IME/IMO one of the advantages of a ported design is that they are often easier to drive and are less affected by box coloration.
Sealed enclosures have to be a lot more dead to deal with the compression forces inside the box.
BTW, passive driver systems are a form of ported enclosure. |
The total design is what maters not if its ported or not. |
Mordante- No they are not. |
Just curious is a acoustic suspended speaker the same as acoutic vented?
Not to sure but I think there have been some speakers that use a closed mid/high cabinet and a vented (sub)woofer. |
Several years ago I experimented with sealed and ported versions of a monitor speaker designed to be used with a sub. In other words, I was focusing on the midrange performance only; the low end didn't matter. I arranged a simple blind listening test (double-blind isn't necessary; it's okay if I know which speaker is playing). To my surprise, the ported speaker was consistently judged to have more natural-sounding midrange. This wasn't what I expected. Rear-firing port, flared inside and out.
Turning now to the low end, I've worked with both types (as well as other technologies) in the course of subwoofer development. It's all just too complicated for me to make a blanket statement that one type is better than the other in the low end. So many variables at play - room size and anticipated speaker placement, enclosure size and efficiency constraints, SPL and low-end extension requirements, whether or not EQ was available, and last but not least, budget. In the end I decided to offer both sealed and ported subs, and try to match them to the specific situation.
The way I sometimes tune a vented bass system is somewhat counter-intuitive; I'll tune it a lot lower than normal, so that it has a slower rolloff than even a very low-Q sealed box across most of the bass spectrum. Of course the rolloff accelerates rapidly below the tuning frequency, but if it's low enough, who cares. If possible, I want the tuning frequency below the claimed passband of the system. Here's why: As notes close to the tuning frequency decay, their energy spectrum actually shifts *towards* the tuning frequency. Obviously that's not a good thing for pitch definition. But this detimental effect is not inevitable! If we design the system so that the tuning frequency is low enough we can minimize this effect, and therefore imo a good vented box can have pitch definition just as good as a good sealed box.
Clio9 mentions the user-adjustable tuning that I incorporate into many of my designs, and I'd say that roughly half of my customers have ended up using a different tuning frequency from what the speakers were shipped with. Either I'm a remarkably lousy designer, or there's enough variation from one system/room situation to another that some ability to tailor the low end is often useful. In many cases, it's possible to improvise a way to lower the tuning frequency of a vented system. In my opinion, this is one advantage of a vented system over a sealed one.
Duke
dealer/manufacturer/possible lousy designer |
There are true transmission lines and "quasi" transmission lines. |
I think of transmission line speakers are a good idea in the "ported" camp and wonder why there's not more of that sort of thing.
They are a good idea. I think the reason you don't see more of them is that their more complicated internal structure makes them more more expensive to build and heavier to ship than a typical braced and ported tower. |
...and then there are speakers that can work both ways. Example, Audiokinesis. Mine have port adjustable tuning (you can tilt or shelf the top end as well) and the ability to seal the port if desired. |
PMC Makes well regarded transmission line speakers that include a bookshelf model, and they aren't so large, and the insanely popular Bose radios are nothing but plastic boxes with a couple of cheap drivers loaded with transmission lines...a concept Bose laughingly claims to have invented. I also had "woofer pumping" issues when I re-introduced my LPs to my system, and that was remedied first with a pair of Nakamichi line filters, and then with the subsonic rolloff switch when I bought a Cambridge 640P...a feature most phono preamps don't seem to have. |
One thing I noticed when I had a pair of ported speakers was the extreme "woofer pumping" during analog playback. I know this can have a lot to do with cartridge/arm matching and isolation issues, but this wasn't as evident with my sealed box speakers. |
Wolf, a true transmission line tends to be rater huge. |
What Brownsfan said. I've owned a plethora of monitors and sealed was the deal. Now I have some Penaudio Cenya monitors and they are ported and sweet. Nicer than my Merlin MME monitors. |
Magicos seem to be the primary example of modern sealed design, but they're so expensive they sort of have their own little world most mortals can't enter. Also, some designs have a port with a passive speaker plugging it up to aid in efficiency and halt the dreaded "port chuff" that I personally haven't ever noticed, but then I don't stick my head near the port very often (unless, unfortunately, I've passed out on the floor behind my speakers). I think of transmission line speakers are a good idea in the "ported" camp and wonder why there's not more of that sort of thing. |
Sealed enclosures used to dominate high end speakers; ported speakers were often dismissed as "frat boy" speakers. However, over time things reversed.
Sealed enclosures may roll off at a gentler 6 dB/octave, but they start rolling off at a higher frequency than a properly tuned ported speaker of similar size. For a small tower, a sealed enclosure starts rolling off at 100 Hz. A ported one is more likely to be flat to 45-50 Hz, which translates into a *much* more realistic tonal balance as it's linear down to the bottom fundamental of a kick drum or bass guitar.
I had a pair of ADS L1090's, a small tower with twin 7-1/2" woofers in a sealed enclosure. For being about 40" tall with twin woofers and as much as it cost me, it sure didn't have much bass. I replaced the L1090's with a pair of Mirage M5si's with dual 6-1/2" woofers and two large diameter ports. It was linear to the mid-30s with clearly audible bass down to the mid-20's. There was no "one not bass," no boominess. Bass is clean, tight, and full.
I also have a pair of petite Mirage floorstanders, the OMD-15. It doesn't have the bass output of the M5si, but it still smokes the L1090 in tonal balance and bass extension. And ports and all, it gives up nothing to the ADS in bass tightness and clarity.
Another cool thing about ported speakers is that you have more ways to match the speaker to the room. Wilson's new Alexandria XLF is made so you can direct the port to the front or the rear. Monitor Audio and PSB both offer several twin-ported models with foam plugs so you can damp the bass alignment four different ways. I used to view ported speakers with disdain, but not anymore. Once designers figured out how to get the bass extension while damping the resonant frequency, you got more and better bass in a smaller enclosure for less money. |
Not many sealed (acoustic suspension) speakers around nowadays. Maybe because manufacturers want specs to sell, maybe because there's a limited amount of drivers available and suitable for sealed enclosures (higher Q drivers relying on the lower Q of the cabinet). Examples of older speakers that were sealed were Dunlavy, Hales and Infinity/Genesis (except for the dipoles). Looking at those names, you might say it's a failed business approach but that's not the why. NHT is still committed to that design.
Every now and then, I still run across an opinion, even one as experienced and respected as Siegfried Linkwitz, that's derogatory to anything other than dipole or sealed, espescially for subwoofers. Everyone is entitled to an opinion, even husbands on occasion. Some have reasons.
Myself, having just built a pair of DIY speakers, chose sealed because of the transient response, being able to fit twice the number of drivers in the same cabinet volume and some forgiveness in the design. Sure, it gives up some deep bass extension but that's what subwoofers are for. Historically, quickly becoming ancient history, I've generally preferred sealed. Still say quality over quantity but not so arrogant to say they're mutually exclusive. There's always a compromise.
For example, let's say the next project is a sub or two. If I want "fast", I could choose a smaller, lighter 10" but in a sealed box that might have an F3 (-3dB) of 40Hz (hardly my idea of a sub). With a port, transmission line or passive radiator, the same driver can be tuned down to the 20's. Or, you start getting bigger, dropping efficiency, adding servo feedback...
Typical snides about ports include "chuffing", time and phase distortions and "wicked, nasty" driver excursion. Even an old fart has to concede something to modern manufacturing techniques, relatively accurate Thiele/Small parameters and the progress of science, albeit sideways, other ways and otherwise. |
One other wrinkle:
There are variations on sealed boxes. Those designs which limit internal cabinet volume relative to maximum driver displacement (usually called "acoustic suspension" speakers) damp the driver's movement to a greater degree than those which use a larger volume box relative to max driver displacement (generally "infinite baffle" speakers).
Caveat: As far as I can tell, these terms are used somewhat imprecisely in audio writing, so you've got to be careful about written descriptions. The less damped infinite baffle designs generally sit somewhere between ported designs and acoustic suspension designs in regard to tight bass, but...
Not all ported designs are created equal, either. Some (Merlin and Ref 3a come to mind) sound (to my ear, anyway) like they're more highly damped than others. That makes it even harder to compare/contrast the two approaches.
In the end, I believe that generalizations are often of limited utility when trying to pin specific qualities back to broad design criteria like "ported" vs. "sealed" speakers.
Marty |
I read an article a few years back that said ported speakers have more bass output but roll off quickly where a sealed enclosure goes down a bit lower (with a smoother rolloff) but has a bit less output.
Based on this information I wonder why more companies do not make sealed enclosure speakers (even if they are a bit less efficient) as it seems sealed enclosures would work in more rooms as well. |
IMHO, in the simplest terms:
Ports can offer better value.
Sealed speakers can offer better performance. |
The only thing that I haven't seen mentioned is that as woofers are used over time, their spec do change. Getting port tuning correct is more critical than the spec's straying a bit for a sealed box. So Sealed boxes tend to stay sounding as designed longer than a ported box.
Tim |
The Sonus Faber Stradivari is WAY more than $20k, and it is ported. The $200k Wilson Alexandria speakers are ported, as are Audionote speakers, Classica Audio, and a host of others. There are plenty of sealed box speakers under $100 a pair.
It is not hard to design and build speakers that are either ported or sealed, so cost is irrelevant. |
It depend on how much you enjoy the sound of the port. |
4 of 5 pair of speakers I run are ported.
In order (largest to smallest):
OHM Walshes: bottom port
Dynaudio monitors: rear port
Triangle monitors: front port
Realistic Minimus 7s: no port
They are all very good, within their specific limits. Performance levels achievable happen to correspond directly to the relative size. |
No speaker design is inherently inferior to any other. It just depends on how well a particular design is implemented, and if the music played on it is appropriate for that design.
That being said, I do like rear ported speakers better than front ported speakers. (no snide remarks on my masculinity now, or my fondness for sheep, please) |
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What are the pros & cons of sealed and ported speakers?
(The port can be used to increase efficiency or extend the low frequency response but not both at the same time. The response drops at 12db per octave below the cutoff whereas a sealed speaker drops 6db per octave below cutoff. Sealed speakers will inherently offer a tighter, better defined bass note than a comparable ported speaker. However, design, materials, and implementation will offer benefits and trade-offs for either design.)
Why are the most expensive types of speakers sealed?
(They are not. Wilsons are ported, Magico's are sealed as two prominent examples.)
Are there any $20k and up ported speakers?
(See above.)
(I have both types of speakers, but overall I prefer the sealed box speakers of which I have three pairs.)
(I always liked the description of the port as a resonating column of air no longer directly controlled by the woofer)
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What are the pros & cons of sealed and ported speakers?
Why are the most expensive types of speakers sealed?
Are there any $20k and up ported speakers?
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"Are ported speakers inherently inferior to sealed speakers?"
No.
Like most things, it all depends the devil is in the details. Generalized conclusions will generate debate but not hold water in all cases. The best/right speaker in any particular case may be ported or not.
The key value of porting is to extend bass extension in a smaller cabinet than otherwise. If that does not matter in a particular case, then there is no reason to go for a ported speaker but expect a bigger product and additional cost to achieve similar results with low end extension if needed. Room acoustics play a big part in regards to what will sound best. |
Ported speaker designs are not inherently inferior.
Perhaps you should have phrased your question "what are the pros and cons of ported vs. sealed designs?" |
For what its worth, here is the perspective of a die hard planar guy. Back in the 70's and 80's, I would have answered this with an emphatic yes. Based on some fairly extensive listening of current designs, it appears to me that the question should be answered no. I was very pleasantly surprised by the sound from a number of ported designs. I think the current ability to use computers in cabinet designs has allowed the capability of ported designs to match that of sealed designs. At this point, I think its not the design approach per se, it's the execution that matters. |
