Reply to thread

Message

<blockquote data-quote="bladebarrier" data-source="post: 5280290" data-attributes="member: 603808">3 Sealed will generally beat a single ported unless you&#039;re talking about a one note box.Here&#039;s why. Each time you double up the surface area you&#039;ll get about 3db more sound, assuming no increase in power. So 2 18&#039;s will be 3db louder than a single, and 3 18&#039;s will be 4.5 db louder than a single. A ported box brings about 3db increase, as it utilizes the back side of the woofer, as if it were a second speaker. Sloppy spl boxes will boost it even more and turn the port into a resonant noise maker (think of the sound you get when blowing across a soda bottle top, when it&#039;s empty) and can get even more than that, but only over a certain frequency range, and can severely restrict the low bass ability of the subs when they operate below the tuning frequency, and act as if they&#039;re not in a box at all.Now, you also need to consider the efficiency and design of the subs. If you take subs designed for a large box, and toss them in sealed boxes that are way too small, you&#039;ll only see this increase in spl occur at higher frequencies that you don&#039;t want your sub to produce. They will become extremely inefficient at low frequencies.If you link some spec sheets for the subs in question, I&#039;ll run some math and give you some spl curves, but if the MJ&#039;s are designed for the smaller sealed box properly, they will almost assuredly out perform a single ported 18 at anything aside from sloppy, narrow frequency range, bass.</blockquote>

[QUOTE="bladebarrier, post: 5280290, member: 603808"] 3 Sealed will generally beat a single ported unless you're talking about a one note box. Here's why. Each time you double up the surface area you'll get about 3db more sound, assuming no increase in power. So 2 18's will be 3db louder than a single, and 3 18's will be 4.5 db louder than a single. A ported box brings about 3db increase, as it utilizes the back side of the woofer, as if it were a second speaker. Sloppy spl boxes will boost it even more and turn the port into a resonant noise maker (think of the sound you get when blowing across a soda bottle top, when it's empty) and can get even more than that, but only over a certain frequency range, and can severely restrict the low bass ability of the subs when they operate below the tuning frequency, and act as if they're not in a box at all. Now, you also need to consider the efficiency and design of the subs. If you take subs designed for a large box, and toss them in sealed boxes that are way too small, you'll only see this increase in spl occur at higher frequencies that you don't want your sub to produce. They will become extremely inefficient at low frequencies. If you link some spec sheets for the subs in question, I'll run some math and give you some spl curves, but if the MJ's are designed for the smaller sealed box properly, they will almost assuredly out perform a single ported 18 at anything aside from sloppy, narrow frequency range, bass. [/QUOTE]

Verification