Why Are Ported Speakers the Dominant Design?

[Ron Texas]

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.

 

[dc655321]

Much like sex, bass sells.
And even when not of particularly good quality, abundant quantity is still not a bad thing.

Joking aside, I think there is an analogy to be made here.
My hypothesis:
Similar to the way that an otherwise identical, but slightly louder system sounds "better", a greater depth of bass reproduction may also be perceived as "better". This may in fact constitute a louder system, so perhaps it's the same mechanism.

 

[Frank Dernie]

A cheaper and smaller way to get a given bass roll off -6dB point.

 

[Matias]

MOAR BASS MOAR BETTAR!!!

 

[pozz]

Many don't like the quick decays of sealed cabinets.

I don't know if bass reflex cabinets are actually cheaper given all the work hours speaker tuning them and dealing with leakages.

 

[KozmoNaut]

Most people want good low-frequency response, and they also want speakers that aren't huge.

Ported speakers solve that problem, with good efficiency as a bonus, which let's people drive them from smaller amps.

Ported speakers can sound extremely good, unless you believe most speaker manufacturers don't know what they're doing, and don't care about sound quality.

 

[audiophool]

Ported is generally superior to sealed for music sound quality. Higher efficiency, lower distortion, and/or higher output. None of the measurable advantages of sealed are audible compared to a properly designed port. Advantage of sealed is a smaller box or when you want extremely deep extension in small room.

 

[Blumlein 88]

The reason for the change was during the 70's the Thiel-Small parameters became widely known. So you could make decisions about cabinet size and your given drivers to make ported speakers that worked pretty well. Before that it was mainly rules of thumb and ported speakers were hit and miss. You can have a trade off with ports of same extension smaller cabinet, greater extension same cabinet, or greater efficiency with in between cabinet size. (this is over-simplified a bit).

 

[Blumlein 88]

Ported is generally superior to sealed for music sound quality. Higher efficiency, lower distortion, and higher output. None of the measurable advantages of sealed are audible compared to a properly designed port. Advantage of sealed is a smaller box or when you want extremely deep extension in small room.

I think much of this is mixed up here.

Sealed boxes for same extension and efficiency are larger.

 

[Ron Texas]

@Blumlein 88 you have hit upon an important part of the history of speaker design.

 

[q3cpma]

I used to think that it was only for MOAR SPL, but seeing that the cream of Genelec, Neumann, Psi (etc...) use it with success, I think it can be done without compromising other parts as long as enough research is put into it.

 

[Patrick1958]

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.

The same reason you don't see much transmission line concept = big cabinets/

 

[Ron Texas]

The same reason you don't see much transmission line concept = big cabinets/

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.

 

[Soniclife]

The reason for the change was during the 70's the Thiel-Small parameters became widely known. So you could make decisions about cabinet size and your given drivers to make ported speakers that worked pretty well. Before that it was mainly rules of thumb and ported speakers were hit and miss. You can have a trade off with ports of same extension smaller cabinet, greater extension same cabinet, or greater efficiency with in between cabinet size. (this is over-simplified a bit).

My perception was it took quite a long time for lots of manufacturers to get good at implementing ports, even after this was available, but these days they really deliver the promised gains.

 

[Blumlein 88]

My perception was it took quite a long time for lots of manufacturers to get good at implementing ports, even after this was available, but these days they really deliver the promised gains.

Thiele had the basic ideas covered in modeling driver parameters as circuits in the early 60's. Small polished and expanded the ideas and provided usable equations in a few AES papers in the early 1970's. It may have taken a little while to come to terms with non-ideal losses in ported designs, but the equations to knock out the designs and measuring the driver parameters became widely known in the 70's. Prior to that it was all rules of thumb and recipe's with hit or miss results founded upon no good explanatory theory. Afterwards, get driver parameters, and a hand calculator or slide rule. You could try out several designs to get a good one and then make adjustments when you built it to fine tune it. In the early 80's I helped people make their own or made a few for use in cars. You had to measure drivers yourself as the spec's weren't reliable. Do that leave some wiggle room in port sizing, and you got pretty good reliable results. Shoot for a Q of 1.1 or 1.2 in small cabs, and .8 or .7 in larger ones. Some makers due to marketing wanted too much and too undamped bass. They also cheaped out on cabinet strength and didn't always make sure there were no leaks. Getting really good results wasn't a problem if you dotted i's and crossed t's.

 

[suttondesign]

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.

 

[Blumlein 88]

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 agree. I prefer sealed if you have to have a box. But they can get pretty darn big if sealed.

 

[Soniclife]

Some makers due to marketing wanted too much and too undamped bass. They also cheaped out on cabinet strength and didn't always make sure there were no leaks.

They were probably making the ones I heard that sounded wrong to me, always difficult to resist the lure of more for less, especially at the bottom of the market. I haven't heard the slow woolly bass boom of a bad port for years.

 

[q3cpma]

I agree. I prefer sealed if you have to have a box. But they can get pretty darn big if sealed.

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

 

[MSNWatch]

I agree. I prefer sealed if you have to have a box. But they can get pretty darn big if sealed.

Or use a smaller box with a built in sub with gobs of power.