BandPass Box issues
Thread Starter
Registered!!
iTrader: (1)
Joined: Jul 2004
Posts: 548
Likes: 0
From: Ottawa, Ontario, Canada
Rep Power: 0 
BandPass Box issues
I have 1 12" sub (that is shot to ****, hole in dust shield etc) in a bandpass box ... hooked up to a Pheonix Gold Octane R 2:5:2 amp bridged.
From what I understand in a bandpass box, you will not be able to hear distortion, even if the sub is being torn apart. Now I dont really care about the sub in their right now (as it is already messed) ... BUT it still pumps bass like mad.
Now when I switched to the PG amp, I was going to pair it with a PG sub, but the guy at the store told me that I would not be able to hear any difference from my shitty sub to the new PG sub. So he advised me to just keep this one until it fizzes out (altho I've had it since I bought the system used which was about 4 years and its still pumpin hard).
Is this persons assesment of the sub true, being in a bandpass box.
From what I understand in a bandpass box, you will not be able to hear distortion, even if the sub is being torn apart. Now I dont really care about the sub in their right now (as it is already messed) ... BUT it still pumps bass like mad.
Now when I switched to the PG amp, I was going to pair it with a PG sub, but the guy at the store told me that I would not be able to hear any difference from my shitty sub to the new PG sub. So he advised me to just keep this one until it fizzes out (altho I've had it since I bought the system used which was about 4 years and its still pumpin hard).
Is this persons assesment of the sub true, being in a bandpass box.
i boogie for the raindrops
Joined: Oct 2001
Posts: 4,497
Likes: 1
From: Jackson, Mississippi
Rep Power: 0 yes and no
90% of bandpass enclosures are designed to get maximum output, with no regard for sound quality, as is yours, because youre obviously just after kaboom.
distortion can be heard, but not in the way he meant. one of the things we as installers use to know if the sub is being driven too far is noises from the sub being driven past it's mechanical limits. because you do not have a direct line of hearing with the sub, your ability to hear such things is impaired. so yes, he is right, in a sense.
personally, i wouldnt touch a prefab bandpass box with a REALLY long stick, and it wouldnt be the best idea to put a random pg sub in that box, since the box wasnt designed for it, but it is your money, and they are your ears
90% of bandpass enclosures are designed to get maximum output, with no regard for sound quality, as is yours, because youre obviously just after kaboom.
distortion can be heard, but not in the way he meant. one of the things we as installers use to know if the sub is being driven too far is noises from the sub being driven past it's mechanical limits. because you do not have a direct line of hearing with the sub, your ability to hear such things is impaired. so yes, he is right, in a sense.
personally, i wouldnt touch a prefab bandpass box with a REALLY long stick, and it wouldnt be the best idea to put a random pg sub in that box, since the box wasnt designed for it, but it is your money, and they are your ears
Joined: Mar 2004
Posts: 51,077
Likes: 4
From: B.C., Canada
Rep Power: 786 
Exactly, doesn't mean the distortion is there, you just can't hear it. It's similar to using a ground loop filter that will pretend to eliminate your ground loop noise when in reality it is just eliminating audible frequencies that would otherwise be in your music.
Get a PG sub but put it in a ported box and see how you like it. If you do the box right, it should dish it out as much as the POS in the POS box you have right now.
I am fairly educated in PG product, so I can help you get a box design if you like.
Get a PG sub but put it in a ported box and see how you like it. If you do the box right, it should dish it out as much as the POS in the POS box you have right now.
I am fairly educated in PG product, so I can help you get a box design if you like.
Electric Boogaloo...
iTrader: (6)
Joined: Mar 2003
Posts: 4,457
Likes: 1
From: Want to play a game?
Rep Power: 328 All you could want to know about a bandpass enclosure(credit to JLaudio.com)... and then some (I have more if you want it).
These enclosures seem to be the latest rage in the car audio world. It would probably surprise many people to know that these designs have been around for many years. The first patent for a bandpass enclosure was filed in 1934 by Andre d'Alton. In the last ten years, interest has been renewed in these enclosure designs and substantial strides have been made in defining their behavior. Many home sub/satellite speaker systems currently use bandpass designs for low-frequency reproduction. Designs from Bose, KEF, AR, and many others have become very popular in home audio circles.
In a bandpass box design, the woofer no longer plays directly into the listening area. Instead, the entire output of the subwoofer system is produced through the port or ports. In a conventional sealed or ported subwoofer system the low-frequency extension is controlled by the interaction of the speaker and the enclosure design, but the high frequency response is a result of the speaker's natural frequency response capability (unless limited by a crossover.) In a bandpass enclosure, the front of the speaker fires into a chamber which is tuned by a port. This ported front chamber acts as a low-pass filter which acoustically limits the high- frequency response of the subwoofer system. The name "bandpass" is really pretty descriptive in that it refers to the fact that the enclosure will only allow a certain frequency "band" (range) to "pass" into the listening environment.
So what? Couldn't the same thing be accomplished by placing a low pass crossover on the subwoofer system? Yes, it could, but a bandpass enclosure can produce significant performance benefits in terms of efficiency and/or deep bass extension that would not be possible in conventional designs of equal size.
By adjusting the volumes of the front and rear chambers and the tuning of the port or ports, significant performance trade-offs can be created. When box parameters are adjusted for a narrower bandwidth, the efficiency of the subwoofer system within that bandwidth increases and can reach gains of up to 8dB (sometimes even higher.) As box parameters are adjusted for wider bandwidths, very impressive low-frequency extension can be produced from extremely compact enclosures at the expense of efficiency and good transient response. Intermediate bandwidths can also be designed which create a compromise between all these characteristics. As if that is not confusing enough, within each bandwidth range, the designer can also manipulate box parameters to shift the range of operation up or down the sub-bass range which also has an effect on efficiency.
As you can see, bandpass enclosures can have very different sound characteristics based on the designer's choice of box parameters. As such, it is not always possible to make blanket statements as to the performance benefits and drawbacks of bandpass enclosures in general.
One characteristic of bandpass enclosures which is universal is that they exert greater control over cone motion over a wider frequency band than conventional designs. Due to controlled, rapidly changing air pressure on either side of the woofer, the woofer is capable of producing high levels of acoustic output without physically moving very much. This means that the woofer is less likely to encounter excursion limits in the main part of the sub-bass range. However, just because the cone isn't moving as much doesn't mean that the speaker's motor assembly isn't still trying to drive the cone hard; it just means that the speaker cone is encountering resistance to motion. This resistance can be very hard on speakers, especially when crazy car audiophiles are at the controls. The conflict between the force generated by the motor assembly and the air pressure in the enclosure can impose extreme stress on the glue joints and suspensions of the woofers. You can literally tear a speaker apart in a bandpass enclosure if you apply too much power. Because the speaker is not moving as much and because noises are masked by the front chamber, it is also very difficult to hear when a woofer is in serious trouble. Many people have been known to crank bandpass enclosures up and blow the speaker to bits within a few minutes because they did not realize that the speaker was having a heart attack. Choosing the right amount of power and carefully setting amplifier gains is very important in order to ensure long- term reliability.
Bandpass enclosures can be divided into two basic types: single- reflex and dual-reflex. In a single-reflex design, the rear chamber is sealed and the front chamber is ported. In a dual-reflex design, both front and rear chambers are ported into the listening area. A variation of the dual-reflex and single-reflex, known as "series-tuned," has a port which connects the rear and front chambers.
The differences between single-reflex and dual-reflex bandpasses are similar to the differences between sealed and ported enclosures. A single-reflex typically exhibits a shallower low-frequency roll- off rate (approximately12dB/octave) and better transient response. A dual-reflex is more efficient and controls cone-motion over a wider range but typically has a sharper (18-24dB/octave) low- frequency roll-off. Because of the difference in low-frequency roll- off rates, a dual-reflex usually has to be larger in size to produce the same low-frequency extension as a single-reflex design.
As compared to more conventional enclosure designs, bandpass enclosures are very complex to design and build. The rules governing the performance of bandpass enclosures leave no room for error. Slight volume miscalculations or sloppy construction can turn a good design into a poor-performing box. Integrating the proper size port or ports can be extremely challenging and often renders designs that looked great on paper completely impractical. The design of these boxes should definitely be left to people with extensive enclosure- building experience.
These enclosures seem to be the latest rage in the car audio world. It would probably surprise many people to know that these designs have been around for many years. The first patent for a bandpass enclosure was filed in 1934 by Andre d'Alton. In the last ten years, interest has been renewed in these enclosure designs and substantial strides have been made in defining their behavior. Many home sub/satellite speaker systems currently use bandpass designs for low-frequency reproduction. Designs from Bose, KEF, AR, and many others have become very popular in home audio circles.
In a bandpass box design, the woofer no longer plays directly into the listening area. Instead, the entire output of the subwoofer system is produced through the port or ports. In a conventional sealed or ported subwoofer system the low-frequency extension is controlled by the interaction of the speaker and the enclosure design, but the high frequency response is a result of the speaker's natural frequency response capability (unless limited by a crossover.) In a bandpass enclosure, the front of the speaker fires into a chamber which is tuned by a port. This ported front chamber acts as a low-pass filter which acoustically limits the high- frequency response of the subwoofer system. The name "bandpass" is really pretty descriptive in that it refers to the fact that the enclosure will only allow a certain frequency "band" (range) to "pass" into the listening environment.
So what? Couldn't the same thing be accomplished by placing a low pass crossover on the subwoofer system? Yes, it could, but a bandpass enclosure can produce significant performance benefits in terms of efficiency and/or deep bass extension that would not be possible in conventional designs of equal size.
By adjusting the volumes of the front and rear chambers and the tuning of the port or ports, significant performance trade-offs can be created. When box parameters are adjusted for a narrower bandwidth, the efficiency of the subwoofer system within that bandwidth increases and can reach gains of up to 8dB (sometimes even higher.) As box parameters are adjusted for wider bandwidths, very impressive low-frequency extension can be produced from extremely compact enclosures at the expense of efficiency and good transient response. Intermediate bandwidths can also be designed which create a compromise between all these characteristics. As if that is not confusing enough, within each bandwidth range, the designer can also manipulate box parameters to shift the range of operation up or down the sub-bass range which also has an effect on efficiency.
As you can see, bandpass enclosures can have very different sound characteristics based on the designer's choice of box parameters. As such, it is not always possible to make blanket statements as to the performance benefits and drawbacks of bandpass enclosures in general.
One characteristic of bandpass enclosures which is universal is that they exert greater control over cone motion over a wider frequency band than conventional designs. Due to controlled, rapidly changing air pressure on either side of the woofer, the woofer is capable of producing high levels of acoustic output without physically moving very much. This means that the woofer is less likely to encounter excursion limits in the main part of the sub-bass range. However, just because the cone isn't moving as much doesn't mean that the speaker's motor assembly isn't still trying to drive the cone hard; it just means that the speaker cone is encountering resistance to motion. This resistance can be very hard on speakers, especially when crazy car audiophiles are at the controls. The conflict between the force generated by the motor assembly and the air pressure in the enclosure can impose extreme stress on the glue joints and suspensions of the woofers. You can literally tear a speaker apart in a bandpass enclosure if you apply too much power. Because the speaker is not moving as much and because noises are masked by the front chamber, it is also very difficult to hear when a woofer is in serious trouble. Many people have been known to crank bandpass enclosures up and blow the speaker to bits within a few minutes because they did not realize that the speaker was having a heart attack. Choosing the right amount of power and carefully setting amplifier gains is very important in order to ensure long- term reliability.
Bandpass enclosures can be divided into two basic types: single- reflex and dual-reflex. In a single-reflex design, the rear chamber is sealed and the front chamber is ported. In a dual-reflex design, both front and rear chambers are ported into the listening area. A variation of the dual-reflex and single-reflex, known as "series-tuned," has a port which connects the rear and front chambers.
The differences between single-reflex and dual-reflex bandpasses are similar to the differences between sealed and ported enclosures. A single-reflex typically exhibits a shallower low-frequency roll- off rate (approximately12dB/octave) and better transient response. A dual-reflex is more efficient and controls cone-motion over a wider range but typically has a sharper (18-24dB/octave) low- frequency roll-off. Because of the difference in low-frequency roll- off rates, a dual-reflex usually has to be larger in size to produce the same low-frequency extension as a single-reflex design.
As compared to more conventional enclosure designs, bandpass enclosures are very complex to design and build. The rules governing the performance of bandpass enclosures leave no room for error. Slight volume miscalculations or sloppy construction can turn a good design into a poor-performing box. Integrating the proper size port or ports can be extremely challenging and often renders designs that looked great on paper completely impractical. The design of these boxes should definitely be left to people with extensive enclosure- building experience.
Thread
Thread Starter
Honda Civic Forum
Replies
Last Post
danace99
Mechanical Problems/Vehicle Issues and Fix-it Forum
23
Jun 28, 2015 08:49 AM
2k2civicballer
I.C.E. (Audio) & Electrical Upgrades
15
Feb 2, 2002 04:44 PM
