Why Are Ported Speakers the Dominant Design?

[Martin]

Siegfried Linkwitz designed open baffle bass, and when equalized, it sounds more natural to me than any box. The difference is not subtle, either. However, the market doesn't want to go this way, presumably because it's more complicated. I am agnostic as between sealed and ported speakers; seems like the implementation quality is the key.

I had the privilege to hear his Orion speakers at an RMAF about a decade ago. 4 amplifiers per speaker and active signal processing / crossovers. They were the best sounding speakers I have ever heard. Pretty amazing.

https://linkwitzlab.com/orion-rev4.htm

Martin

 

[Ron Texas]

The KH310 isn't that big, though. I guess that you can always compensate with more power.

Is the KH310 sealed? $2200 each at Sweetwater, plus sales tax in some states.

 

[pozz]

Is the KH310 sealed? $2200 each at Sweetwater, plus sales tax in some states.

It is. And the measurements are excellent as well, although it's designed for one-seat control room monitoring.

 

[JeffGB]

I've always preferred the sound of a sealed woofer. I believe the ported systems are mostly used to increase efficiency. A sealed woofer can be in a very small enclosure, however the laws of physics would dictate that the resonant frequency of the driver be very low, with a relatively high Qts. That was the big improvement provided by Edgar Vilchur of AR fame, and called "air suspension" due to the very weak mechanical suspension used to provide the low resonant frequency of the driver and the air "suspension" of the sealed box. The combination gave strong, clean bass in a small cabinet. The trade off was efficiency because the mass of the cone needed to be relatively high. Listen to a good pair of AR-3a's or original Advent's to get a full measure of the bass quality.

I still prefer the bass of the LS3/5a over that of the LS-50. The LS-50 goes much louder and has lots of punch, but the very low frequencies are missing by comparison. I bottomed out the LS3/5a more times than I care to remember though, and not at high volumes.

 

[pozz]

Has anyone ever heard the sealed Benchmark SMS1 speakers? I'd like to pick those up one day for a listen.

 

[splattened]

I was wondering this myself. The Klipsch Heresy IV will be released soon and will be ported after decades of a sealed design. I'd love to know the thought process behind the change.

The criticism I read of ported design is that it "smears" the bass and can be boomy/woolly/undefined/insert adjective here. Of course like most things in audio, this is often accompanied by a brief, vague, yet plausible explanation as to why that is the case and a novice like me going "Sure I guess." If that is indeed true of ported speakers, then I wonder why Klipsch would adopt it for the Heresy line which is well known for its tight and well-defined bass even though the extension is limited (-4 db at 58 Hz).

All I know is I had to plug the ports on the last pair of rear-ported bookshelf speakers I owned because it caused a large spike in the 80-100 Hz range, so I wasn't getting the benefit of the ports anyway. Whatever they're good for, they seem to exacerbate the problem of speaker placement and room interaction which was by far the most difficult problem for me to solve in my current room. It made me wish there were more sealed options out there.

 

[Zog]

Back in the 70's I recall most speakers were sealed boxes. Today the vast majority are ported, except for subwoofers where sealed boxes compete with reflex designs. Offhand, the BBC mini monitor replicas are sealed and so are the expensive Magico line. There are also passive radiator designs. While there are not that many, they are a bit more mainstream with speakers from KEF and Goldenear, among others.

My personal hunch is ported speakers can be built with smaller cabinets, and cabinets are expensive. Likewise, a passive radiator costs more than drilling a hole in the box.

I have the Magico A3s. They have better bass than my previous speakers despite them not being ported, less sensitive, and smaller. They are 70 liters compared with Triangle Magellan's 170 liters. I guess there are other variables in play, such as the mass of the drivers, but that is one example.

 

[Ilkless]

Has anyone ever heard the sealed Benchmark SMS1 speakers? I'd like to pick those up one day for a listen.

https://cdn.shopify.com/s/files/1/0321/7609/files/HFN_Benchmark_SMS1.pdf

Specs are uncharacteristically bad for Benchmark. It's OEM'd by Studio Electric.

 

[Wombat]

I've always preferred the sound of a sealed woofer. I believe the ported systems are mostly used to increase efficiency. A sealed woofer can be in a very small enclosure, however the laws of physics would dictate that the resonant frequency of the driver be very low, with a relatively high Qts. That was the big improvement provided by Edgar Vilchur of AR fame, and called "air suspension" due to the very weak mechanical suspension used to provide the low resonant frequency of the driver and the air "suspension" of the sealed box. The combination gave strong, clean bass in a small cabinet. The trade off was efficiency because the mass of the cone needed to be relatively high. Listen to a good pair of AR-3a's or original Advent's to get a full measure of the bass quality.

I still prefer the bass of the LS3/5a over that of the LS-50. The LS-50 goes much louder and has lots of punch, but the very low frequencies are missing by comparison. I bottomed out the LS3/5a more times than I care to remember though, and not at high volumes.

LS3/5A Design Paper LF -3dB point ~100Hz.

 

[Sal1950]

Transmission line cabinets are complex woodwork, aside from being large. Somewhere I read a passive radiator behaves the same way, but I really don't know what that behavior is.

Or horn bass cabinets, the mouth has to be huge to dig deep.
IMO that would be the best, if you had the room

Some ones been reading this months Stereophile Art Dudley's - Listening

 

[Wombat]

General LF response comparison:

 

[Wombat]

Or horn bass cabinets, the mouth has to be huge to dig deep.
IMO they would be the best, if you had the room

Especially if the horns aren't folded - takes a big room.

 

[Cosmik]

The criticism I read of ported design is that it "smears" the bass and can be boomy/woolly/undefined/insert adjective here. Of course like most things in audio, this is often accompanied by a brief, vague, yet plausible explanation as to why that is the case

I would be biased the other way round: asking the question why wouldn't it be like that? I am adding on a mechanical resonator. The unkind way to think about it is as a 'rumble hole'. The aim is to build up a resonance at a particular frequency. It changes the signal in the time domain, needing time to build up and time to die away - if it doesn't do those things it doesn't work. It isn't a miracle; it isn't a free lunch.

 

[Sal1950]

Especially if the horns aren't folded - takes a big room.

I remember seeing come custom builts where the driver was in the basement and horn mouth led up to open into a whole wall like 15'w X 10'h

 

[Blumlein 88]

I remember seeing come custom builts where the driver was in the basement and horn mouth led up to open into a whole wall like 15'w X 10'h

Like this subwoofer built/cast into the basement.

Or these lesser attempts. I helped someone mount one like this in an attic where it vented into the theater room via the soffit.

 

[Sal1950]

Now that's a bass system!

 

[sfdoddsy]

I had the privilege to hear his Orion speakers at an RMAF about a decade ago. 4 amplifiers per speaker and active signal processing / crossovers. They were the best sounding speakers I have ever heard. Pretty amazing.

https://linkwitzlab.com/orion-rev4.htm

Martin

I owned (slightly-tweaked) Orions for over ten years, and have owned variations on the theme ever since then.

IMHO, although dipole bass is difficult to achieve at sensible volumes it is better in-room than sealed/ported monopole bass.

However, if you EQ the sealed bass (both for extension and for room EQ) the dipole advantage diminishes so much the hassle of doing it becomes debatable.

Basically dipole bass requires four times the equivalent driver area as sealed bass does.

I used to be a dipole purist, but after spending years bottoming out dual long-throw 12 inches per side, I now cross to sealed bass drivers with EQ.

 

[Wombat]

I would be biased the other way round: asking the question why wouldn't it be like that? I am adding on a mechanical resonator. The unkind way to think about it is as a 'rumble hole'. The aim is to build up a resonance at a particular frequency. It changes the signal in the time domain, needing time to build up and time to die away - if it doesn't do those things it doesn't work. It isn't a miracle; it isn't a free lunch.

So you don't understand 'controlled-resonance'?

Don't ask me for an explanation in a forum post. Just to say it is fundamental in the field of Control Systems. Google search brings up hits but which are worthwhile?

 

[Cosmik]

So you don't understand 'controlled-resonance'?

Don't ask me for an explanation in a forum post. Just to say it is fundamental in the field of Control Systems. Google search brings up hits but which are worthwhile?

If you control it to the point it does nothing bad, it does nothing good, either.

 

[Wombat]

If you control it to the point it does nothing bad, it does nothing good, either.

Come again!