4th order bandpass

[SpeakerBoy 64]

I recently read Galamonkeys avalanche build and the specs of the box were something like 4cuft sealed chamber for two 18" btls, with a high tuned ported chamber. He commented saying the lows were quite good. now, separetly a 4cuft sealed box for two 18" btls would sound bad, and a high tuned box would not hit any lows. How does that add together and work well? Off the top of my head, it seems like a large sealed chamber with a low tuned ported chamber would be the smart choice. I've never been able to experiment with bandpass boxes, so cut me a little slack.

[tyoung515 7]

generally 4th orders are tuned higher than a normal ported box ie 45-55 hz i cant explain the mechanics right now that just how that box works somebody else can go more in depth

[ABXX49 20]

My first system was a 4th order. It got loud, but as a whole, I found myself liking ported enclosures much more.

Again though, it's all dependent on your goals and space for what type of enclosure you want.

[///M5 2,833]

They are called Bandpass enclosures for a reason. They roll off quick up high and down low and work in a very narrow range.

[ABXX49 20]

They are called Bandpass enclosures for a reason. They roll off quick up high and down low and work in a very narrow range.

Hence why mine was 'loud.' The type of music I was listening to at the time took full advantage of the range that my box worked in. If I tried to play anything other than a specific type of music, it was terrible in my opinion.

[Julian 641]

They are called Bandpass enclosures for a reason. They roll off quick up high and down low and work in a very narrow range.

Hence why mine was 'loud.' The type of music I was listening to at the time took full advantage of the range that my box worked in. If I tried to play anything other than a specific type of music, it was terrible in my opinion.

Typically you'll find fourth order bandpasses with "cheaper" subwoofers. Quote from The 12Volt

he port extends the low frequency response of the basic sealed enclosure usually providing a lower cut-off frequency. The enclosure offers a good transient response (second to that of a sealed enclosure), good power handling within it's bandpass region, and excellent efficiency making it a popular choice for many competitors and everday users, but below the tuned frequency power handling is poor and damage to the woofer is likely to occur if over driven.

[tyoung515 7]

basicly when designed right they sound great and get loud while doing it, just needs to be done off the cars r/f profile and by somebody who knows what they are doing. i like them more than ported for daily seems to have a better response.

[REVpuggie 23]

Don't build an enclosure just because you want to build something else or because someone else made something like it , build something that fits your woofer and goals ... who cares what kind of box gets the job done ....

better of posting the woofer you've got and the goals you want to achieve in how big a space, asking what type of box would suit you best

[///M5 2,833]

basicly when designed right they sound great and get loud while doing it, just needs to be done off the cars r/f profile and by somebody who knows what they are doing. i like them more than ported for daily seems to have a better response.

"Sound great and get loud" -- nice description, lol.

Not as loud as a ported enclosure and significantly limited frequency response in comparison. Difficult to design right as well. Liking the more for daily just means you got UBER lucky on your design or had a really crappy ported design. "Seems to have a better response" leads me to believe that it is all luck or placebo effect.

Don't build an enclosure just because you want to build something else or because someone else made something like it , build something that fits your woofer and goals ... who cares what kind of box gets the job done ....

better of posting the woofer you've got and the goals you want to achieve in how big a space, asking what type of box would suit you best

x10,000 ... and Chris should know this as EVERY thread he makes I make that comment

[tyoung515 7]

i ahve built many ported, 6th order, 4th order box's... 4th has the best transient response as long as the pass band is where you want it to be, for most 30-60 hz is what they have there woofers playing

taken from diysubwoofers

"The 4th order or sealed rear chamber bandpass system is basically a sealed enclosure system with the addition of an acoustic filter in front of the driver. The resulting system usually provides a lower cutoff frequency, the tradeoff being a larger enclosure. The enclosure can be reduced in size by using two drivers in an isobaric configuration.

4th order bandpass systems usually demonstrate better power handling characteristics than the other main systems considered here. Its transient response is second only to the sealed enclosure systems, making it a good choice for subwoofer applications.

As all of the output of the 4th order bandpass system is via the port, the largest port diameter possible for the enclosure should be used in order to minimize port noises. The ports should be flared whenever possible, for the same reasons.

The 4th order bandpass system rarely exhibits a perfect bandpass response - there is usually some out-of-band noise present in its output. A simple notch filter can be used to reduce this noise if it is audible. Alternatively, a low-pass filter can be used in series with the driver, but the in-band response of the system may also be affected if this approach is taken"

[///M5 2,833]

Don't copy something from somewhere else, explain things yourself. You don't have to explain a 4th order bandpass to me anyways, just why YOU say they have a better response.

[tyoung515 7]

well put lol was just using a site some would know, but in my experience 4th order's play all music well, they handle a double drum roll and then can turn around and play long bass line in rap well, and when built off the cars r/f profile will have a flatter response, now it is true that a quality ported can sound great but my self i prefer the warm sound of a 4th order

[///M5 2,833]

well put lol was just using a site some would know, but in my experience 4th order's play all music well, they handle a double drum roll and then can turn around and play long bass line in rap well, and when built off the cars r/f profile will have a flatter response, now it is true that a quality ported can sound great but my self i prefer the warm sound of a 4th order

So in other words you haven't heard a difference but think there is and have decided to use a bandpass instead of a 4th order ported.

[tyoung515 7]

ok again i think i has a warmer sound and works with all music better, ported can get sloppy on some music depending on design..... 90% of how a woofer sounds is in the box design placement and the car its in, so what ever fits the bill better is what i would go with, he still hasent said what his goals are yets so this is kinda useless

[///M5 2,833]

So is stating absolutely that an alignment is always better than another and that you can hear the difference and it is "warmer". Most definitely 90% is in the box design and recommending that someone try a 4th order without being willing to try many variants really isn't helpful to them as the net result will be worse than a standard 4th order ported unless they get super lucky.

[tyoung515 7]

well from the original post it sounds like he wants to try a 4th order so recommending a ported does not help to much lol, we are starting to clutter his thread though so if you want to talk just pm me lol, to the op mostly the sealed side is smaller than the ported and they are tuned 45-55hz

[///M5 2,833]

And I know the OP and he shouldn't try a 4th order as it won't work out right. Exactly why I am clarifying.

[tyoung515 7]

well he hasent said yet but if its a trunk car he can port into the cabin to eliminate trunk rattle and increase output a bit, but if he knows you then i guess you know best and he should have just asked you instead of posting it on a forum to see me and you argue....

[///M5 2,833]

Not what I meant by I know him. Far from it. Read his other threads and you'll understand.

[tyoung515 7]

sry if that sounded bitchy just got done working 13 hours lol long days make you cranky lol

[SpeakerBoy 64]

Not what I meant by I know him. Far from it. Read his other threads and you'll understand.

true dat....

Just curious as to why you tune higher. Guess it's back to books for me!

Edited February 16, 2010 by SpeakerBoy