Good to hear that you have panels and tweeters in hand. That's always a hurdle; finding the correct drivers, for a 'clone' project. While I don't know how close you want to match a RM-40, and I'm not sure what woofers are listed in the substitute parts thread, I 'believe' Brian at one time used these woofers, from MCM Electronics, in several designs:
http://www.mcmelectronics.com/product/55-3550Maybe they'll work out better. They might not need as big of an enclosure as standard 40 woofers.
If my memory is correct, Brian usually mentioned crossover frequencies of around 280Hz for the low pass/band pass point, and 7KHz for the tweeter. These frequencies varied up and down a few Hz, as Brian tweaked designs, but I 'think' they're close enough to start with. Also, drivers were wired in-phase, using series crossovers, usually starting at a 6DB per octave roll off. The roll off was sometimes increased to 12DB further out of band.
If using a Behringer DEQ2496, you can experiment with much steeper slopes, along with crossover type: Butterworth, Linkwitz-Riley,. etc.
Plus, I like your idea of a passive crossover for the tweeter. A cap on the tweeter not only creates the crossover, but also offers some protection from amp turn on 'thumps', and DC offset.
Otherwise, this sounds like a fun project. Keep us updated, and post build pictures, if possible.
Like I said, I am slowly picking up the pieces for this build and would like to hear any comments or advice from the people on this board that know way more about speaker building than me. I can handle the woodworking part of the build, I’m just a little ignorant when it comes to the finer details of driver integration and crossovers that will be needed to make this build a success.
