Neither ported or sealed speakers have flat responses. This is almost impossible to do with a passive speaker (transducers and crossovers with amplified input) without a huge amount of expense.

To my knowledge, sealed speakers have the advantage of a well known response - which is something like 6dB/octave below the resonant frequency. Couple this with an appropriate crossover and you can get a reasonably flat response with only a few components.

While it's true that cheap speaker designs use porting simply to get some extra oomph at low frequencies, it has valid uses in "real" speakers too. Some speaker manufacturers tune the bass port to be resonant at frequencies which the bass cone naturally isn't because of the material it's made of. I remember reading that the B&W DM-60x series have it aligned to the null frequencies of the kevlar cone. There's also the issue of phase that porting can either address or destroy - depending on how well it's tuned. A well tuned bass port will deliver bass in-phase to the midrange/tweeter cones.

The ideal speaker design would use all active components (powered at line or digital, not amp level). I've been toying with the idea of buying myself a decent measurement microphone, recording a frequency sweep from my speakers, and using that to adjust the response in software, digitally.

For the measurement mic, www.linearx.com's M31 microphone ($150) comes with a floppy disk with all the calibration data (frequency response measured in anechoic room with known speakers). If I aligned my speakers to that, I'd have a response as good as the microphone, which is +/-1dB. Has anyone had any experience with measurement microphones, speaker measurement or anything related? In theory, I can get some absolutely superb sounding speakers simply by applying the inverse of their response. No idea how it'll turn out in practice, but I'm sure I'll have fun trying :)

Anyway - just a few thoughts I wanted to throw in...


- John (from empeg)

(The above may not represent the views of empeg :)