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View Full Version : sealed, ported, and bandpass questions



.::DuD3::.
11-07-2006, 11:14 PM
ok ive really been reading my stuff lately, and i have a few questions that i cant seem to find explained very well.

1. in sealed boxes, ive read its favorable mainly because of the transient response. what exactly is transient response?

2. bandpass boxes are built primarily around a given frequency, and because of this, it can sometimes become a "one note system." is this correct? if it is correct, what is the purpose of bandpass systems? is it mainly for competitions, to have a given frequency for burps and what not?

3. from what ive read, ported enclosures allow up to an octave more of frequency response. how is this related to sealed enclosures if you were to compare?

these are the questions i dont really have clear answers on, after searching my anus off.

80INCHES
11-07-2006, 11:20 PM
www.bcae1.com
http://www.diysubwoofers.org/ <--read this first for immediate answers
read these 2 websites .......it will aswer your questions

80

Flipx99
11-07-2006, 11:23 PM
I xan help some from experience...

The output on ported > the output on 4th order

HOWEVER, the 4th order 'blended' with the rest of my setup much better.

squeak9798
11-07-2006, 11:40 PM
1. in sealed boxes, ive read its favorable mainly because of the transient response. what exactly is transient response?

It is related to the damping abilities of the enclosure on the subwoofer.....or, it's ability to control the sub's overshoot and/or ringing, etc....how quicly and accurately it can respond to the signal. This is commonly called the "Q" of the system (for sealed enclosures, it is specifically the Qtc of the system).

The higher the Q, the lower the damping of the system, which can lead to ringing/etc....or, in other words, the subwoofer would not be "stopping" it's motion as quickly as it should. Likewise, the lower the Q, the higher the damping abilities.

Ported enclosures are inherently a high Q system, thus they do not offer the damping abilities of a typical sealed enclosure.

Mind you, that is a very basic and brief description. Transient response is really be a very involved subject.



2. bandpass boxes are built primarily around a given frequency, and because of this, it can sometimes become a "one note system." is this correct?

It can be, depending on the design.


if it is correct, what is the purpose of bandpass systems?


The enclosure is designed to create both an acoustic highpass and lowpass filter on the subwoofer (creating an acoustic bandpass filter on the driver...hence the name ;) ). This helps raise the efficiency within the passband (the frequency range not affected by the acoustic filters).

The narrower the passband, the more efficiency you gain within the passband. The wider the passband, the less efficiency you gain.

80INCHES
11-07-2006, 11:44 PM
bandpass boxes r more efficient (louder)than ported or sealed boxes...only within the bandwidth(frequecy range )

the interesting part is bandpass come in different orders
8thorder(one of the most efficient types of bandpass boxesbut has the the steepest slope)>6th order>4th order
there very hard to design but when done right....omg...priceless

80

NebBlackshirts
11-07-2006, 11:48 PM
http://www.lightav.com/car/boxes/char.html

this might help

.::DuD3::.
11-07-2006, 11:55 PM
It is related to the damping abilities of the enclosure on the subwoofer.....or, it's ability to control the sub's overshoot and/or ringing, etc....how quicly and accurately it can respond to the signal. This is commonly called the "Q" of the system (for sealed enclosures, it is specifically the Qtc of the system).

The higher the Q, the lower the damping of the system, which can lead to ringing/etc....or, in other words, the subwoofer would not be "stopping" it's motion as quickly as it should. Likewise, the lower the Q, the higher the damping abilities.

Ported enclosures are inherently a high Q system, thus they do not offer the damping abilities of a typical sealed enclosure.

Mind you, that is a very basic and brief description. Transient response is really be a very involved subject.




It can be, depending on the design.




The enclosure is designed to create both an acoustic highpass and lowpass filter on the subwoofer (creating an acoustic bandpass filter on the driver...hence the name ;) ). This helps raise the efficiency within the passband (the frequency range not affected by the acoustic filters).

The narrower the passband, the more efficiency you gain within the passband. The wider the passband, the less efficiency you gain.
so if you were designing a bandpass system, what would be optimal frequency to aim for? (i hope im thinking of this correctly, assuming you filter out low frequency and high frequency)

.::DuD3::.
11-07-2006, 11:59 PM
It is related to the damping abilities of the enclosure on the subwoofer.....or, it's ability to control the sub's overshoot and/or ringing, etc....how quicly and accurately it can respond to the signal. This is commonly called the "Q" of the system (for sealed enclosures, it is specifically the Qtc of the system).

The higher the Q, the lower the damping of the system, which can lead to ringing/etc....or, in other words, the subwoofer would not be "stopping" it's motion as quickly as it should. Likewise, the lower the Q, the higher the damping abilities.
so if the sealed box can "respond to the signal more quickly and accurately," i take it this is why sealed boxes are commonly referred to as the boxes for optimal sound quality?

80INCHES
11-08-2006, 12:01 AM
so if you were designing a bandpass system, what would be optimal frequency to aim for? (i hope im thinking of this correctly, assuming you filter out low frequency and high frequency)

depends on wat u looking 4
but when tuning a bandpass u have 2 tune in the middle of the passband

80