I really wanted to go ported at 28Hz, but i don't know if i have enough room in my trunk (for 3.5 cu.ft., if someone has had success doing this, please let me know), so i might have to end up going sealed, at 34Hz. How big is the difference between the two?
what did you guys tune yours to?

 

My box for my W7 is tuned at 30hz. And its a really big box to. I dont really hear any bass above 60hz though.

 

whatever a 12L7 is tuned at in a 1 cu ft. sealed box.

 

Using a standard second-order crossover, you do too...

 

3.5 damn...what size subs/how many?

 

I do too what???????

Sorry kinda lost long day just got out of a accoutning test that I pulled a all nighter.

 

2 12's. I thought that was pretty common, but i guess not. If I stick that in the trunk, no room for the amps.

 

I might just go w/ the sealed (first time making a box anyway), but at 34Hz is that more "punchy" or "boomy"? <----if that makes sense

 

I'm not sure, but I think you might want to consider sealed vs. ported before worrying too much about tuning frequency. (Admittedly I'm no expert though--I usually just build mine to the sealed size the manufacturer recommends).

For the record, I'm a fan of sealed enclosures...

 

uncleb, you're making a fairly common mistake. The tuning frequency of a box does NOT mean you have a peak in overall response at the tuning frequency.

A well-designed enclosure will take the response of the woofer and extend its frequency response without rolloff. Sealed boxes start rolling off at some point - and ported boxes do too, but if they're designed right, they start doing so lower in frequency.

When they do start rolling off, they do so at twice as steep a rate, so it's crucial to get that tuning frequency right.

Unfortunately, humans have a strong tendency to simplify things, and in many cases, we seize on one aspect and oversimplify. That's kindof what you're doing. It happens a lot in the audio world because stuff just isn't simple but we often want it to be.

I would suggest going to Parts Express and buying BassBox software from them. It would help you design the box and give you graphs and such... it's not the best out there but it's OK... or TermPro from termpro.com.

 

^^your first line there is EXACTLY what i thought to be true.....so apparently i was wrong.


eld, what does roll off mean?? how does it affect what you hear and at what point is it bad?

the reason i threw out those two numbers is because i was going directly off of manufacturer's specs. they gave specs for ported at 28Hz, and sealed at 34Hz.

 

OK, I'll take a crack at that, you post the actual factory info, K? I think you're misunderstanding it.

Rolloff means the point at which a speaker starts to get quieter. When you hit 3dB down, that's considered the practical limitation of that speaker in terms of output performance. A "perfect" sub would play down to 20 Hz.

Usually doesn't happen.

I suspect that the factory info gives you a way to build a ported box that does NOT play as low as a sealed box (typical) but has more output above that point (typical too).

Most sealed boxes do NOT play within 3dB down to 28 Hz, - maybe they were specing 10dB, but maybe they play really low.

The -3db point does NOT affect SQ above that point directly -0 so again, you can't decide what it will sound like by looking at that number in a vacuum.

uncleb, go to www.bcae1.com, and scroll down the bar on the right side to #115, Speaker Response Curves. Then read the page and look at the screenshots. That will give you a visual explanantion of rolloff and what I'm talking about, and possibly give you the insight into what you're trying to decide.

(BTW, the curve is NOT describing SQ - two woofers with the same curve don't sound the same... the RTA is more precise but not as accurate, in a sense, as the human ear).