ESL-57, Refurbishing QUAd ESL 57 with Elvamide , but how much to apply for a Bass or treble Panel ?

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Thomas G2018-01-18 15:11

Hello ,

I am going to refurbish my old QUAD ESL 57 Panels, because two of them were defect. I need to replace the diaphragm and add new coating to both sides of the new tensioned diaphragm.

I obtained Elvamide and prepared a solution in 'spititus' - Ethanol, using 100cc Spiritus and 8 grams Elvamide.
I further diluted this elvamide solution by adding 100% Ethanol(forming a new 50% / 50% solution) before applying it to the diaphragm (both sides) of 3 Bass panels.
Unfortunately, I didn't consider to use the exact same amount of elvamide solution for each of the panels, so that their output SPL now differs by a few dbs.
Searching the internet, I find different statements about the amount of elvamide solution to be applied:
Here on the audio cicuit pages it states that "25 grams of Elvamide, resulting in 300cc solution would be suitable for 4,5 m2 diaphragm single sided, and from '' it is stated, that 10 cc of the final elvamide solution shall be used for 1 side of the diaphragm, so that by calculating this into m2, would result 8 grams Elvamide, solved in 100 cc Spiritus / diluted further to 200 cc final solution will by sufficient for 20 Panels single sided each 0,2 m2 which is 4,0 m2.

So if anybody can state, how much Elvamide - preferable in grams) should be applied to the diaphragm single sided or double sided of the Bass Panel with 12 micron foil and to the treble panel with 6 micron foil, I would feel on the save side.
Many thanks,


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