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ESL Diaphragm coating
ESL Diaphragm coating
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Old 28th November 2018, 09:36 AM   #1141
wout31 is offline wout31  Netherlands
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Quote:
Originally Posted by MJ Dijkstra View Post
If the coating has damping properties why is the cumulative spectral decay of a quad not better than lets say audiostatic? According to measurements done by Stereophile (take a google search) the ES100 does a better job than Quad 2805 regarding the CSD plot. Maybe the CSD plot was much worse if the Quad had not this 'damping' coating, we only can find out when measuring an original panel against a panel with new Mylar without damping......
I also think there are better ways to kill spurious resonances and such thick coatings only degrade high freq. response (quad rolls off at high freq.....)
I guess the extra layer of coating would make things worse instead of better. Extra thickness is extra weight. So in theory it would take the diaphragm more time to come to a stop and make it slower to respond. And I agree with MJ Dijkstra it would have a bad effect on higher frequency response. The damping as it was designed by Peter Walker is done by the mesh on the rear stator. Be aware that some people abuse this mesh by obstructing a large amount of the mesh with glue in an attempt to better fix the stator without removing and reapplying the stator. They just drop a big amount of glue along the ribs of the ABS frame on top of the stator. That will affect the damping as intended because less air can pass through the mesh. I also think that the thick "damping" coating will kill the effect of the delay lines which are crucial in creating a 3D sound image and creating the virtual point source. Pulse will be affected in a negative way. The total thickness of Mylar and both coatings sum up to 10-12 micron. I can't think of any positives.
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Old 28th November 2018, 12:26 PM   #1142
misterdog is offline misterdog  United Kingdom
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My cheap surface resistance meter arrived yesterday, I've not had chance to check the accuracy of the reading yet, it has proved a bonus in not tearing the membrane though.

Click the image to open in full size.

A broken panel from old 63's, S/no 1692 with 2 part coating showing a surface resistance of 10^6/10^7.

Click the image to open in full size.

A 'new' panel as fitted by Quad at Huntingdon March 2014.
Surface resistivity 10^8/10^9. 1 part sprayed coating with convex corner pattern, damping mesh to rear stator is a mauve colour.

Last edited by misterdog; 28th November 2018 at 12:31 PM.
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Old 28th November 2018, 03:50 PM   #1143
bolserst is offline bolserst  United States
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Quote:
Originally Posted by MJ Dijkstra View Post
If the coating has damping properties why is the cumulative spectral decay of a quad not better… such thick coatings only degrade high freq. response (quad rolls off at high freq.....)
I don’t think the coating has much if any effect on the CSD (just not an effective way to damp diaphragm modal behavior), and you are absolutely right about the added mass degraded the HF response.

What the damping coating DID do was reduce the crinkly noises that the mylar makes when you handle it. If the crinkly nature of mylar adds a coloration to the sound, this damping coating would go a long way toward eliminating it.
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Old 28th November 2018, 04:28 PM   #1144
MJ Dijkstra is offline MJ Dijkstra  Netherlands
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Originally Posted by bolserst View Post

What the damping coating DID do was reduce the crinkly noises that the mylar makes when you handle it. If the crinkly nature of mylar adds a coloration to the sound, this damping coating would go a long way toward eliminating it.
Crinkly noises.....you mean that is like the Mylar ads sound which is not present in the original signal? I presume such colouration would show up in the CSD-plot as a ringing signal......
Maybe there is simply no good reason for adding this stuff.....or it is with a good idea in mind but not supported by evidence.....
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Old 28th November 2018, 06:08 PM   #1145
misterdog is offline misterdog  United Kingdom
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Quote:
Originally Posted by MJ Dijkstra View Post
Crinkly noises.....you mean that is like the Mylar ads sound which is not present in the original signal?
It does if the dust covers loose tension (drumming). Or the panel membrane.
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Old 29th November 2018, 12:51 AM   #1146
esl 63 is offline esl 63
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The membrane rottening is most likely from arcing that is generating ozone. The ozone in turn is higly reactive and will very fast brake the molecule chains in the polyester.
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Old 29th November 2018, 12:26 PM   #1147
alexberg is offline alexberg
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There is no need for ark(ing) per say to produce ozone. It's called DBD and is caused by displacement current through dielectric/isolator.
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Old 5th December 2018, 05:43 PM   #1148
wout31 is offline wout31  Netherlands
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My last testing is with coating test number #353 (I'm mixing and testing for 3 years now)

As I wrote in earlier posts I'm now testing with different humidities. This last coating has a blink interval of several minutes at humidity 50%. The interval is 15 seconds at 65% humidity and 2 seconds at 85%. So although the blink interval is much much longer at normal humidity levels than with my earlier coating, I cant improve the interval between blinks at the 85% humidity level. So I leave it at that. As I mentioned before the humidity in my country hardly ever reaches 70% and mostly it is between 40% and 55%. The thickness aof the Mylar with the coating is 4 micron and the weight is 6 grams/m2 both measured with my cheap China made scale and thickness meter. It is a PEDOT based coating hence the colour blue.
Now on with further testing on sound, SPL, sensitivity for spark damage, durability etc.
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