Substituting driver motors; ferrite and alnico

[bldozier]

Thanks,
I had been speaking with a member about the ultimate contruction of a nla
Jbl driver. My advise was to use a larger compatible motor for a 3" voice coil.
If I wanted to use a different magnet assembly ie. Alnico or ferrit could I change it out
For its counterpart?

[remusr]

I think this is what you are asking... Civil wars in Africa (Zaire?) in the late 1970's caused Cobalt, and therefore Alnico, to be temporarily unavailable. JBL rapidly created ferrite replacements for Alnico drivers in order to be able to continue producing their existing systems with no re-engineering. So the ferrite drivers had to match the Alnico drivers performance sonically and electrically. Due to the approx 50% lower magnetic energy of ferrite/ceramic magnets vs Alnico the magnet assembly was much larger and slightly different configuration but I believe that in general the sound is the same where there is a direct replacement, ie 2231H for 2231A. So yes you can swap a ferrite driver for an Alnico one. You could give more information as to specifics.

[bldozier]

Hi your information is greatly appreciated brother.
2103a drivers are supremely hard to locate, I've located baskets from a
Jbl twelve inch (2204h) however im building alnico cabinets.
I wanted to remove the ferrite in place of its counterpart. It was not clear if I could
Swap the motors not the entire speaker just the magnet.
Thanks.

[remusr]

JBL speakers are designed as a whole. I would not recommend swapping the magnet assemblies.

[bldozier]

That does not answer my question.

[Robh3606]

No net improvement going from ferrite back to alnico using the same motor. Actually a step backwards using the old alnico motors from that time. You are going to have to take out the cones if you can do it at all. Methods of attaching the motors may be different if they updated the frame when they did the ferrite conversions. Changing the motor changes the driver to a ???.

Rob