2 Questions

[Skooter 10+ year member]

Well, I have a question for myself, and a question for a friend as well.

I'm looking for a subwoofer that performs well in SQ, but still allows me to get loud every now and then. I don't want to spend a huge amount of money, but if the difference isn't too much then I suppose that's fine. Also, wondering if I should go sealed or ported? I know that sealed is able to give you quicker, punchier bass, but I have also been told that this is possible also with a long port or transmission line. Please shed a little light on this for me. The subwoofers I have been looking at are as follows. I chose them because they have comparable surface area and prices, and I have been told they do well in sealed boxes, which is what I assumed I should be going for.

1 Sundown X18

1 Fi Q18

1 RE SX18

2 RE SEX15's

3 Sundown SD-2 12's

Ok, so question two. A friend of mine currently has two Sundown SA 12's, and he is wondering if he can add to them, another set of 15's, using all 4 subs. I'm not sure whether two different sized subwoofers would cause phase cancellation of any sort. Again, please shed a little light on this for me.

Thank you, everyone.

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[bbeljefe]

If you're in it for SQ in a vehicle you don't need that much cone area. Sound quality means that the bass isn't 4 times louder than the rest of the frequency range and that can be accomplished with one 10 in a vehicle cabin.

Now, if you're actually interested in enhanced bass, then two 15s or one 18 make sense. I'd go with the Sundown subs but that's just preference.

As for sealed bass being quicker... no it isn't. A 30 Hz sound wave is ~37.5 feet long at the speed of sound and if you speed it up, it's no longer a 30 Hz tone. Likewise if you slow it down. This whole idea that sealed boxes sound better is as subjective as your preference for ice cream flavors as opposed to mine. If you like flat response from your subs then a sealed box will be fine. If you like them loud, then ported or some other alignment would be better.

But in the end, a properly designed ported box will be as "quick" and "tight" as any sealed box and, it will always be capable of more sound pressure. Likewise, a t-line will be even better than a conventionally ported enclosure.

As for choosing which sub to buy, I would first decide what sort of enclosure I wanted and then make sure I had room for it. After that, I'd choose a sub that will perform well in the enclosure style I've chosen and then... I'd build it and start beating. ;-)

If you choose sealed or 4th order, look for a low EBP sub and if you choose any other vented alignment, look for a high EBP sub. If the manufacturer doesn't list EBP, simply divide Fs by Qes and that's the EBP. Generally speaking ,below 50 low, 50-90 is mid and above 90 is high... although I would say that anything below 60 is low.

As for mixing sub sizes, you can do it if you like but just don't put different sized subs in the same chamber.

 

[T3mpest 10+ year member]

Ported boxes can sound very good as long as you tune lower. If your at all concerned about output on an 18, I'd go ahead and port it tune low and see what you think of that. How much space do you have?

For the second question NO it will NOT cause cancellation. The speakers will still be moving in and out at the same time. However, it looks pretty ghetto (very ghetto) and wont' sound as good generally because your frequency response will be an average of what each size is giving you in each box, unless you get lucky it won't be smooth nor easily predicted so without an EQ to play with, I wouldn't. If he wants to upgrade and has the room, keep the 15's and do a large ported enclosure for them. Probably not as loud as running all 4, but depending on the acoustics it could be and should sound better If you can convince you friend to do the 15's, keep his 12's and add one or two more yourself. If you can get a decent deal from him on the used ones that will be a lot of bass on a good budget... It's a win win.

 

[Skooter 10+ year member]

I have always used sealed boxes in the past, but with my current setup I went ported with 2 E8V3's at 32Hz off a MB Quart ONX1.1000D. The output is impressive for 8's, but the response is far from linear, most likely due to the frequency of my cabin as well, which is 38Hz. As far as the subs being too loud, there's a bass knob for that, and mine is usually around 50%, but sometimes I run it 100% for bass songs when I'm in a bass mood.

I have an SUV, a Buick Rainier, so I have space to work with, as it's very similar to a TrailBlazer. Here's my build log to see it better: http://www.caraudio.com/forums/car-audio-build-logs-cars-trucks-suvs/579410-2005-buick-rainier-build-log.html Also, I'm not going PURELY SQ, however, I do plan to go to competitions for the fun of competing and seeing how I do. I also enjoy good sound quality over being loud. It's more of a daily driver that I can use in competition every now and then for fun. In MECA SQ Street Class, I pulled a 70 and got first place in my first competition, and intend to keep attending them.