What the fåååk is this??
6moons audio reviews: TakeT H2+ & Trafomatic Audio T2+
Seems to be a diaphragm for headphone.
With varius depth of the pleats.
Båndsei
It is a piezo "film" Head phone ,with a tube amp.
6moons audio reviews: TakeT H2+ & Trafomatic Audio T2+
Bernt
6moons audio reviews: TakeT H2+ & Trafomatic Audio T2+
Bernt
I have bought new magnets:
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25x50x12mm
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My "old" magnets: 25x25x10mm.
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Assembled
Measurements later.
Bernt
25x50x12mm
My "old" magnets: 25x25x10mm.
Assembled
Measurements later.
Bernt
If the membrane has the same thickness as before, the extra millimeter at the front and the back will for sure bring down the distortion.
Measurements.
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With "Horn"
Membrane is app. 9x40x160mm.
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[url=http://www.diyaudio.com/forums/gallery/showphoto.php/photo/13005][img]
[IMG][url=http://www.diyaudio.com/forums/gallery/showphoto.php/photo/13005][IMG]https://origin.dastatic.com/forums/gallery/data/500/medium/dobb_kithara_100cm_vith_horn.jpg[/url][/IMG]
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First picture at 100cm.
Next 100cm with "Horn"
Next at 30cm
Next 30cm with "Horn"
Bernt
With "Horn"
Membrane is app. 9x40x160mm.
[url=http://www.diyaudio.com/forums/gallery/showphoto.php/photo/13005][img]
[IMG][url=http://www.diyaudio.com/forums/gallery/showphoto.php/photo/13005][IMG]https://origin.dastatic.com/forums/gallery/data/500/medium/dobb_kithara_100cm_vith_horn.jpg[/url][/IMG]
First picture at 100cm.
Next 100cm with "Horn"
Next at 30cm
Next 30cm with "Horn"
Bernt
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So the wave guide picks the level up in the low but at the same time it messes up the middle.
Considering the Q&D wave guide, that is a good start though!
See that you got the back pole piece reflections as well; the distortion level is high due to the reflection at 8 kHz and the signal level is high at double that frequency where the front wave and reflected back wave are in phase.
Considering the Q&D wave guide, that is a good start though!
See that you got the back pole piece reflections as well; the distortion level is high due to the reflection at 8 kHz and the signal level is high at double that frequency where the front wave and reflected back wave are in phase.
Q&D ?
Quick and Dirty? I made it Quick.
I like the sensivity. My membrane is 2.1 ohm.
I think I continue with my open structure, using larger magnets though.
Got some 30x 30x7,5mm 10pcs. Need 10 pcs. more to make one AMT
Bernt
Quick and Dirty? I made it Quick.
I like the sensivity. My membrane is 2.1 ohm.
I think I continue with my open structure, using larger magnets though.
Got some 30x 30x7,5mm 10pcs. Need 10 pcs. more to make one AMT
Bernt
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Looks great, Bernt.
Will you have different widths of the aluminium strips?
BTW, use B.n to get the wanted field, not /B/.
B.t will show you the unwanted tangential field.
Will you have different widths of the aluminium strips?
BTW, use B.n to get the wanted field, not /B/.
B.t will show you the unwanted tangential field.
Hello Bernt.
I like the work you have been doing!
Great stuff you have created.
That peak around 8 khertz might be a function of either the motor width ( most probably)
Or a reflection off of the lower board you have in the picture ( possibly )
I know from the commercial AMT work I have been doing that there is a very direct correlation between the width of the slots and the resonances measured.
I like the work you have been doing!
Great stuff you have created.
That peak around 8 khertz might be a function of either the motor width ( most probably)
Or a reflection off of the lower board you have in the picture ( possibly )
I know from the commercial AMT work I have been doing that there is a very direct correlation between the width of the slots and the resonances measured.
I'd say with dense back pole pieces, the back wave hits the back pole pieces and most of it gets reflected.
It'll then superimpose on the front wave.
At 8 kHz lambda/2 is 21,5 mm.
An open configuration that Bernt now is working on will not have that problem.
Instead it will have problems with weak and non-linear magnetic field densities.
But I'll reckon you will solve that Bernt.
It'll be rather easy to compute the width of each aluminium strip in order to have the same force on each pleat and then let the Silhouette machine do the rest.
It'll then superimpose on the front wave.
At 8 kHz lambda/2 is 21,5 mm.
An open configuration that Bernt now is working on will not have that problem.
Instead it will have problems with weak and non-linear magnetic field densities.
But I'll reckon you will solve that Bernt.
It'll be rather easy to compute the width of each aluminium strip in order to have the same force on each pleat and then let the Silhouette machine do the rest.
Look on the horizontal plane.
All the commercial designs are a plate with slots punched out.
The slot width produces a very nasty peak in the response.
This is measured out of the near field. Similar to Bernt's measurement.
In the near field a few millimeters away from the diaphragm the response looks awesome.
You will never guess which response curve gets published?
All the commercial designs are a plate with slots punched out.
The slot width produces a very nasty peak in the response.
This is measured out of the near field. Similar to Bernt's measurement.
In the near field a few millimeters away from the diaphragm the response looks awesome.
You will never guess which response curve gets published?
So the use of different slot widths makes the effects of this more distributed?
Well that's easily tested, just narrow half of the slots and see what happens.
Well that's easily tested, just narrow half of the slots and see what happens.
Yes sir!
I have a new design that pretty much eliminates the present problem and is still fairly easy to manufacture.
Bernt's designs would be very difficult to sell. OEM's don't like expensive drivers.
But Bernt's designs are probably very enjoyable to listen to.
If you want some help in designing a wave guide for the AMT send me an email.
I have done just a few of them.
I have a new design that pretty much eliminates the present problem and is still fairly easy to manufacture.
Bernt's designs would be very difficult to sell. OEM's don't like expensive drivers.
But Bernt's designs are probably very enjoyable to listen to.
If you want some help in designing a wave guide for the AMT send me an email.
I have done just a few of them.
News
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Just finished
Higher sensivity than my other "open" models.
Measurements later.
Thank's for the comment's.
I use same with for the strips. Not sure it matters as current is the same in all strips.Weight is not,so maybe it matters .
In this FEM simulation the results are the same, I am avare it's not always so.
Bernt
Just finished
Higher sensivity than my other "open" models.
Measurements later.
Thank's for the comment's.
I use same with for the strips. Not sure it matters as current is the same in all strips.Weight is not,so maybe it matters .
In this FEM simulation the results are the same, I am avare it's not always so.
Bernt
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As it is the current density and the magnetic field density that makes up the resulting force, a wider strip means less force on the strip.
Compare with the non linear magnetic flux density across the gap in a ribbon loudspeaker:
So the ribbon has wider strips where the field is denser:
So the ribbon has wider strips where the field is denser:
With Horn
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9,5mm thick membrane 100cm dist. 2,8V.
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Same at 20 cm.
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6,5mm thick membrane 100cm dist 2,8V.
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Same at 20 cm.
The 9,5mm diaphragm is not done optimal.I will make a new with 160mm wide tape from Solhaga, thank´s again.Have to make a tool to apply the tape to the alu.
Bernt
Bernt
9,5mm thick membrane 100cm dist. 2,8V.
Same at 20 cm.
6,5mm thick membrane 100cm dist 2,8V.
Same at 20 cm.
The 9,5mm diaphragm is not done optimal.I will make a new with 160mm wide tape from Solhaga, thank´s again.Have to make a tool to apply the tape to the alu.
Bernt
Bernt
Which measuring program do you use?
Is the distortion level absolute or relative the frequency response level?
There seems to be very high distortion level for the 2nd HD at 8 kHz but it might just as well be that the frequency response is that higher at 16 kHz.
If the AMT had back pole pieces the higher level could be explained by the reflecting back wave (full wave length and half wave length), but since this is an open structure that can't be the explanation.
So either it is the non-linearity of the membrane's foil strips or perhaps that magnet's "backside" shouldn't be exposed to the sound wave:
BTW:
In Holm (From PartExpress Tech Talk):
"If the fundamental at 1k is 90 dB, and the distortion is 40 dB, then the display shows -50 dB.
If the fundamental at 500 hz is 20 dB lower, ie 70 dB, and the distortion is 40 dB, then the distortion is displayed as -30 dB."
So in the measurement depicted below, the distortion level at 1 kHz is 60 dB down from the fundamental as shown, not -65 - -15 = 40 dB down:
Is the distortion level absolute or relative the frequency response level?
There seems to be very high distortion level for the 2nd HD at 8 kHz but it might just as well be that the frequency response is that higher at 16 kHz.
If the AMT had back pole pieces the higher level could be explained by the reflecting back wave (full wave length and half wave length), but since this is an open structure that can't be the explanation.
So either it is the non-linearity of the membrane's foil strips or perhaps that magnet's "backside" shouldn't be exposed to the sound wave:
An externally hosted image should be here but it was not working when we last tested it.
BTW:
In Holm (From PartExpress Tech Talk):
"If the fundamental at 1k is 90 dB, and the distortion is 40 dB, then the display shows -50 dB.
If the fundamental at 500 hz is 20 dB lower, ie 70 dB, and the distortion is 40 dB, then the distortion is displayed as -30 dB."
So in the measurement depicted below, the distortion level at 1 kHz is 60 dB down from the fundamental as shown, not -65 - -15 = 40 dB down:
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