| final 0.3 er audio repair kit - Click HERE for Original Thread |
| brian t |
| hi,am in the process of fitting new diaphrams to these this is my second attempt but i have a problem when i power up the panel you can here a crackling sound as if the membrane is moving its the same on both speakers i tensioned it with the supplied guage from er audio and have tried heating the membrane with a hair drier but it makes no difference you can here the panel making this noise even after its been powered down for half an hour they do produce sound but distort when the volume is increased any advice you can give me would be great. cheers |
|
|
| vitalstates |
Hi Brian
without more info it sounds like the diaphragm is leaking/arcing. I'm not familiar with the final and its associated isolation techniques.
Any chance of more info?...I presume you've discussed this with Rob Mackinlay and followed his advice. If not I thoroughly recommend it.
Ed |
|
|
| brian t |
| ed, i am sure its the diaphram moving when the panel is charged up the sound is just like the plastic stretching but i dont quite understand why it should make this sound all the time does not matter if you have sound comming out or not, am trying to put more tension on the film with a hairdryer but not having much luck. the diaphram was tensioned to 1,5 kg as per instruction but i am wondering if this is enough |
|
|
| moray james |
| you unplug the high voltage power supplies? If the noise goes away then the simple answer is that you are leaking diaphragm voltage to ground. |
|
|
| Calvin |
Hi,
You need considerable tension on the diaphragm. 1.5kg is a term of no information at all. You´d need to say what force per which unit of diaphragm width You apply.
Use a hairdryer for what its intended...haidrying! It won´t lead to any reaction when pointed towards the film. It simply doesn´t reach the required temperatures. You need a heat- gun or the plate of an oven and a temperature of ~150°C to shrink the film.
When You have applied too low tension, the diaphragm is pulled into the stator and keeps sticking there. Then You´ll here a constant tickling noise from the low level arcing. This will go on till the moment that nearly all charge has leaked away and the membrane jumps back into its intended position with a ´Blobb´ sound.
To give You an idea what tension is necessary. Pull so hard that the membrane elongates ~1-2% in length!
jauu
Calvin |
|
|
| brian t |
| calvin, yes i think you are right about the membrane being too slack but i followed the instruction with the kit and on my second attempt increased tension on the panel but obviously not enough ! the kit is suplied with a spring tension guage and the instructions are to pull on the film to a force of 1.5 kg as shown on the guage and this is then supposed to be right amount of tension. will remove film again and increase force. cheers for info |
|
|
| vitalstates |
Hi Brian
1.5kg is a lot of tension in Rob Mackinlay terms, depending on the size of panel.....If I remember the esl3 used about 800gms for 2 48"x8" panels....its 5 years since I last did this so my memory may be suspect.........what does Rob say, after all it is his kit.
so, for 1.5kg knowing the size of panel would give an idea of whats going on.
To follow up on what Moray has said, what happens when you turn the bias supply off and then on again after say 10 mins??
I'm still behind the leaking argument at the moment
Ed |
|
|
| brian t |
| ed, when you switch off the supply you still get the same noise, it gradually goes as the charge dissapates, when you re- connect the supply it starts again. the diaphram er audio supply is thinner than the normal final one just wondering if its too thin to get a good tension, will run out of film if i dont get the third effort right. appreciate your input. thanks brian |
|
|
| moray james |
| your static charge is not static, it's on the move. You need to make sure that there is no path to ground for the charge on the diaphragm. This could be some form of contaminant like fluff dust hair but since these are newly built and both are doing the same thing it is probably a short that you caused when you applied the diphragm coating. One other important question needs to be asked. Is the diaphragm(s) centred between the stators or is it colapsed? This really should have been asked first but here we are. Do the speakers play and make reasonable levels? If every thing seems to be fine but for reduced level and the arcing noise then you should look to the contact point on the diaphragm (for the HT supply) first. After that you will need to see if you can locate the short to ground on the diaphragm. You could play music loud in the dark and watch to see where the light show is. You may need to split the stator panels and clean the inside surfaces with a good degrease type of compound. Don't use detergent as that will leave residue that is conductive. Solvent and a soft brush would also do. Short of all this you might consider getting some local help to rebuild for you. Did the speakers exhibit any arcing problems prior to your rebuild? If the answer is yes then you might be up against problems that will not go away. So you will have to think things through and find out where/what the problem is. Additional film cost is not a big worry you have to sluth out the problem here before you can repair it. |
|
|
| Calvin |
Hi,
again I regard to the weight-problem.
The simple 1.5kG or later named 800gr.... what does it mean? Nothing at all! realize that it´s a completely useless value as long as You don´t add to which membrane unit it applies. Do You apply 1.5kg of pulling force to which width? Is it 1.5kg/cm is it 1.5kg/5cm or what?
1.5kg/5cm would already mean a quite low value of tension.
All Your descriptions of the tickling noise just indicate a collapsed diaphragm. If You for example lay down alminium foil directly on the stator and connect this to the HV-supply You´ll hear a sound that reminds very much of the purling of a little creek. ;-) It fades away slowly as the PS is discharging.
So you have to apply more tension to the diaphragm. This can be done in two ways. First is to encrease the mechanical tension and the second is to decrease freely vibrating distances of the membrane by decreasing the distance of the spacers or by adding supporting points.
See how Audiostatic uses silicon dots to decrease the distance and to support the membrane.
Also it might help to use a little indicator circuit (the blinker) that gives You an idea about the quality of the insulation (leakage)
search for the blinker circuit in thje ESL-Threads. It consist odf a small glow discharge lamp and a capacitor.
jauu
Calvin |
|
|
| moray james |
| a small neon bulb that is bypassed by a low uf value (but high voltage) capacitor in series with the HT supply connection. When the lamp is on the supply is delivering current to the diaphragm. This allows you to monitor the status of the static charge on the diaphragm. The lamp normally comes on only when charge is lost from the diaphragm that means if the lamp is on all the time you have a dead short. Do you have a high voltage probe? If not you should get one. You can use the probe to measure voltage on the diaphragm and a lot of other useful things. You need to be able to check what is working an what is not working so you can figure where the problem is. For example you can connect your high voltage suply to one of your stators and use a probe to look for leaks on the stators. Perhaps if you start at the beginning and provide some real information we might be able to sort your troubles out. As it stands we are guessing and there has been little to no real information provided by you. Sorry but you have us shooting in the dark. At this point Calvin is probably right in that you do not have enough tension on the diaphragms but it is difficult to say for sure. IF these speakers are older and well used what was the condition of the stock diaphragm? Did it have a lot of small pin holes in it? If that is the case then you may well have a lot of burnt holes in the stator wire insulation. This gets back to what I was saying about you having problems that may not go away. You cannot really fix those holes. Yes there are things that you could do but the work involved is about as much as building new and you will not have a new panel in the end. Are the panels ones you have owned since new or did you get them for a deal because they were cacked? We don't really have any idea what we are dealing with here. Your time and money may be better spent with a local ESL rebuilder. We are going round in circles. |
|
|
| brian t |
| guys, have done some more tests placed a straight edge across the film and its definately sagging in the middle panel size is 6"x47" thats the problem its to slack. have stripped panels again and tested the bostik 7432 superglue by sticking a small piece to the panel frame and its not holding in place. must admit never been a big fan of super glue. can anyone give me an alternative glue i can use . cheers |
|
|
| TimA |
Brian,
You haven't mentioned the two strips running down the stator which divide the stator into three and keep the diaphragm centered. Have you replaced these? They, or something equivalent, need to be there!
Tim. |
|
|
| brian t |
| tim, hi yes have replaced those strips this was my 4th attempt at fitting new panels and am almost out of film and conductive coating this time i stretched the film much tighter before glueing in place to see if that made any difference, it didnt have even tried heating the film up to try and shrink it but no joy, would be grateful for any advice you can give me otherwise its back to moving coils for me! |
|
|
| vitalstates |
Hi Brian
It does sound like maintaining tension is an issue here. Again, more information would help. What is the frame material you are bonding to?..Which film are you using? Did you get the glue from Rob with the kit, and if so did it have a bottle of primer with it.
IME bonding mylar to plastic(some plastics) works perfectly with a primer.
Ed |
|
|
| TimA |
Brian,
You could try some of MT Audio's ESL adhesive. I've used it on Quads and it works very well - an instant and strong bond. I've also used epoxy without problems.
I have a pair of Final 0.3s here which I am about to rebuild. The panels are already opened and as soon as I find some suitable replacement foam strip I shall finish the job. I'd prefer to use rows of plastic bolts/washers as this could probably result in a better panel, but I am thinking through the possible practical problems of doing this. For what it is worth I plan to use slow epoxy and gently stretch the diaphragm finger tight before it sets, then heat shrink. In my experience this results in a lasting tension. With my Quads I used a pneumatic stretching jig.
Check the perforated metal stator for flatness, mine are far from flat on close inspection, particularly after having been opened up.
A long shot, but if you happen live in the vicinity of Dorset I could have a look at yours and offer a second opinion.
Tim. |
|
|
| Calvin |
Hi,
somehow I get the impression, that you do something, but not what is recommended. :xeye:
The final stators are simple flat metal pieces. Installing a membrane and tightening it is the easiest of all designs.
what you need:
- the right film: I assume that You got that.
- the right glue: epoxy works, some PU-glues and even some double sided carpet tapes. You should test the glue joint on its strength and stability before.
- the right tension: This seems to be the problematic point here. So do it this way:
- With a pen draw a first set of marking lines on a flat surface (rectangle). Now draw a second set of lines with >1% to <1.5% larger dimensions. Lay down a piece of diaphragm film on that surface. Fix it with some sticky tape (a strip every 1"-2") so that it is just straightened (no tension yet). Mark the film exactly at the same position as the ´first´ rectangle on the flat surface with a pen.
Now start tensioning the film by pulling at the tape strips.
Work always in a crossed way fashion. You will have to do this several times (don´t try to get the final tension just in one go), thereby increasing tension in small steps to the final value. You are finished when the markings on the film reach the ´second´ larger marking on the flat surface. And don´t be astonished....the pulling forces will be quite high! Keep an eye on the ´corners of the film. Here the stress on the diaphragm material is very high. I recommend to put some sticky tape over the edges to reinforce these joints.
Then glue the stator to the membrane (You need a lot of pressure when working with ´wet´ glues like epoxy).
If your stator allows for (metal sheets normally do) you might glue strips of double sided sticky tape on the ´outside´rim of the stator sheet (~1/2" wide) before glueing the stator onto the film. This is especially useful when you use double sided sticky tape throughout!
Tape may give in to the tension over time. By making the ´contact area´larger it resists the pulling forces much better.
When the glue has dried, peel off the tape strips in a way that slowly reduces the tension on the film (it may tear otherwise).
Now peel off the lining of the double sided sticky tape and glue the film onto it with a good pull. Then trim the film along the tape edge with a very sharp knife or razor blade (You must not cut into the insulating of the stator though).
If You haven´t already glued the spacers into the stator You can now press some silicone dots at the right places through the stator holes. Keep in mind the 1/70 to 1/100 rule!
When the silicone drops have dried, turn over the stator and control Your work. The membrane should be axactly flat and levelled.
Now use a heat gun and start the heat treatment.
Work in a zigzag fashion over the membrane area. You can come quite close to the diaphragm (1"-2") with the nozzle but You shouldn´t be too slow in your waving motion (1Hz zigzag) or even stop at any point. You´ll see the membrane relaxing and retightening. The tension will be lower than before, but the stresses within the membrane will be reduced and more even. The membrane will settle very close to the final working point. This way results are more predictable, stable and with closer tolerances (Fs can be within less than +-2Hz).
When You´re done with this you can coat the diaphragm and install diaphragm contacting strips.
Do a second heat treatment.
Test the coating on function by connecting the HV-supply to the stator and membrane. You should see the membrane bowing towards the stator, but it shouldn´t touch it. If You worked cleanly (sweaty fingerprints are a proven method of generating invisible leakage paths ;) ) the tickling sounds (which every panel exhibits at least at first start-up) should vanish within a couple of seconds to minutes.
If they don´t and/or the mebrane is pulled into the stator then You have to add more spacers to reduce the freely vibrating distances. The membrane tension would be too small in this case, so that the membrane comes too close to the stator so that the field density becomes to large and saturated and lowlevel flashovers occur (You could lower the polarizing voltage, but this cure should rather be no option here!).
When the test passed succcessfully, switch off the HV and lay the second stator on the first. Run the test procedure again!
When the test passed you can glue the two stator halves together and let them dry. Install the membrane and stator contacts (if that hasn´t been done yet).
You could do a third heat treatment if you wish, but the mebrane should have settled to its final working point already.
Now you should hold a working panel in your hands.....wasn´t that easy? :D
jauu
Calvin |
|
|
| Few |
Nice set of instructions Calvin.
What problems have you encountered if you eliminate the heat shrinking step? Since it lowers the tension of a pre-stretched diaphragm it seems it would be nice just to avoid the heat shrinking unless doing so causes other problems.
Few |
|
|
| brian t |
| thanks for info guys, tim i have some foam strip left over from the kit i had there is enough to do your speakers and i am in poole am happy to deliver it around to you sometime if that helps. cheers |
|
|
| TimA |
Brian,
It seems you're just down the road! I have sent you an email to arrange contact.
Tim. |
|
|
| Calvin |
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 |
|
|
| Bazukaz |
Hello Calvin,
I remember reading somewhere that heat shrunk membranes lose some strength and long - term dimension stability. Not sure if this is correct. Maybe it is better to apply more uniform mechanical force. Do ESL manufacturers use heat shrinking method ?
Regards,
Lukas. |
|
|
| Calvin |
Hi,
if You use proper film material the loss of tension should be no problem for years.
ESL manufacturers use thermal treatmet of the film....at least the good ones ;)
jauu
Calvin |
|
|
| MJ Dijkstra |
Calvin, could you tell us which manufacturers use heat shrinking?
As far as I know, and based on my own experience, the tension achieved with heat shrinking is quite limited so I doubt if this is the one and only perfect method. |
|
|
| arend-jan |
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! |
|
|
| MJ Dijkstra |
Hi A-J
That's an interesting method. Are there any specific benefits?
Maybe a more uniform distribution of the tension? |
|
|
| TimA |
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. |
|
|
| arend-jan |
| quote: | Originally posted by MJ Dijkstra
That's an interesting method. Are there any specific benefits?
Maybe a more uniform distribution of the tension? |
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. |
|
|
| Calvin |
Hi,
Q: Who?
A: Acoustat, Capaciti, Purist and probablely some more
The rest has already been explained by AJ.
jauu
Calvin |
|
|
| TimA |
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. |
|
|
| ironblue |
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!!! |
|
|
| ER Audio |
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 |
|
|
| ironblue |
brian
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 problem..you are on the home straight now!! |
|
|
| ironblue |
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! |
|
|
| Calvin |
Hi,
| quote: | | This is between 220.C and 260.C (very hot). |
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.
| quote: | | 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 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 |
|
|
| brian t |
| 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 |
|
|
| ER Audio |
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 |
|
|
| ER Audio |
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 |
|
|
|
|
|
