I'm trying to plan an enclosure for an Infinity Kappa Perfect 12d VQ, and I've got a couple questions. I decided on a sealed enclosure, but infinity recommends a 1.0 cu. ft. enclosure and when I run through the calculations I end up with about a 1.7 cu. ft. enclosure that has better bass extension and is a little louder. I guess what I'm asking is if I am missing something. Is there something else that degrades (like SQ) as the box gets bigger?
If the ported box is built correctly, it can have better sq than a sealed box. It does depend on your own ears too. Bass does sound different coming from a sealed box and coming from a vented box, the difference isn't bad, you can just tell what kind of box it is usually.
Actually, screw that, I just need to stop second guessing myself and stick with the sealed, what do you think would be a good F3 to shoot for that won't noticeably degrade the SQ, but will add a few more Hz to the lower range?
It would be pretty hard to explain. But I can definitely tell. I'm not really saying one type of box is better than the other, it just depends on what your going for. If you want max spl you'll probably go with a ported box. If you want good sq and still spl I'd prolly recommend a sealed box built to specs. I've loved every ported box I've ever had, but I also like the sound of sealed boxes.
if you like that type of music go sealed. If you listened to alot of rap I would say go ported. They both sound very good I preffer sealed over ported but thats me. why dont you call up infinity and see what one of their tech's has to say I am sure they would be happy to help you out. who knows maybe he has tested it in a bigger sealed box and could tell you the pro's and con's.
Actually, large sealed boxes are better for SQ purposes. They are superior for overall bandwidth and transient response, and produce a flatter curve. Small sealed boxes have higher resonance and poorer transient response, making them better for SPL if you have enough power, but worse for sound quality. Your focus on a sealed box should be the QTC, .707 is considered to be the best mix of power handling, transient response, and bandwidth. A well built ported box will have SQ just as good as sealed (some consider it better), it just requires a custom box for best results. With a low tune and large port area, SQ and SPL will be excellent.
Hey, Jonathan... when you say "low tune" how low are you talking (I've heard 34 Hz tossed around a lot), and what do you mean by "large port area"... port diameter maybe?
So, if I went from the suggested 1.0 cu. ft. sealed enclosure to a 1.7 cu. ft. and kept the Qtc at 0.707 do you think the SQ would be close (if not better) to the 1.0 cu. ft. box?
Low tune would be in the 20s, 32-34hz is a good all around performer, 35 and above is getting a little more SPL inclined, 45 and above disregards purist SQ altogether and leans to SPL. By large port area, it could be diameter, it's basically the crossarea of a port. The reason I said port area is because you have square ports, round ports, and slot ports. They need to be large to get good sound quality and reducing any port noise. It also helps SPL and helps the transient response.
Nick, note that the reason Infinity recommends 1.0 is because they also recommend you use a lot of polyfill within the box, so essentially it gives the effect of a larger box (approaching that ideal 1.7 box size). It will give a smaller box size while still having the effect of a larger box due to the polyfill.
Yeah, that I can understand, but wouldn't the smaller box with tons of damping cut down on the lower extension regardless? Personally, I'm coming out with an F3 of 41.59 Hz on a 1 cu. ft. box with heavy damping, and on the 1.7 cu. ft. box using minimal damping I'm getting an F3 of 35.69.
It's always best to build the correct box and not use polyfill as a crutch, but a little polyfill aids in damping the enclosure. The low end of the larger box will be better. Personally I'd build a box closer to 1.5 and use a little polyfill.