4th order sp4

[frogcase2002 393]

sure will make it hard to put the flames out!

LOL. I was cracking up

[ncc74656 2]

LMFAO!!!!!!!!!  im running a fire dust cap this time. it seems fitting.

 

so a 4th order vented enclosure is what i have now right? its a vented box with a 35hz tuning and a 24db slope xover.

[nadcicle 77]

Everybody knows 4th order bandpasses don't really exist unless you keep your windows up! You put your windows down in your vehicles and bam 6th order lol Your vehicle acts as a chamber too!

 

I don't act like I know anything about enclosures anymore

[ncc74656 2]

the orders only pertain to the cross over slope tho right? so a box is a box and coupled with what ever xover is what determines its order. right?

[///M5 2,833]

the orders only pertain to the cross over slope tho right? so a box is a box and coupled with what ever xover is what determines its order. right?

Almost but no.  It has nothing to do with the crossover you apply electronically, but the mechanical crossover that occurs because of the box design.  The 4th order boxes will have a 24dB/oct slope with NO electronic crossover (of course outside of an SSF it is not so logical to put a HP).  This is irregardless of whether it is a normal bass reflex (ported) box or a bandpass.  The bandpass has an additional mechanical filter which is a Low Pass that will roll off the higher frequencies as well.  Personally I'd much rather apply this filter electronically instead of mechanically as it will allow you to change both the slope and F3 point of the filter.

[nadcicle 77]

the orders only pertain to the cross over slope tho right? so a box is a box and coupled with what ever xover is what determines its order. right?

Almost but no.  It has nothing to do with the crossover you apply electronically, but the mechanical crossover that occurs because of the box design.  The 4th order boxes will have a 24dB/oct slope with NO electronic crossover (of course outside of an SSF it is not so logical to put a HP).  This is irregardless of whether it is a normal bass reflex (ported) box or a bandpass.  The bandpass has an additional mechanical filter which is a Low Pass that will roll off the higher frequencies as well.  Personally I'd much rather apply this filter electronically instead of mechanically as it will allow you to change both the slope and F3 point of the filter.

 

I really like this answer. Thumbs up sir!

[ncc74656 2]

man i understand so much more now. why do all the sites that explain boxes not go into this mechanical vs electronic slope?

[///M5 2,833]

Most people on other sites don't know.  Here if you take the time to ask you'll get an answer.

 

Either way, for your application a normal ported ie bass reflex ie 4th order ported is probably best suited.  Doesn't mean your woofer is going to like playing high, but if you can't change it you might as well maximize it.

[ncc74656 2]

k, ill build 2 more boxes on both extremes. a 32hz tune and a 45hz tune and ill see what it souds like

[///M5 2,833]

...adjustable port...

[ncc74656 2]

i had talked about building an octo port earlier but everyone said it was a bad idea and a gimmic so i never bothered.

[frogcase2002 393]

Build one that you can slide different slot ports in.

[///M5 2,833]

i had talked about building an octo port earlier but everyone said it was a bad idea and a gimmic so i never bothered.

It is.  Adjustable ports do NOT need to be octo and they just add extra work for ZERO benefit.  The easiest is of course external and if it is temporary that is a perfect solution.  

[ssh 924]

You can buy circular cement forms in different radii for the port area you need. Mount them externally, calculate port length for x hz tuning, play, cut down y in from port length for z hz tuning, and so on.

[95Honda 486]

You can get the form tubes where one slides right into another, there is your adjustable port...

[ncc74656 2]

how do you guys account for the change in net volume as you replace ports?

[ricksi30 923]

how do you guys account for the change in net volume as you replace ports?

Mathematically, if port volume changes everything else does.

[ncc74656 2]

i understand that but a sub tuned to 34hz in a 7 cubic enclosure will sound different than a sub tuned to 34hz in a 6.2 cubic enclosure no?   so when you remove port and change the tuning do you add wood inside to balance the cubic footage as well?

[A.SMALL 17]

The frequency response will be different when using the same tuning and different volumes. You could use wood to make up for the difference in airspace. That's the draw back with using removable ports that take up internal volume vs fully external ports.

[///M5 2,833]

Since you were going to build a couple enclosures anyway, build a test box that is large, use an external port and change the volume internally by adding stuff into it. Then you can test tons of variations.

[ncc74656 2]

not a bad idea... ill do that.

 

does an external port vary in any way from an internal port?

Edited August 21, 2013 by ncc74656

[ricksi30 923]

not a bad idea... ill do that.

 

does an external port vary in any way from an internal port?

It doesn't take up internal volume, which is the only real difference.

[ncc74656 2]

i played around with frequencies a bit today. my preferred range for bass is 60-115hz, thats what i want to be the loudest.

[///M5 2,833]

i played around with frequencies a bit today. my preferred range for bass is 60-115hz, thats what i want to be the loudest.

that is mid bass, not sub bass

[shizzzon 461]

holy god!  name a song you listened to that made you think that?  I must analyze this.