Ok, lets discuss the tuning of different boxes. Iíd like to learn more about the technical side of things.
If I am wrong about anything, please do correct me
Starting off, sealed. Smaller sealed boxes are ďtunedĒ higher and donít have good low-end response. To my understanding, itís better to have a larger box up to a certain point. I forget when, but a large sealed box acts similar to IB after a certain number of times larger than the subís VAS.
Two peaks in the response curve are the subís resonant frequency and the enclosureís resonant frequency.
Next is ported, which gets a lot more complicated.
Port length and area the same, making a box larger lowers tuning. Making a box smaller raises tuning. I donít remember if larger or smaller boxes are more peaky.
Box volume and port area the same, increasing port length lowers tuning. Decreasing port length raises tuning.
Box volume and port length the same, increasing port area raises tuning. Reducing port area lowers tuning. Increasing port area increases efficiency and makes response more peaky at the tuning frequency. Reducing port area makes response ďflatterĒ and less efficient. However, you canít reduce port area too much, or you will get port noise. There is debate on what amount of port area is necessary per cube. Aeroports are generally accepted as being more efficient than slotted ports, and flared aeroports are the most efficient, therefore requiring less square inches per cube.
Three peaks in a ported boxís response curve iirc. First is subís resonant frequency, then the boxís resonant frequency, and the portís resonant frequency.
Ok, 4th order bandpasses. Here, Iím not knowledgeable. I know there are general ratios of sealed to ported volumes that people follow for different design goals. Iíve never paid attention to or researched 4th orders, because Iíve never had room for them. Now i do, and would like to be informed about them.
How does changing each chamberís volume affect tuning? Which chamber do you want tuned higher and why?
I see lots of big builds running 4th orders. Would a 4th order be better than a ported wall if Iím looking to play as loud and flat as possible from 25hz to 50hz?
Quasi Sixth orders. I would really like to build one of these. The inside ported box is usually smaller than the outer chamber. How does changing the volume, port area, and port length of each chamber affect tuning and overall response?
Buck is designing me a quasi sixth order. I would just like to learn a lot more about them, so i can fine tune things after building the box and testing.
Going to look like a much larger version of this:
Here is a link to my other thread asking for help with a 6th order:
DD Z 6th order help!
With roughly 30 cubes of space and two 18ís, what box type would be best for me? I would really like to do a quasi sixth. I am willing to learn all I need to know, and spend lots of time building/tuning/adjusting. Would consider a 4th if there are some serious advantage to it over a ported wall.