http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=5703123950&category=14977

Here is a borrowed pic. Anyone ever seen or used one of these?

Crown offered a similar model. These are very useful for experimenting with different combinations of crossover frequencies quickly and easily. Once you have determined the optimal parameters for your combination of drivers and enclosure, you can design and build a passive network to do approximately the same thing. Or you can use it for a bi amplified or tri amplified sound system which works even better.

I owned one of these units about 15 years ago. Although it was very versatile and fun to look at it added a fog to the sound. As soundmind said it can be very useful for experimenting with crossover points and slopes.

tcdriver