Time aligning LCY ribbon tweets on baffle

[j.burtt]

I am using LCY ribbon tweets on the project I will soon be building. I am guessing I should align the actual foil of the ribbon with the the voice coil on the midrange.

Which LCY tweet(108,110 or 130) should I use in an open baffle with a Scan Speak 12M/4631G 4.5" midrange ?

The baffle will sit on top of a bass module with 2 - 8" woofers and all will be controlled via a Marchand active X-over.

[DIY_newbie]

Have you already bought the midrange? I would consider a larger midrange if possible. The major shortcoming of an open-baffle is that you'll need to compensate for baffle roll off. There are four well accepted methods of making up for the roll-off.

1) High effeciency drivers or multiple lower efficiency drivers.
2) High xmax drivers and bigger amplifiers
3) Large Sd drivers to produce more SPL/xmax
4) Large baffles

Personally I prefer Large, high efficiency, low xmax drivers. But the choice is really up to you.. Looking at the one you've chosen, the efficiency is pretty low at 89db, but it has relativly large xmax (+/-3mm) for a driver of this size. In a moderate sized baffle you will probably have to cross over to the woofers ~350-400hz. This would put the cross over in the lower vocal range which IMHO is not a good idea. You might want to look at some of the larger mid-bass or midrange drivers. I also noticed that the driver you chose appears to have a cone breakup aroung 700hz (seen as a blip on the impedance chart)

Maybe you could look at this one :

15M/4531K00
Same sliced paper cone, 2x the cone area same excursion, similar breakup modes but they look a little smoother on the impedance and FR

I also like the look of the 18W sliced paper cones in the mid-woofer sections. Similar breakups and much more area 3.5x.

--Chris