thanks for the speaker link, it looks promising. i will consider those, i sure would like to hear them befor hand. also, i feel you just cant be sold on the fact that a bandpass pushes deeper and lower bass tone than a sealed or a ported box. i have no idea how you can even toy with the idea that i can get deeper bass on a ported box than a bandpass. their is just no way. not in my experience. but again, thanks for all the info.
Please explain to me how you are constructing a bandpass that can play deeper than a ported enclosure tuned to 18hz-22hz. Most common bandpass designs are tuned to around 50hz or so. Physics will dictate they cannot play deeper. They almost always rely on being in a confined space to help emphasize the low end response below 40hz-50hz.
I have been building enclosures for about 11 years now, I have yet to come across a bandpass enclosure that plays deeper than a low tuned proted enclosure. The sheer size of a bandpass enclosure tuned to such frequencies would be impractical. Most band pass enclosures when properly done (without a large bump in response near 60hz) typically end up about 25% larger than a ported counterpart. Even then they still do not play as deep. Bandpass designs may yield great efficiency, but they lack some detail due to the woofer not being exposed to the ambient air. There is some delay, though minimal, in the air having to escape through ports only.
I am not discounting that a properly designed bandpass enclosure cannot be done, it is just they do not serve much practical purpose anymore. Not to mention most woofers now days are more or less designed for sealed, ported, or passive radiator applications.
My guess is you may not have heard heard a really well done, low tuned, ported enclosure with a fair amount of port area. Perhaps you have not enough experience with ported enclosures tuned accordingly to allow such deep low end extension.
Think about it this way, if bandpass offered such great advantages, don't you think most high end sub manufacturers would be using the design? The fact is they don't for many of the reasons I highlighted above. In car audio they have a purpose (though diminishing), for home audio, not so much.