The problems with the jury is that there's a long turnaround time for the verdicts and that the jury is more or less blind how the culprit (the membrane) behaves; it only got the measurement to judge by:
The knife should last long, have you compared the knives under a magnifying glass?
The knife should last long, have you compared the knives under a magnifying glass?
Checking the knife under a magnifying glass is a good idea, I'll do that.
But on the topic of membranes, we have a new best membrane (dual 3 mm wide 20 um thick traces + 14 um outer fill):
First we can compare efficiency, the last weeks squiggly fill with dual sided self adhesive 30 um aluminum was pretty inefficient compared to the current best (single sided 6 mm traces, 20 um traces and fill):
1. The red is last weeks squiggly membrane.
2. The yellow is the single sided 6 mm traces, 20 um traces and fill.
3. The blue is the new 3 mm wide 2x20 um traces with 20 um fill.
4. And lastly the pink is 3 mm wide 2x20 um traces but with 14 um fill, so slightly lighter.
The new dual sided membranes (blue and pink) are as afficient or more so than the previously best. Below 1.4 khz the efficiency of the blue and pink is identical but above that the lighter is slightly more efficient, 1-2 dB.
But the interesting part is the equalized distortion:
Considering the efficiency is pretty much the same, the reduction in distortion is pretty amazing. This is pretty much the nail in the coffin for 6 mm wide traces. When I get time I'll redo the measurement to compare the 2x20 with 20 vs 14 um fill and see if the increased distortion of the lighter 14 um fill is a measurement artifact or the truth.
If the measurements are accurate and the membrane with the lowest distortion is the 2x20 um + 20 um fill then that is my current best candidate. It is slightly less efficient above 1.4 khz but that is not a problem for me, it is still plenty efficient enough.
I did another membrane though. Since the 3M 77 spray is not as convenient to use I made a 30 um traces + 14 um fill which uses the kapton tape as adhesive. The distortion is as low as the 2x20 um traces + 14 um fill, but less efficient. It would be interesting bump the 30 um traces to 40 or 50 um though, in that case it should be as efficient as the dual 20 um traces membranes. Such thick aluminum is harder to source though, only sources I've found requires me to buy a lot.
But on the topic of membranes, we have a new best membrane (dual 3 mm wide 20 um thick traces + 14 um outer fill):
First we can compare efficiency, the last weeks squiggly fill with dual sided self adhesive 30 um aluminum was pretty inefficient compared to the current best (single sided 6 mm traces, 20 um traces and fill):
1. The red is last weeks squiggly membrane.
2. The yellow is the single sided 6 mm traces, 20 um traces and fill.
3. The blue is the new 3 mm wide 2x20 um traces with 20 um fill.
4. And lastly the pink is 3 mm wide 2x20 um traces but with 14 um fill, so slightly lighter.
The new dual sided membranes (blue and pink) are as afficient or more so than the previously best. Below 1.4 khz the efficiency of the blue and pink is identical but above that the lighter is slightly more efficient, 1-2 dB.
But the interesting part is the equalized distortion:
Considering the efficiency is pretty much the same, the reduction in distortion is pretty amazing. This is pretty much the nail in the coffin for 6 mm wide traces. When I get time I'll redo the measurement to compare the 2x20 with 20 vs 14 um fill and see if the increased distortion of the lighter 14 um fill is a measurement artifact or the truth.
If the measurements are accurate and the membrane with the lowest distortion is the 2x20 um + 20 um fill then that is my current best candidate. It is slightly less efficient above 1.4 khz but that is not a problem for me, it is still plenty efficient enough.
I did another membrane though. Since the 3M 77 spray is not as convenient to use I made a 30 um traces + 14 um fill which uses the kapton tape as adhesive. The distortion is as low as the 2x20 um traces + 14 um fill, but less efficient. It would be interesting bump the 30 um traces to 40 or 50 um though, in that case it should be as efficient as the dual 20 um traces membranes. Such thick aluminum is harder to source though, only sources I've found requires me to buy a lot.
How I used 30 um traces & 14 um fill with the adhesive on the kapton tape:
First cut and weed the traces and the fill separately. For the 30 um traces I added sticky transfer tape as protection on top since the trace gap is only 0.4 mm. The fill does not have such small gaps and could be cut without any top protective layer at all.
Use transfer tape to extract the traces
Now reuse the same sticky tape and extract the fill. Here I rushed so the traces are slightly off lengthwise, but not off enough to short to the fill so in the end it was within my margin of error.
Now pull the fill + the already connected traces with the sticky tape
Tadaa!
Now the top is plain aluminum without any glue, we can apply it to kapton tape with the adhesive facing upwards
Carefully remove the sticky tape without damaging the membrane
Now use a tweezer and remove the sticky tape used when cutting the traces
Now the only thing left is to cut the edges of the membrane. Because the adhesive is facing up and I don't want an accident where I ruin the membrane, I first covered the adhesive with some masking tape before cutting.
Then I cut the excess with a scissor. Here is the cut membrane (it wants to roll so I needed to weigh it down to photograph)
First cut and weed the traces and the fill separately. For the 30 um traces I added sticky transfer tape as protection on top since the trace gap is only 0.4 mm. The fill does not have such small gaps and could be cut without any top protective layer at all.
Use transfer tape to extract the traces
Now reuse the same sticky tape and extract the fill. Here I rushed so the traces are slightly off lengthwise, but not off enough to short to the fill so in the end it was within my margin of error.
Now pull the fill + the already connected traces with the sticky tape
Tadaa!
Now the top is plain aluminum without any glue, we can apply it to kapton tape with the adhesive facing upwards
Carefully remove the sticky tape without damaging the membrane
Now use a tweezer and remove the sticky tape used when cutting the traces
Now the only thing left is to cut the edges of the membrane. Because the adhesive is facing up and I don't want an accident where I ruin the membrane, I first covered the adhesive with some masking tape before cutting.
Then I cut the excess with a scissor. Here is the cut membrane (it wants to roll so I needed to weigh it down to photograph)
Nice foils and nice jigs i must add !! by the way how long is this tweeter and how wide unsupported ? sinnce i have kind of the same distortion patern
the units tend to have quite some distortion starting early although FR looks really nice. only making them extreme long counters this as far as i seen. my long 140cm ones do hardly anything down low in distortion except near resonance. these smaller ones tend to creep up in distortion (earlier then i thought, they are not at all near there xmax usually) and in your picture the resonance is not even the highest peak witch i would expected. it is still really good by any means !! i am just wondering whats happening. since i got the same thing. i wonder if a slight tension sideways or more stiffer alu (i know that screws the idea low res small foil width idea) it might help the low end. what are your thoughts ?
ooh and since your res is already rather low i assume the unsupported width between foams is rather larger already ? you might want to try horizontal pieces of a tape. like the ones from themaskingshop.co.uk its 40 mic rather heavy but if you do a few of them (they are 3 mm wide) every ....cm it will make the foil more stilf sideways, but because the tapes are so small it wont hurt the top end all that much. but it will or should show in the lower end. or thinner pieces, since they will eb folded over there length it becomes rather rigid sideways.
anyway , the FR looks stunning ! smooth, the roll off might be the mic >? i myself have troubles as well with these constructions to go flat to 20khz. i think it also has to do with there length. same foil same mylar will do 20khz with easy if smaller in length
the units tend to have quite some distortion starting early although FR looks really nice. only making them extreme long counters this as far as i seen. my long 140cm ones do hardly anything down low in distortion except near resonance. these smaller ones tend to creep up in distortion (earlier then i thought, they are not at all near there xmax usually) and in your picture the resonance is not even the highest peak witch i would expected. it is still really good by any means !! i am just wondering whats happening. since i got the same thing. i wonder if a slight tension sideways or more stiffer alu (i know that screws the idea low res small foil width idea) it might help the low end. what are your thoughts ?
ooh and since your res is already rather low i assume the unsupported width between foams is rather larger already ? you might want to try horizontal pieces of a tape. like the ones from themaskingshop.co.uk its 40 mic rather heavy but if you do a few of them (they are 3 mm wide) every ....cm it will make the foil more stilf sideways, but because the tapes are so small it wont hurt the top end all that much. but it will or should show in the lower end. or thinner pieces, since they will eb folded over there length it becomes rather rigid sideways.
anyway , the FR looks stunning ! smooth, the roll off might be the mic >? i myself have troubles as well with these constructions to go flat to 20khz. i think it also has to do with there length. same foil same mylar will do 20khz with easy if smaller in length
Last edited:
ah you used different foils, for one membrane ? interesting! complicated 🙂 but interesting. in the end i do not know if the kaptopn does not screw it all ? i mean kapton has a more pronounced sound to it and is more heavy then a mylar foil. and if you are gone make them big... Mylar will handle that fine , i think ? i noticed quite a difference between my regulr 12 mic mylar vs that expensive 12-12 kapton.
i did order some really thin alu tape so you can use mylar ... and have alu with acrylic adhesive, making it handle much more power due to the glue layer 🙂 (more damping to) i did not receive it yet so proof is in the pudding... you know how it goes. but ill send you a message when it arrives might be interesting for your build as well. alu is +- 14 micron according to them...
Exactly!
The reason is I have to, to get good performance. As proven by solhaga, the ideal trace width is 3 mm given my configuration of magnets, gap and steel thickness. If I had a tensioned membrane, I could have 3 mm traces and all would be well since the gaps in between can be empty. But with a corrugated membrane I need to fill the outside area around traces to add stiffness, since there is no tension. The problem, however, is that 3 mm traces only cover 22% of the membrane, thus 78% of the aluminum weight would be just the structural fill, which kills efficiency. And kill as in the order of -6 dB less efficient if I remember correctly. By using different thicknesses I can double the relative aluminum weight of the traces and bring the driven weight to 50% which is on par with a normal membrane where the traces cover 60% of the magnet-ctc, which brings the efficiency up to the same level as wide traces.
I have the the following configuration, which is shamelessly stolen from solhagas diagram here based on his excellent simulations. I also kidnapped the diagram from there and added orange for the foam:
The width of the membrane is 55 mm, where the outer 5 mm on each side is supported by the foam (45 mm unsupported).
The total length of the membrane is currently 26.25 cm under magnets, but they portrude a few cm top and bottom.
When I have dual sided 20 um traces, but with the thin 14 um outer fill, I also get the same distortion pattern:
As I do with a single sided 30 um traces, same thin 14 um outer fill:
I have not confirmed this on a single sided membrane, but based on my current problems the problem seems to go away when I use a heavier foil, 20 um, for the outer fill:
For my design goal, less low end distortion is worth more than 1-2 dB efficiency above 1.4 khz so using a heavier foil for the outer fill is a no brainer, but depends on your design goal.
Could definently be interesting. The question is about glue weight though. My 30 um self adhesive foil has a 30 um thick acrylic glue, the glue weighs as much as 150 % of the 12 um mylar or kapton! Shame, since the self adhesive foil is extremely easy to cut. That is why I used the kapton tape adhesive on the single sided since it is a 12 um silicone adhesive and much thinner than the self adhesive acrylic glue.
In my tests I haven't found any sonical difference between kapton vs mylar, but if anything the kapton membrane has slightly lower distortion.
Last edited:
On the topic of self adhesive aluminum tape, I just ordered a roll of 100 mm wide, 50 um thick aluminum tape. I'll have too see how thick the acrylic adhesive is but hopefully not more than 50 um, hopefully less.
The idea is to experiment with the dual sided thickness but on a single side which might be easier to cut.
The idea is to experiment with the dual sided thickness but on a single side which might be easier to cut.
OOh nice ! really nice clarification ! i thought you had the 12/12 kapton ? so 12 micron glue and 12 kapton ? its the same company you bought it from i believe that has that. expensive though 🙁. well the alu if it will ever arrive.... i got some custom problems. is 30 cm wide.. and has according to them.... 13 mic alu and 17-20 micron adhesive and a liner, so its more easy to cut, pretty nice... if it arrives. and then you could use 6 micron mylar if you like... i really wonder what the horizontal traces would do. if ur ok with losing some SPL, i myself always go for getting low or FR above spls.. its the last thing i care about but everyone to there own. nice project btw really well documented !!
Last edited:
I have multiple variants 🙂
I have the 12/12 kapton + silicone adhesive you mention, that is the one I used in the last post single sided membrane which had 30 um aluminum traces and 14 um aluminum rest area fill.
I also have non adhesive 12 um kapton, where I use either the 3M 77 spray (which is the lightest glue I have used) or 30 um aluminum foil with 30 um acrylic self adhesive.
In this post I weighed mylar / kapton + the aluminum and the glues given a fixed dimension.
If we recalculate all weights in the unit of how thick um alu it is comparable to:
30 um alu = 30 um alu
30 um acrylic adhesive = 12 um alu
12 um silicone adhesive on the kapton = 9 um alu
Light coat of 3M 77 spray = 6 um alu
12 um mylar / kapton = 8 um alu
6 um mylar / kapton = 4 um alu
This is pretty much the reason I stopped playing around with 6 um mylar, since even the lightest glue I can use is still so much heavier that it is not worth it, at least in my opinion.
But on the topic on the 14 um alu tape: if it has 30 um adhesive, then, for the same weight, we could instead have 20 um alu with the 3M 77 spray. Which based on my measurements, is a lot stiffer. Or less weight and higher efficiency on the top end.
If I could get my hand on aluminum tape with 15 um acrylic adhesive though... in various thicknesses... I would be very happy 🙂
haha yes i agree 77 is the thinnest. not he most reliable. but still. slightly over spray,and is heavy 🙂 well if i get the alu i let you know.who knows....
Have you consider to have one layer of cutout driven aluminium foil on one side and only non cut aluminium foil on the other side?
Then you'll get rid of any alignment predicaments.
Oh yes it is unreliable. Or at least not as reliable as the kapton glue or self adhesive foil. And in my weight comparison I used a really light coat so it would probably be safer to spray slightly more and then we get basically the same weight as the kapton, but not as consistent.
One application of the 14 um tape you are writing about is that I could use non adhesive 20 um foil for the traces and fill on the front with kapton glue as adhesive, and then use 14 um tape for the rear traces.
20 um tape with acrylic adhesive would be better, but as long as both the front and the rear is in series then the fact that the rear is thinner doesn't matter except that total efficiency will be slightly lower. But since only ~ 29 % of the series resistance will be with traces on the rear I believe the effiiciency losses would be negligable.
I could, but it would be heavier. And even with my sloppy alignment in my latest 3 foils it was still good enough to perform excellent. And I expect when I try adjust and correct for alignment errors that the precision will be better. In the end I am not convinced that alignment is a problem.
Even if it will be (in my opinion, marginally) heavier, there will be no bare Kapton; the membrane should be stiffer and behaving more like a beam:
That is true.
Would be interesting to try. Say if I repeat the single sided 30 um traces with 14 um fill but like you say the whole side with 14. Then I use self adhesive 30 um on the other side.
If that performs better then I'd wish I could buy aluminized kapton with 12 um kapton + 14 or 20 um alu. I only saw listings for 12 um kapton + 1 um alu.
Would be interesting to try. Say if I repeat the single sided 30 um traces with 14 um fill but like you say the whole side with 14. Then I use self adhesive 30 um on the other side.
If that performs better then I'd wish I could buy aluminized kapton with 12 um kapton + 14 or 20 um alu. I only saw listings for 12 um kapton + 1 um alu.
Last edited:
I made 2 more membranes:
12 um kapton with silicone adhesive, glued to 14 um alu covering the whole membrane without any cutouts around the traces. Then 30 um self adhesvie aluminum on the rear.
As a weight comparison, the same membrane with cutouts around the traces and non adhesive 30 um alu (using the kapton adhesive), weighs 1.40 grams. So not having cutouts around the traces and using a slightly heavier adhesive for the traces adds 24 % weight, but the interesting part is to compare how it performs, if the distortion is lower. I would like to also compare against a memgrane with traces cutouts but with 20 um alu instead of 14. This would also add comparable weight, would be interesting to see what gives best performance per weight, completely solid fill or thicker alu around the traces.
That comparison would also tell us if the distortion we observed in the previous measurements is due to flapping around the traces, which will definently be fixed by using solid fill, or if it is the outer fill that is flapping in case it would not be fixed.
Also for the sake of documentation: The rear fill obviously had no precision but that meant that I had no reference of where to cut the outer edge of the membrane. So I added a border around the traces and then cut such that I cut away exactly all of this border:
12 um kapton, dual sided 30 um self adhesive aluminum traces + 20 um outer fill glued with 3M 77 spray.
This time I was more careful to keep things aligned, and worked quite well:
And on the topic of adhesives again, this is how it looks:
The grains are quite big, might not be an issue for larger areas like the fill but probably not a good idea on traces 1 mm wide or less. It is probably a good idea to use self adhesive aluminum foil or the kapton glue for the traces, since I will run my shading network in the membrane which will result in lots of thin traces. If anything the self adhesive alu probably has the best glue.
And I took some photos of the assembly. I split the driver into bottom and top parts where the bottom is 3x as long. The reason for making the top part shorter is to make it easier to mount since the magnet force is not as large in pushing away so I don't have to force it as much. Also if I accidentally squish my fingers in between two pieces there is less total force crushing them.
Note that the foam has an adhesive, but I haven't peeled away the plastic liner. When I removed it and tried to glue the foam to the steel I just kept catching the edge of the magnets so the foam didn't stay flat. With the liner it stays flat no problem, I haven't had any problems with the membrane not being centered since.
Since one of my goals is that I want to be able to assemble my driver one piece at a time, I have threaded inserts in two of the holes in the plastic edge. The edge also has a small cutout such that the foam liner can catch under the edge, which keeps it in place. That way I don't have to worry about the foam falling out when mounting everything together.
Could be an idea, but would need to be small. But to be honest soldering the wires to the membrane is only a problem when the traces are glued with the 3M 77 spray, which I probably won't do due to concerns about reliability and consistency. When I use the kapton silicone glue it doesn't come loose even when I heat it during solderering. And when using acrylic glue the pad gets slightly loose when soldering but when it cools the glue hardens again. Nothing like the 3M 77 spray where the whole pad and parts of the connecting trace releases from the kapton when heated.
12 um kapton with silicone adhesive, glued to 14 um alu covering the whole membrane without any cutouts around the traces. Then 30 um self adhesvie aluminum on the rear.
As a weight comparison, the same membrane with cutouts around the traces and non adhesive 30 um alu (using the kapton adhesive), weighs 1.40 grams. So not having cutouts around the traces and using a slightly heavier adhesive for the traces adds 24 % weight, but the interesting part is to compare how it performs, if the distortion is lower. I would like to also compare against a memgrane with traces cutouts but with 20 um alu instead of 14. This would also add comparable weight, would be interesting to see what gives best performance per weight, completely solid fill or thicker alu around the traces.
That comparison would also tell us if the distortion we observed in the previous measurements is due to flapping around the traces, which will definently be fixed by using solid fill, or if it is the outer fill that is flapping in case it would not be fixed.
Also for the sake of documentation: The rear fill obviously had no precision but that meant that I had no reference of where to cut the outer edge of the membrane. So I added a border around the traces and then cut such that I cut away exactly all of this border:
12 um kapton, dual sided 30 um self adhesive aluminum traces + 20 um outer fill glued with 3M 77 spray.
This time I was more careful to keep things aligned, and worked quite well:
And on the topic of adhesives again, this is how it looks:
The grains are quite big, might not be an issue for larger areas like the fill but probably not a good idea on traces 1 mm wide or less. It is probably a good idea to use self adhesive aluminum foil or the kapton glue for the traces, since I will run my shading network in the membrane which will result in lots of thin traces. If anything the self adhesive alu probably has the best glue.
And I took some photos of the assembly. I split the driver into bottom and top parts where the bottom is 3x as long. The reason for making the top part shorter is to make it easier to mount since the magnet force is not as large in pushing away so I don't have to force it as much. Also if I accidentally squish my fingers in between two pieces there is less total force crushing them.
Note that the foam has an adhesive, but I haven't peeled away the plastic liner. When I removed it and tried to glue the foam to the steel I just kept catching the edge of the magnets so the foam didn't stay flat. With the liner it stays flat no problem, I haven't had any problems with the membrane not being centered since.
Since one of my goals is that I want to be able to assemble my driver one piece at a time, I have threaded inserts in two of the holes in the plastic edge. The edge also has a small cutout such that the foam liner can catch under the edge, which keeps it in place. That way I don't have to worry about the foam falling out when mounting everything together.
Could be an idea, but would need to be small. But to be honest soldering the wires to the membrane is only a problem when the traces are glued with the 3M 77 spray, which I probably won't do due to concerns about reliability and consistency. When I use the kapton silicone glue it doesn't come loose even when I heat it during solderering. And when using acrylic glue the pad gets slightly loose when soldering but when it cools the glue hardens again. Nothing like the 3M 77 spray where the whole pad and parts of the connecting trace releases from the kapton when heated.
I have been redesigning my corrugator also. The last variant didn't push the push the cogs together and had a fixed distance. Only my bigger teethed roller worked, and the corrugations are not as deep as they could be. My finer teethed roller had too little distance between the rollers so just crushed the membrane. But if it worked it would produce less tall but more corrugations, so would be interesting to compare.
Here is the modified model: I split the bottom roller ball bearing holder into a separate piece (red) that can move up and down freely, but is locked otherwise. The blue cylinder is a die spring, where I can adjust the tension by adjusting the height of the red cap at the bottom with the small guiding axle nub to keep it under the spring.
I also did some preliminary testing with a filled plane instead of having cuts around the traces. First a word of caution: I have had some measurement problems with 1 membrane + driver (30 um traces, 20 um fill with cutouts) so I need to redo those measurements. I also accidentally pulled out the membrane of the 14 um traces + 14 um fill with cutouts from the driver so I had to remake the corrugations but I didn't make them deep enough, so not exactly comparable as before.
The important thing is that when I get my 50 um aluminum tape, I will redo all the following membrane configurations:
(all single sided)
50 um traces, 14 um fill with gaps
50 um traces, 14 um solid filled plane (traces on the rear)
50 um traces, 20 um fill with gaps
50 um traces, 20 um solid filled plane (traces on the rear)
But with that disclaimer in mind, here are some preliminary results:
First efficiency of solid fill vs gap around traces. The gapped membrane is more efficient on the top end yes but the solid is more efficient on the bottom. But the interesting part to me, which disclaimer: might just be a measurement artifact due to rushing the measuring, is that the solid fill looks like it has a smoother response. The wiggles are smaller, and overall the response is more smooth. If that is not just a measurement fluke then that alone will probably make me go with the solid fill. Although the fact that I don't have to worry about alignment is nice too 😀
On the topic of distortion:
First the 30 traces with 14 um outer fill with gaps, it has higher distortion than last weekend which might be because I pulled the membrane? Maybe it will be fixed if I re-roll the corrugations?
This one should be like the above but with less distortion, but obviously not. But then again, something is very wrong so I need to take this one apart.
Then the solid fill. This one is interesting because it has by far the least tall order distortion. Solid fill might be a really good idea.
As a comparison I threw in a 3x 30 um dual sided traces with 20 um fill with gaps around the traces. It is by far the most efficient but it too has higher tall order distortions than the solid filled one.
Tomorrow I will swap in the previously best performing membrane, which was the 2x 20 um traces + 20 um fill with gaps. And swap the massively distorting 30 + 20 with gaps with another membrane and see if the problem is the membrane itself or the rest of the driver.
Here is the modified model: I split the bottom roller ball bearing holder into a separate piece (red) that can move up and down freely, but is locked otherwise. The blue cylinder is a die spring, where I can adjust the tension by adjusting the height of the red cap at the bottom with the small guiding axle nub to keep it under the spring.
I also did some preliminary testing with a filled plane instead of having cuts around the traces. First a word of caution: I have had some measurement problems with 1 membrane + driver (30 um traces, 20 um fill with cutouts) so I need to redo those measurements. I also accidentally pulled out the membrane of the 14 um traces + 14 um fill with cutouts from the driver so I had to remake the corrugations but I didn't make them deep enough, so not exactly comparable as before.
The important thing is that when I get my 50 um aluminum tape, I will redo all the following membrane configurations:
(all single sided)
50 um traces, 14 um fill with gaps
50 um traces, 14 um solid filled plane (traces on the rear)
50 um traces, 20 um fill with gaps
50 um traces, 20 um solid filled plane (traces on the rear)
But with that disclaimer in mind, here are some preliminary results:
First efficiency of solid fill vs gap around traces. The gapped membrane is more efficient on the top end yes but the solid is more efficient on the bottom. But the interesting part to me, which disclaimer: might just be a measurement artifact due to rushing the measuring, is that the solid fill looks like it has a smoother response. The wiggles are smaller, and overall the response is more smooth. If that is not just a measurement fluke then that alone will probably make me go with the solid fill. Although the fact that I don't have to worry about alignment is nice too 😀
On the topic of distortion:
First the 30 traces with 14 um outer fill with gaps, it has higher distortion than last weekend which might be because I pulled the membrane? Maybe it will be fixed if I re-roll the corrugations?
This one should be like the above but with less distortion, but obviously not. But then again, something is very wrong so I need to take this one apart.
Then the solid fill. This one is interesting because it has by far the least tall order distortion. Solid fill might be a really good idea.
As a comparison I threw in a 3x 30 um dual sided traces with 20 um fill with gaps around the traces. It is by far the most efficient but it too has higher tall order distortions than the solid filled one.
Tomorrow I will swap in the previously best performing membrane, which was the 2x 20 um traces + 20 um fill with gaps. And swap the massively distorting 30 + 20 with gaps with another membrane and see if the problem is the membrane itself or the rest of the driver.
And I was inspired by @solhaga to buy some new foam strips to use as the suspension. Not because the one I have now is bad, but because it is 9 mm wide and I only have room for 6 mm so I have to cut it with a scissor. And I'm not cutting it as precisely as I want, so I have decided to order 6 mm wide strips instead so I don't have to cut them.
It will let me streamline and speed up mass production of parts with good consistency.
It will let me streamline and speed up mass production of parts with good consistency.