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Old 22nd July 2008, 02:07 PM   #31
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Join Date: Jul 2008
brian Ive made the same kits and they have worked perfectly ..have replaced the diaphragms several times due insects,serious volume,clumsy screwdriver technique and robs new coating..all with absolute simplicity and excellent results..if you interpret and follow the instructions correctly..and as previously with Rob if in doubt(he is v approachable and a wealth of information)!!!.
I had the hiss problem at one stage too...simple fix..the voltage was too potent..dropped it back a little also replaced the 12v power supply with a multiple voltage unit and tweaked between helped.
ignore suggestions to heat the diaphragms..these units don't need that.
1.make sure all framing,edges etc are straight and will produce uniform spacing between stators and diaphragm.
2. using the spring tensioner and as MANY TAPE STRIPS AS YOU CAN FIT ON THE DIAPHRAGM during the process will produce the correct and uniformly tensioned result.
3. apply as much weight to the frame /diaphragm gluing process as you can achieve and LET IT DRY FOR AT LEAST 24 HOURS(bitter experience here. i always rush it and end up redoing the job!)

4.persist....there is no better sound than these units for detail and clarity anywhere!!(have a 30 year interest in the area and as listening is usually free I have maxed the freebie opportunities!!) I believe they are better than the latest quads heard some months back. am about to build a set of the acorns for the unadulterated esl experience as I have hybridised for bass but the (quite good) isobaric bass units(xover@175h) can't match the esl clarity and detail so am pushing for a fuller esl bass(might be an oxymoron!!??.
as rob says can't go back once you've heard the esl sound.
my ears anyway!!
reiterate...speak to rob about the problems...he does have the answers!!!
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Old 22nd July 2008, 02:07 PM   #32
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Hi all, I'm new to this forum so please forgive me if I don't follow the protocol exactly.

A client advised me that there was some confusion over the tension method used in a Final repair.

Brian, the film supplied in the repair kit is not a heatshrink type of material. heating it after bonding it to the panel will result in a slackening off of tension. The film will only shrink when it is heated almost to its melting point. This is between 220.C and 260.C (very hot).

From the description of the problem I would say the tension is too low causing the diaphragm to be pulled over to one side.

The active area of the film is quite narrow for the gap that is used on these speakers so the film should be stable with low to moderate tension. It's also possible (but unlikely) that the foam tape is deflecting under the force of the field causing the film to be drawn to one stator. You could use a stiffer foam (draft excluder) to try this out.

The reason films are heat treated is to create a more crystaline structure within the film and to re-align the molecular chains. This will indeed result in a film that will hold its tension consistently over a long period of time. The downside is that the film becomes more brittle and can fracture along the suspended edge where the film meets the air gap spacer. To ease this problem the spacer should have a small radius machined / sanded on the inner edge.

Calvin, the terms of 1.5kg and 800 gms etc relate to a 5cm wide element of the film. In the case of the Final panel which is around 1200mm long, there will be around 20 pieces of tape holding 1.5kg tension.
The tension per element is calculated to achieve the desired resonant frequency of the panel. Some panels such as the Quad 63 have very high tensions per element, others such as the bass section on the Quad 57 have low tension.

Arend - Jan is quite correct in his comments about heat treatment and heat shrinking.

Tensioning by heat shrinking requires films that have high shrinkage capability and is carried out after the film has been bonded to the panel. An example would be the type of polyester and polypropylene films used by modellers to cover their aircraft wings.
Heat treatment must be carried out when the film can change its dimension while still under tension, this requires a tension jig that will maintain the tension during the heating process. After the film is heated it is bonded to the panel while held under tension by the jig.

Hope this helps

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Old 22nd July 2008, 11:30 PM   #33
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minor correction..the ER Audio units I have are the esl 3's..and may differ somewhat from yours..Rob(ER Audio ) has joined the forum and commented on your are on the home straight now!!
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Old 23rd July 2008, 02:37 AM   #34
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Join Date: Jul 2008

The penny has dropped-the "Final 0.3" units you speak of are an entry-level hybrid Dutch speaker and not an "ER audio" unit at all. apologies if some of my earlier comments may have confused. I presume you simply sourced some electrostatic speaker components via "ER audio" to repair/improve your units? Hence the dimensions and other information you've been providing don't relate to any of the ER audio speakers at all.
That probably explains some of your problems too-the complete speaker kits supplied by ER audio are meticulously crafted and very comprehensive-you would not experience any of the problems you are currently having.
Good luck with your "hybridised" electrostatic repairs-I note your earlier comment that if it doesn't work you would go back to moving coils-don't do that-instead -do yourself a favour and get one of ER audio's complete speaker kits and make yourself a set of the best sounding electrostatics around at a fraction of the price of commercial units. Incidentally-I have no commercial barrow to push-I'm just a very happy customer of ER Audio's!
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Old 23rd July 2008, 11:51 AM   #35
Calvin is offline Calvin  Germany
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Location: close to Basel

This is between 220.C and 260.C (very hot).
There are few films that dont shrink. 220C -260C will almost certainly and always melt the film!
If it is a heat shrinkable film they normally shrink around 150C.

The downside is that the film becomes more brittle and can fracture along the suspended edge where the film meets the air gap spacer. To ease this problem the spacer should have a small radius machined / sanded on the inner edge.
The film wont become brittle with as low shrink temperatures as 150C unless it is not exposed to this temperature for several hours (which would very probably soften or even destroy any glue joint too).
The fracture of the film can happen with thin and hard drying materials like epoxy glue joints, especially if the spacers have a rather sharp edge too. Using silicone or tapes this effect wont happen. Sanding sharp edges might help too (though there will still be the problem that a bit of glue is pressed out of the chink between spacer and film, that could cut into the film when dryed out). A proven cure is to lay a bead of silicone around the inner edge of the spacer, such that no epoxy glue reaches the edge.

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Old 23rd July 2008, 02:12 PM   #36
brian t is offline brian t  United Kingdom
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rob, have now got the film bonded to the frame with sufficient tension but am still having problems, is the two foam strips supposed to have addesive on both sides ? or should the strips be placed on both stators. as an experiment i have done one panel with double sided foam tape the other without result? the panel with foam strip just stuck to the rear stator works fine no noise from it at all when powered up with both stators just laid on top of each other in a horizontal position but as soon as i installed it in the framework its quite a tight fit to push into the channels and switch on again its back to the same problem of sound of the diaphram arcing . i can only presume the diaphram is being pulled towards the front stator and there is no foam strips there to stop it touching it but am surprised it is pulled that far as i have the film under a good tension would be grateful for your input. cheers
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Old 23rd July 2008, 11:47 PM   #37
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Hi Calvin,

The temperatures I quoted were the melting point of the films, not the temperature at which you heat treat. Typically you need around 180 to 200.C to heat treat the film effectively.

All films are not the same, some have a higher temperature range than others, hence the variation.

Hope this clarifies my comment.


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Old 23rd July 2008, 11:47 PM   #38
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Hi Brian,

If you have foam tape that is the same thickness as the air gap depth, it is better to have thin double sided tape anchoring the film to the stator and use the adhesive on the foam tape to anchor the film. This will stop the film being pulled to the front stator.
If the foam tape is a little thicker than the depth of the air gap then it would be better to apply it to both stators creating a sandwich, this will ensure the same gap exists on both sides of the diaphragm. This is very importent for maintaining low distortion levels of the reproduced music.

Hope this helps

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