final 0.3 er audio repair kit

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
 
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
 
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
 
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
 
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
 
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
 
So you have a short to ground...

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.
 
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
 
Good suggestion Calvin...

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.
 
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
 
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!
 

TimA

Member
2002-11-17 5:39 pm
UK
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.
 
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