Originally Posted by bosso
BTW, it doesn't take the kind of overkill many here engage in to get full BW replay at normal (-10dBRL with the sub running a bit hot) levels and the subsonic reproduction is simply a consequence of using the 2nd order roll off sealed alignment
Just build a sealed L/T'd system and stick the box in a corner and there you go. If you prefer higher SPL, add more. Pretty simple if you ask me. Never saw what the fuss was about.
4-18" IB drivers and a budget amp will cover reference level LFE for any room I've been in for $1500.
Aside from the fact that this all doesn't really work, it's a great story
Ilkka's measurements (which are still posted on the internet at a different forum) of a sealed Adire Tumult 15" show 100% or greater THD at 10hz at 2m GP at 90db. Corner load the sub to gain more output sensitivity, but the distortion comes with it. You're looking at about 60db 2m GP before the distortion becomes reasonable at 10hz
. How little amplitude before it becomes reasonable at 5hz, 20db? Sure, don't forget your room gain of about 6-8db per octave starting around 25hz, but the distortion comes with it. You're going to need a ton of drivers to accomplish what you speak of without >100% THD my friend, a ton.
He then went on to measure the LMS-5400 18", what many would consider the most capable low distortion subwoofer driver available. 93db at 2m GP at 10hz with about 25% THD. 83-84db to get to a level where the THD is reasonable. How much amplitude to make that reasonable at 5hz, maybe 30db? Thats a lot of drivers to get to 118db, as spl grows by 6db when you double displacement, so driver count gets out of hand really quick. Don't forget the amps!
Now don't get me wrong, going for full subwoofer bandwidth is something I am in favor of. Using drivers - especially sealed - is just too inefficient though, especially if you want less than 100% THD. If we get this rotary subwoofer going as a diy project, then 0.1-120hz capability at reference with far less than 100% THD may be available for the masses.....or at least the <1% of the masses who are interested.
Didn't mean to interrupt discussion about the new Dayton mic, but I couldn't let that go unchallenged.