Diy AMT

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I use REW.
I think it is relative.
Bernt
Ok. Then you could use the RTA and the sound generator.
It is very good at spot distinct distortion frequencies.
I think it is relative too. So the 8 kHz peak in distortion level is about - 30 dB then.

Magnets "backside" is this the gap betvine the magnets?
Bernt
Yes. Check what happens if you fill the gap.
Perhaps with tape to start with.
And, what does the B.t field look like? It might twist the pockets in the membrane at the magnets so they actually "blow" into the gap between the magnets.

Not the same configuration that you have above, but it shows what could happen:
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Gap is filled with the frame:
7_5mm_magn_fem.JPG
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7_5mm_magn_B_t.JPG
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Now i think I know your concerns
I t is the movement in the other axis due wrong field direction.
Seems that it is a small problem here.Small field strength in the other direction.
Thank you for the patience.Magnetism is difficult.

Bernt
 
But you must look at the B.t-plots also in the perimeter of the foil and not just in the center:

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In your design, check also the tangential field at the perimeter:

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mk9_7_5mm_15cm_UH-2.jpg
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This is from my latest magnet system with 7,5mm thick membrane. Measured at 15cm distance.
Resonance freQ. 350 Hz.
Now i will try to make a optimal horn.(waveguide)
What is a Q and D horn?
Horn (waveguide) begins with 32mm x150mm, and 50degrees angle, 30mm long.

Bernt
 
Thank you Solhaga.
I could not find it on Google.
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Hawthorne has an amt with waveguide that plays down to 500 Hz.
27cm high 40cm wide,and15cm.deep.
I will try to make something like that.

Bernt
 
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So I finally reread the whole tread :) so niceeee.

As for etching method bandsei, I now don't use a laser printer but a solid ink printer from Xerox , you can get a second hand for around 75 euro. It prints wax directly on the aluminum foil. First have to rough it and clean it. Then etch with the same solution you used early copper sulfate and salt. And you are done I have not yet have a failed etch with your foil as of yet. Only downside I don't think the printer can't print longer the a4 size I believe just like a laser it first creates the image on a drum, which is the size of an a4 I guess :(
 
Has anyone tried RAAL 140-20D (14×2cm) against their AMTs? Opinions?

I have the Beyma TPL-150 but my ring radiator horn tweeter beats it in clarity in the top (10-18kHz) when I cross them from 4kHz and up. But it does not sound clear enough so I am considering the RAAL.
 
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Bernt I have been working with horns since 1994.

I like the concept.

Did you do any calculation?

Or just go and make seemed to be the best idea for a horn shape?

Do you have a frequency response measurement?

Just looking at the picture and having worked with planars and horns I have a guess as to what may be happening. You might have a notch or dip in the response due to the dimensions of your horn. Specifically the width. The notch may be present in the region starting around 7 kilohertz if i remember the dimensions of your horn correctly.
 
Bernt I have been working with horns since 1994.

I like the concept.

Did you do any calculation?

Or just go and make seemed to be the best idea for a horn shape?

Do you have a frequency response measurement?

Just looking at the picture and having worked with planars and horns I have a guess as to what may be happening. You might have a notch or dip in the response due to the dimensions of your horn. Specifically the width. The notch may be present in the region starting around 7 kilohertz if i remember the dimensions of your horn correctly.

That is my experience as well. While it might do wonders (gaining 5-6 dB due to the mouth's dimensions) in the low frequency region, it really screws up the response in the high frequency region, that is corresponding to the throat's dimension and curve. A carefully simulated throat is a must along of course with a really smooth design and making.
 
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