Posted by Cam on January 31, 2000 at 10:50:54:

In Reply to: Other Drivers & tweeters for Straight 8, is it possible ? posted by SBK on January 31, 2000 at 07:05:11:

SBK -

I have thought about something like this, but yes, it would in no way be a Straight-8. I really like the sound of the Vifa PP drivers. I think the Vifa silk tweeters are a pretty good and much less expensive alternative to the Scan Speaks, too.

You have enough tweeter sensitivity to match with 2 Vifa bass/mids, but as Doc said, going to 3 or more will require 2 or more tweeters, or a much more efficient tweeter. I think the multiple tweeter approach is good, but of course it would get really expensive if you use Scan Speaks.

If you study Lynn Olson's development info on his Ariel you'll get a good idea of the difficulty of applying a 1st order crossover (as in the Straight-8) to the Vifa bass/mid. Even though it has a nice roll-off, a 2nd order filter was used to get a really good blend. But apparently some have made Ariels with a 1st-order or no filter on the bass/mid, and the D'Appolito configuration may have an influence on this as well.

The aluminum bass/mid in the Straight-8 has an EXTREMELY extended top end, and this is the only way to properly implement a 1st-order filter with a tweeter that has a typical low-end roll-off and resonance.

I think I would use 4 of the bass/mids to start with, in either a D'Appolito or with the tweeter(s) on top, and not get too fancy with the enclosure until I settled on a configuration and crossover. Running the tweeters vertically alongside the bass/mids is another possibility. With 8 of those suckers you start to get issues with back-EMF as well as expense, and 4 of them ought to drive nicely with 5+ watts.

Definitely a pretty intense development project. Do you have some modelling software and measurment equipement? If you try it I'd like to know how it goes.

Cam