8" 2-way or 6.5 MTM

[crash813]

Hello everyone, been watching this forum for a while but this is my first post. Unfortunately, I'm already hooked. I'm currently finishing up a set of Tangband Needles and am already looking ahead at the next project.

This next setup will need to be a comprimise for Music and HT. As always, putting the cart before the horse, I already bought a batch of drivers. The original plans called for 6.5 MTMs for the front L/R channels, but I also acquired a set of 8's as well. So the question is what are the tradeoff's between the 2. Either the 8" 2-ways or 6.5 MTMs. None of the drivers are in a refined kit so fairly generic crossovers will be used, but hopefully will later be refined with actual measurements (time table unknown).

Any comments are appreciated.

Drivers in question are similar to the Vifa MG series. Same motor and cone material.

[KBK]

If you've never designed an MTM crossover before, stick to the 8" two way. If you want a real challenge, go for the MTM. Good, clean, phase coherent MTM crossovers are not easy. In my opinion, they can be more difficult at times (depending on the driver mix) than designing a three-way speaker.

Some of the hassles when designing a three way,and a clue to that misery:
In any two way, if the one of the tweeters is wired out of phase... the BASS will dissapear, in both speakers. Think about it. Passive crossover design is all about phase tradeoffs. Imagine this issue with a three way.

One big point about MTM's, is that the crossover frequency for the tweeter/woofer balance, tends to need to be about 2.2khz or so, not much higher if at all. This issue is created by the 'center to center' distances between the two woofer's acoustical centers. It is essential to have a tweeter that has great power handling, and a low, low fs. I perfer (read: I won't use anything else) the open backed, low resonance tweeters, for ANY MTM design work.

For example, I like the Morel MDT-33. It is great for MTM design. The open backed Vifas work well too. Seas tweets are a bit dull for my tastes. Won't use 'em. Bit I await any given company's new product with open mind and arms. Boy'o'boy..I'm starting to get alot of extra tweeters floating about. ....

Finding good tweeters is seemingly the -biggest- hassle.