Greg-
Well here are my thoughts behind saying not to use a ported box. I will agree with you that it can be louder, and might sound OK, but I don't necessarily believe that a ported box will sound as good as a sealed box with an amp that provides the peak watts (RMS) of the subs. Tons of power in a sealed box, with the correct internal volume will yield a great sound. I have built a 1500W system using Eclipse
MRV-1507. The amp was bridged to provide 1500W continuous power to the subs. The Pioneer 9300 series deck took care of crossing-over the subs at 80Hz. I also dynomatted the ENTIRE rear of the vehicle, and the inside of the enclosure. This combo provided enough power to punch the front windshield (intact) out of the seal, honest to god.
The sound was very tight. The local car audio joint that we bought all the hardware from offered me a job after seeing the install. But they were really convinced after they took a dB meter and it measured 122dB inside the car, sitting on the front console!
I called my bud up, and asked him to snap some pics. The install is pretty sweet too... I set the amp into the hole in the truck for the spare tire with a plexi-glass cover, carpeted every new surface, lit everything with purple neon triggered by the deck light switch, and designed and fabbed up the 1" MDF box myself.
Not that I expect Brandon's setup to produce similar results, but sealed boxes CAN produce very tight sound. They do tend to be the route to go when using high-powered amps.
This is getting wordy but I found <a target="_blank" href=http://www.lightav.com/car/boxes/char.html>this</a> online:
<blockquote><font class="small">In reply to:</font><hr>
Sub-30Hz Behavior
Sealed box designs and single-reflex bandpasses are much better at controlling excursion at extremely low-frequencies (below 30Hz.) For this reason, they can usually handle more power in these frequency ranges than ported designs and dual-reflex bandpass designs which makes them less prone to low-frequency induced speaker damage. At frequencies below the tuning frequency of the port, a woofer in a ported box (or a dual-reflex bandpass) starts to de-couple. This means that the controlling function of the enclosure begins to disappear. The collapse is gradual rather than immediate, but at some point below the tuning of the port, the speaker behaves as if it were operating without an enclosure and suffers from potentially damaging over-excursion. (This is why it is a good practice to use a sub-sonic filter when running a ported enclosure or a dual-reflex bandpass. Some high-quality electronic crossovers like the AudioControl 4XS incorporate a programmable subsonic filter circuit.)
Related to the loss of enclosure damping, ported and dual-reflex bandpass designs also exhibit higher distortion levels at very low frequencies than sealed or single-reflex bandpass designs. The importance of this is questionable, however, since little program material extends to below 30Hz.
Sealed enclosures and single-reflex bandpass designs have a rather shallow low-frequency roll-off rate of around 12dB/octave, whereas ported enclosures and dual-reflex bandpasses typically exhibit 18- 24dB/octave roll-off. For this reason, sealed enclosures and single-reflex bandpass boxes can have much higher -3dB points (the frequency at which the output dips 3dB below the reference efficiency of the speaker) than ported designs while still producing very good ultra-low frequency output.
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This is why I use enclosed boxes, but as stated, it depends on many variables including: type of subs, the output power of your amp, your style of music, your personal sound preferences... etc.
I think I have said enough... just to show that there is nothing wrong with sealed enclosures, expecially in high-powered systems.
Hope I didn't go off too badly !
And by all means, I don't claim to know everything, so please correct me if I am wrong...
<font color=red>GOT MUD???</font color=red>
My license plate reads:<font color=blue> 8 YR SUV</font color=blue>
454/TH400/NP205 - 14BFF/D60/w/ 4.10s - 36" TSLs
