Hi,
the problem with untempered membranes are:
- consistency of parameters within a series
- working points are initially way off and need a settling time of many hours (never asked why a ML sounds so thin and bad when it comes right off of the shipping cartonage?)
- tension/stress within the membrane area is not consistent
- it sounds worse
Designing a flat stator I wouldn´t recommend to solely use mechanical tensioning any more. With the above described method and following the 1:70-1:100-rule and using the typically recommended films of 4mm-6µm thickness the Fs should be >100Hz when tensioning mechanically >1% and heat treating.
Only mechanical tensioning is necessary though with typical films and curved stators. To allow for heat treatment of curved membranes You have to take a different way (that´s one of the mysterious specialties of my new curved stators
)
jauu
Calvin
the problem with untempered membranes are:
- consistency of parameters within a series
- working points are initially way off and need a settling time of many hours (never asked why a ML sounds so thin and bad when it comes right off of the shipping cartonage?)
- tension/stress within the membrane area is not consistent
- it sounds worse
Designing a flat stator I wouldn´t recommend to solely use mechanical tensioning any more. With the above described method and following the 1:70-1:100-rule and using the typically recommended films of 4mm-6µm thickness the Fs should be >100Hz when tensioning mechanically >1% and heat treating.
Only mechanical tensioning is necessary though with typical films and curved stators. To allow for heat treatment of curved membranes You have to take a different way (that´s one of the mysterious specialties of my new curved stators
)jauu
Calvin
Hi MJ
The one company that I am 100% sure of to do heat treatment is Quad, both on the ESL as the ESL63. But they don't do it like that.
The crucial difference being that the heat treatment is performed with an oven while the diaphragm tension is being held constant (so it is free to change it's dimensions). This is also the way I do it for my Quad panels.
I suspect that the way Calvin describes it, the final tension will be mostly determined by the properties of the film, and one would be rather lucky if this would happen to coincide with the proper tension required for this particular speaker.
The way I see it.
P.S. This is heat setting of the film, not to be confused with heat shrinking!
The one company that I am 100% sure of to do heat treatment is Quad, both on the ESL as the ESL63. But they don't do it like that.
The crucial difference being that the heat treatment is performed with an oven while the diaphragm tension is being held constant (so it is free to change it's dimensions). This is also the way I do it for my Quad panels.
I suspect that the way Calvin describes it, the final tension will be mostly determined by the properties of the film, and one would be rather lucky if this would happen to coincide with the proper tension required for this particular speaker.
The way I see it.
P.S. This is heat setting of the film, not to be confused with heat shrinking!
A-J
As I understand it mylar will either shrink (within its limitations) to a specific tension, or it will stretch to that same tension if it is already under greater mechanical tension. Either way, under heat it will shrink or stretch to this specific tension. So can you please explain how a greater tension than that achieved by heatshrinking alone can be obtained using heat and mechanical tension as the same time if the application of heat is constantly 'resetting' the mylar to its specific tension, for example with the Quad 63 where a higher tension is necessary?
Tim.
As I understand it mylar will either shrink (within its limitations) to a specific tension, or it will stretch to that same tension if it is already under greater mechanical tension. Either way, under heat it will shrink or stretch to this specific tension. So can you please explain how a greater tension than that achieved by heatshrinking alone can be obtained using heat and mechanical tension as the same time if the application of heat is constantly 'resetting' the mylar to its specific tension, for example with the Quad 63 where a higher tension is necessary?
Tim.
MJ Dijkstra said:
There are two distinct advantages that I know of:
1. It sounds better. Supposedly because of the relief of odd tensions caused by mechanical stretching.
2. It stabalizes and strengthens the film so it can hold it's exact tension for decades.
This is why you won't find a Quad panel with a slackened film, not even if it's 40 years old.
Perhaps worth pointing out is a slight design weakness in the Final 0.3 - the self adhesive strips of tape running down the inside of the rear stator (presumably there to offer some 'resistance' to the diaphragm at its resonant frequency) are not stuck on particularly well. Close inspection reveals adhesion only at the points where the stator is at its thickest at five tiny points around each perforation. Most of the tape's area is unattached to the stator. The tape has a tendency to vibrate loudly on occasions, this can be simulated by blowing on it.
Tim.
Tim.
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 advised..talk 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 voltages...it 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 ..you 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!!!
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 voltages...it 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 ..you 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!!!
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
Rob
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
Rob
Brian
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!
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!
Hi,
If it is a heat shrinkable film they normally shrink around 150°C.
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 won´t 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.
jauu
Calvin
There are few films that don´t shrink. 220°C -260°C will almost certainly and always melt the film!
If it is a heat shrinkable film they normally shrink around 150°C.
The film won´t become brittle with as low shrink temperatures as 150°C 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 won´t 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.
jauu
Calvin
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
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.
BR
Rob
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.
BR
Rob
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
Rob
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
Rob
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