Diy AMT - Page 15

båndsei · 20th January 2013, 06:34 PM

Hyab magnets Sweden.
[IMG]

[/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]

[/IMG]
[IMG]

[/IMG]

Bernt

ticovski · 20th January 2013, 07:04 PM

Quote:

Originally Posted by båndsei

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?

solhaga · 20th January 2013, 08:30 PM

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:

Wouldn´t for example a 5x5x40 mm block be too fragile to be in front?

båndsei · 20th January 2013, 08:52 PM

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

solhaga · 20th January 2013, 09:14 PM

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!

SEdwards · 21st January 2013, 06:22 AM

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.

solhaga · 21st January 2013, 09:58 AM

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).

solhaga · 21st January 2013, 02:07 PM

"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.

båndsei · 08:14 PM

I have bee able to make this tool:
[IMG]

[/IMG]
[IMG]

[/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.

SEdwards · 25th January 2013, 09:20 AM

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.

20th January 2013, 06:34 PM	#141
båndsei diyAudio Member Join Date: Dec 2008	Hyab magnets Sweden. [IMG][/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][/IMG] [IMG][/IMG] Bernt

22nd January 2013, 08:06 PM	#149
båndsei diyAudio Member Join Date: Dec 2008	I have bee able to make this tool: [IMG][/IMG] [IMG][/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 08:14 PM. Reason: new picture

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20th January 2013, 08:30 PM	#143
solhaga diyAudio Member 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: Wouldn´t for example a 5x5x40 mm block be too fragile to be in front?

20th January 2013, 08:52 PM	#144
båndsei diyAudio Member Join Date: Dec 2008	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

20th January 2013, 09:14 PM	#145
solhaga diyAudio Member 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!

21st January 2013, 06:22 AM	#146
SEdwards diyAudio Member 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.

21st January 2013, 09:58 AM	#147
solhaga diyAudio Member 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).

21st January 2013, 02:07 PM	#148
solhaga diyAudio Member 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.

25th January 2013, 09:20 AM	#150
SEdwards diyAudio Member 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.