Some thoughts on the ported vs sealed debate

[Steve81]

This is a copy/paste of some thoughts I posted over at ASR, with some additional detail.

This experience is derived from my ownership of the SVS PB13U and later the Funk 18.0 (and later addition of the 21.0LX).

In my room, I measured that when set to sealed mode, the PB13 essentially achieved a flat response down to the (admittedly limited) limits of my Omnimic. This result caused me to pursue sealed subs for further applications.

I decided to purchase a Funk 18.0 subwoofer, with the expectation that I might loose a little something in the low end, but should net me a little more infrasonic output. After calibration, I felt that the Funk sub was markedly superior to the PB13.

My explanation for this is fairly straightforward. Content is typically dominated, not by material at 20Hz, but by material in the 40-80Hz spectrum. Here, the Funk has a significant advantage thanks to a more efficient driver and more power from the amplifier. Where this content might cause the PB13’s amp to run out of steam, the Funk is happily cruising along. I believe Mark Seaton of Seaton Sound observed the same effect in talks I’ve had with him, which explains why he designed the Submersive exactly the way he did, and consequently why it was so highly regarded.

While it is possible to design a ported subwoofer that can achieve such sensitivity in the upper band, and gain the efficiency advantage of a vented design around port tune, the resulting subwoofer would be quite large. See Funk’s Ultra LFE as an example (happily he provided the dog for scale), and ask if you can support that in your theater?

 

[TLS Guy]

This is a copy/paste of some thoughts I posted over at ASR, with some additional detail.

This experience is derived from my ownership of the SVS PB13U and later the Funk 18.0 (and later addition of the 21.0LX).

In my room, I measured that when set to sealed mode, the PB13 essentially achieved a flat response down to the (admittedly limited) limits of my Omnimic. This result caused me to pursue sealed subs for further applications.

I decided to purchase a Funk 18.0 subwoofer, with the expectation that I might loose a little something in the low end, but should net me a little more infrasonic output. After calibration, I felt that the Funk sub was markedly superior to the PB13.

My explanation for this is fairly straightforward. Content is typically dominated, not by material at 20Hz, but by material in the 40-80Hz spectrum. Here, the Funk has a significant advantage thanks to a more efficient driver and more power from the amplifier. Where this content might cause the PB13’s amp to run out of steam, the Funk is happily cruising along. I believe Mark Seaton of Seaton Sound observed the same effect in talks I’ve had with him, which explains why he designed the Submersive exactly the way he did, and consequently why it was so highly regarded.

While it is possible to design a ported subwoofer that can achieve such sensitivity in the upper band, and gain the efficiency advantage of a vented design around port tune, the resulting subwoofer would be quite large. See Funk’s Ultra LFE as an example (happily he provided the dog for scale), and ask if you can support that in your theater?

We have had this debate again and again. Sealed subs have a high F3, but they can and are equalized. Usually a sealed sub will have a native F3 around 40 Hz give or take a few Hz. The power required to equalize this is 12db per octave. Every 3db of eq. doubles to power drive from the amp.

So this makes it more expensive as it requires a bigger amp and a driver with a much more powerful motor, and also one that is linear over a much greater excursion.

A ported sub is much more efficient, but can not be equalized as the driver decouples from the box. So less lower is required, but a larger box. The driver does not need large excursion as the driver almost stops still in the tuning range, and the output is from the port. A port couples to the room better than a loudspeaker cone.

What it boils down to is that the only advantage of a sealed sub is a smaller box, otherwise it is all downsides.

However the box alignment has to be done with skill. Because of marketers wanting the lowest F3, they usually go for extended bass alignments, which give poorer SQ. I do not do that unless an extended bass alignment models exceptionally well.

I personally favor transmission line designs, as I find they give the best SQ, and the most even distribution throughout the room. The bass is incredibly realistic.

 

[Steve81]

We have had this debate again and again. Sealed subs have a high F3, but they can and are equalized. Usually a sealed sub will have a native F3 around 40 Hz give or take a few Hz. The power required to equalize this is 12db per octave. Every 3db of eq. doubles to power drive from the amp.

So this makes it more expensive as it requires a bigger amp and a driver with a much more powerful motor, and also one that is linear over a much greater excursion.

A ported sub is much more efficient, but can not be equalized as the driver decouples from the box. So less lower is required, but a larger box. The driver does not need large excursion as the driver almost stops still in the tuning range, and the output is from the port. A port couples to the room better than a loudspeaker cone.

What it boils down to is that the only advantage of a sealed sub is a smaller box, otherwise it is all downsides.

However the box alignment has to be done with skill. Because of marketers wanting the lowest F3, they usually go for extended bass alignments, which give poorer SQ. I do not do that unless an extended bass alignment models exceptionally well.

I personally favor transmission line designs, as I find they give the best SQ, and the most even distribution throughout the room. The bass is incredibly realistic.

We're not disagreeing, precisely, Dr. Mark. The smaller box portion, combined with a spectral analysis of content, is the key issue in engineering a proper solution. We want a system that is highly efficient from say 32Hz-80Hz because that's where most of the content is; it makes sense, because commercial theaters can rarely produce much at 20Hz given the auditorium sizes, along with the fact that the general public doesn't have or care to own the large subwoofers necessary to produce 20Hz content efficiently.

An efficient sealed system ala the Submersive gives us the best of both worlds to address things: a relatively compact box (~4.5 cu ft IIRC) and huge efficiency in the requisite bandwidth. It utilized a modified version of the Eminence LAB15 driver; this isn't a cheapo driver by any means, but it's not extremely costly either. It certainly required equalization to give good results in terms of extension in room, but as you say, that's normal. I posit that this isn't an issue. The fact that the Submersive was so vastly more efficient than a subwoofer like the SVS PB13U in utilizing its available amplifier power from 32Hz on up made all the difference in the world. On scenes that would tax the PB13U's amplifier due to its high mass, inefficient driver, the Submersive's amp wouldn't be stressed at all, leaving plenty of power available to account for the equalization necessary to handle the low end.

It's only because of an overly simplistic analysis of CEA2010 data, and a focus on 20Hz, that we got ourselves into this mess. 20Hz is great and all, but it's not really where the content is unless you're running sine waves. That explains why the Submersive got significantly better subjective results than the PB13U, even when both were running a 1kW amplifier (Seaton later upgraded to a 2.4kW model).

 

[TLS Guy]

We're not disagreeing, precisely, Dr. Mark. The smaller box portion, combined with a spectral analysis of content, is the key issue in engineering a proper solution. We want a system that is highly efficient from say 32Hz-80Hz because that's where most of the content is; it makes sense, because commercial theaters can rarely produce much at 20Hz given the auditorium sizes, along with the fact that the general public doesn't have or care to own the large subwoofers necessary to produce 20Hz content efficiently.

An efficient sealed system ala the Submersive gives us the best of both worlds to address things: a relatively compact box (~4.5 cu ft IIRC) and huge efficiency in the requisite bandwidth. It utilized a modified version of the Eminence LAB15 driver; this isn't a cheapo driver by any means, but it's not extremely costly either. It certainly required equalization to give good results in terms of extension in room, but as you say, that's normal. I posit that this isn't an issue. The fact that the Submersive was so vastly more efficient than a subwoofer like the SVS PB13U in utilizing its available amplifier power from 32Hz on up made all the difference in the world. On scenes that would tax the PB13U's amplifier due to its high mass, inefficient driver, the Submersive's amp wouldn't be stressed at all, leaving plenty of power available to account for the equalization necessary to handle the low end.

It's only because of an overly simplistic analysis of CEA2010 data, and a focus on 20Hz, that we got ourselves into this mess. 20Hz is great and all, but it's not really where the content is unless you're running sine waves. That explains why the Submersive got significantly better subjective results than the PB13U, even when both were running a 1kW amplifier (Seaton later upgraded to a 2.4kW model).

There is a law, which says you can have efficiency or bass extension but not both.

If you are content with an F3 just north of 32 Hz, you are correct, but plenty of us lunatics are not.

Your point about movie theaters is correct, to produce 20 Hz in a large theater would be a very complex engineering problem, and therefore costly. So they choose efficiency and spl. over bass extension. However, that in my view is not a good yardstick for home audio enthusiasts. Your claim 0f increased efficiency is illusory.

Lets say we have a sealed sub with a F3 of 40 Hz. That would be typical. So we have a drive of 2 watts. The power required at 20 watts is 32 watts. But at 30 Hz it is about 8 watts. On the other hand the ported enclosure will need 2 watts at 30 Hz and at 20 Hz, if its 3db point is in that neighborhood.

In general the sealed will generally pay are larger penalty, as the heavy motor system and higher Q of the driver will in general make for a less sensitive driver.

If you are happy cutting out the last half octave that is fine. Many people are, as that reproduces most acoustic instruments.

However if you are a pipe organ enthusiast as I am, or a movie buff it is not good enough.

For organs a sub like you suggest would not reproduce the lowest pedal notes of the organ which if you were watching the pedal board would be obvious.

My lines get the job done. But I agree for some 32 Hz may be all they require. As usual one size will not fit all.

Lastly it is important to give equal attention the whole span of the audio spectrum.

 

[TLS Guy]

I have looked at that Eminence driver, and frankly it is a pretty wimpy driver. It is not sensitive, is low excursion and has a highish Fs at 28 Hz.. Sealed its F3 is 64 Hz, to to get to 38 Hz you have to increase to power ten fold to get to 32 Hz, and then you would have to high pass it and cut it off sharp, so as to not blow up the driver. The vented F3 is 31 Hz.

Honestly that is not a driver I would waste my time designing for. It is just plain wimpy. It is not close to meeting my standards.

Talking of standards, movie theaters in general have a much lower SQ all around than my home theater room.

 

[Danzilla31]

This is a copy/paste of some thoughts I posted over at ASR, with some additional detail.

This experience is derived from my ownership of the SVS PB13U and later the Funk 18.0 (and later addition of the 21.0LX).

In my room, I measured that when set to sealed mode, the PB13 essentially achieved a flat response down to the (admittedly limited) limits of my Omnimic. This result caused me to pursue sealed subs for further applications.

I decided to purchase a Funk 18.0 subwoofer, with the expectation that I might loose a little something in the low end, but should net me a little more infrasonic output. After calibration, I felt that the Funk sub was markedly superior to the PB13.

My explanation for this is fairly straightforward. Content is typically dominated, not by material at 20Hz, but by material in the 40-80Hz spectrum. Here, the Funk has a significant advantage thanks to a more efficient driver and more power from the amplifier. Where this content might cause the PB13’s amp to run out of steam, the Funk is happily cruising along. I believe Mark Seaton of Seaton Sound observed the same effect in talks I’ve had with him, which explains why he designed the Submersive exactly the way he did, and consequently why it was so highly regarded.

While it is possible to design a ported subwoofer that can achieve such sensitivity in the upper band, and gain the efficiency advantage of a vented design around port tune, the resulting subwoofer would be quite large. See Funk’s Ultra LFE as an example (happily he provided the dog for scale), and ask if you can support that in your theater?

Man that Funk Ultra LFE looks awesome

 

[Steve81]

Your claim 0f increased efficiency is illusory.

Except that it's not. To get a driver to achieve a lower Fs, typically you add mass to the driver. What is the effect of that? Lower efficiency. You're pushing a heavier object with a permanent magnet and an electromagnet; it necessarily takes more power to the electromagnet do that. No free lunches here.

Data-bass appears to be down, so we'll have to settle for looking at stuff on the webarchive version of it. Let's take the BMS 18N862 8 ohm driver as a pretty good balance of Fs, Mms, and SPL Sensitivity. Those metrics are 29.1Hz, 255.2g, and 93.78dB. In a Josh's sealed text box (4.0cf IIRC), and driven by Josh's beast of an amp, it delivers substantial CEA2010 passing output from 40-125Hz, on the order of 119.8-131.4dB. CEA2010 passing output at 20Hz and 16Hz respectively is 103.8dB and 99.2dB.

Now lets examine another system, built around the TC Sounds LMS-R 12". This is as close to an approximation of the PB13U driver as we're likely to get. Fs, Mms, and SPL Sensitivity are 30.5Hz, 316.8g, and 83.87dB. See the difference in sensitivity already? Josh loaded the TC Sounds unit into a vented box; not sure of its precise volume, but IIRC, it was as large or larger than the 4.0cf sealed test box used for 18" drivers. The box in question had 3 different tunes, 13Hz, 18Hz, and 27Hz. Using the very same amplifier, and the most favorable 18Hz tune, the TC Sounds driver delivers 113.3 - 116.2dB of output from 40-125Hz, and it achieves 109.6dB and 103.3dB at 20Hz and 16Hz respectively.

Starting to see the issue? For a given box size, you can stuff significantly more firepower into a sealed system than you can a vented system. Yeah, the little pee-wee TC-Sounds driver can deliver a bit more output at 20Hz and 16Hz, highlighting what a vented box can do, but we're talking about a very small bandwidth here, and the BMS is hardly choking. Pretty much everywhere else, the BMS is wiping the floor with the LMS-R 12. It's hard to compare costs, given that TC Sounds is long defunct; it certainly wasn't an inexpensive driver at the time, however. It needed a big motor to get the job done. The BMS isn't cheap these days, though a lot of that was the choice to utilize neodymium instead of ferrite magnets.

Looping back to the PB13U and the Submersive, they were reasonably close in size and cost, making it a regular topic of comparison. The PB13U utilized a single 13.5", high mass/low sensitivity driver in a large vented box, and it did pretty well for itself. The Submersive was a different beast. It packed not one, but two high efficiency 15" drivers in a similar volume; right off the bat, that's double the voice coils, and roughly 2.5x the cone area. Is it a wonder the Submersive was deemed the more dynamic subwoofer? Mark never wanted the Submersive measured (as much as I bugged him about it; I was skeptical at the time), so we don't know precisely what it can do. But, given the results of various tests, some blind, conducted over at AVS, it held its own with subs like the mighty JTR Captivator, and was generally preferred to stuff like the SVS.

I have looked at that Eminence driver, and frankly it is a pretty wimpy driver.

Like I said, it was customized. Only Mark Seaton knows exactly what the specs are.

 

[shadyJ]

Both subs have advantages, obviously, so I don't think that one is superior to the other. It depends on the application and tastes of the listener. Most people would be happy with an in-room F3 of 30Hz so long as it has adequate dynamic range to back that extension up. As was said, going deeper than that is for audio enthusiasts. Most commercial theaters do not even have a flat response down to 30Hz. So the average person would much prefer the space savings of a sealed subwoofer over the extra extension of a ported sub, and in that sense, the sealed sub is better, aty lest for them. It takes a true crazy person to want to give up significant room space for deep bass.

But even in terms of extension, sealed can still have an advantage, in medium to small rooms that get pressure vessel gain- so long as the sealed sub is not high-pass filtered to kill off its natural 12dB/octave roll-off. I was recently told about a survey of -in-room responses from a calibrator that showed sealed subs tend to yield deeper extension than ported in-room. However, most home-audio sealed subs use high-pass filters to protect the driver. So, as TLSguy said, you need a beefy driver and decent amp to pull that off, and that means the sub has to be pricier.

I would say if performance is high priority but cost is at all an issue, ported subs are the answer. For this reason, I think most audio enthusiasts who want extension and dynamic range but don't have super-deep pockets are better off with ported- at least if they want serious dynamic range below 30Hz.

I also think that qualitatively, ported subs have an edge, at least for louder levels. The back pressure from the port keeps the driver out of trouble. Yes, ports can produce chuffing, but audible distortion from over-driving a sealed driver would occur sooner than audible artifacts of port turbulence. A lot of audio enthusiasts say that sealed sounds better, but I think this is just from the fact that deep bass does add such a sense of weight to the sound that they think it sounds 'slow.' I am sure that if you EQ'd the responses to be the same, you would see that these guys would have a difficult time telling them apart (so long as the ported sub is properly designed and has a deep tuning frequency, and the sealed design isn't pushed past linear excursion).

 

[Steve81]

Hey James! I was wondering when you'd peek in.

I was recently told about a survey of -in-room responses from a calibrator that showed sealed subs tend to yield deeper extension than ported in-room. However, most home-audio sealed subs use high-pass filters to protect the driver. So, as TLSguy said, you need a beefy driver and decent amp to pull that off, and that means the sub has to be pricier.

I would say if performance is high priority but cost is at all an issue, ported subs are the answer. For this reason, I think most audio enthusiasts who want extension and dynamic range but don't have super-deep pockets are better off with ported- at least if they want serious dynamic range below 30Hz.

I also think that qualitatively, ported subs have an edge, at least for louder levels. The back pressure from the port keeps the driver out of trouble. Yes, ports can produce chuffing, but audible distortion from over-driving a sealed driver would occur sooner than audible artifacts of port turbulence.

Alright, plenty to unpack. Now keep in mind, most sealed subs on the market today...well they suck. Obviously I don't know how much SVS (as an example) did to optimize the driver they chose for sealed use between the PB16U and the SB16U, but given that they use the same amp, just a different enclosure, you can evaluate what they did by looking at the top of the subwoofer's passband on the CEA2010 charts. From what I see, it doesn't look like much more than a shorting ring to control inductance, and thus eliminate that top end rolloff the PB16U exhibits. Super impressive work...

What Seaton did was cost effective and just plain good engineering (now I feel like TLS Guy). He didn't need big motors. He didn't need huge xmax. There was nothing obviously extraordinary about any individual part in the Submersive, at least not until Mark upgraded from a 1kW ICE amp to a 2.4kW SpeakerPower model. He just chose a pair of appropriately sized drivers to get huge Sd compared to competitors of the day, optimized them so that they would have a good balance of Fs and SPL sensitivity (Mms and I think some suspension changes as well), added an appropriately sized enclosure to make sure rolloff didn't occur too early and keep low-end efficiency relatively good, and programmed the DSP to achieve the requisite FR and engage limiters before the drivers could actually get into any trouble. The basics of the design don't really require a lot of cost; they require a lot of smarts. That's why Mark was able to keep his prices so relatively low, in spite of the fact that he was competing against companies with big advantages in economies of scale.

In any case, the results were clear: huge power where it mattered, and enough low end output to be capable of useful infrasonic output when you had multiples. Honestly, I'm surprised a competitor didn't just buy a Submersive and reverse engineer the thing. Though thinking about that, given the similarities between PSA's old XS15se and XS30se, which also use modified LAB15's in a similar sized enclosure (on a per driver basis), maybe your good buddy Tom did

 

[shadyJ]

Hey James! I was wondering when you'd peek in.



Alright, plenty to unpack. Now keep in mind, most sealed subs on the market today...well they suck. Obviously I don't know how much SVS (as an example) did to optimize the driver they chose for sealed use between the PB16U and the SB16U, but given that they use the same amp, just a different enclosure, you can evaluate what they did by looking at the top of the subwoofer's passband on the CEA2010 charts. From what I see, it doesn't look like much more than a shorting ring to control inductance, and thus eliminate that top end rolloff the PB16U exhibits. Super impressive work...

What Seaton did was cost effective and just plain good engineering (now I feel like TLS Guy). He didn't need big motors. He didn't need huge xmax. There was nothing obviously extraordinary about any individual part in the Submersive, at least not until Mark upgraded from a 1kW ICE amp to a 2.4kW SpeakerPower model. He just chose a pair of appropriately sized drivers to get huge Sd compared to competitors of the day, optimized them so that they would have a good balance of Fs and SPL sensitivity (Mms and I think some suspension changes as well), added an appropriately sized enclosure to make sure rolloff didn't occur too early and keep low-end efficiency relatively good, and programmed the DSP to achieve the requisite FR and engage limiters before the drivers could actually get into any trouble. The basics of the design don't really require a lot of cost; they require a lot of smarts. That's why Mark was able to keep his prices so relatively low, in spite of the fact that he was competing against companies with big advantages in economies of scale.

In any case, the results were clear: huge power where it mattered, and enough low end output to be capable of useful infrasonic output when you had multiples. Honestly, I'm surprised a competitor didn't just buy a Submersive and reverse engineer the thing. Though thinking about that, given the similarities between PSA's old XS15se and XS30se, which also use modified LAB15's in a similar sized enclosure (on a per driver basis), maybe your good buddy Tom did

I wouldn't say most sealed subs suck. Maybe they aren't sufficient for dedicated home theater duty, but most buyers are pretty happy with them.

The SB16 and PB16 actually have different motors. If I remember right, the PB16 is an underhung design, and the SB16 is an overhung design.

The Submersive is a nice design, but it does sacrifice deep bass for midbass, and that isn't the tradeoff I would have made unless I were optimizing it for conventional music playback. The SB16 is nearly the opposite, it has a somewhat low sensitivity in midbass but it has a ton of displacement for deep bass. And that makes sense for its design; many of its buyers are not going to crank it to the point of rattling the home foundations, but they still want decent deep bass output, just not from a gigantic enclosure. The Submersive might be better for a dedicated home theater, but for most people, the SB16 is the more sensible choice, since most people do not have dedicated home theaters, so they don't want a large box and aren't ever going to drive their systems to 115dB.

I know it's fashionable to rip on SVS among hardcore home theater enthusiasts, mostly because they are popular but aren't winning CEA-2010 drag races at their price points, but their designs and performance are solid.

 

[TLS Guy]

Except that it's not. To get a driver to achieve a lower Fs, typically you add mass to the driver. What is the effect of that? Lower efficiency. You're pushing a heavier object with a permanent magnet and an electromagnet; it necessarily takes more power to the electromagnet do that. No free lunches here.

Data-bass appears to be down, so we'll have to settle for looking at stuff on the webarchive version of it. Let's take the BMS 18N862 8 ohm driver as a pretty good balance of Fs, Mms, and SPL Sensitivity. Those metrics are 29.1Hz, 255.2g, and 93.78dB. In a Josh's sealed text box (4.0cf IIRC), and driven by Josh's beast of an amp, it delivers substantial CEA2010 passing output from 40-125Hz, on the order of 119.8-131.4dB. CEA2010 passing output at 20Hz and 16Hz respectively is 103.8dB and 99.2dB.

Now lets examine another system, built around the TC Sounds LMS-R 12". This is as close to an approximation of the PB13U driver as we're likely to get. Fs, Mms, and SPL Sensitivity are 30.5Hz, 316.8g, and 83.87dB. See the difference in sensitivity already? Josh loaded the TC Sounds unit into a vented box; not sure of its precise volume, but IIRC, it was as large or larger than the 4.0cf sealed test box used for 18" drivers. The box in question had 3 different tunes, 13Hz, 18Hz, and 27Hz. Using the very same amplifier, and the most favorable 18Hz tune, the TC Sounds driver delivers 113.3 - 116.2dB of output from 40-125Hz, and it achieves 109.6dB and 103.3dB at 20Hz and 16Hz respectively.

Starting to see the issue? For a given box size, you can stuff significantly more firepower into a sealed system than you can a vented system. Yeah, the little pee-wee TC-Sounds driver can deliver a bit more output at 20Hz and 16Hz, highlighting what a vented box can do, but we're talking about a very small bandwidth here, and the BMS is hardly choking. Pretty much everywhere else, the BMS is wiping the floor with the LMS-R 12. It's hard to compare costs, given that TC Sounds is long defunct; it certainly wasn't an inexpensive driver at the time, however. It needed a big motor to get the job done. The BMS isn't cheap these days, though a lot of that was the choice to utilize neodymium instead of ferrite magnets.

Looping back to the PB13U and the Submersive, they were reasonably close in size and cost, making it a regular topic of comparison. The PB13U utilized a single 13.5", high mass/low sensitivity driver in a large vented box, and it did pretty well for itself. The Submersive was a different beast. It packed not one, but two high efficiency 15" drivers in a similar volume; right off the bat, that's double the voice coils, and roughly 2.5x the cone area. Is it a wonder the Submersive was deemed the more dynamic subwoofer? Mark never wanted the Submersive measured (as much as I bugged him about it; I was skeptical at the time), so we don't know precisely what it can do. But, given the results of various tests, some blind, conducted over at AVS, it held its own with subs like the mighty JTR Captivator, and was generally preferred to stuff like the SVS.


Like I said, it was customized. Only Mark Seaton knows exactly what the specs are.

It is illusory as you are not properly accounting for the power required for the Eq. The db. law/intensity equation is against the sealed sub. That is just physics. I am not saying that sealed subs are bad, but I am just pointing out the inefficiency of a sealed sub, which is inherent in its design. You do usually need to high pass them at the point they run out of xmax. If you don't you will have a blown driver.

That is why I use transmission line subs, which are even more efficient and assist the driver over a wider frequency range.

I have designed subs for a number of members here over the years and they have been very happy with them.

By the way I measure my speakers and publish them here.

This is the FR of one of my active TL mains.

That is the correct FR for the room.

This is all speakers driven at the MLP.

Front active three. All TLs, right and left are dual TLs.

This is what a TL looks like.

This was designed for in wall.

FR with crossover at 80 Hz.

I view efficiency as a desired parameter. However as you reduce size you always reduce sensitivity and efficiency. There is no escape from that.

 

[TLS Guy]

I wouldn't say most sealed subs suck. Maybe they aren't sufficient for dedicated home theater duty, but most buyers are pretty happy with them.

The SB16 and PB16 actually have different motors. If I remember right, the PB16 is an underhung design, and the SB16 is an overhung design.

The Submersive is a nice design, but it does sacrifice deep bass for midbass, and that isn't the tradeoff I would have made unless I were optimizing it for conventional music playback. The SB16 is nearly the opposite, it has a somewhat low sensitivity in midbass but it has a ton of displacement for deep bass. And that makes sense for its design; many of its buyers are not going to crank it to the point of rattling the home foundations, but they still want decent deep bass output, just not from a gigantic enclosure. The Submersive might be better for a dedicated home theater, but for most people, the SB16 is the more sensible choice, since most people do not have dedicated home theaters, so they don't want a large box and aren't ever going to drive their systems to 115dB.

I know it's fashionable to rip on SVS among hardcore home theater enthusiasts, mostly because they are popular but aren't winning CEA-2010 drag races at their price points, but their designs and performance are solid.

As usual we agree.

 

[Steve81]

It is illusory as you are not properly accounting for the power required for the Eq. The db. law/intensity equation is against the sealed sub. That is just physics. I am not saying that sealed subs are bad, but I am just pointing out the inefficiency of a sealed sub, which is inherent in its design. You do usually need to high pass them at the point they run out of xmax. If you don't you will have a blown driver.

The Submersive is a nice design, but it does sacrifice deep bass for midbass, and that isn't the tradeoff I would have made unless I were optimizing it for conventional music playback.

Two points.
1. Seaton didn't really have to apply much boost because he didn't undersize the heck out of the enclosure volume, which dominates the system sensitivity at low frequencies. I remember looking at all the sealed 18's tested out in the same test enclosure, and their low end sensitivity was pretty much identical. That's Hoffman's Iron Law at work. Would a vented box boost sensitivity around tuning? Sure. But that's point 2. PS: These days, modern DSP limiters do the job just fine, no high-pass needed. Nathan @ Funk let me screw around all I wanted, though he did recommend a particular configuration of filters to avoid needlessly wasting power. I think I ended up just high-passing them anyway because infrasound in my space was a mostly useless endeavor. I made a door vibrate, whee. More power for the real stuff anyway.

2. The EQ doesn't actually matter. What matters is if the amplifier has the power to deliver the output asked of it, which directly relates to the sensitivity of the subwoofer across its bandwidth; Josh measured this aspect on numerous raw drivers in his test box. It doesn't matter how much or how little boost you apply; the sub is going to top out at the same spot if you drive it with a 20Hz sine wave. The EQ merely makes the FR conform with our requirements to achieve a good in-room response. Why this matters is because of all that top end sensitivity that Seaton achieved with his design. If you only need ~10W of power to reproduce content in the 40+Hz range, that leaves a ton of juice on tap for any deep stuff that's along for the ride. A low-sensitivity vented design like the PB13U has to expend far more amplifier power on the 40+Hz range, because it's not remotely as efficient there.

This means that even though the PB13U is more sensitive around port tune (a relatively narrow bandwidth), it's got a lot less available power on tap with real world content to make use of that advantage. Unless you're driving both subs with content heavily skewed towards the narrow range the PB13 has an advantage, the SubM will have no trouble keeping up with the PB13U, even around port tune. It may even get LOUDER once you factor in port compression. That's the genius of Mark's design, and why in every test, blind or sighted, that I've ever seen between the PB13U and the SubM, the PB13U lost, and it wasn't close. This aligns with my own experiences as well. I fully expected to lose some low end output, given that the PB13U has a ~7dB advantage over the FW18.0 that replaced it at 20Hz. It just didn't happen. The Funk 18.0 vibrated my couch and made small children cower in fear (yes, this happened) better than the PB13 ever did.

Here's what the spectral content looks like for some bass flicks.

Flight of the Phoenix - Barrel Roll


How To Train Your Dragon - Dragon Crash


War Of The Worlds - Pod Emergence (I think...and yes, the image is tiny because I pulled it off a GIF BossoBass made)


It's NOT just a red line going down at 20Hz.

I wouldn't say most sealed subs suck. Maybe they aren't sufficient for dedicated home theater duty, but most buyers are pretty happy with them.

The SB16 and PB16 actually have different motors. If I remember right, the PB16 is an underhung design, and the SB16 is an overhung design.

Let me reword. I'd say most sealed subs on the market are glorified lifestyle products. Great for the masses, not for enthusiasts. Kind of like a soundbar or some Bose speakers Re: the SB16U; honestly, I'd have expected a totally different driver for an Ultra product. This is supposed to be their flagship sealed sub; it's barely more capable than the aforementioned XS15se, especially when you remove the outlier at 31.5Hz. Considering the old PSA (it was previewed back in '14) was smaller, lighter, and blessed with a far less powerful amp, not to mention considerably cheaper, this has to be some kind of joke... (yes yes, different measurement rigs, different days, blah blah).

 

[Danzilla31]

As usual we agree.

I would love you to design me some transmission line subs but they have to be huge don't they? And I wouldn't have the ability to build them into my walls. I don't think I'd have the room size for them

 

[TLS Guy]

Two points.
1. Seaton didn't really have to apply much boost because he didn't undersize the heck out of the enclosure volume, which dominates the system sensitivity at low frequencies. I remember looking at all the sealed 18's tested out in the same test enclosure, and their low end sensitivity was pretty much identical. That's Hoffman's Iron Law at work. Would a vented box boost sensitivity around tuning? Sure. But that's point 2. PS: These days, modern DSP limiters do the job just fine, no high-pass needed. Nathan @ Funk let me screw around all I wanted, though he did recommend a particular configuration of filters to avoid needlessly wasting power. I think I ended up just high-passing them anyway because infrasound in my space was a mostly useless endeavor. I made a door vibrate, whee. More power for the real stuff anyway.

2. The EQ doesn't actually matter. What matters is if the amplifier has the power to deliver the output asked of it, which directly relates to the sensitivity of the subwoofer across its bandwidth; Josh measured this aspect on numerous raw drivers in his test box. It doesn't matter how much or how little boost you apply; the sub is going to top out at the same spot if you drive it with a 20Hz sine wave. The EQ merely makes the FR conform with our requirements to achieve a good in-room response. Why this matters is because of all that top end sensitivity that Seaton achieved with his design. If you only need ~10W of power to reproduce content in the 40+Hz range, that leaves a ton of juice on tap for any deep stuff that's along for the ride. A low-sensitivity vented design like the PB13U has to expend far more amplifier power on the 40+Hz range, because it's not remotely as efficient there.

This means that even though the PB13U is more sensitive around port tune (a relatively narrow bandwidth), it's got a lot less available power on tap with real world content to make use of that advantage. Unless you're driving both subs with content heavily skewed towards the narrow range the PB13 has an advantage, the SubM will have no trouble keeping up with the PB13U, even around port tune. It may even get LOUDER once you factor in port compression. That's the genius of Mark's design, and why in every test, blind or sighted, that I've ever seen between the PB13U and the SubM, the PB13U lost, and it wasn't close. This aligns with my own experiences as well. I fully expected to lose some low end output, given that the PB13U has a ~7dB advantage over the FW18.0 that replaced it at 20Hz. It just didn't happen. The Funk 18.0 vibrated my couch and made small children cower in fear (yes, this happened) better than the PB13 ever did.

Here's what the spectral content looks like for some bass flicks.

Flight of the Phoenix - Barrel Roll
View attachment 62987

How To Train Your Dragon - Dragon Crash
View attachment 62988

War Of The Worlds - Pod Emergence (I think...and yes, the image is tiny because I pulled it off a GIF BossoBass made)
View attachment 62989

It's NOT just a red line going down at 20Hz.



Let me reword. I'd say most sealed subs on the market are glorified lifestyle products. Great for the masses, not for enthusiasts. Kind of like a soundbar or some Bose speakers Re: the SB16U; honestly, I'd have expected a totally different driver for an Ultra product. This is supposed to be their flagship sealed sub; it's barely more capable than the aforementioned XS15se, especially when you remove the outlier at 31.5Hz. Considering the old PSA (it was previewed back in '14) was smaller, lighter, and blessed with a far less powerful amp, not to mention considerably cheaper, this has to be some kind of joke... (yes yes, different measurement rigs, different days, blah blah).

View attachment 62990

You seem to have odd ideas about speaker design. Both vented and sealed enclosures have optimal volumes. You don't pull enclose volumes out of thin air. There is a size for each that gives an optimal response.

Here you can see a sealed and a vented design for the same driver. A well regarded potent 12" sub driver, and you can see the differences between the two forms of loading. Both designs are optimized. It is obvious that the vented design scores on efficiency in the lower frequencies. This applies to ALL drivers, except that some drivers can be unsuitable for one or the other form of loading.

 

[Steve81]

You seem to have odd ideas about speaker design. Both vented and sealed enclosures have optimal volumes. You don't pull enclose volumes out of thin air. There is a size for each that gives an optimal response.

Here you can see a sealed and a vented design for the same driver. A well regarded potent 12" sub driver, and you can see the differences between the two forms of loading. Both designs are optimized. It is obvious that the vented design scores on efficiency in the lower frequencies. This applies to ALL drivers, except that some drivers can be unsuitable for one or the other form of loading.

I'm aware of these things; I did write an article for this site on designing a DIY sealed subwoofer, and discussed how to model for a desired Qtc factor. I would presume Seaton took this into account as well, which means your argument likely further proves just how finely tuned / optimized the SubM actually was. None of the individual pieces were extraordinary, they just weren’t off the shelf parts. Seaton knew what he wanted to do, and had the driver built to achieve that. The fact that plenty of audio enthusiasts know what a Submersive is today is testament to how everything played out. There aren’t a lot of other subs that have stood the test of time like that on the market. If I asked James to tell me all about the SVS PB10-ISD, without the benefit of a Google search, I don’t expect him to know wtf I’m talking about by contrast (though he’s a bright fellow, so he might know anyway).

 

[Steve81]

@shadyJ Any way you could loop Ed Mullen in on this conversation?

 

[shadyJ]

Re: the SB16U; honestly, I'd have expected a totally different driver for an Ultra product. This is supposed to be their flagship sealed sub; it's barely more capable than the aforementioned XS15se, especially when you remove the outlier at 31.5Hz. Considering the old PSA (it was previewed back in '14) was smaller, lighter, and blessed with a far less powerful amp, not to mention considerably cheaper, this has to be some kind of joke... (yes yes, different measurement rigs, different days, blah blah).

Here is where CEA-2010 departs from reality. The SB16 Ultra driver is going to have a lot more displacement, period. It is simply going to be more capable in deep bass. The driver it is based on, the Peerless STW-350, is nearly perfect for getting deep bass out of a small enclosure. Even disregarding CEA-2010's repeatability problems, you would still have to look at the entire suite of measurements to really compare the two subs.

 

[shadyJ]

If I asked James to tell me all about the SVS PB10-ISD, without the benefit of a Google search, I don’t expect him to know wtf I’m talking about by contrast (though he’s a bright fellow, so he might know anyway).

I would know what you are talking about. I nearly bought one many years ago!

@shadyJ Any way you could loop Ed Mullen in on this conversation?

Lol, nope, not gonna drag Ed in here; I am sure he has enough problems! Anyway, I doubt he would say that any one design is superior over others, and that application and context has to be considered.

 

[Steve81]

Here is where CEA-2010 departs from reality. The SB16 Ultra driver is going to have a lot more displacement, period. It is simply going to be more capable in deep bass. The driver it is based on, the Peerless STW-350, is nearly perfect for getting deep bass out of a small enclosure. Even disregarding CEA-2010's repeatability problems, you would still have to look at the entire suite of measurements to really compare the two subs.

Indeed it does have more displacement, but it only really shows up at one frequency in terms of CEA2010 passing output. It probably produces more if you ignore distortion, but that’s not exactly something to recommend it.

An 18” driver custom built for a 3.5 cube box ala the FW18.0 would have been a better choice. With economies of scale, and maybe ditching the neodymium, costs wouldn’t have been a lot more. They may have even been less, because it clearly takes a lot of motor to push that driver to get the desired results.