==To the usual Mylar/Polyester used for diaphragms with various coatings...
How about Polythene coated with anti-static 'licron' or whatever its called....
Polythene is a whole lot easier to get....
How about Polythene coated with anti-static 'licron' or whatever its called....
Polythene is a whole lot easier to get....
Assuming you were referring to "polyethylene", it would work of course but it would be a poor choice compared to polyester because it has significantly lower tensile strength, much higher elongation and much lower surface energy. Hence, it would not hold tension as well and Licron Crystal would not adhere to it nearly well.
Do you know how Licron differs from graphite powder?
I have used the later successfully applied on kitchen wrap (Sanitas brand) membrane (=5 microns thick) for headphones, which easily stretches and holds tension while it applies much less force on the frame and obviously transfers less vibrations -and it's heat-shrinkable to correct any wrinkles with a hair-dryer after several years.
I'm interested because soon I'll make a new, improved pair and I consider other materials.
Only reason I asked was because I have some 20uM parcel/item wrapping poly film--Like an industrial cling-film that Ive used to make dust shields with for ESL57 bass-panels, Works rather well, at the time of my O/P I couldn't find the correct mylar films for them.
Since then, Ive found a seller in Taiwan on ebay selling both the films in Dupont Mylar and the original Nylon based coatings suitable for the 57 speakers, here--
Electrostatic Speaker Mylar C 6um 40M + Elvamide 60g | eBay
My choice now is, Do I stick with the original thicknesses or use say a thinner for the treble--What would you do/use? What advantages if any, would I see changing the thicknesses?
They supply down to 2uM while the original ESL57 treble is 6uM and the bass is 12uM
I have a complete spare set of 6 panels from a scrapped ESL57 pair I can rebuild and experiment with, while still keeping my original ESL57 good working panels as they were made...
Since then, Ive found a seller in Taiwan on ebay selling both the films in Dupont Mylar and the original Nylon based coatings suitable for the 57 speakers, here--
Electrostatic Speaker Mylar C 6um 40M + Elvamide 60g | eBay
My choice now is, Do I stick with the original thicknesses or use say a thinner for the treble--What would you do/use? What advantages if any, would I see changing the thicknesses?
They supply down to 2uM while the original ESL57 treble is 6uM and the bass is 12uM
I have a complete spare set of 6 panels from a scrapped ESL57 pair I can rebuild and experiment with, while still keeping my original ESL57 good working panels as they were made...
Yes, the simple one, not the one for microwave ovens -that must be new.
After 17 years, it still works. I had to apply heat with a hair dryer once, after leaving them for a decade unused, from the outside of the headphones -and it was stretched perfectly.
That said, I haven't tried other materials so I can't compare it.
I can only say that I'm very happy with the sound quality (which I liked more than a Stax model I tried after I made them), although the Stax one was 2-4 times louder (obviously due to less distance -0.6 vs 1.6mm).
The advantage of thin diaphragms is less treble loss due to diaphragm mass, but chances are that QUAD corrected for the treble loss somehow, so I wouldn't change it.
@Alastair E
Until someone else that has actually tried different thicknesses for ESLs responds, I can only say that I would take the following into account:
1. The mass of the air that is moved, is usually much heavier than the mass of the film itself.
2. Still, in high frequencies the less mass, the better.
Obviously a thinner film will have a higher frequency response -whether that would be significant or not, I can't say.
3. The resonance will also be higher and weaker.
4. A thinner film will transfer less vibrations to the frame due to less stretching force, more elasticity and resistance.
5. A thinner film will be more vulnerable to sparks that create tiny holes -that depends on the voltage, I haven't seen any holes to the wrap film at 1KV.
Until someone else that has actually tried different thicknesses for ESLs responds, I can only say that I would take the following into account:
1. The mass of the air that is moved, is usually much heavier than the mass of the film itself.
2. Still, in high frequencies the less mass, the better.
Obviously a thinner film will have a higher frequency response -whether that would be significant or not, I can't say.
3. The resonance will also be higher and weaker.
4. A thinner film will transfer less vibrations to the frame due to less stretching force, more elasticity and resistance.
5. A thinner film will be more vulnerable to sparks that create tiny holes -that depends on the voltage, I haven't seen any holes to the wrap film at 1KV.
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Thanks guys for the input.
I think I'll use the same thicknesses as originals, Who am I to try and second guess and 'improve' something that has such a stellar reputation, while not completely understanding every nuance of their functionings!
My working speakers do sound really very nice with their 40-50 year old panels, so they must have got it right.
--Everything is available at a reasonable cost to repair my spare set very closely to the original specs......
Ive stripped down the first treble panel this evening to examine the arc damage, Pretty horrible, and surprising how much melting there is of the stator material, but with a little care, I should be able to renovate it.
I think I'll use the same thicknesses as originals, Who am I to try and second guess and 'improve' something that has such a stellar reputation, while not completely understanding every nuance of their functionings!
My working speakers do sound really very nice with their 40-50 year old panels, so they must have got it right.
--Everything is available at a reasonable cost to repair my spare set very closely to the original specs......
Ive stripped down the first treble panel this evening to examine the arc damage, Pretty horrible, and surprising how much melting there is of the stator material, but with a little care, I should be able to renovate it.
At the end of the day its a catch 22, guess it’s a matter of choosing your poison.
Cleaner treble will make the sound lighter & that will offset the balance of the sound.
Merry Xmas
Cleaner treble will make the sound lighter & that will offset the balance of the sound.
Merry Xmas
This has been discussed, DIY'er Bolserts has shown some graphs of the high end roll off due to various mylar thicknesses.
Sorry I don't have that link handy, as i don't remember the Key words to find it.
Cheers!!
Jer 🙂
Its complicated
In principle, to understand the overall behaviour of the ESL you should consider the stators, membrane, dustcovers, and grills together.
However, the the membrane thickness does have a fairly simple overall effect very much like a low-pass filter. The cutoff frequency of the low-pass response is about 97 kHz divided by the membrane thickness in microns.
Therefore:
3.5 um mylar has a cutoff frequency of about 28 kHz.
20 um mylar has a cutoff frequency of about 5 kHz.
3.5 um mylar membrane with two 2 um dustcovers on the outside of the ESL gives an overall response much like an ESL with a 7.5 um membrane and a cutoff frequency of about 12 kHz.
To these thicknesses must be added a micron or two for the high resistivity coating - depends what coating you use - Licron is a micron or two.
So you should use
(i) the thinnest practical mylar for the dustcovers.
(ii) < 5 um for high frequency sections
(iii) May use 20 um for bass sections.
When multiple layers of mylar are involved, the response is much more complicated than a low-pass filter due to reflections between the different membranes, but the overall trend is low pass as described.
If the designer has done the job properly, all of these effects and the transformer resonance will have been considered. Pays not to fiddle unless you have an idea of the likely effect of any changes.😕
regards
R
In principle, to understand the overall behaviour of the ESL you should consider the stators, membrane, dustcovers, and grills together.
However, the the membrane thickness does have a fairly simple overall effect very much like a low-pass filter. The cutoff frequency of the low-pass response is about 97 kHz divided by the membrane thickness in microns.
Therefore:
3.5 um mylar has a cutoff frequency of about 28 kHz.
20 um mylar has a cutoff frequency of about 5 kHz.
3.5 um mylar membrane with two 2 um dustcovers on the outside of the ESL gives an overall response much like an ESL with a 7.5 um membrane and a cutoff frequency of about 12 kHz.
To these thicknesses must be added a micron or two for the high resistivity coating - depends what coating you use - Licron is a micron or two.
So you should use
(i) the thinnest practical mylar for the dustcovers.
(ii) < 5 um for high frequency sections
(iii) May use 20 um for bass sections.
When multiple layers of mylar are involved, the response is much more complicated than a low-pass filter due to reflections between the different membranes, but the overall trend is low pass as described.
If the designer has done the job properly, all of these effects and the transformer resonance will have been considered. Pays not to fiddle unless you have an idea of the likely effect of any changes.😕
regards
R
Measurements .vs. theory were posted here for 3 different thicknesses of mylar:
Electrostatic speakers as microphones?
Measurements showing mass added by Licron Crystal coating posted here:
David Lucas ESL
As golfnut already mentioned, once you start adding stators and dustcovers the high frequency behavior gets much more complicated. But, the general trend will always be influenced by the roll-off from diaphragm mass.
Note that the small difference in constant value(93.4kHz .vs. 97kHz) used in my formula and golfnut's(Post#13) is due to the change in speed of sound and air density with temperature. My formula used room temperature values, golfnut's formula uses temp ~ 0degC.
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I do use this : reddingsdeken - Google Search
It's just to try this because it does have an insulated alu conductive layer. I do wipe away the gold paint a the coppertapes to get the HV on the alu. It play's very well!
I don't know how long it will last... but till now it looks ok.
It's just to try this because it does have an insulated alu conductive layer. I do wipe away the gold paint a the coppertapes to get the HV on the alu. It play's very well!
I don't know how long it will last... but till now it looks ok.
you also want to use a film which is biaxially oriented. It is important for the film to have the same stretch characteristics in both length and width dimensions. Films which are dimension-ally stable is also an important consideration. So it is easy to see why capacitor grade film is a favorite, these are polyester (Mylar). Drafting Mylars are stable and are surface treated so ink can grip the film also good for adhesive grip but drafting Mylars are much thicker than required for loudspeakers.
Dissipative polyester film
DPF-100 polyester film | Wolfgang Warmbier Online-Shop
I sent them an email if they could manage to find 4micron film..
DPF-100 polyester film | Wolfgang Warmbier Online-Shop
I sent them an email if they could manage to find 4micron film..
coated films will result in shunt capacitance. That is the advantage of being able to put the coating onto the diaphragm so that it does not extend out to the frame.