IMF revamp - worthwhile?

This thread is in parallel to the one I started a couple of days ago (DIY speaker design, based on ATC SM75-150 mids), which has moved on a bit for those who visited only on the first day. My alternative option, hence this additional thread, is to revamp the drivers in my IMF speakers.

This won't have spouse-appeal, however IF it would make a significant improvement in sound quality, and more so than the option in my other thread, then I can try to persuade that it is worth the money…. Otherwise, and if my complete change as in the other thread will result in a lowering of quality, I'd be better off saving my money!

My IMFs are early Professional Monitors (their top-of-the-range). No mark number on them so may be the first version, although they appear idetical to a picture I've seen of the MkIII. I.e. 35-40 years old. Bass driver is the earlier version of the B139 (SP6171), for which the original KEF spec claimed a resonance of 20Hz. Other drivers are KEF B110 (I think, though it is ~5in across widest part), Celestion HF1300 and a supertweeter (not KEF T27, and it doesn't look like any pics I've seen of Coles 4001). The following links give reviews/details of it: http://imf-electronics.com/Promon/ontest/index.html http://www.marklev.com/IMF/Promon/promonmkiii.html

Possible replacement drivers are: Volt 250.8 (suggested by Wilmslow Audio for this loading), ATC SM75-150, and Scanspeak R2904/710003. WA say they can design a suitable XO. Any observations on this bass unit, or alternatives, for this TL enclosure? Any comments in general? Easy to assume that the best of modern drive units will be better, but the big question is, will they???

Thanks in advance!
Paul

 

wilmslow are very good and produce some good speakers ....as long as you have the cross over points a reengineered crossover of a similar design should provide a similar sound to the original