Originally posted by TType84
dont get a bandpass...
i dont know all the details but from what ive read..
sealed box = sq
ported box = spl
bandpass = sucks
This is just a personal opinion but I have built many of the 3 designs mentioned above and if designed correctly and built properly, all three can hammer and sound great but the bottom line is that the choice of which sounds better will be totally subjective to your taste in the sound that you like and desire. Each one has different characteristics which yields its "pros" and "cons". here is some F.Y.I. that I found on the enclosures mentioned that might help you with a better understanding with cabinet design:
Sealed woofer cabinets The sealed (aka: air-suspension, acoustic-suspension) enclosure is a classic box design. Patented in 1949 by Harry Olson and popularized in the 1950's by Acoustic Research, this design has stood the test of time and has been adopted by many home and car audio companies.
In a sealed enclosure, the woofer is tightly controlled by a trapped volume of air in the enclosure which acts as a spring (hence the name "air-suspension.") The woofer must literally pull the air with it as it moves outward thus decreasing the air pressure inside the box and compress the air inside the box when it moves inward, which increases the air pressure inside the box. Since the air pressure inside the box seeks to equal the barometric pressure of the atmosphere, it acts as a controlling force over the motion of the speaker. The more the speaker moves inward or outward, the greater the pressure exerted by the air-spring of the sealed enclosure in the opposite direction.
The relationship between the parameters of the speaker being used and the volume of air inside the enclosure dictates the performance of the sealed subwoofer system. By making the box larger, the air spring limits cone motion less and allows the system to play lower and with flatter overall response (lower Qtc) at the expense of power handling. If you go too large, however, you begin to lose efficiency in order to gain the additional low frequency extension. By making the box smaller, the air spring exerts more control and limits cone motion at low frequencies which increases power handling but does not let the system play as low and produces a more peaked response (higher Qtc.) For any speaker competently designed for sealed box applications there is a range of enclosure volumes that will produce good high-fidelity sound. Changing the enclosure volume within that range can fine-tune the response to suit the tastes of the listener and/or the acoustic properties of the vehicle.
Ported woofer cabinets Ported enclosures (aka: Bass-Reflex, Vented) have actually been around longer than sealed designs. The ported enclosure was patented in 1932 by A.C. Thuras. Further development since then has defined the behavior of ported systems much more precisely. A.N. Thiele and Richard Small are generally credited with having done the most definitive work in this area, which is why enclosure/speaker parameters are commonly referred to as Thiele-Small parameters.
The coupling of a port or duct to the air inside the enclosure allows the subwoofer system to take advantage of the work being done by the rear of the woofer cone to reinforce the low-frequency response. The resonant characteristics of the column of air in a port, when installed in a given box, are adjusted by altering its resistance to motion, which is accomplished by changing the dimensions of the port. In some designs, instead of a port, a speaker cone with no motor assembly or a flat diaphragm is used to achieve the same effect. This is known as a passive radiator. The resonance of a passive radiator system can be adjusted by altering the radiator's surface area, mass and compliance (stiffness of suspension.)
In a ported enclosure, there is a delicate relationship between the volume of air in the box, the resonant effect of the port, and the parameters of the speaker being used. When these three factors are correctly integrated, the rear output wave of the speaker is delayed just enough so that when it comes out of the port, it is in relative phase with the wave being produced by the front of the speaker. The result is constructive output from the port limited to a desired low- frequency range. This low-frequency reinforcement is one of the big advantages of a well-designed ported system. Using the work of the rear of the cone in a constructive manner means that a gain in efficiency of about 3dB over a broad band in the sub-bass range can be achieved as compared to a sealed enclosure using the same woofer. The other big advantage is that the interaction of the port, the enclosure and the speaker's resonant characteristics also reduces cone motion and, therefore, distortion at higher volume levels in the frequency range controlled by the port. The down side is that at frequencies below the tuning of the port, the speaker gradually begins to act as if it were not enclosed at all (more on this later.)
The increased output combined with reduced distortion in the "meat" of the bass range (35-60Hz) is a big reason why many home speakers and high-power sound-reinforcement systems use ported enclosures for low-frequency reproduction. The vast majority of recording studios also use ported enclosures as monitors for the same reasons.
The rules governing the behavior and proper design of ported speaker systems are considerably more complex than those for sealed enclosures. For this reason, it is a good practice to follow the advice of the speaker manufacturer or an experienced enclosure designer when it comes to designing a ported system. It is very easy to screw up a ported box if you just guess at the size and length of the port or the tuning frequency for the box. Not only will a poorly designed box sound bad, but it can easily damage the speaker if it is played hard.
Band-pass woofer cabinets 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.
Don't let someones opinion influence what your choices are in the car audio market. Your ears are the ultimate judge and your wallet has the final judgement!!
Like I said, they are all good designs with pros and cons providing that they are designed and constructed properly. Its all about personal preferences.
