soft/clean cloth.
That said, if you are in a relatively dry environment and don't smoke, you can easily get by WITHOUT the dust covers. If need be, brush the surface every so often with a soft/clean cloth.
Your post is completely off-topic, but maybe it's a bit also by my fault. My fault, because I unfortunately wrote, as the very last sentence of my first post:
"any comments welcome".
Obviously, I should not have done so. Because, as written, it's an way too general invitation, agreed. It's an invitation maybe also to talk about anything from the kitchen sink design to the fakeness or not of the apollo program. Why not ...
The subject you rise of omitting the dust protection is also not new. It has been discussed over and over and over again in other threads. But you rise a point which is new to me: The assumption about the hygroscopic properties of the coatings, which indeed might be interesting as such. I will not comment on that one, because, once again, this topic is not in the center of interest here. I do not intend a discussion about coatings. So you may please open another and own thread to discuss eventual hygroscopic properties of coatings and the best potential workarounds.
I am purposely very direct in writing so and hope this is not offending. I simply don't want this thread bloated with exostuff right from the beginning. And I hope this directness of mine is not intimidating any potential posters interested in and wanting to contribute to the subject I rose.
So let me be have a 2nd try and thereby be a bit more precise:
Comments about the utility of acoustically test assessing dust protection film materials for ESL's and comments about the mentionned test setup are welcome (what a mouthful of a sentence ...).
🙂
"any comments welcome".
Obviously, I should not have done so. Because, as written, it's an way too general invitation, agreed. It's an invitation maybe also to talk about anything from the kitchen sink design to the fakeness or not of the apollo program. Why not ...
The subject you rise of omitting the dust protection is also not new. It has been discussed over and over and over again in other threads. But you rise a point which is new to me: The assumption about the hygroscopic properties of the coatings, which indeed might be interesting as such. I will not comment on that one, because, once again, this topic is not in the center of interest here. I do not intend a discussion about coatings. So you may please open another and own thread to discuss eventual hygroscopic properties of coatings and the best potential workarounds.
I am purposely very direct in writing so and hope this is not offending. I simply don't want this thread bloated with exostuff right from the beginning. And I hope this directness of mine is not intimidating any potential posters interested in and wanting to contribute to the subject I rose.
So let me be have a 2nd try and thereby be a bit more precise:
Comments about the utility of acoustically test assessing dust protection film materials for ESL's and comments about the mentionned test setup are welcome (what a mouthful of a sentence ...).
🙂
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I woud be interested in the linearity of damping materials (in regards to amplitude). I think that it might explain the perception of dull sound some people experience with (over?-) dampened panels.
Https://www.mdpi.com/2076-3417/11/16/7713
This research paper hints to nonlineair behaviour of airchannels etc. Closer to the soundsource, like the mesh in quad speakers, the effect may be more pronounced.
This research paper hints to nonlineair behaviour of airchannels etc. Closer to the soundsource, like the mesh in quad speakers, the effect may be more pronounced.
You raise an interesting subject. ESL63 are a quite complex sandwich in terms of reflections and absorbtion (== damping):
First the central membrane
Then a situatively both symmetric and asymmetric cushion of air of variable thickness of approx. symmetric 2mm when idle and approx. asymmetric 0.5mm/3.5mm when at max. amplitude.
Then the asymmetrically meshed/non meshed perforated stators, leading to a compression ratio of approx. 1:2 and trapping some air in holes of lenghts of 1.2mm (== thickness of the stator)
Then the array of all the multiple sqare and open pipes of approx. 25mm lenght formed by the stator carriers structure
Then a layer of air
Then the dust protection film
Then another layer of air
Then the metal grid
Then the textile sock
Then finally the free ambient air
So where occurs "panel damping"? I guess and potentially bit everywhere. And also reflections might occur a bit everywhere within this complex sandwich. Think all these abrupt changes of acoustic impedance on the first +-7cm (centerline) to +-4cm (laterally) of the wave's pathway. This is way too complex for me to understand at once and as a whole, and this is why I would understand at least the acoustic properties of one single of all these structures: The behavior of the dust protector. In an acoustically more or less linear, simple and isolated environment such as in the mentionned test setup.
If by choosing a best suited material for the dust protection you could, in interaction with the other parts of the sandwich further linearize the whole sound wave transfer, then it could have been worth the effort to investigate on this single pair of sandwiched dust protective films or structures.
First the central membrane
Then a situatively both symmetric and asymmetric cushion of air of variable thickness of approx. symmetric 2mm when idle and approx. asymmetric 0.5mm/3.5mm when at max. amplitude.
Then the asymmetrically meshed/non meshed perforated stators, leading to a compression ratio of approx. 1:2 and trapping some air in holes of lenghts of 1.2mm (== thickness of the stator)
Then the array of all the multiple sqare and open pipes of approx. 25mm lenght formed by the stator carriers structure
Then a layer of air
Then the dust protection film
Then another layer of air
Then the metal grid
Then the textile sock
Then finally the free ambient air
So where occurs "panel damping"? I guess and potentially bit everywhere. And also reflections might occur a bit everywhere within this complex sandwich. Think all these abrupt changes of acoustic impedance on the first +-7cm (centerline) to +-4cm (laterally) of the wave's pathway. This is way too complex for me to understand at once and as a whole, and this is why I would understand at least the acoustic properties of one single of all these structures: The behavior of the dust protector. In an acoustically more or less linear, simple and isolated environment such as in the mentionned test setup.
If by choosing a best suited material for the dust protection you could, in interaction with the other parts of the sandwich further linearize the whole sound wave transfer, then it could have been worth the effort to investigate on this single pair of sandwiched dust protective films or structures.
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I agree with you that the situation is quite complex when considering all the elements. When limiting to dustcovers I invite you to do a simple subjective experiment. It requires making a frame with Mylar glued on. Put it in front of any source ( can be a dynamic loudspeaker, or a real instrument, noise of the street or whatver is continous and conveniant) and listen. Then remove and keep on listening. Do you hear a difference? I did this once....I found the single sheet 6 micron Mylar acoustically transparant except from som bass resonance. So the tension of the dustcover is another variable which has to be taken into account. To make it complex again added damping will change the Q of the resonance. Anyway it is very positive that someone takes the effort to investigate this subject .