Hi,
Thanks for sharing you experience.
On the cureve plate, do you have to make a curve form to hold the stator in shape. I couldn't convince myself that the shape will hold by it self... A part from this, I feel that curve panels are really any more difficult to construct then a flat one...
Another very stupid question,
Does the nerrow dispersion of the ESL really matters in small listening areas?
Cheers
Thanks for sharing you experience.
On the cureve plate, do you have to make a curve form to hold the stator in shape. I couldn't convince myself that the shape will hold by it self... A part from this, I feel that curve panels are really any more difficult to construct then a flat one...
Another very stupid question,
Does the nerrow dispersion of the ESL really matters in small listening areas?
Cheers
Some like to argure otherwise, but my experience with my self-built flat panel speakers and my Quad ESL-63s is that the narrow dispersion afforded by flat panel speakers results in better "imaging". The drawback is that the sweet spot really is a spot, but that spot is a slice of heaven. When listening to speakers with wider dispersion (such as the Quads), you're less likely to hear complaints from people who aren't in the spot, but even in the spot, there is some reduced imaging and transient quality, I suspect due to multipath resulting from wider dispersion of mid and high frequencies. There may also be some effect due to the aiming of the speakers at the ears. The left ear, slightly off axis with the right speaker, will experience a slightly different frequency response for the right channel, and vice-versa.
A flat speaker with nothing done to broaden dispersion has a predictable frequency response- 6 dB per octave rise in level if I recall correctly. This is very easy to make a filter to flatten for on axis listening. As soon as you do things to broaden dispersion, if you do it sucessfully, you now have a more complex on-axis response pattern to try to even out.
I_F
A flat speaker with nothing done to broaden dispersion has a predictable frequency response- 6 dB per octave rise in level if I recall correctly. This is very easy to make a filter to flatten for on axis listening. As soon as you do things to broaden dispersion, if you do it sucessfully, you now have a more complex on-axis response pattern to try to even out.
I_F
Hi,
there might be a positive effect with a strong curvature (btw. ML used to use 30°, i.e. +-15° on older panels. The new panels use less curvature) but You might experience greater problems when mounting the film. Stability of the panel is increased substantially even with such a slight curvature. It will be strong enough as soon as the panel is fixed along its sides with a mounting frame. I use an aluminium profile that has an 10mm wide slot in which the Panel (~6mm thick) is pushed. Between panel and slot walls is a layer of damping foam.
The process of curving is imo the easiest and cheapest way to improve stability! There is no time consuming or extra costing difference in the other building steps. So the choice is to curve the sheets, which is done in a few seconds on a machine, or to fix some bracing elements onto at least one stator (how for example?).
ML´s choice was the curved stator since ML not only built good speakers but speakers with terrific looks and lowest production costs.
Sonically there is a difference between panels where the complete film area is driven (wether they feature a curvature or be they flat) and panels with electrical segmentation. Dynamics in the upper freq-range improve with complete panels, but it will cost seriously in the distribution character department. Imho the sonic result is a matter of taste. I like the strong dynamics of a complete panel, but since I wasn´t prepared to fix my head on a tiny little spot area I curved the panel to give at least a slightly better dispersion. So for me curving payed off twice
If You want at least a second person to have a good listening, You have to care for the distribution character of the panel.
jauu
Calvin
ps: simple etching just puts off material of the sheet, so sheet thickness will be reduced and hole diameter rises generally. Electropolishing on the other hand works best at sharp edges and small points (the points of hig filed strength). All etching processes have the advantage that the surface area becomes bigger and that the bond of the coating to the stator improves.
there might be a positive effect with a strong curvature (btw. ML used to use 30°, i.e. +-15° on older panels. The new panels use less curvature) but You might experience greater problems when mounting the film. Stability of the panel is increased substantially even with such a slight curvature. It will be strong enough as soon as the panel is fixed along its sides with a mounting frame. I use an aluminium profile that has an 10mm wide slot in which the Panel (~6mm thick) is pushed. Between panel and slot walls is a layer of damping foam.
The process of curving is imo the easiest and cheapest way to improve stability! There is no time consuming or extra costing difference in the other building steps. So the choice is to curve the sheets, which is done in a few seconds on a machine, or to fix some bracing elements onto at least one stator (how for example?).
ML´s choice was the curved stator since ML not only built good speakers but speakers with terrific looks and lowest production costs.
Sonically there is a difference between panels where the complete film area is driven (wether they feature a curvature or be they flat) and panels with electrical segmentation. Dynamics in the upper freq-range improve with complete panels, but it will cost seriously in the distribution character department. Imho the sonic result is a matter of taste. I like the strong dynamics of a complete panel, but since I wasn´t prepared to fix my head on a tiny little spot area I curved the panel to give at least a slightly better dispersion. So for me curving payed off twice
If You want at least a second person to have a good listening, You have to care for the distribution character of the panel.jauu
Calvin
ps: simple etching just puts off material of the sheet, so sheet thickness will be reduced and hole diameter rises generally. Electropolishing on the other hand works best at sharp edges and small points (the points of hig filed strength). All etching processes have the advantage that the surface area becomes bigger and that the bond of the coating to the stator improves.
Hi,
i think there are always arguments pro and con dispersion.
For my experience it need to be a combination of both dispersion options.
The segmentation of my flat panels is optimized in such way, that dispersion is very good between +/15° and decreases rapidly at higher angles.
The mentioned better image of narrow dispersion panels has nothing to do with the dispersion itself, but with the interaction of early room reflexions. As long the dispersion is limited to avoid early reflections, preferably from side walls, it should have identical image.
On the other hand the discussion need to consider the frequency range we are talking about. I would say that all ESL show comparable dispersion up to 2 Khz and just differ at higher frequency. And high frequencies will be better absorbed by air, thus minimizing wall reflexions.
capaciti
i think there are always arguments pro and con dispersion.
For my experience it need to be a combination of both dispersion options.
The segmentation of my flat panels is optimized in such way, that dispersion is very good between +/15° and decreases rapidly at higher angles.
The mentioned better image of narrow dispersion panels has nothing to do with the dispersion itself, but with the interaction of early room reflexions. As long the dispersion is limited to avoid early reflections, preferably from side walls, it should have identical image.
On the other hand the discussion need to consider the frequency range we are talking about. I would say that all ESL show comparable dispersion up to 2 Khz and just differ at higher frequency. And high frequencies will be better absorbed by air, thus minimizing wall reflexions.
capaciti
Hi,
Thanks guys,
Looks like dispersion is up to individual taste... No quarms with that
Curve plate will definately stiffen the panels, but my question is the how well will the stator hold up its profile during construction? please do elaborare more.
I really like the idea of curve panel, I am tempted to make a tube to hold the panels, and the cavity behind the panel (in the tube) can be filled with fibre..etc resistive materials to absorb the back wave. Like a vented box... the looks is appealing (to me at least)What do you think?
Cheers
Thanks guys,
Looks like dispersion is up to individual taste... No quarms with that
Curve plate will definately stiffen the panels, but my question is the how well will the stator hold up its profile during construction? please do elaborare more.
I really like the idea of curve panel, I am tempted to make a tube to hold the panels, and the cavity behind the panel (in the tube) can be filled with fibre..etc resistive materials to absorb the back wave. Like a vented box... the looks is appealing (to me at least)What do you think?
Cheers
Hi,
MartinLogan manufactures curved panels by the thousands.
1mm thick sheets are already quite strong and there are no such great forces while manufacturing that the curvature could be endangered in any way apart from maybe stomping on them
I strongly recommend not to use any kind of box or chamber.
One of the biggest advantages of an ESL is that You can get rid of it, because every compartement is an unwanted energy reservoir. And thats audible!
Since an ESL is constructed -and works- different to a dynamic driver, the demands for an compartement differ significantely anyway.
PJ Walker gave some hints of what could be used in praxis -and those compartments definitely look different
- but as we know, he never gave up on building open/boxless ESLs, for thats the best way to build an ESL.
jauu
Calvin
MartinLogan manufactures curved panels by the thousands.
1mm thick sheets are already quite strong and there are no such great forces while manufacturing that the curvature could be endangered in any way apart from maybe stomping on them
I strongly recommend not to use any kind of box or chamber.
One of the biggest advantages of an ESL is that You can get rid of it, because every compartement is an unwanted energy reservoir. And thats audible!
Since an ESL is constructed -and works- different to a dynamic driver, the demands for an compartement differ significantely anyway.
PJ Walker gave some hints of what could be used in praxis -and those compartments definitely look different
- but as we know, he never gave up on building open/boxless ESLs, for thats the best way to build an ESL.jauu
Calvin
Hi,
Since this thread is about easily obtainable methods as well , i'd like to continue it a bit to this direction.
Currently , i am experimenting with conductive coatings. I found a few methods to do this , each having its own disadvantages.
One method is to use PVA based adhesives.Some types of these adhesives are hygroscopic , and will attract moisture. However , PVA , being water based , does not wet mylar well.Adhession to film is not very good either. The resistance is on the low side.
Another method is shoe cream rubbing.This method probably works because the cream contains carbon black(?). The resistance is too low as well , though it is possible to rise it by cleaning with wet cloth.
I tried some other methods , like dissolving nylon fishing line in acetic acid. This method gives very high resistance, but is hard to work with due to vapors of acid.
Any other ideas ?
Regards,
Lukas.
Since this thread is about easily obtainable methods as well , i'd like to continue it a bit to this direction
.Currently , i am experimenting with conductive coatings. I found a few methods to do this , each having its own disadvantages.
One method is to use PVA based adhesives.Some types of these adhesives are hygroscopic , and will attract moisture. However , PVA , being water based , does not wet mylar well.Adhession to film is not very good either. The resistance is on the low side.
Another method is shoe cream rubbing.This method probably works because the cream contains carbon black(?). The resistance is too low as well , though it is possible to rise it by cleaning with wet cloth.
I tried some other methods , like dissolving nylon fishing line in acetic acid. This method gives very high resistance, but is hard to work with due to vapors of acid.
Any other ideas ?
Regards,
Lukas.
PVA adhesive
Lukas if you want PVA adhesive like Weldbond to stick to mylar you only need follow the directions. The trick is to dilute with water (5 parts water to 1 part weldbond) and then simply use a small hand held mister bottle to apply a lifht even coating. Let dry and you will hav excellent adhesion. You can also dope the water that you use to make it work better try a non sented dryer antistatic sheet soaked in the water. You can search under Quats
here is part of a theradWeldbond Post #5
Something that I will post to stimulate experimentation. Weldbond white glue which is a modified PVA adhesive is made by Frank T. Ross & Sons Ltd. in Toronto. (www.weldbond.com) when diluted one part glue to five parts water can be sprayed or brushed onto mylar and dries to a fine cloudy thin film. This bonds extreemly well to mylar. You can experiment with quaternium ammonium salts to dope the adhesive to achieve the desired resistivity. The most simple source would be to take a non sented Downy dryer sheet and soak it in some water. Then use the water to dope the adhesive. Many anti static products like hair conditioner or shampoo with added hair conditioner contain such salts and could also be experimented with. Easy to play with and almost free. Weldbond can be found at most any craft store as it is considered a universal adhesive. By the way Weldbond is totally non toxic. Best regards Moray James.
Lukas if you want PVA adhesive like Weldbond to stick to mylar you only need follow the directions. The trick is to dilute with water (5 parts water to 1 part weldbond) and then simply use a small hand held mister bottle to apply a lifht even coating. Let dry and you will hav excellent adhesion. You can also dope the water that you use to make it work better try a non sented dryer antistatic sheet soaked in the water. You can search under Quats
here is part of a theradWeldbond Post #5
Something that I will post to stimulate experimentation. Weldbond white glue which is a modified PVA adhesive is made by Frank T. Ross & Sons Ltd. in Toronto. (www.weldbond.com) when diluted one part glue to five parts water can be sprayed or brushed onto mylar and dries to a fine cloudy thin film. This bonds extreemly well to mylar. You can experiment with quaternium ammonium salts to dope the adhesive to achieve the desired resistivity. The most simple source would be to take a non sented Downy dryer sheet and soak it in some water. Then use the water to dope the adhesive. Many anti static products like hair conditioner or shampoo with added hair conditioner contain such salts and could also be experimented with. Easy to play with and almost free. Weldbond can be found at most any craft store as it is considered a universal adhesive. By the way Weldbond is totally non toxic. Best regards Moray James.
Hi,
with curved stators I wouldn´t use heat tensioning but solely mechanical tensioning with the highest possible value..of course just tension in the straight direction. The tension in curved direction should be as low as possible....just enough to straighten out any folds. But when You apply very high tension in the straight direction, You even get away with quite strong tension in the curved direction (obeying the 1:70...1:100 rule for d/s)!
You can do this with a mechanical stretching frame with curved ends.
I use only instant bonding glue or tape. After application of the glue or tape to the backside stator I stretch the membrane and lay ist on the stator. The stretching frame presses the membrane onto the glue joint by its weight. With 3M-Tape the instant bond is very strong but increases over some hours to its final value. Then I release the pressure of the tensioning frame and cut the panel free leaving some diaphragm material left. Now I glue some thin doublesided tape on the outside (backside) of the stator and turn the diaphragm over its rim and glue it on the thin tape. This way You have much less trouble with tapes that might not have the shear strenth to hold the constantly high diaphragm tension over a long time for You have much more glued area. If there were some tiny wrinkles left on the frontside of the stator, You could even pull those flat since the foam tapes I use as spacers allow for those small final corrections.
The soft foam introduces some damping to the membrane which I regard as positive for less standing wave-Q and less stress on the membrane itself at this joint. CSD Measurement showed very good results. MartinLogan used to glue the membrane on the stators backside too..but only in the straight direction.
jauu
Calvin
with curved stators I wouldn´t use heat tensioning but solely mechanical tensioning with the highest possible value..of course just tension in the straight direction. The tension in curved direction should be as low as possible....just enough to straighten out any folds. But when You apply very high tension in the straight direction, You even get away with quite strong tension in the curved direction (obeying the 1:70...1:100 rule for d/s)!
You can do this with a mechanical stretching frame with curved ends.
I use only instant bonding glue or tape. After application of the glue or tape to the backside stator I stretch the membrane and lay ist on the stator. The stretching frame presses the membrane onto the glue joint by its weight. With 3M-Tape the instant bond is very strong but increases over some hours to its final value. Then I release the pressure of the tensioning frame and cut the panel free leaving some diaphragm material left. Now I glue some thin doublesided tape on the outside (backside) of the stator and turn the diaphragm over its rim and glue it on the thin tape. This way You have much less trouble with tapes that might not have the shear strenth to hold the constantly high diaphragm tension over a long time for You have much more glued area. If there were some tiny wrinkles left on the frontside of the stator, You could even pull those flat since the foam tapes I use as spacers allow for those small final corrections.
The soft foam introduces some damping to the membrane which I regard as positive for less standing wave-Q and less stress on the membrane itself at this joint. CSD Measurement showed very good results. MartinLogan used to glue the membrane on the stators backside too..but only in the straight direction.
jauu
Calvin
Hi,
This is super informative!! Thanks guys!!
More stupid questions...
MJ,
Don't think I'll find them in my local stores..
Could you help me nerrow down the search by tell me what are their "normal" application? then I can start reading label and contents in the store like I'm in a book shop...
Calvin,
I have been told many time about tension high and low but I don't have a feel for thatis ther any indication of "high-tension" , is there any indiction that I can fall on? eg weight for stretching, pressure applied? something? anything...
I am getting confused with the d & s value.. is it,
d=Panelwidth, &
s= Panel length?
Are you saying that the bicycle tube stretch table is no use in your technique? In stead you have a rectangular frame to do the work?
Cheers
This is super informative!! Thanks guys!!
More stupid questions...
MJ,
Don't think I'll find them in my local stores..
Could you help me nerrow down the search by tell me what are their "normal" application? then I can start reading label and contents in the store like I'm in a book shop... Calvin,
I have been told many time about tension high and low but I don't have a feel for thatis ther any indication of "high-tension"
, is there any indiction that I can fall on? eg weight for stretching, pressure applied? something? anything...I am getting confused with the d & s value.. is it,
d=Panelwidth, &
s= Panel length?
Are you saying that the bicycle tube stretch table is no use in your technique? In stead you have a rectangular frame to do the work?
Cheers
Hi,
d/s means diaphragm-to-stator-distance....usually ~ 0,5---5mm
To ensure that the diaphragm will not touch one of the stators when playing music the membrane should be supported at distances of 70 to 100 times the d/s. For a d/s of lets say 1,0mm supports should be distanced between 70 and 100mm apart. You see those supports by MartinLogan as clear horizontal spacers, or with Audiostatic as simple silicon dots.
When tensioning a material it is first just tensioned. When You stretch harder there will be a point where the material starts to ´flow´ and the tension won´t increase any more but the material starts to become thinner. With a film You can easily feel this point, since the stretching force doesn´t increase anymore but decreases. Furthermore if You listen to the ground resonance by e.g letting fall a pingpong ball on the film the resultant tone doesn´t get higher. Depending on the film this point is reached between 2% and 4% of length increase. I´d first test the film on this property.
I usually stretch around 2% which gives strong tension.
The good point about the tubed stretcher is, that it can develop a very even tension over the complete area and in every direction. With curved panels You need to stretch only in one direction. You could probabely use a tubed stretcher when You ensure that it stretches only in the straight direction as the mechanical stretcher does. The tube doesn´t have an advantage over the mechanical stretcher in this case as it has in the case of a flat panel with tension in 2 directions
jauu
Calvin
d/s means diaphragm-to-stator-distance....usually ~ 0,5---5mm
To ensure that the diaphragm will not touch one of the stators when playing music the membrane should be supported at distances of 70 to 100 times the d/s. For a d/s of lets say 1,0mm supports should be distanced between 70 and 100mm apart. You see those supports by MartinLogan as clear horizontal spacers, or with Audiostatic as simple silicon dots.
When tensioning a material it is first just tensioned. When You stretch harder there will be a point where the material starts to ´flow´ and the tension won´t increase any more but the material starts to become thinner. With a film You can easily feel this point, since the stretching force doesn´t increase anymore but decreases. Furthermore if You listen to the ground resonance by e.g letting fall a pingpong ball on the film the resultant tone doesn´t get higher. Depending on the film this point is reached between 2% and 4% of length increase. I´d first test the film on this property.
I usually stretch around 2% which gives strong tension.
The good point about the tubed stretcher is, that it can develop a very even tension over the complete area and in every direction. With curved panels You need to stretch only in one direction. You could probabely use a tubed stretcher when You ensure that it stretches only in the straight direction as the mechanical stretcher does. The tube doesn´t have an advantage over the mechanical stretcher in this case as it has in the case of a flat panel with tension in 2 directions
jauu
Calvin
Hi Calvin,
Thanks for clearing my cloud over the tension part Now I'm crystal clear.
But
But in the earlier suggestion of having 250mm x 1,200mm panel, using 1mm gap (stator to diapharm), has already exceeded the 1:100 ratio, am I understand properly that we can get over this by havingpoint support or strip sectionalised the panels to keep the 1:100 d/S ration and we can go as big a panel as we wish with still keeping the 1mm gap?
Cheers
Thanks for clearing my cloud over the tension part
Now I'm crystal clear.But
But in the earlier suggestion of having 250mm x 1,200mm panel, using 1mm gap (stator to diapharm), has already exceeded the 1:100 ratio, am I understand properly that we can get over this by havingpoint support or strip sectionalised the panels to keep the 1:100 d/S ration and we can go as big a panel as we wish with still keeping the 1mm gap?
Cheers
Hi Calvin,
Your method of Mylar tensioning may be too high. While the high membrane tension is desirable for stability, Mylar service life in vicinity of spacers may be considerably shortened (as seen on many failed DIY and commerical ESL panels).
You tension Mylar to yield ("flow") point and the resulting stresses (membrane stresses) are uniform across the membrane thickness. Close to spacers the membrane is subject to significant curvatures and bendig stresses that should be superimposed to the membrane stresses.
Cyclic loading (read fatigue) of this magnitude (close to yield) are responsible for delamination of coatings in this area (read loass of bias) and ultimately tears parallel to the spacers (read panel rebuilding).
Regards
Your method of Mylar tensioning may be too high. While the high membrane tension is desirable for stability, Mylar service life in vicinity of spacers may be considerably shortened (as seen on many failed DIY and commerical ESL panels).
You tension Mylar to yield ("flow") point and the resulting stresses (membrane stresses) are uniform across the membrane thickness. Close to spacers the membrane is subject to significant curvatures and bendig stresses that should be superimposed to the membrane stresses.
Cyclic loading (read fatigue) of this magnitude (close to yield) are responsible for delamination of coatings in this area (read loass of bias) and ultimately tears parallel to the spacers (read panel rebuilding).
Regards
weldbond
If you are into experimenting with coatings weldbond is an amazing product to play with. You can find information on weldbond and where you can buy it. Your best possible chance of finding weldbond would be in a craft and hobby store. Regards Moray James.
http://www.franktross.com
I am sure if you email weldbond they will inform you of where you can purchase thier product. I hav even seen it on ebay.
If you are into experimenting with coatings weldbond is an amazing product to play with. You can find information on weldbond and where you can buy it. Your best possible chance of finding weldbond would be in a craft and hobby store. Regards Moray James.
http://www.franktross.com
I am sure if you email weldbond they will inform you of where you can purchase thier product. I hav even seen it on ebay.
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