Ported Vs. Unported. Educate me

[Assumer]

Just wondering what are the benefits of each.

 

[shadyJ]

First of all, what do you mean by 'unported'? There are a variety of designs aside from ported. As for ported, the advantages are very big gains in deep bass for very small cone movements. The ports in subwoofers are a function of Helmholtz resonance, which is the same physical effect that produces a 'note' when you blow over the top of an empty soda bottle or jug. The woofer in the subwoofer enclosure is doing the same thing to the port. The port is producing a very deep bass sound, and lots of it. The drawbacks are that the subwoofer does not produce much bass below the port's tuning frequency, however, that tuning frequency can be so low that it doesn't matter much. You might try a google search on this subject, but your query results may result in a lot of bogus information. There is a lot of BS flying around out there on this subject.

 

[Auditor55]

Just wondering what are the benefits of each.

You might be alluding to ported vs sealed. Typically speaking, it is opined that a sealed sub is better for music and a ported sub is better for movies.

 

[ski2xblack]

You might be alluding to ported vs sealed. Typically speaking, it is opined that a sealed sub is better for music and a ported sub is better for movies.

Opinions are great and all, but maybe it would be easier to grasp and potentially less misleading to the OP if we stick to the facts rather than common memes that may or may not hold water.

For a given enclosure volume, a sealed alignment will result in a higher f3 and 12db/oct slope roll off, where the port will result in a lower f3 but steeper 24db/oct roll off.

Steeper slopes equate to greater phase shifts, but provided this occurs down low enough we're pretty insensitive to it. This is worth considering if trying to blend ported mains with subs; they should be crossed well above their inherent f3 to avoid unnecessarily lumpy response.

Shallower slopes allow useful bass below f3 when cabin gain is taken into effect; ported designs do not benefit as much from cabin gain because...

Ported enclosures are resonant devices, and below f3 the port and active driver quickly go out of phase (hence the steeper roll off), with the result being excessive driver excursion with no added output at those frequencies. A hpf takes care of this, and many of the big ported subs employ such protection. Somewhat related, above f3, at frequencies where the port is doing most of the work, the active driver moves very little. This generally reduces distortion at those frequencies.

Neither sealed nor ported alignments care if they're reproducing music or a movie soundtrack. The "best" choice is determined by the dictates and limitations of each particular person's room(biggest factor)/desired goals/budget/WAF and whatever else.

 

[fmw]

The advantage of a ported sub is higher efficiency and the ability to reproduce lower frequencies. The advantage of sealed subs is that they can and usually do have smaller enclosures for a given driver size.

 

[Auditor55]

Opinions are great and all, but maybe it would be easier to grasp and potentially less misleading to the OP if we stick to the facts rather than common memes that may or may not hold water.

For a given enclosure volume, a sealed alignment will result in a higher f3 and 12db/oct slope roll off, where the port will result in a lower f3 but steeper 24db/oct roll off.

Steeper slopes equate to greater phase shifts, but provided this occurs down low enough we're pretty insensitive to it. This is worth considering if trying to blend ported mains with subs; they should be crossed well above their inherent f3 to avoid unnecessarily lumpy response.

Shallower slopes allow useful bass below f3 when cabin gain is taken into effect; ported designs do not benefit as much from cabin gain because...

Ported enclosures are resonant devices, and below f3 the port and active driver quickly go out of phase (hence the steeper roll off), with the result being excessive driver excursion with no added output at those frequencies. A hpf takes care of this, and many of the big ported subs employ such protection. Somewhat related, above f3, at frequencies where the port is doing most of the work, the active driver moves very little. This generally reduces distortion at those frequencies.

Neither sealed nor ported alignments care if they're reproducing music or a movie soundtrack. The "best" choice is determined by the dictates and limitations of each particular person's room(biggest factor)/desired goals/budget/WAF and whatever else.

There are facts which to base those opinions on. So opinions doesn't necessarily equate to no merit.

 

[Auditor55]

Please read: http://www.audioholics.com/loudspeaker-design/sealed-vs-ported-subwoofers


"While not all sealed subwoofers are created equal, properly done the alignment has a lot to offer. Size is typically manageable; the earlier pictured SB13-Ultra is effectively a 17.5” cube, giving it a lot of flexibility in placement as well as a high SAF (spouse acceptance factor). While small size tends to come at the expense of extension, sealed subwoofers generally have a shallow low-end roll-off profile, which corresponds with good performance in the time domain (i.e. group delay / ringing). Last but not least, sealed subwoofers offer some degree of protection against bottoming out the driver, though it is still possible with sufficient power and the right content

"However, below the tuning frequency, the driver is no longer loaded by the enclosure, and acts as if it is in free air. This results in a much steeper roll off rate of 24dB/octave relative to the 12dB/octave slope typical of sealed subwoofers; as a consequence, group delay is typically higher in ported models"

Higher group delay means slower which is not optimal for music.

 

[ski2xblack]

Higher group delay means slower which is not optimal for music.

Sure, if it is occurring at frequencies of musical content. Some of the more ginormous ported subs manage to push this group delay down into subsonic frequencies where it's simply not a big deal. (I personally don't care if T-Rex's foot falls are half a cycle off.)

 

[Assumer]

Wow. Thanks for the info.

 

[shadyJ]

Please read: http://www.audioholics.com/loudspeaker-design/sealed-vs-ported-subwoofers


"While not all sealed subwoofers are created equal, properly done the alignment has a lot to offer. Size is typically manageable; the earlier pictured SB13-Ultra is effectively a 17.5” cube, giving it a lot of flexibility in placement as well as a high SAF (spouse acceptance factor). While small size tends to come at the expense of extension, sealed subwoofers generally have a shallow low-end roll-off profile, which corresponds with good performance in the time domain (i.e. group delay / ringing). Last but not least, sealed subwoofers offer some degree of protection against bottoming out the driver, though it is still possible with sufficient power and the right content

"However, below the tuning frequency, the driver is no longer loaded by the enclosure, and acts as if it is in free air. This results in a much steeper roll off rate of 24dB/octave relative to the 12dB/octave slope typical of sealed subwoofers; as a consequence, group delay is typically higher in ported models"

Higher group delay means slower which is not optimal for music.

In any competently designed ported sub, the group delay will not be audible. The group delay must be higher than at least 1.5 cycles. In low bass below 30 Hz, group delay is not likely to be audible even well beyond 1.5 cycles. And, like ski2xblack says, in any competently designed ported sub, group delay will definitely not be any worse in the music ranges than that of a sealed sub.

 

[Auditor55]

Personally, I own sealed subs do to my living arrangement, don't have lot of room for big ported box. I don't have a dedicated theater room. If I did I probably would own ported subs. I have more of a multi-media room, where I listen to music at least 60/40 percentage over movies. I like the deep bass, room shaking and output ported subs give you for movies.

 

[3db]

I dunno. I would pit my Rythmik ported sub against any sealed sub in terms of articulate bass and u would be very impressed with it's quality of bass.

 

[Auditor55]

Sure, if it is occurring at frequencies of musical content. Some of the more ginormous ported subs manage to push this group delay down into subsonic frequencies where it's simply not a big deal. (I personally don't care if T-Rex's foot falls are half a cycle off.)

If the focus is critical listening, we would not be concerned T-Rex foot stomp in Jurassic Park because movie watching is not about critical listening, music is.

 

[fmw]

If the focus is critical listening, we would not be concerned T-Rex foot stomp in Jurassic Park because movie watching is not about critical listening, music is.

I don't understand the concept of critical listening as defined by audiophiles. To me critical listening would be the process of criticizing a musical performance for its good and bad characteristics. When I listen to music I don't do it critically unless someone asks me to. I just listen for the pleasure of hearing music.

Back in my high end audio days, I once had my piano coach over for dinner. After dinner I put some piano music on my high end system and played some his favorite kinds of music. I wondered what he thought about the the sound of the system so I asked him what he thought. He said he liked the way the pianist played the left hand arpeggios. He was involved in critical listening.

 

[shadyJ]

I don't understand the concept of critical listening as defined by audiophiles. To me critical listening would be the process of criticizing a musical performance for its good and bad characteristics. When I listen to music I don't do it critically unless someone asks me to. I just listen for the pleasure of hearing music.

Back in my high end audio days, I once had my piano coach over for dinner. After dinner I put some piano music on my high end system and played some his favorite kinds of music. I wondered what he thought about the the sound of the system so I asked him what he thought. He said he liked the way the pianist played the left hand arpeggios. He was involved in critical listening.

Bingo, and this nicely illustrates where someone is listening to their system as opposed to where someone is listening to the performance. If you are listening to your system, than this is just a technical hobby. Music lovers pay attention to the performance. All the notes will come through, even in a modest system. Probably a lot of us here are a bit of both. I like the sound capability of a nice beefy audio system, but if I am captivated by a piece of music, I don't think about the system its being played on.

 

[Auditor55]

I don't understand the concept of critical listening as defined by audiophiles. To me critical listening would be the process of criticizing a musical performance for its good and bad characteristics. When I listen to music I don't do it critically unless someone asks me to. I just listen for the pleasure of hearing music.

Back in my high end audio days, I once had my piano coach over for dinner. After dinner I put some piano music on my high end system and played some his favorite kinds of music. I wondered what he thought about the the sound of the system so I asked him what he thought. He said he liked the way the pianist played the left hand arpeggios. He was involved in critical listening.

Critical listening was probably not the best use of words here. When I say critical listening I really mean content that require hearing only (music) without the distraction of video (movies). I didn't mean it in exactly the way audiophiles do.

 

[fmw]

Fair enough.

 

[Klipschhead302]

I like the sound capability of a nice beefy audio system, but if I am captivated by a piece of music, I don't think about the system its being played on.

I agree except when listening on and I may get flak for this, but going to my brothers house where he insists on buying from the Walmart bargain bin (not because he has to) and then invites me over to hear his awesome RCA and Bose acoustimas "Audiophile" system only to hear the poor bass module trying hopelessly keep up with the music he is playing... actually causing headaches.

He has amassed a large quantity of these systems into one huge... mess that even his wife hates to listen to. It's that bad, I don't know about any of you, but to listen to a system that everything sounds horrid on, is torture that would be best used against ISIS.