4th order banpass build Log

[KU40 173]

Couple major things that make no sense. You forgot the second chamber and a 4th order won't buy you what you are looking for as it will be quieter than a ported enclosure.

I was kinda thinking similar. I didn't really know what that was. It seems more like a horn than a BP, and the ported section may have acted more like a leaky ported box. You might also not want the woofer to fire into a corner on the opposite wall. I'd think you'd want it firing either 90 or 180 degrees from the port.

[sundownz 197]

IMO... port is way too big. Shrink it down and try metering again

PS: I agree that a 6th order may be worth a shot.

[JimJ 11]

Go 6th order...

If the Qts is as high on that woofer as it was on the other PAP products you've linked to, I wouldn't want it anywhere near anything resembling a horn.

[80INCHES 0]

i agree do a 6th order...

.rear chamber 3cubes tuned to 40hz with 50 square inch port

plying into

5.5 cube front chamber with a 120 square inch port tuned to 75hz

u should be over 146.6 off 1 sundown amp...

80

[KU40 173]

one thing I meant to say when I was talking about the ported box/horn confusion is that the inside of your port is tapered away, which may "confuse" the box as to where the port starts. As I'm sure you know, the port area on the inside of the box is just as important as the port area on the outside of the box. I think you would have had better results if you had simply made the baffle that the sub on straight across at a 90 degree angle from the side and port, making it a square sealed box inside. Might be worth a shot at trying before you tear this box apart.

[Lord Baccus 1]

I have no idea what a 6th order is or where to begin ???

does anyone have an example of this ?

diagram ?

plot sheet ???

[///M5 2,833]

google first, then ask questions.

[ford302redneck 15]

google first, then ask questions.

Hell, I google everything.

[danracer 0]

[///M5 2,833]

/\ don't try to replace those ports with horn openings either...

[Lord Baccus 1]

google first, then ask questions.

google first, then ask questions.

Hell, I google everything.

you mean 1 of these http://www.speakerplans.com/index.php?id=subplans

i allready have plans for the X1

[///M5 2,833]

You can't just put any driver in any enclosure

[loudcav 1]

You can't just put any driver in any enclosure

he dosent seem to understand that fact tho

[80INCHES 0]

http://www.diysubwoofers.org/bnd/6thorder.htm

80

Edited May 20, 2008 by 80INCHES

[Lord Baccus 1]

You can't just put any driver in any enclosure

he dosent seem to understand that fact tho

just asking if that was an Example of a 6th order bandpass enclosure.

it seemed that the X1 was what you were reffering to ?

does anyone have build pics of a 6th OBP boxx ???

[DevilDriver 28]

A little background info for you, LB...

When we say "4th order" or "6th order", this refers to the rate at which the response rolls off at its upper and lower "corner" frequencies. In other words, above a certain frequency (say, 60 Hz), response will rolloff (the driver/enclosure combo will be quieter). The same can be said for below a certain frequency (say, 30 Hz).

So what are these rates of rolloff? Pretty simple: 1 order = 6 dB/octave rolloff. Extrapolating for a moment, you will see that a 4th order enclosure will have a rate of rolloff of 24 dB/octave, while a 6th order enclosure will have a rate of rolloff of 36 dB/octave.

To understand that part, you need to know that an octave above a frequency is double that original frequency; an octave below is half that original frequency. Also, note that this is just referring to a type of mechanical filter that behaves in the same way as, say, your low-pass filter on your amplifier.

To bring this all together, suppose a driver/enclosure combination that produces 100 dB from 30 Hz - 70 Hz. We'll say that the 30 Hz is the lower corner frequency (the frequency that the high-pass filter begins) and the upper corner frequency (the frequency that the low-pass filter begins) is 70 Hz. Suppose this enclosure is of the 4th order (24 dB/octave) variety. Looking at the low end of the spectrum, we will see that response is 100 dB at 30 Hz, 76 dB at 15 Hz, 52 dB at 7.5 Hz, etc (although it should be noted that at frequencies this low, your subwoofer will typically lack the throw to get much meaningful response). On the top end, we will see that response is 100 dB at 70 Hz, 76 dB at 140 Hz, 52 dB at 280 Hz, etc.

Now to apply this to specific types of enclosures. One of the simplest enclosures (the sealed variety) usually demonstrates a rolloff of 12 dB/octave (aka 2nd order). Bass Reflex enclosures (usually called "ported") exhibit a 24 dB/octave rolloff (4th order). However, neither of these two types will rolloff on the top end (aka they do not make for a mechanical low-pass filter).

Now bandpass is different. By definition, bandpass means you will see rolloff on the top end and on the bottom end (both low-pass and high-pass filters, respectively). So a 4th order bandpass exhibits the same rolloff as a ported enclosure, but this occurs below AND above the bandwidth it is used in. A 6th order bandpass also has rolloff below and above the bandwidth it is used in, although the rate of rolloff is obviously quicker (36 dB/octave). Why is this a good thing? Well, it isn't for many people as limiting the top end may be the opposite of what they want. For SPL competitors, however, this means that we gain more output in the bandwidth between these filters. In fact, the faster the rate of rolloff on the top and bottom end, and the smaller the bandwidth is, the more output at a central frequency you will see.

Hopefully that makes sense and provides at least a cursory understanding of what these enclosures are about. The problem with bandpass enclosures is that they are typically quite large (especially those of the 6th order or 8th order variety as the ports consume a fair bit of a volume themselves).

If you need to make a small step into understanding them further, you can simulate response with the spreadsheet on Brian Steele's website. If you want to visualize what some of these enclosures can look like, check out The12Volt.com.

As mentioned above, many drivers require enclosures built specifically for them using the Thiele/Small parameters supplied. The higher the order, the more sensitive the enclosure is to miscalculation and poor building. Read for a little while and ask questions if any of this is unclear.

[Lord Baccus 1]

Thank you

[the727kid 1]

I'll have build pics of a 6th order this weekend hopefully =)

[sundownz 197]

I built a small 6th order for an SI BM 10" before, worked quite well.

[Lord Baccus 1]

I built a small 6th order for an SI BM 10" before, worked quite well.

i would love to see a build pics session of a boxx like that, as the 1 dimentional drawings leave a lot to imagining

hence my Wonder F-up boxx

it hitt realy well from 30hz to 40hz then NOTHING till 120Hz to 200Hz (freeking Loud ) then the Suv tried to come apart.

but 80Hz is the cuttoff for SPL events

[80INCHES 0]

I'll have build pics of a 6th order this weekend hopefully =)

yes im dying to know how it performs

if it perform well in a sealed..u should be happy with it in a 6th order

80

[the727kid 1]

Haha I'm pretty happy with it in the big ass box it's in right now =D I'm excited for this box.

[Basshead 3]

devildriver...that was a good read lots of nice info

[galacticmonkey 0]

If you have enough scrap wood for an extra box, build a bandpass for the 12.

Go 1 cube sealed, 1.25 ported, with about 40 sq in of port tuned to around 55hz.

Im glad you know so much about bandpass, and built so many of them.

Got more experience with them than you do.

And besides, that isnt even my design. Thats a design Steve Cook used to build 15 years ago. Then Jethro Eason started building it, and now everyone around here has been doing the 1 cube sealed and 1.25 ported for about 10 years now.

[ford302redneck 15]

If you have enough scrap wood for an extra box, build a bandpass for the 12.

Go 1 cube sealed, 1.25 ported, with about 40 sq in of port tuned to around 55hz.

Im glad you know so much about bandpass, and built so many of them.

Got more experience with them than you do.

And besides, that isnt even my design. Thats a design Steve Cook used to build 15 years ago. Then Jethro Eason started building it, and now everyone around here has been doing the 1 cube sealed and 1.25 ported for about 10 years now.

oh yeah? You say so?

You sure you got more than me?

Im pretty sure, a 1 sealed to 5 ported would do a better job.