1. ## Re: The 4th order thread

Or single reflex bandpass. But that could include a series tuned "6th" order and quasi 8th too, I suppose.

Anyway... why don't you go into detail about how you arrived at the graph and the tuning for the box you posted for those who don't know. And why we tune to sealed resonance.
I purchased a DATS (first I did some math but I will delve into that later) placed my enclosure in the tahoe, vehicle sealed, loading wall off of the enclosure. Then I ran an impedence sweep, which showed me at what frequency my imp. peaked at. That is called the Fc or sealed resonance.
And how one might arrive at tuning without a "Woofer Tester."
the equation is (Vas/Vb)+1, then sqrt that number, and multiply by the fs of the woofer. when I did this I got an Fc of 45.5 hz, real world with the dats was 45.09. quite close if you ask me, so I would have no problem trusting the equation.
How ratios affect bandwidth.
to put it in simple terms, large ratio= smaller passband smaller ratio=larger passband. but I have found that is not always the case. many more factors that have control over your bandwidth than just the ratio
How to figure port area. And how tuning or other factors affect said area.
im a test and find out type of guy, but I usually start off with 1/2 port area to cone are (my enclosure uses a single 12" aero, because I have 2 12s) I prefer to go bigger, because shrinking down is easy. But some people have luck with 1/3 port to cone area. I have had good luck with 1/2 though. But many things come into play here such as goals, woofers, vehicle, etc. just like any other enclosure.
How the size of the sealed chamber affects response.
more simple terms, typically, large rear= lots of low end, but lacks on the higher end from what I have seen, and the opposite applies for smaller rear ends. But I am a fan of my Fc being in the 45-48hz range for daily.

I am not the best at explaining things, because I cant really put them into simple terms very well. hopefully everyone understands this. Also, I am no 4th order master, I dont have all of the answers, but I do know a good amount, mostly from testing, and educating myself. So please, if anyone else has some things that they would like to add, feel free to do so, I could always use some more information!

2. ## Re: The 4th order thread

Originally Posted by DbDesigns
more simple terms, typically, large rear= lots of low end, but lacks on the higher end from what I have seen, and the opposite applies for smaller rear ends. But I am a fan of my Fc being in the 45-48hz range for daily.
I'm right there with you.

3. ## Re: The 4th order thread

Originally Posted by Buck
I'm right there with you.
like I said too... lots is woofer dependent as well. Thats why the sa series is my favorite. they are kind of a middle category woofer. they can work well in almost anything, and they really shine in the 4th orders. plus they dont need a large rear chamber at all.

---------- Post added at 02:35 PM ---------- Previous post was at 02:34 PM ----------

but yeah, thats why I said "typically" lol power is a factor as well

4. ## Re: The 4th order thread

Power is a big factor especially when trying to mix lows with high power, trying to balance the lower Fc with mechanical handling. Low Fs woofers really make that easy, like the RE XXX.

5. ## Re: The 4th order thread

Originally Posted by Buck
Power is a big factor especially when trying to mix lows with high power, trying to balance the lower Fc with mechanical handling. Low Fs woofers really make that easy, like the RE XXX.
fur sure lol

6. ## Re: The 4th order thread

I've always thought home theater 4th order were interesting. It's where you do something like 3:1 ratio, except your larger section is the sealed one and the smaller one is the ported. Gotta get those 10 hz lows.

7. ## Re: The 4th order thread

This thread makes me want to grab a pair of AA Havocs

8. ## Re: The 4th order thread

Originally Posted by Tenacious.
This thread makes me want to grab a pair of AA Havocs
get some sa's yo. cheap, and they can get stupid. at least mine do... lol

9. ## Re: The 4th order thread

The end plan in my explorer is 8 sa-15's in a 4th order wall

10. ## Re: The 4th order thread

Originally Posted by Buck
I've always thought home theater 4th order were interesting. It's where you do something like 3:1 ratio, except your larger section is the sealed one and the smaller one is the ported. Gotta get those 10 hz lows.
id just get that fan that can play down to 1hz... you may not be able to hear it, but you can def feel 1hz @120 db lol

11. ## Re: The 4th order thread

Originally Posted by Buck
The end plan in my explorer is 8 sa-15's in a 4th order wall
one of my buddies is doing 12 12s in a 4th, and another guy I know just did 8 15s in a 4th on 4 ns1s.

12. ## Re: The 4th order thread

Fi IB3 is where it's at. I say some video where this dude was shaking his old house with 4 18's mounted in a wall, like literally in one of his walls on his house. His ceiling fan was shaking up and down like in an earthquake playin like 5 hz or something stupid.

13. ## Re: The 4th order thread

Originally Posted by Buck
The end plan in my explorer is 8 sa-15's in a 4th order wall
Before or after you completely destroy the thing from flex? lol

14. ## Re: The 4th order thread

Originally Posted by Tenacious.
Before or after you completely destroy the thing from flex? lol
I'll build the wall when the hatch is unrepairable.

15. ## Re: The 4th order thread

Originally Posted by Buck
I'll build the wall when the hatch is unrepairable.
If you wake up with a destroyed hatch one day.... it wasn't me

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