how do you defined underpowering? compare to what, ppi rating? aren't they rated something like 80w rms?
400 seems a bit high, i would set my gain around 250 first and then go higher if they take it without stressing
150w per side passive should be about right. For active you can get away with more power when set up correctly.
I have a buddy who's worked for Directed (they own a/d/s and PPI) for decades. He has the a/d/s 346cs in his daily driver with a Sony XES active electronic crossover. Here's his input on the a/d/s 346cs which is almost identical to the newer PPI 356cs that replaced them.
On a/d/s 346cs vs PPI 356cs: "Same tweeters, virtually identical crossovers, the woofers were modified to use a lighter cone and they added a phase plug. [...]our speaker designer says they fixed all of the issues the 346cs had with the mid/woofer not keeping up with the tweeters."
On running active vs passive: "Tough call... on the one hand, being able to set the levels on the tweeters actively is the best way to make the 346cs shine. On the other hand, more power usually sounds better plus you risk adding noise or phase shifts with the additional crossover in the signal path. As far as power, I'm running about 150WPC to the 346cs mids and around 100WPC to the tweeters, with no passive networks at all & that works great. Some of the credit for that is in the XES processing though with its sharp cut-off's and other tweaks. "
On crossover points in an active setup: "I get away with 2.82kHz but there's signs of strain on very strong vocal cuts & I'm running 36dB/octave filters (or 72dB; can't remember the XES spec for that). Would be thinking more like 3.5kHz or so with a 12dB slope. "
I'm planning on (finally) getting mine installed this weekend.
My initial plan is to bandpass the mids at 80Hz & 3.1kHz @ 24dB/octave, and high pass the tweets at 3.1kHz @ 24dB/octave.
My head unit is an Eclipse CD7000 which I'll be using as my active crossover. The mids will be getting 100w each from a 2 channel Boston Acoustics GT-22 and the tweets will be getting 55w each from 2 channels of a Boston Acoustics GT-40. The other two channels are bridged to 240x1 to an Elemental Designs SQ10.
I'm sure there will be some tweaking to be done, especially getting the gains set correctly on the two amps so that the mids and tweets blend well.
