Good point
It migh succeed
You have the tape full width.I use 2-4 pcs. 50mm tape.
You might use a helper for the aplying of tape.It is a lot of cutting/work to loose.
If you cant get resistance right i have 10my alu/paper from my research for 7my.
Bernt
It migh succeed
You have the tape full width.I use 2-4 pcs. 50mm tape.
You might use a helper for the aplying of tape.It is a lot of cutting/work to loose.
If you cant get resistance right i have 10my alu/paper from my research for 7my.
Bernt
It went very well, I didn´t bother to powder the table.
Should have had assistance though, got some folds in the middle so the membrane is effectively 158 mm high, it´ll do 😎.
Resistance is 6,7 ohms 😀!
Weight is 4,7 grams but the membrane is 10 % too long now.
Maybe it´ll be just above 4 grams when cut to right size.
Again, the area is 960 square centimeters so there´s no need to worry about the hf response.
On the contrary, it might be good to have that weight when it comes to the lf response.
I will still apply the cotton threads for the suspension and then a second layer of film on the aluminium side as well. So maybe the membrane will weigh some 6 grams.
I´ll know in a short while...
Should have had assistance though, got some folds in the middle so the membrane is effectively 158 mm high, it´ll do 😎.
Resistance is 6,7 ohms 😀!
Weight is 4,7 grams but the membrane is 10 % too long now.
Maybe it´ll be just above 4 grams when cut to right size.
Again, the area is 960 square centimeters so there´s no need to worry about the hf response.
On the contrary, it might be good to have that weight when it comes to the lf response.
I will still apply the cotton threads for the suspension and then a second layer of film on the aluminium side as well. So maybe the membrane will weigh some 6 grams.
I´ll know in a short while...
With a second film layer and cotton threads for suspension the whole membrane weighs 7,6 grams.
So in 4 hours I made my first AMT membrane. With a little practice one could do it in 2 hours.
Still have to fold and bake it, though.
Pictures later, have to take a break now and walk the dog.
So in 4 hours I made my first AMT membrane. With a little practice one could do it in 2 hours.
Still have to fold and bake it, though.
Pictures later, have to take a break now and walk the dog.
Some pictures then.
Measured according to above:
Re-used the rods to get the correct cutting distances: two cuts 3 mm inbetwenn every 10 mm:
Measured according to above:
Re-used the rods to get the correct cutting distances: two cuts 3 mm inbetwenn every 10 mm:
AMT playing
The suspension was a little tricky to apply, but I managed in the end.
I think I have some work to do on that:
Anyway, AMT is playing. Some resonanses in the low but from 300 Hz there´s usable output.
A couple of dBs rise per octave up to 13 kHz where acoustic lense of 3 mm makes the directional output drop.
It´s a totally different soundstage compared to my focused line arrays
Next step is to come up with a better solution for the suspension, hopefully the resonances in the low will be fewer, and build a complete pair.
The suspension was a little tricky to apply, but I managed in the end.
I think I have some work to do on that:
Anyway, AMT is playing. Some resonanses in the low but from 300 Hz there´s usable output.
A couple of dBs rise per octave up to 13 kHz where acoustic lense of 3 mm makes the directional output drop.
It´s a totally different soundstage compared to my focused line arrays
Next step is to come up with a better solution for the suspension, hopefully the resonances in the low will be fewer, and build a complete pair.
The bad lf response is probably due to that the membrane is too stiff in the folds.
So I´ll make the next membrane with only one film layer.
The suspension will be from the middle of each pleat, so there will be a second layer on that pleat.
Also I will try to remove the glue in the folds, I noticed that it accidently came off in some folds when I did the first membrane.
I don´t know if the hf response is desirable or not.
I guess I´ll know better when I have a stereo pair.
So I´ll make the next membrane with only one film layer.
The suspension will be from the middle of each pleat, so there will be a second layer on that pleat.
Also I will try to remove the glue in the folds, I noticed that it accidently came off in some folds when I did the first membrane.
I don´t know if the hf response is desirable or not.
I guess I´ll know better when I have a stereo pair.
"The suspension will be from the middle of each pleat, so there will be a second layer on that pleat."
I´ll change the suspension to having pieces of yarn on both sides of the membrane at the top and bottom. That ought to keep the membrane centered but still allow the membrane some sideways movement, especially a bit in the membrane.
The yarn has to be supported at the bottom of course, perhaps with some tape.
I´ll change the suspension to having pieces of yarn on both sides of the membrane at the top and bottom. That ought to keep the membrane centered but still allow the membrane some sideways movement, especially a bit in the membrane.
The yarn has to be supported at the bottom of course, perhaps with some tape.
So I did a new membrane with another alu/paper combo (see båndsei´n thread for picture). Film only on one side.
It´s 10 um aluminium and the finished membrane´s resistance is below 4 ohms.
The new membrane weighs 8,12 grams.
The alu weighs 56 % of the total alu/paper weight.
So I guess it´ll be under 5 grams if I can peel the paper off.
It´s 10 um aluminium and the finished membrane´s resistance is below 4 ohms.
The new membrane weighs 8,12 grams.
The alu weighs 56 % of the total alu/paper weight.
So I guess it´ll be under 5 grams if I can peel the paper off.
The paper came off really easy.
The membrane weighs 6 grams without the paper and the resistance is 3,6 ohms.
Feels like this membrane really gonna hit the lows.
The membrane weighs 6 grams without the paper and the resistance is 3,6 ohms.
Feels like this membrane really gonna hit the lows.
Use "Renset Benzin" petrol cleaned.Use a cloth an soak it.
I have tested diaphragms with and without the glue in the folds and goes deeper without.
Test om a piece of 3m tape.
Bernt
I have tested diaphragms with and without the glue in the folds and goes deeper without.
Test om a piece of 3m tape.
Bernt
Ok, I got it. It is called "Kemiskt ren bensin" in Sweden.
No danger to the glue under the alu I guess?
No danger to the glue under the alu I guess?
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