That's definitely a pretty good sized box and if the driver is still in decent shape, it should be capable of good low frequency response. Is the box sealed or vented ? Sean
The Bozak woofer makes an excellent subwoofer in my opinion. It has a natural roll off at a fairly low Hz and as such, it does not need a very sophisticated upper crossover. In fact, I have used them for woofers in conjunction with Lowther PM6 drivers which are extremely efficient. The Bozaks are not as efficient, but their true bass output is strong and they can still be matched to do the job with the Lowthers.
The woofer and the tweeters are on an aluminum frame to fit a hole for a 15inch speaker. When you remove them, the B199 woofer fits in the hole of a standard 12 inch speaker.
The box is sealed, though removing the midrange driver would make it vented! I'm not sure if it would be better to leave the mid in and allow it to vibrate passively, or to take it out and glue a piece of wood down over the hole (from the inside). Also, we'd need to take out the driver and look it over. It was making bass without incident 5 years ago, but I don't know what shape the foam surround is in. If the driver wasn't built to be a "subwoofer", does that imply that the foam surround (even in best condition) may not hold up to the bass energy? I doubt it. If the foam surround is going bad, would it be best to just purchase a new driver designed specifically to be a subwoofer or get a new foam kit?
Thanks for your input. It will be fun to make this work!
I would start off by investigating the condition of the driver. If everything seems okay i.e. the driver moves freely without dragging or scraping, the surround ( foam, cloth, etc... ) is in good shape, etc.. If that all checks out, I don't see a problem with using what you already have. I would personally pull all of the other drivers out out and seal the cabinet as best possible. While you are in there, install some decent wire and connect it directly from the input jacks ( whatever they may be on the cabinet ) to the terminals of the speaker itself. In other words, bypass any / all of the existing wiring and crossover parts.
Using this as a subwoofer is actually easier on the driver since it will only have to cover a smaller portion of the band that it used to have to cover as a full fledged woofer. How great it will work or how long it will hold up as a "true" SUB-woofer is another story. I'm sure that it will more than supplement the little bookshelf's that you Dad is currently using and should be capable of pretty solid bottom end in a box that size. If the driver does not hold up ( although i see no reason that it shouldn't other than foam rot ), you can always replace it with another driver that would be more suitable for this specific application. Sean