ok since most of you will argue about what enclosure is the best out there lets have a discussion on it. Any opinions are welcome but pls give facts over fiction.
i copied an articles about it. Read and share your view:
Ported systems are all around good performers, and most commercial home speakers use some type of ported enclosure. Automotive subwoofer manufacturers also like the ported enclosure, and most design drivers for this type of installation. The tuned port in these systems increases efficiency by nearly 3 dB in an optimum enclosure, and the roll-off frequency can be much lower, often by as much as 1/3 - 1 octave below a sealed enclosure. Think of the extra 3 dB as equal to the output you would get using twice the amplifier power on the driver. Add several ported drivers together and you can achieve impressive SPL's indeed! Because of the ports damping characteristics on the driver above Fb, distortion levels are also lowered because driver excursion is less. So, with nothing more than a properly designed optimum vented enclosure, you have very efficient bass reproduction with several advantages over an optimum sealed enclosure.
So, why in the world would anyone waste the time designing and building a sealed enclosure? Like anything, there are compromises in all designs, and ported systems are no exception. A very clear advantage for a sealed enclosure is simplicity - you can get good performance with nearly any driver with an EBP of less than 90 in a simple sealed box. Enclosure volume is not critical with these designs, and a volume change of +/- 10 - 20% will not adversely affect the sound. Ported boxes must be fairly precise in volume and tuning. Consider also the fact that sealed boxes have very gentle roll-off characteristics after F3 at -12 dB/octave. Because ported system cut-off is a steep -24 dB/octave, often lower bass can be realized with a sealed design even if the ported F3 is lower. (Note: attenuation slopes after cutoffs are almost never exactly these values, and may be steeper or more gentle depending on alignments).
On the downside, a sealed driver reaches maximum excursion at resonance, which adds considerably to the distortion produced at high output levels. A ported system receives maximum damping at resonance, with minimal driver excursion. The port "takes over" at Fb, and the driver hardly moves at all. This minimizes low frequency distortion, but ported systems progressively lose damping from the enclosure the lower you go below Fb, which amounts to a loss of control for the driver at very low frequencies. This is definitely a factor to consider if you are planning on building a ported system much smaller than optimum, as the tuning frequency may approach 50+ Hz, a frequency generally considered quite usable by most listeners. Subsonic filters can help with this unloading experienced with some ported systems.
While a ported enclosure is damped by the port at resonance, the sealed enclosure is wholly dependent upon the air trapped behind it in the enclosure. Once placed in the enclosure, the Fs turns into Fc, or the box/driver resonant frequency. The air in the box acts as a restoring force upon the driver cone, with a larger Vb usually meaning the driver can respond to lower frequencies (to a point).
so what do you think? B)
i copied an articles about it. Read and share your view:
Ported systems are all around good performers, and most commercial home speakers use some type of ported enclosure. Automotive subwoofer manufacturers also like the ported enclosure, and most design drivers for this type of installation. The tuned port in these systems increases efficiency by nearly 3 dB in an optimum enclosure, and the roll-off frequency can be much lower, often by as much as 1/3 - 1 octave below a sealed enclosure. Think of the extra 3 dB as equal to the output you would get using twice the amplifier power on the driver. Add several ported drivers together and you can achieve impressive SPL's indeed! Because of the ports damping characteristics on the driver above Fb, distortion levels are also lowered because driver excursion is less. So, with nothing more than a properly designed optimum vented enclosure, you have very efficient bass reproduction with several advantages over an optimum sealed enclosure.
So, why in the world would anyone waste the time designing and building a sealed enclosure? Like anything, there are compromises in all designs, and ported systems are no exception. A very clear advantage for a sealed enclosure is simplicity - you can get good performance with nearly any driver with an EBP of less than 90 in a simple sealed box. Enclosure volume is not critical with these designs, and a volume change of +/- 10 - 20% will not adversely affect the sound. Ported boxes must be fairly precise in volume and tuning. Consider also the fact that sealed boxes have very gentle roll-off characteristics after F3 at -12 dB/octave. Because ported system cut-off is a steep -24 dB/octave, often lower bass can be realized with a sealed design even if the ported F3 is lower. (Note: attenuation slopes after cutoffs are almost never exactly these values, and may be steeper or more gentle depending on alignments).
On the downside, a sealed driver reaches maximum excursion at resonance, which adds considerably to the distortion produced at high output levels. A ported system receives maximum damping at resonance, with minimal driver excursion. The port "takes over" at Fb, and the driver hardly moves at all. This minimizes low frequency distortion, but ported systems progressively lose damping from the enclosure the lower you go below Fb, which amounts to a loss of control for the driver at very low frequencies. This is definitely a factor to consider if you are planning on building a ported system much smaller than optimum, as the tuning frequency may approach 50+ Hz, a frequency generally considered quite usable by most listeners. Subsonic filters can help with this unloading experienced with some ported systems.
While a ported enclosure is damped by the port at resonance, the sealed enclosure is wholly dependent upon the air trapped behind it in the enclosure. Once placed in the enclosure, the Fs turns into Fc, or the box/driver resonant frequency. The air in the box acts as a restoring force upon the driver cone, with a larger Vb usually meaning the driver can respond to lower frequencies (to a point).
so what do you think? B)