i just spent over an hour on a reply only to find out it did not go through for some reason.i hate to type let alone retype every thing! so here it goes : on my first prototype i made a double sided coating,by disconecting the bias on one side at a very very low level i could hear a .5 to 1db drop in level(maybe more) not scientificaly measured but noticeable.at a higher level it was not as noticeable but was still there.I concluded it was not worth the extra licron(as it is not cheap per can) or mass it add to the diagphram.I had talked to roger sanders about this (and a whole bunch other) he suggested too coat both sides and stated either way it would work and it did.then we discussed different types of coatings and he explained that using graphite renders a smoother surface with no sharp peaks that could disipate the charge and cause arcing thus burning a hole.i did expreince this but i solved that with better stator insulation and the arcing went away.so therefor i did not have any issue after that.now,i have not tried the pva glue trick yet. maybe a higher dilution with more ink or graphite could work.but the wetting of the film becomes an issue here,the same for licron also,it can be done with one coat but difficult so i use two.isn't that what r&d is about (i love to r&d)!anyway,i use a micrometer to measure the thicknes of the mylar&coating on .25 mil i get .5 to .65mil and .8 or more using .5mil mylar.I have even got good results using monokote before i discovered that the adhiesve backing could be washed off with acetone.which is a .5mil "p.e.t. film" as they call it.the question is can you hear the difference?i can if i know what it is i'm looking for.the average person cannot nor do they care espeicialy when they just paid $400 to $800 per box and they get p.o.ed when you tell em it only cost $200 to build 2 or 3 pair(he,he,he)!just some food for thoght.anyway, i cherished the conversation i had with guru of esl's. so feel free to pick my brain at anytime as i will learn from all of you aswell. jer p.s. working on d.d. amp also if good quality can be acheived at any level it is more than worth the weight(wait) of a transformer at todays prices! by the way "can't" is not in my vocabulary.
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Hi,
regarding the glue-formula.
The water-based glue consists mostly of water, which evaporates while drying. The amount of solids in the glue is of low percentage. So You could as well speak of contaminated water with a certain sticky feature
This solution is thinned further by lots of more water.
If You add now a tiny amount of black ink, typical writing ink for pens, which is a low-percentage-of-solids-water-based solution too, the added mass is in the µg-range. For 100mL of coating I add 2 small drops of Ink, that I pull with a toothpick. The coating looks slightly greyish then.
The wet thickness of a sprayed-on water-based coating is between 25µm-50µm when the wet surface is perfectly smooth and You can expect that only around 1% of that is left after drying. So You can expect the dried coating to be in the sub micron thickness range.
It seems that either the PVA or maybe the ink reduces the surface tension of the water. If the coating builds up droplets You may add a small amount of surfactant.
Alternatively You can wipe the diaphragm with a lint free cloth.
Wiping produces an even thinner coating. So thin that You only can see -watching against a light source- glares like gasoline on water.
Resistance may be too high with this way of applicating, but You may simply overcoat a second or third time.
Using alcohol based glue makes only a difference in drying time and visibility. The alcohol evaporates within a few seconds and might generate white streaks and it might be dry before You finished the coating procedure. Water based coating dries within a couple of minutes which leaves enough time to dispense the coating evenly and uniform.
jauu
Calvin
regarding the glue-formula.
The water-based glue consists mostly of water, which evaporates while drying. The amount of solids in the glue is of low percentage. So You could as well speak of contaminated water with a certain sticky feature
This solution is thinned further by lots of more water.
If You add now a tiny amount of black ink, typical writing ink for pens, which is a low-percentage-of-solids-water-based solution too, the added mass is in the µg-range. For 100mL of coating I add 2 small drops of Ink, that I pull with a toothpick. The coating looks slightly greyish then.
The wet thickness of a sprayed-on water-based coating is between 25µm-50µm when the wet surface is perfectly smooth and You can expect that only around 1% of that is left after drying. So You can expect the dried coating to be in the sub micron thickness range.
It seems that either the PVA or maybe the ink reduces the surface tension of the water. If the coating builds up droplets You may add a small amount of surfactant.
Alternatively You can wipe the diaphragm with a lint free cloth.
Wiping produces an even thinner coating. So thin that You only can see -watching against a light source- glares like gasoline on water.
Resistance may be too high with this way of applicating, but You may simply overcoat a second or third time.
Using alcohol based glue makes only a difference in drying time and visibility. The alcohol evaporates within a few seconds and might generate white streaks and it might be dry before You finished the coating procedure. Water based coating dries within a couple of minutes which leaves enough time to dispense the coating evenly and uniform.
jauu
Calvin
Hi,
I didn´t test scractch resistance, but haven´t experienced efficiency losses over several years and quite stressing circumstances either and I haven´t heard of others suffering from SPL loss so far.
To my experience the glue formula is in the group of the few reliable and stable coatings.
One remark. I usually mix a second solution with increased conductivity which I use to ´spill´ over the metal connection strip. It is often the joint between high conducting metal and low conducting coating that fails overtime. Someone else mentioned he used a small strip of coating-sucked paper between metal and coating.
The problem of the joint failure seems to increase with incresing voltages, which is besides safety another reason for low voltages/low stepup figures.
jauu
Calvin
I didn´t test scractch resistance, but haven´t experienced efficiency losses over several years and quite stressing circumstances either and I haven´t heard of others suffering from SPL loss so far.
To my experience the glue formula is in the group of the few reliable and stable coatings.
One remark. I usually mix a second solution with increased conductivity which I use to ´spill´ over the metal connection strip. It is often the joint between high conducting metal and low conducting coating that fails overtime. Someone else mentioned he used a small strip of coating-sucked paper between metal and coating.
The problem of the joint failure seems to increase with incresing voltages, which is besides safety another reason for low voltages/low stepup figures.
jauu
Calvin
Elvamide dissolves fine in denaturated alcohol or technical spirit. It takes about an hour of stirring (I used a milk "frother" /blender thing) and kept the temperature at about 65degC.
I will coat diaphragms and assemble my stats this weekend and will post some photos possibly also microscope photos of the diaphragm.
Regards
Bent
I will coat diaphragms and assemble my stats this weekend and will post some photos possibly also microscope photos of the diaphragm.
Regards
Bent
Hi,
my first attempt of coating with Elvamide was done tonigth.
I used the "standard" Elvamide solution as described on AudioCircuit. Elvamide dissolved in alcohol. I also added 2 drops of black india ink.
This produced a black solution that I rolled on the mylar diaphragm that was taped to a tamporary frame.
I leared two things:
The elvamide solution does not wet the mylar perfectly; I will try to wash the diaphragm with alcohol before next coating.(old photo film developing trick to avoid marks and bubles on film when developing)
After coating the diaphragm the diaphragm was slightly grey and cloudy.
As others have described, the Elvamide did easily rub off after drying for 20 minutes.
Then I fired up the hot air gun and heatet the mylar to it shrinked and tensioned on the frame. The clouding dissapeared, and the Elvamide solution fused to the mylar perfectly.
I did burn a hole in the diaphragm as I wantet to test how much heath I could apply, but it is not a problem to heath-shrink mylar as long as one keep the hot air gun at a few inches distance, and keep it moving constantly.
I would have discarded the diaphragm anyhow because of the poor wetting.
I was planning on building a advanced diaphragm stretcher, but found that the mylar stics perfectly to a table. I just flattend it out at stretced out all wrinkles, and placed my temporary frame on top. Then I wrapped the mylar around the frame and stretched and taped it thoroughly.
I will take some photos on my next try.
Regards
Bent
my first attempt of coating with Elvamide was done tonigth.
I used the "standard" Elvamide solution as described on AudioCircuit. Elvamide dissolved in alcohol. I also added 2 drops of black india ink.
This produced a black solution that I rolled on the mylar diaphragm that was taped to a tamporary frame.
I leared two things:
The elvamide solution does not wet the mylar perfectly; I will try to wash the diaphragm with alcohol before next coating.(old photo film developing trick to avoid marks and bubles on film when developing)
After coating the diaphragm the diaphragm was slightly grey and cloudy.
As others have described, the Elvamide did easily rub off after drying for 20 minutes.
Then I fired up the hot air gun and heatet the mylar to it shrinked and tensioned on the frame. The clouding dissapeared, and the Elvamide solution fused to the mylar perfectly.
I did burn a hole in the diaphragm as I wantet to test how much heath I could apply, but it is not a problem to heath-shrink mylar as long as one keep the hot air gun at a few inches distance, and keep it moving constantly.
I would have discarded the diaphragm anyhow because of the poor wetting.
I was planning on building a advanced diaphragm stretcher, but found that the mylar stics perfectly to a table. I just flattend it out at stretced out all wrinkles, and placed my temporary frame on top. Then I wrapped the mylar around the frame and stretched and taped it thoroughly.
I will take some photos on my next try.
Regards
Bent
Well, the elvamide solution becomes a layer on top of the mylar. When it has dried, it becomes "flake" that rubs off if you scrats on it with a finger.
But, after heathing with the hot air gun it "fuses" or glues to the mylar perfectly and becomes perfectly clear. I believe that was the point of the youtube video referred to earlier in this thread.
Anyways, I will take som photos during my next attempt.
Regards
Bent
But, after heathing with the hot air gun it "fuses" or glues to the mylar perfectly and becomes perfectly clear. I believe that was the point of the youtube video referred to earlier in this thread.
Anyways, I will take som photos during my next attempt.
Regards
Bent
the suggestion of "contact cement" is NG because contact cement hardens over time, and it is way way way to heavy to start with.
Low mass counts in ESL construction.
the problem with "mylar" is that it is a type of plastic that does not like to be bonded to by most things...
the stuff they use to color mylar balloons might prove interesting... but I diverge.
The "nylon 6.6" might be the best solution to the problem so far... dunno.
Most other coatings, graphite, PVA and antistatic compounds all have in some way a limited life when used in an ESL - the question is how long, and IF that is sufficient or not.
Many graphite doped ESLs worked for 20-30 years, but OTOH some did not.
_-_-bear
Low mass counts in ESL construction.
the problem with "mylar" is that it is a type of plastic that does not like to be bonded to by most things...
the stuff they use to color mylar balloons might prove interesting... but I diverge.
The "nylon 6.6" might be the best solution to the problem so far... dunno.
Most other coatings, graphite, PVA and antistatic compounds all have in some way a limited life when used in an ESL - the question is how long, and IF that is sufficient or not.
Many graphite doped ESLs worked for 20-30 years, but OTOH some did not.
_-_-bear
i personaly didn't mind using graphite except ,as others have stated,getting a consistant coating is very diifficult and time consuming ,practice,practice,practice, is not worth the time and cost of wasting the material and imo you cant go buy color alone.becuase once it is rubbed in it's in.there seems to be a few good materials and methods available.so we must figure out the pro's and con's of each one.the formost difficult being longgivity of adhesion.granted some may work 20 or 30 yrs some 1 or 2 or even less.one other problem is availablity can any one tell me where to find phenol or elevamide in small quanity's without spending a fortune.the reseach i did on this subject was 7 years ago although i am willing to do it again. im finding it harder to aquire certain chemicals and even for such simple things like making mirriors at a low cost(not mention certification) due to the 911 attack.back then i could have gotten a 20 lb bag of elevamide for $8.00 but don't need that much and with todays economy shipping would be 3 to 10 times the cost of the product.what are some your thoughts on this?
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Sorry to step backwards a few weeks, but what is "plasma sputtered coatings". I vaugely remember Martin Logan's panels going milky, but don't recall the details. They were eagerly giving aways free panels if I remember correctly. Does anyone know what they use or used?
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Try Google: plasma sputtered coating
For example:
http://134.147.148.178/ispcdocs/ispc15/content/15/15-0479.pdf
For example:
http://134.147.148.178/ispcdocs/ispc15/content/15/15-0479.pdf
Hi,
the stuff was afaik ITO Indium Tin Oxide sputtered PET-film of 12m thickness and it was a film with a rather low surface resistance used intended originally for TFT-displays. I was told that neither the transport mechanisms nor the heat capacitance of the base film allow for less than 12µm thickness, which would rule out thinner diaphragms that don´t suffer from mass-related HF-amplitude decrease.
It seems that nearly all metals and metal compounds fail under ESLs working conditions, even sputtered Gold.
jauu
Calvin
the stuff was afaik ITO Indium Tin Oxide sputtered PET-film of 12m thickness and it was a film with a rather low surface resistance used intended originally for TFT-displays. I was told that neither the transport mechanisms nor the heat capacitance of the base film allow for less than 12µm thickness, which would rule out thinner diaphragms that don´t suffer from mass-related HF-amplitude decrease.
It seems that nearly all metals and metal compounds fail under ESLs working conditions, even sputtered Gold.
jauu
Calvin
Are there any long term results of this process:
espacenet — Bibliographic data
known?
It´s a sputter process too, and was developed in cooperation with the Fraunhofer Institut.
Wishes
espacenet — Bibliographic data
known?
It´s a sputter process too, and was developed in cooperation with the Fraunhofer Institut.
Wishes
Some years ago I was experimenting with Anti-static stretch film:
Anti-Static Hand Stretch Film
This film has no conductive layer, the plastic itself was conductive!
I was able to build a pretty good sounding Esl Bass speaker, the highs were not so good, the film is 20 uM thick. It was very difficult to transfer the bias voltage over to the membrane, you have to have wide copper strips around the whole membrane perimeter..and good pressure between strips and film. On the picture you can see that I use massive Alu bars for the bias!
I think that this film must be the most long living membrane that exists, that is that it isn't bio degradable!
Anti-Static Hand Stretch Film
This film has no conductive layer, the plastic itself was conductive!
I was able to build a pretty good sounding Esl Bass speaker, the highs were not so good, the film is 20 uM thick. It was very difficult to transfer the bias voltage over to the membrane, you have to have wide copper strips around the whole membrane perimeter..and good pressure between strips and film. On the picture you can see that I use massive Alu bars for the bias!
I think that this film must be the most long living membrane that exists, that is that it isn't bio degradable!
Attachments
Hello,
I noticed the array of 12 small transformers on the floor behind your ESL.
Could you provide some details on these units?
What are the step up ratios, and how did you wired them up together.
Any problems with core saturation?
Thanks,
bolserst
Yes, they have their secondaries in series and primarys in parallell, 230/9volt which gives a step up to about 25 times and 300 times for the array.4.5 watts each and worked ok down to 50 Hz and up to 7-8kHz depending on the capacitive load.
Qualitäts-Trafos, Transformatoren der HAHN Elektrobau GmbH Transformatorenbau
Qualitäts-Trafos, Transformatoren der HAHN Elektrobau GmbH Transformatorenbau