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Old 23rd April 2013, 11:56 AM   #101
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No.

Bernt
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Old 23rd April 2013, 03:32 PM   #102
solhaga is offline solhaga  Sweden
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So I got rid of the glue in the folds - and lost one gram!
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Old 4th May 2013, 05:19 AM   #103
solhaga is offline solhaga  Sweden
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Some pictures from the manufactoring of the new membranes with 10 um aliminium and peelable paper back.
This material is much easier to cut as the paper has less friction.It is much easier to

Cut and taped:
Click the image to open in full size.

Cutout raw membrane:
Click the image to open in full size.
Previous membrane had attached terminals, they were not reliable and caused heat. Now the aluminium itself extends as terminals. A piece of kapton tape supports the fragile bare aluminium.

Flip the membrane and peel of the paper:
Click the image to open in full size. Click the image to open in full size.
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Old 4th May 2013, 05:27 AM   #104
solhaga is offline solhaga  Sweden
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Removing superfluous glue:
Click the image to open in full size. Click the image to open in full size.
Gaining a gram and it will be much easier to remove the membrane from the tool.
The membrane is shortened by a couple of cm from the theoretical 600 mm, reality showed that there were too many folds.

I´ll fold:
Click the image to open in full size.

Baked and ready:
Click the image to open in full size. Click the image to open in full size. Click the image to open in full size.
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Old 4th May 2013, 05:29 AM   #105
solhaga is offline solhaga  Sweden
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Re-using the alu sticks from the folding tool to make a gluing tool:
Click the image to open in full size. Click the image to open in full size. Click the image to open in full size.

Almost ready to assemble:
Click the image to open in full size.
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Old 4th May 2013, 05:35 AM   #106
solhaga is offline solhaga  Sweden
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The top and the bottom will be accessible, but what about the sides?
Trying with a 1 mm alu stick taped outside the first and last folds.

Click the image to open in full size.
Again some Kapton tape, this time to attach the sticks to the membrane.

It doesn´t work that well, the 1 mm alu stick is not stiff enough.
I´ll try with a jig saw blade, it is stiffer and would also adhere to the magnetes.
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Old 4th May 2013, 05:37 AM   #107
solhaga is offline solhaga  Sweden
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Assembly:
Click the image to open in full size.

Covering the top and bottom in a misguided attempt to hide the ugly glue and to get better frequency response:
Click the image to open in full size.
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Old 4th May 2013, 06:00 AM   #108
solhaga is offline solhaga  Sweden
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Did som initial listenening, great sound stage and all, but something was wrong.

Swept with Holm, almost the same characteristics as for the former membrane: 200 Hz till 20 kHz, 6 dB/oktavs increase after efter 2-3 kHz, a dip at vid 15 kHz.
I will try the thin foil (7 um alu) as well with this building practice to see if there´s any different response in the lows.

That the response is only from 200 Hz is really not a problem, my OBs matches that well. In fact, I could probably have no filter at all for the AMTs. Well, apart from some DC-protection then.

I will try some baffles anyway, but I suspect that they will mess up the sound stage as usual.

Quote:
a misguided attempt
Continued with REW in order to do same fault finding, discovered vibrations at 230 Hz and 460 Hz. They didn´t match any dimensions at first but several halvings of the wavelenght revealed a standing wave of 18 cm corresponding to the pipe I have made when I sealed the top and the bottom .

Got rid of the tape, got rid of the vibrations .

Had another vibration at 510 Hz, the glue had no contact with the steel at one end. Easily corrected as well: Happiness is a warm glue gun!


NOW IT IS REALLY PLAYING!!
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Old 4th May 2013, 06:57 AM   #109
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That is great news.
I realy like your gluing tool.I can use thís idea.
Well done!!!

Bernt
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Old 4th May 2013, 07:09 AM   #110
solhaga is offline solhaga  Sweden
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Thanks, Bernt!

Any idea what a 7 um alu would do compared to the 10 um alu?
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