Does the box matter?

I actually disagree with you here.  In my quest to figure out how I wanted to do my front speakers for my home theater, I learned something from my boss.  In designing a speaker system, the most important part is the crossover.  It is what gives the speakers it's voice.  He said that speaker selection is second in importance, and enclosure being a distant third.  Now with subs, the crossover is a little less since the subwoofer plays so little of the source material.  The speaker design is very important though.  It will determine if you can get decent extention, whether you can get a decent Q in the needed space, and how much distortion it will have.  An example of the latter being DD's LGLC design compared to JL's W7. 

I know I'm nitpicking.  You are right that the enclosure is very important.  Just throwing a sub in a box is not the way to get the best results.  Especially when one of the coices is a bandpass enclosure.  I just don't think it's more important than speaker selection.

Steven Kephart

Adire Audio

Well, in my experience enclosure design can make very fine quality loudspeakers sound like crap.  A poor enclosure design can over-extend or underextend loudspeakers, limit their frequency response, cause severe colorization, destroy off-axis response, create terrible time alignment problems, destroy power handling ability, create boom or lack of highend in bass. etc. etc. etc.  I also know that the "right" enclosure can make cheap, poorly designed loudspeakers sound like a million dollars.  In fact I have put together systems for people with less than $25 spent on drivers, but in a good, properly designed and properly tuned enclosure they rivaled anything from anyone (except, of course, in power handling.)  :)  Enclose design is at least as important as speaker selection, and in many cases is more so, in my opinion.

In full-range systems I would agree that the crossover is incredibly important and indeed will determine the overall sound characteristics of a system.  But you HAVE to start with good loudspeakers and they HAVE to be in the proper enclosure for your desired application, or nothing else matters.  In subs, the crossover only matters in so far as it is set to the proper frequency and slope characteristics required by the system, and if it is a passive Xover that you have included a zobel network.

In the case of bandpass VS sealed, these are two so radically different enclosure systems that the same speakers in each will sound entirely different, as I'm sure you know.  Thus, the enclosure design ends up being more important to the sound than the loudspeaker choice.

I'm starting to think that this is more a matter of opionion.  I can come up with many points on how the dirver is detrimental in how the end result will sound.  But the way I see it, the speaker selected will determine the Qtc. , frequency response, efficiency, and power handling for a given enclosure size.  Usually in an install, the enclosure that can be used is limited.  So if you choose a driver that doesn't work well in the space available, your end results won't be satisfactory.  Also, the enclosure won't get rid of distortion products of the subwoofer. 

Or we can go a different direction.  When you are building an SPL vehicle, driver selection is important as well.  For an enclosure, you want it to be as big as you can get.  But for driver selection, it is best to have a driver with a huge amount of motor force, a great deal of suspension travel, high power handling, a low Qts (for a better peak at resonance), a higher Fs, etc.  We have one competitor who uses 9 of our subs in his vehicle with 10 kilowatts per driver.  Another company wanted him to use their drivers, so he installed them.  He metered 3 dB less, so he took them out and put our drivers back in. 

I guess I just see this "it's all in the install" a little too much.  Sure the install can make or break a system.  But so can poor speaker selection as I pointed out above.  Sure a cheap speaker can sound pretty decent in the right enclosure.  But if you want the best results, speaker selection is key. 

Well that depends on the speaker used.  I don't have much experience with bandpass enclosures.  But if you took a driver that works best in a ported enclosure, it will sound much better that way than in a sealed enclosure.  And I don't care what you do to that enclosure (becides porting it), you won't make it sound good.

This is an interesting discussion though.  And whether anyone's right or wrong here, I'm sure people can learn from this discussion.

Steven Kephart

Adire Audio

The thing is this:  the original post asked, " What benefit does a box like this (bandpass) have over a box like this (sealed)?"  It is not a question on speaker selection, but just a question about enclosures.  To answer it with a discourse about speaker selection would be to change the subject, and the author of this thread would not get the answer he was seeking.  If one who is replying had to qualify every answer he makes with every variable that might have some affect on the total system performance, the intended response would get lost in the paragraphs.

Keeping responses short and sweet and to the point makes for good reading and useful help.  Now, this topic is off the course of its original intent.

But back to the point:  read the selection guide DYohn has linked you to for a good primer course on enclosures.  It can be difficult reading at times, but go back to it a few times and it will prove to be a helpful guide for you when choosing the overall sound you want.