Works like a charm! Everything original, even the phenolic suspension. In a horn, if you want the ultimate performance, field coil is the best. IMHO, of course, but many of my audio-friends agree.
We do see those, but with an astronomical price tag attached - virtually thousands of $$. Fortunately, there are still many used FC drivers that float on ebay at a reasonable cost.But we digress...on the subject of bass...I noticed (maybe I'm simply growing older and something is happening to my hearing) that too little bass id much preferable to too much bass. There just needs to be a hint at the fundamentals and the mind will fill in the rest. Until recently, I had a 35Hz sub, but it had to go on account of very low ex WAF. No, nothing will come close to horn sub, but... That's why I'm going through the trouble of building two sealed box subs.
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I can see why massive field coils and associated power supplies have to be expensive when in a retail driver. But so are trick magnets and the equipment to make them.
On the other hand, folks who roam surplus electronics stores might be able to make one cheaply. How about that?
Footnote on bass:
Some judgments the ear makes poorly. But ironically, using test gear you can educate your ears as to what truly low bass sounds/feels like. Likewise for high treble.
As Toole's research shows, ears have trouble distinguishing a treble boost from an upper bass droop, etc.*
Ben
*present company excepted
On the other hand, folks who roam surplus electronics stores might be able to make one cheaply. How about that?
Footnote on bass:
Some judgments the ear makes poorly. But ironically, using test gear you can educate your ears as to what truly low bass sounds/feels like. Likewise for high treble.
As Toole's research shows, ears have trouble distinguishing a treble boost from an upper bass droop, etc.*
Ben
*present company excepted
No, I haven't and I'm afraid to do this. Because the system performs fabulously and I'm happy. What if I measure and find out that performance is not very linear and there are all sorts of anomalies? How am I supposed to sleep after that? Been there, done that. Generally speaking, I'm very sensitive to brightness and my speakers tend to be somewhat rolled off because I tend to bring tweeters down by a db or two.
Well, you see, measurements and linearity is a strange beast - especially when it comes to horns. A system may measure very linear but your years will tell you that something is not right. And then you start listening and tweaking and end up with a system that doesn't measure all that well. I say, trust your years. Because it's you who you ultimately trying to please.
I think the quality of the driver is important no matter what frequency it is reproducing. Of course, there is no direct, invariable relationship between quality and price. But I never heard the lower frequencies reproduced the way I imagined they could be until I invested in a pair of used TAD TL-1601b and put them in 170L ported cabinets. Probably not suitable if you want explosions and 16 Hz cannon shots, but fabulous for music.
Imo it comes down to space and cash, if you have space but little cash lots of 10-12 inch subs give the best displacement per dollar and can be built small, large nicer drivers can get away with less boxes and more power handling but cost 6x as much at times. I almost always go the 4 driver route because some auto drivers are verrryy respectable mechanically and are dirt cheap. Ymmv, if a customer is willing to pay for the best driver, I give them what they want 
They manage it with MRI machines. (Kidding of course)
But the general configuration doesn't have to closely match permanent magnet models. The pole metals can be chosen according to heat flow considerations.
Frankly, I have little intuition about what a field coil would look like. Or even if it had to have an unvarying force.
Ben
Field coil is just that - a coil of copper wire. Hook up a power supply to it and vous a la - you've got a magnet.
The field coil strength is still limited by the saturation of the ferro magnetic return structure wether it be a low carbon steel or some other more exotic material. Nowadays neodymium is the fashionable choice for a number of practical reasons, but there are still some applications IMO where a field coil might be the better choice. The NRT or Neo-Radial long gap configuration could probably achieve a higher field strength in the gap if someone put some time into it.
Dan - thank you for recognizing I wasn't asking a simple-minded question, whether about coils or MRI machines.
I suppose the magnet design issues are similar whether talking about a lump of copper coil or a lump of neodymium. But there must be opportunities for fresh thinking using coils, as you suggest.
But now I would like to ask a simple question because I don't know much about magnets: in a new thread.
Ben
Imo it comes down to space and cash, if you have space but little cash lots of 10-12 inch subs give the best displacement per dollar and can be built small, large nicer drivers can get away with less boxes and more power handling but cost 6x as much at times. I almost always go the 4 driver route because some auto drivers are verrryy respectable mechanically and are dirt cheap. Ymmv, if a customer is willing to pay for the best driver, I give them what they want
Any specific suggestions for a 2 sq ft sealed box?
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