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Old 22nd July 2013, 12:54 PM   #241
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You are right.
Here a better pic.I Count 27 folds.
[IMG]Click the image to open in full size.[/IMG]

Bernt
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Old 24th July 2013, 07:03 PM   #242
srinath is offline srinath  United States
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In this design the pleats move closer to each other/away from each other right, not towards you and away from you ?

I am once again in awe of you guys ...
I'll do the magnet motor structure sometime, but that's my limit, the diaphragm is crazy.
I have thought about making it with a bunch of neo-magnets with them facing the diaphragm held in place with a wood or aluminum frame. That eliminates the edge being so close to the magnet ...
Also shiny neos look cool compared to the steel to my eye.

Cool.
Srinath.
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Old 24th July 2013, 08:26 PM   #243
solhaga is offline solhaga  Sweden
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Quote:
Originally Posted by srinath View Post
In this design the pleats move closer to each other/away from each other right, not towards you and away from you ?
Yes

Quote:
Originally Posted by srinath View Post
I have thought about making it with a bunch of neo-magnets with them facing the diaphragm held in place with a wood or aluminum frame. That eliminates the edge being so close to the magnet ...
Also shiny neos look cool compared to the steel to my eye.

Cool.
Srinath.
In my opinion the field will not be linear enough.
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Old 25th July 2013, 02:10 AM   #244
srinath is offline srinath  United States
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Yes you're right in the case of the field, unless you put these magnets very very close and they are very very thin ...
That of course means more and more $$$ ...
I have an amt, I am sure its a N8 or something magnet, I wonder what would be the result if I replace em with a 38 or 42 ...
Cool.
Srinath.
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Old 25th July 2013, 07:01 AM   #245
solhaga is offline solhaga  Sweden
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You´ll have to simulate it!
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Old 28th July 2013, 10:32 PM   #246
solhaga is offline solhaga  Sweden
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My first membrane for the new motor 60 x 160 mm.
Alu-ratio is 5/3 mm. Resistance 3,8 ohm, weight 2,5 grams:

Click the image to open in full size.

Membrane is folded as 6,5/1,5 mm:

Click the image to open in full size.

Measurements (red is with a crude waveguide):
Click the image to open in full size.

Perhaps usable lf response down to 350 Hz can be achieved with some EQ, another thing is of course how it sounds.
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Old 29th July 2013, 01:45 PM   #247
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I'm impressed that the HF can be so good with wide 6.5 mm traces. That gives a nice width to be able to divide into 2 traces in serial. I've been experimenting with that a little bit but have had very little time due to my wedding last weekend!

One other thing to try is to thin the aluminium chemically after making the traces. Question is whether it's easy to easily etch away the thickness evenly.

With the one decent 1 mil kapton diaphragm that I've managed to make (traces about 6 mm with 2 mil gaps) the HF drops off around 15 kHz or so.
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Old 29th July 2013, 07:43 PM   #248
solhaga is offline solhaga  Sweden
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Good idea with etching away some aluminium after the trace cutting.
If the etchant (Natriumperoxidisulfate) is stired during etching it should be even.
It is also important that the temperature doesn´t rise.
Perhaps one can measure the resistance during etching and just stop (pull out and rinse) when desired resistance is reached?

It should be easy to test with a leftover membrane.
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Old 30th July 2013, 09:22 AM   #249
solhaga is offline solhaga  Sweden
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Default First serious attempt on making a waveguide

First a skeleton to get the shape:

Click the image to open in full size.

I used the same foam as sides as in my Cornus (floor dampening XPS):

Click the image to open in full size. Click the image to open in full size.

Quick fastening:

Click the image to open in full size. Click the image to open in full size.

When all four sides are made, the back will get "foam sealed".

Last edited by solhaga; 30th July 2013 at 09:36 AM.
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Old 30th July 2013, 10:46 PM   #250
solhaga is offline solhaga  Sweden
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Default Measurements with waveguides

Measeruments done at listening range, red is with a waveguide made according to above, blue is a previous and inferior attempt:

Click the image to open in full size.

EQ -6 dB from 300 to 1000 Hz and -6 dB from 5 to 15 kHz.
XO is practically at 300 Hz, but there will be a "DC protection" at 150 Hz or so.
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