Why are sealed box woofers out of fashion

Out of fashion with who?

Sealed box may not be very common among commercial hifi speakers... and it is rather uncommon among commercial professional monitors.

But it is much more commonly found in custom designed listening rooms and studios. It is definitely common among active designs.

For a given woofer Vd (cone area x linear excursion), and all else being equal, a vented box system has 3 dB more SPL capability than does a sealed box system. On the other hand, the sealed box system almost always has a smaller cabinet volume, often half the volume. The vented box system will have a lower F3 point, but the F9 point of both systems will usually be about the same.

When you are building speakers to sell to the public, specs matter a lot, and an F3 of 39 Hz (vented) is more impressive than an F3 of 51 Hz (sealed) in advertising. Price matters a lot also... For a given F3 and SPL target, a vented box is probably the least expensive way to achieve the spec.

j.
 
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Err, the gain with ported systems is somewhat more than 3dB. The cone excursion, which is the dominant factor for the low frequencies is dramatically reduced on fb, with minor excursion peaks at lower and higher frequencies. This results in gains of easily more than 6dB max SPL on fb. WinISD and Basta!-sims give quite reliable examples on this, if you’d like to check.
 
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Maybe the thread title refers to woofers with parameters better suited to sealed vs. vented. I do find that most woofers from the usual suppliers tend to be targeted at vented boxes but my research is not exhaustive. I have a pair of Eton 8-412 woofers that are great in sealed designs. The list of suitable drivers was not a long list.
 
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Err, the gain with ported systems is somewhat more than 3dB. The cone excursion, which is the dominant factor for the low frequencies is dramatically reduced on fb, with minor excursion peaks at lower and higher frequencies. This results in gains of easily more than 6dB max SPL on fb.

Yeah, I just checked 3 different woofers in VituixCad, all of them with Qts in the 0.3 to 0.38 range so that they could be plausibly used in either a sealed box or vented. Yep, about 6 dB advantage to the vented boxes. This is assuming that one could fit the very large vents that some of these systems would require in order to remain linear at Xmax.

I'm not sure how I got confused about this. I know that in most cases, 2 woofers in a sealed box with LT eq can give the same SPL as a single woofer in a vented box... somehow my brain did a shortcut to equate that to 3 dB rather than 6 dB. Sorry for any confusion I caused.
 
The big advantage of sealed woofers is that the box can be used to create a more uniform spring than the normal spider surround mechanics of a woofer. This is the "acoustic suspension" of the AR, KLH and Advent speakers. Most modern woofers have very low compliance, and are excursion limited by the suspension. As stated by soundchaser, the manufacturers have gravitated to woofers designed primarily for vented or "dual purpose" applications. There are currently no woofers designed exclusively for sealed applications.
 
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could you show us your design with the eton ? have you got a thread about it on here ? I like sealed designs better and find it a bit frustrating there seems to be an imbalance with most drivers aimed towards vented
It's nothing extraordinary.

A DXF file is attached for the box.

Nearfield response (bass only) looks like this. probably about 18+20dB higher than what it actually is. I have a baffle step at 400Hz or so. Crossover is DSP.
1715648150592.png
 

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The big advantage of sealed woofers is that the box can be used to create a more uniform spring than the normal spider surround mechanics of a woofer. This is the "acoustic suspension" of the AR, KLH and Advent speakers. Most modern woofers have very low compliance, and are excursion limited by the suspension. As stated by soundchaser, the manufacturers have gravitated to woofers designed primarily for vented or "dual purpose" applications. There are currently no woofers designed exclusively for sealed applications.
Changes in temperature and barometric pressure with a sealed box driver leads to coil offsets. Coil heating in the box, can also lead to an offset.

Drivers are mass limited on their upper corner, ( also inductance ) suspension limited on their low corner. Weak motors and soft suspensions are capable of wider bandwidth, but can exhibit issues with high power inputs.
 
Yeah, I just checked 3 different woofers in VituixCad, all of them with Qts in the 0.3 to 0.38 range so that they could be plausibly used in either a sealed box or vented. Yep, about 6 dB advantage to the vented boxes. This is assuming that one could fit the very large vents that some of these systems would require in order to remain linear at Xmax.

I'm not sure how I got confused about this. I know that in most cases, 2 woofers in a sealed box with LT eq can give the same SPL as a single woofer in a vented box... somehow my brain did a shortcut to equate that to 3 dB rather than 6 dB. Sorry for any confusion I caused.
I’m going out on a limb here but I think sealed or vented or whatever can be equally efficient. BR enclosures can often reach lower than AS but that’s because of the system, the drivers themselves have various efficiencies. There can be inefficient BR systems and efficient AS systems. Bass response is also dependent on the design. I make sealed systems that reach to 35 hz and are 89db efficient. That’s better than many vented systems. Having said that, most pro audio systems are vented systems because high output, high power drivers with stiff suspensions need the vented alignment to get any bass at all. They are loud efficient drivers but I don’t think they reach any lower than an air suspension driver can.

A driver made for BR simply won’t have any bass in a sealed enclosure, I don’t think this has anything to do with efficiency. An AS driver will disintegrate in a vented box and must be output limited. It’s silly to compare the drivers alone, we should be comparing systems.
 
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It’s silly to compare the drivers alone, we should be comparing systems.
yes absolutely.

I'll expand, morning coffee break :)
For example room modes have huge part of perceived bass performance, and as such it's part of playback system. I see two main issues with bass in general: effects of room modes and having enough volume displacement to get enough SPL capability and bandwidth.

If playback system consists of two small bookshelf type speakers there isn't going to be enough bass due to small volume displacement, so it makes a lot of sense to get some more by porting. Hense we see all commercial small speakers having ports (or passive radiator). On the other hand, if there was additional subs in the system to help extend the bandwidth, and help with the room modes, and give extra SPL capability, then the mains might be highpassed so port would be for nothing on the mains. Subs might benefit porting hough, if they are small. But if one got this far the system likely has an EQ and enough volume displacement so porting is not necessary which simplifies things. Can you find these kind of systems from hifi stores? probably not as they are hard to sell them, too hard to setup and too expensive for most, too much cabling, and so on.

In DIY land there is possibilities outside of commercial systems. Ports, or not having one, or any other design feature, comes with trade-offs and it's important to understand what those are and whether they are aligned with goal in mind. Port can make noise and "leak" mids from inside the box, which means extra bass came with possible cost in system midrange fidelity. If goal for the system was high fidelity it makes no sense to sacrifice mids to get bass, right? To be aligned with the goal of high fidelity any and all trade-offs need to be outside of audio, in cost and complexity for example.

So, is there any alternatives to get more SPL and bandwidth for lows than a port? Thinking for a second, wavelength of lows is so long one can get more bass just by adding more bass sources into the room. More sources can help even out effect of the room modes and increase volume displacement so SPL and bandwidth. Basically add few subs in addition to mains, to avoid ports. Where is the trade-off then? in cost and complexity mostly, which is nicely aligned with the goal for high fidelity. Bass system is now relatively independent of mains, which now can be optimized for mids and highs separately. It doesn't have to be subs, it could be just more volume displacement on mains, a three way mains with big bass woofer instead of a two way for example, but this doesn't necessarily help with room modes, unless it's gradient pattern system, which needs even more volume displacement.

If goal was to get some sound cheaply instead of absolutely high fidelity, then smaller and ported speaker system would be better suited no question.

So, it's important to have a goal for a playback system. The more one is into audio quality the more important system thinking becomes. One could include the music collection, "sound ideal", auditory system, the room, the aesthetics, everything, even cost and complexity to maintain realistic, but thorough, goal for a system. Power in DIY is the ability to tailor fit, and the system might end up with port, or no port. And, there is no reason to follow fashion, unless goal of the system is to satisfy ego.
 
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Well that is an adequate summary. Any design should start with reasonably accurate (global) goals, keeping an eye on room for improvement on details. Put otherwise, don’t let (possibly irrelevant) details get in your way, especially if they aren’t set in the bigger picture.