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btdickey99
01-09-2008, 07:33 PM
I was just wondering the advantages/ disadvantages of going with a 1st order bandpass, 2nd order, 3rd, 4th etc?

How would this be compared to a ported box?

This is assuming that both type boxes are built properly

Thanks

chillin
01-09-2008, 07:37 PM
I believe a properley built bandpass will be louder but take up more space. But Ive been wrong before.

Immacomputer
01-09-2008, 08:16 PM
Um... there is no such thing as a 1st order Bandpass or second or third. The order comes from the DE used -- it's not just a name.

btdickey99
01-09-2008, 10:13 PM
Um... there is no such thing as a 1st order Bandpass or second or third. The order comes from the DE used -- it's not just a name.

shows how much I know.....

sorry guys

<-----Idiot

PV Audio
01-10-2008, 12:33 AM
I may be wrong in this assumption, but it makes sense to me. I believe the word bandpass is derived or is directly related to passband, which is an area of the audio spectrum. In a filter circuit, you have a low pass and a high pass circuit. For 3-way designs, you add a bandpass filter which comprises the middle of the spectrum. This is called the passband, or area between your upper and lower limiting frequencies. It looks roughly like a plateau which rolls off very quickly at either end i.e.
http://www.rjbaudio.com/AlpheusMkII/Alpheus&#37;20MkII%20crossover%20response.jpg
The red is your highpass rolloff, green is the lowpass rolloff, and the blue hump is the bandpass rolloff, or passband for this particular filter.

What a bandpass enclosure does is that it essentially chooses two frequencies to be tuned to (literally for a 6th order bandpass, but we'll keep it to 4th order), and the area, or passband, between those two frequencies is greatly enhanced or boosted, much like a ported enclosure. However, much UNLIKE a ported enclosure, the bandpass enclosure's frequency response is very narrow in comparison, which is why you generally only use the design on low frequency drivers where they only have a small bandwidth to cover. As such, they are very easy to design, but extremely difficult to design correctly. I know not of a single commercial bandpass box that is designed correctly, and they consequently get loud, but sound absolutely awful (akin to farting, as some put it). Hope that helped, but if not, just let me know or someone else correct me so you can get a better explanation. :)

-Dave

btdickey99
01-10-2008, 12:38 AM
I may be wrong in this assumption, but it makes sense to me. I believe the word bandpass is derived or is directly related to passband, which is an area of the audio spectrum. In a filter circuit, you have a low pass and a high pass circuit. For 3-way designs, you add a bandpass filter which comprises the middle of the spectrum. This is called the passband, or area between your upper and lower limiting frequencies. It looks roughly like a plateau which rolls off very quickly at either end i.e.
http://www.rjbaudio.com/AlpheusMkII/Alpheus%20MkII%20crossover%20response.jpg
The red is your highpass rolloff, green is the lowpass rolloff, and the blue hump is the bandpass rolloff, or passband for this particular filter.

What a bandpass enclosure does is that it essentially chooses two frequencies to be tuned to (literally for a 6th order bandpass, but we'll keep it to 4th order), and the area, or passband, between those two frequencies is greatly enhanced or boosted, much like a ported enclosure. However, much UNLIKE a ported enclosure, the bandpass enclosure's frequency response is very narrow in comparison, which is why you generally only use the design on low frequency drivers where they only have a small bandwidth to cover. As such, they are very easy to design, but extremely difficult to design correctly. I know not of a single commercial bandpass box that is designed correctly, and they consequently get loud, but sound absolutely awful (akin to farting, as some put it). Hope that helped, but if not, just let me know or someone else correct me so you can get a better explanation. :)

-Dave

That did help a lot and appreciate it....So to sum up things..... If designed correctly the bandpass box will be a better box for burping?

PV Audio
01-10-2008, 12:41 AM
That did help a lot and appreciate it....So to sum up things..... If designed correctly the bandpass box will be a better box for burping?Maybe, I don't compete so I'm not sure. Ask someone like tommyk who actually does. I don't want to tell you yes since I don't know.

BrianChia
01-10-2008, 01:33 AM
I know not of a single commercial bandpass box that is designed correctly

BOSE :fyi:

:)

Blinkdogo2
01-10-2008, 01:37 AM
bandpass is not better for burping, look at the world record holders they dont use bandpass, why would u want to turn an 18" sub into a couple 4" ports,, bandpass is to make ****** subs sound better

BrianChia
01-10-2008, 01:39 AM
bandpass is not better for burping, look at the world record holders they dont use bandpass, why would u want to turn an 18" sub into a couple 4" ports,, bandpass is to make ****** subs sound better

false

btdickey99
01-10-2008, 01:41 AM
Now I am confused and would like to have someone with a great deal of experience answer the question

JimJ
01-10-2008, 01:43 AM
bandpass is not better for burping, look at the world record holders they dont use bandpass, why would u want to turn an 18" sub into a couple 4" ports,, bandpass is to make ****** subs sound better

:hilariou:

duece212
01-10-2008, 01:46 AM
bandpass is not better for burping, look at the world record holders they dont use bandpass, why would u want to turn an 18" sub into a couple 4" ports,, bandpass is to make ****** subs sound better

didn't somebody win some driveby event at a record level with a bandpass enclosure in a van recently?

bdawson72
01-10-2008, 01:46 AM
:hilariou:

:hilariou::hilariou:

btdickey99
01-10-2008, 01:47 AM
^^^hes laughing at you

btdickey99
01-10-2008, 01:47 AM
bandpass is not better for burping, look at the world record holders they dont use bandpass, why would u want to turn an 18" sub into a couple 4" ports,, bandpass is to make ****** subs sound better

wow thats 2 laughing at you

BrianChia
01-10-2008, 01:51 AM
It depends on the driver. Sub X may reach its potential in a bass reflex design. Sub Y may reach its potential in a 4th order bandpass. Sub Z may reach its potential in a 6th order. No enclosure is superior to another. It depends on the driver, the vehicle transfer function, resonant frequency, the enclosure design etc.

What a bandpass design does is use port resonance to control cone excursion. A bass reflex controls excursion near Fs with a single port. A 4th order controls low end excursion by loading the driver in acoustic suspension while the port controls high frequency (above the passband) excursion. A 6th order uses ports to control overexcursion at both ends of the passband.

80INCHES
01-10-2008, 02:20 AM
didn't somebody win some driveby event at a record level with a bandpass enclosure in a van recently?

yes eric
he had a 6th order series tuned bandpass


box types
1st order(free air)

2nd order(sealed)

3rd order(ported)

4th order(bandpass with 1 sealed chamber playing into 1 ported chamber)

5th order(4th order bandpass with a low pass filter)

6th order parallel tuned(bandpass with the rear chamber ported while the sub is playing into another ported chamber...both ports are seen)

6th order series tuned(bandpass with the rear chamber ported playing into a front ported chamber...one one port is seen and its fron the front chamber)

7th order(bandpass with the rear chamber using a passive radar while the sub is playing into a ported chamber..only the passive radar and the front chamber port are seen)

8th order( bandpass with both the front and rear chamber ported and both ports playing into another ported chamber...only 1 port is seen but theres 3 ports all 2gether)


80

btdickey99
01-10-2008, 02:42 AM
Thanks you for clearing up my stupidity