I intend to use the fronts, I thought that it may be a lot easier to modify the throat/mouth on the driver if I disassembled the front from the compression part (the complex slots after the diaphragm) so that I have a clean hole to work with. I intend to modify it reversably, so that the driver can be easily restored to original without damage. But if the front disk is hard to remove, I will skip this idea. Mayby Le Cleac'h knows, he seems to have used the driver on 1" horns.
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The screws at the rear are the only mechanical fixing holding the front part on. However they are generally quite well stuck on. I gently tapped it away, ensuring I didn't shock the driver much to avoid damaging the diaphragm or the magnet. You could try twisting the front part , utilising the horn mounts. Take your time but it will come off without using excessive force.
Bruno,
Definitely the way to go! Do keep us posted on how you get on. The nice thing is it's a very short distance to the phase plug if you do remove the casting, if the horn has the right sort of angle at its throat, it should be a nice smooth continuous flare from the phase plug all the way out.
Somewhat related: I want to try a field coil conversion at some point but having attempted to dismantle the motor (even tried baking one to unglue the magnets!) am resigned to having to machine most things but the phase plug (which pops out easily).
Cheers
cv
Definitely the way to go! Do keep us posted on how you get on. The nice thing is it's a very short distance to the phase plug if you do remove the casting, if the horn has the right sort of angle at its throat, it should be a nice smooth continuous flare from the phase plug all the way out.
Somewhat related: I want to try a field coil conversion at some point but having attempted to dismantle the motor (even tried baking one to unglue the magnets!) am resigned to having to machine most things but the phase plug (which pops out easily).
Cheers
cv
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I have seen no real science that would show that a field coil motor would have any real benefits over a permanent magnet. I think much of that is purely hope and speculation that you can make a field coil motor outperform or even match a well done Neo or ALNICO motor in reality, It just doesn't make sense that you can make a filed coil with as stable a magnetic field as a permanent magnet.
At the same time I commend you CV for going to the trouble to find out. It just doesn't make any sense to me to go backwards 100 years to end up back at the same place.
At the same time I commend you CV for going to the trouble to find out. It just doesn't make any sense to me to go backwards 100 years to end up back at the same place.
Well, I've heard a field coil conversion of a ferrite Radian...
As a more sound comparison, I've heard an alnico Lowther vs the field coil ... no contest.
I'm happy to accept I was fooled, or the above were not optimally implemented motors, but I've head a number of field coils and they do seem to have similar traits - a relaxed yet vivid character - that makes me feel it's at least worth a shot.
The Yamahas seem to have a proper Alu shorting ring and I have a flux probe, so if I do ever manage it, we can at least have a principled comparison. Although the originals are ferrite...
If there is a difference, and I'm not fooling myself, I would love to understand why. You are assuming of course that a more stable magnetic field is a good thing
Best,
cv
As a more sound comparison, I've heard an alnico Lowther vs the field coil ... no contest.
I'm happy to accept I was fooled, or the above were not optimally implemented motors, but I've head a number of field coils and they do seem to have similar traits - a relaxed yet vivid character - that makes me feel it's at least worth a shot.
The Yamahas seem to have a proper Alu shorting ring and I have a flux probe, so if I do ever manage it, we can at least have a principled comparison. Although the originals are ferrite...
If there is a difference, and I'm not fooling myself, I would love to understand why. You are assuming of course that a more stable magnetic field is a good thing
Best,
cv
CV,
I don't know enough to compare the field coil against a ceramic magnet but I can say that the ceramic magnets are probably the worst choice that can be made. That decision is made strictly on price alone as far as I am concerned. Ferrite magnets have the highest inherent distortion of the current materials used in loudspeakers.
I don't know enough to compare the field coil against a ceramic magnet but I can say that the ceramic magnets are probably the worst choice that can be made. That decision is made strictly on price alone as far as I am concerned. Ferrite magnets have the highest inherent distortion of the current materials used in loudspeakers.
http://www.eighteensound.com/Portals/0/Img/Img_tech/doc_tech/18_Sound_AIC.pdf
This was also used on some old field-coil cone drivers.
This was also used on some old field-coil cone drivers.
AIC is not a simple shorting ring.
0017 10NDA610 - Active Impedance Control 10NDA610 : Eighteen Sound - professional loudspeakers
"an additional coil fixed on the pole piece and connected in parallel to the moving coil. The magnetic field generated by this coil has the following effects: 1) Impedance linearization 2) Acoustic and electric phase linearization 3) Significant increase of sensitivity and total SPL 4) Total harmonic distortion reduction 5) Constant power transfer The A.I.C. offers substantial advantages to the sound quality by not absorbing the moving coil's electromagnetic energy."
0017 10NDA610 - Active Impedance Control 10NDA610 : Eighteen Sound - professional loudspeakers
"an additional coil fixed on the pole piece and connected in parallel to the moving coil. The magnetic field generated by this coil has the following effects: 1) Impedance linearization 2) Acoustic and electric phase linearization 3) Significant increase of sensitivity and total SPL 4) Total harmonic distortion reduction 5) Constant power transfer The A.I.C. offers substantial advantages to the sound quality by not absorbing the moving coil's electromagnetic energy."
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