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Old 20th January 2013, 07:34 PM   #141
diyAudio Member
 
Join Date: Dec 2008
Hyab magnets Sweden.
[IMG]Click the image to open in full size.[/IMG]
This is from my new horn and 38x170mm diy amt.
I have a little problem with distortion.I think it can ´be solved with a new fixture for diaphragm,li´ke the one from Adam.
[IMG]Click the image to open in full size.[/IMG]
[IMG]Click the image to open in full size.[/IMG]

Bernt
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Old 20th January 2013, 08:04 PM   #142
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Join Date: Jul 2002
Location: N-W Balkans
Quote:
Originally Posted by båndsei View Post
This is from my new horn and 38x170mm diy amt.
I have a little problem with distortion.I think it can ´be solved with a new fixture for diaphragm,li´ke the one from Adam.
Very nice! What is the sound impression?

How far was mic from AMT during measurement?

If I recalls correct horn is better with very smooth surface.

From this article:

http://profesional.beyma.com/ingles/...oudspeaker.pdf

comes that AM1 and AM2 have fs around 1000 Hz so seems that is the main reason for not going below that fq. If we want to go lower we need more emitting area and more mass.

Are there any particular reason(s), apart from usable magnetic field, why AMT can not be wider? Eg. 10 cm wide or so?
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Old 20th January 2013, 09:30 PM   #143
solhaga is offline solhaga  Sweden
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Join Date: Jun 2009
Location: Värsta Götaland
Yeah, I know about Hyab. Hard to get to their online web catalogue though.

Anyway, according to Hyab's product sheet they got Neodym blocks with:

lenght [mm] 2,0-120
width [mm] 2,0-50
thickness [mm] 2,0-15,0


I was thinking of the link you supplied that included this picture of an AMT motor:

Click the image to open in full size.

Wouldn´t for example a 5x5x40 mm block be too fragile to be in front?
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Old 20th January 2013, 09:52 PM   #144
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I measured at 1meter and a bit off axis.I have not listened to music yet.
Neo's are not that fragile ,more like ceramic,so dont smack them.
You could try to simulate a system with 5x5 iron in front and back,and neos in betwene.

Bernt
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Old 20th January 2013, 10:14 PM   #145
solhaga is offline solhaga  Sweden
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Join Date: Jun 2009
Location: Värsta Götaland
Yes, iron in front is one thing.

I was curios about the configuration SEdwards was talking about with "planks of neos across the front" and I thought the picture showed just that.

According to my first simulations it is hard to get an even field in the gap.
It is much simpler with iron pole pieces. But I would really like to be proven wrong.

Anyway, keep up the good work båndsei!
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Old 21st January 2013, 07:22 AM   #146
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Join Date: Dec 2011
One thing that I would like to try is to have less field strength at the edges of the diaphragm where it is fixed. I think that less distortion may be possible this way. Plus if the loudest sound is from the center dispersion should be better. That's one of the reasons to consider neo planks.

The horn looks really cool.
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Old 21st January 2013, 10:58 AM   #147
solhaga is offline solhaga  Sweden
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Join Date: Jun 2009
Location: Värsta Götaland
Sorry for the crappy ascii art, but could a formed iron pole piece do?
(
|
|
(

At the edges the field will be farther away and thus weaker.

Or you can make a compound "plank" suspended with non-magnetic steel screws in the beginnng and at the end.

Just my 10 öre (Swedish for cent).
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Old 21st January 2013, 03:07 PM   #148
solhaga is offline solhaga  Sweden
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Join Date: Jun 2009
Location: Värsta Götaland
"Or you can make a compound "plank" suspended with non-magnetic steel screws in the beginnng and at the end"

Sorry about that, it won´t obviously not work.
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Old 22nd January 2013, 09:06 PM   #149
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Join Date: Dec 2008
I have bee able to make this tool:
[IMG]Click the image to open in full size.[/IMG]
[IMG]Click the image to open in full size.[/IMG]
By mistake it is made with 2mm alu,my idea was 1,5mm. Maybee good for large amt's
Depth is variable, length max 175mm.
I have listened and adjusted the horn/sub system 800 hz 48db crossover.I might have another bas/sub,this one is too slow.

Bernt.

Last edited by båndsei; 22nd January 2013 at 09:14 PM. Reason: new picture
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Old 25th January 2013, 10:20 AM   #150
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Join Date: Dec 2011
Love all the progress. I was looking at plexiglass as a possibility for the planks, since you can score and snap it with straight lines.

Any update with the THD? 2 and 1/2 weeks and I should be able to start building stuff, can't wait.
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