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haralanov wrote:

You may not believe me, but the driver start to  roll off (very smoothly) after 14kHz and at 20kHz is at -6dB. I intentionally do not use it so high, because I have ultra light weight alnico paper tweeter: http://www.bgaudio.org/forums/viewtopic.php?p=9833971#p9833971  So my eliptical driver is able to reproduce almost all of the high frequency information, and as I already said - without any trace of harshness.

Of course it has no “trace of harshness” – it has too heavy cone to operate in the zone where harshness might take place. Yes, the diaphragm does not work as a piston as the properly implemented break-up might do very good job. I also have no doubts that your driver goes to 14kHz and has -6dB at 20kHz.  However, the question is not how far it goes but what kind HF it reproduce, if it possible to get the same 14kHz from another dedicated HF driver and if those “dedicated” HF might be better in quality. My experience shows that use of light cone MF drivers and to push them into HF does not produce the stimulating enough HF. Even if you got some kind of very unique cone, and 4.4g (with suspension) shall be very good, then how low you driver this 4.4g cone? Thins about the Doppler and intermodulation distortion for this type of the driver… Anyhow, it is not my philosophy to try pushing a driver to work in widest bandwidth – I truly see no reason to do it. You can put on cello the short strings and try to play soprano or mezzo violin, the question would be why one need it to play a quarter? The whole point to have 4 individual instruments in a quarter is because when they play together then the combination of them gives birth of new interesting possibility, particularly in the moments of complex polyphony. Anyhow, your accomplishment with this MF driver might be very good for what you are looking for but it is not a direction that I personally find perspective. All my experiences with similar topology that you advocate lead me to confirmed it.

haralanov wrote:

My field coils are powered ot 120V, not at 12V, and the batteries are wired in series

THAT is VERY interesting in context of this thread. I did not pick it up while you were talking above with “be” about impedance that your driver use 120V magnetizing coil. Do you see advantages in it? A am not sure that I do. OK, less current but who cares? From different perspective you shall have much more isolation on coil to handle high voltage. I do not think it is a problem as well. So, what the advantage? When you were talking about high voltage motors I did not realized that it is 120V!!!! To do it you shall have a coil with high amount of DCR and it would tale a LOT of copper to wind. More turns would make more layer and more layer would make the external layers be less affective from perspective of flux/temperature ration.  I do not know how it all works, I would need to consult with my coil people but I do not immediately see any advantage to go for high voltage in electromagnet. Care to educate me on the subject?

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