PB-2000 not impressed

[VonMagnum]

@bravo79 - All I got from that is Sealed RULES and ported is a compromise created by a need for more output efficiency at the cost of accurate reproduction. You're at least a full cycle off (distortion of a sort) before it even exits the port. Period. No getting around the fact ALL ported enclosures are distorted. If you can live with knowing your system is not accurate, well more power to you (literally). If you need to know it's accurate, you NEED Sealed (and not just sealed, but sealed with a damn good driver and enough power to drive it).

Too simplified? Well, that's the only thing the guy really needed to say. The rest is just subjective opinion by people that make unsubstantiated claims.

Keep in mind none of that is my personal opinion, simply what I got out of the video.

 

[bravo79]

It’s interesting that he said some manufacturers claim their sub can perform as sealed and ported. He said a sealed use a driver built for sealed and as well as for ported sub.

 

[shadyJ]

@bravo79 - All I got from that is Sealed RULES and ported is a compromise created by a need for more output efficiency at the cost of accurate reproduction. You're at least a full cycle off (distortion of a sort) before it even exits the port. Period. No getting around the fact ALL ported enclosures are distorted. If you can live with knowing your system is not accurate, well more power to you (literally). If you need to know it's accurate, you NEED Sealed (and not just sealed, but sealed with a damn good driver and enough power to drive it).

Too simplified? Well, that's the only thing the guy really needed to say. The rest is just subjective opinion by people that make unsubstantiated claims.

Keep in mind none of that is my personal opinion, simply what I got out of the video.

The video is kind of right. Ported subs will have more group delay in port generated output. However it is almost exactly 1 cycle behind the driver signal, so it really sounds matched to the driver output. The only way it would ever sound unmatched is if the signal changed so drastically that one cycle is entirely unlike the next cycle. That doesn't really happen very much, and our ability to discern group delay and phase distortion at low frequencies is not very good as it is. So a cycle of delay centered around a really deep port tuning frequency like say 25 Hz is just fine. It's more of an issue in port tunings in upper frequencies where our hearing is far more acute. In fact this is where ported subs get a bad reputation for sound quality, its from crappy bandpass subs that come in HTiB sets with port tuning around 50 Hz. A GOOD ported sub sound is as sharp as a tack.

And a qualitative disadvantage regarding sealed designs that is only mentioned once and glossed over by the video is the toll taken on the driver from trying to reproduce low frequencies in a sealed design. In a ported design, at port resonance, the driver's motion actually lessens, so the coil stays in a very controlled region within the motor. So ported designs can be seen to lower in distortion as they approach the port tuning frequency from higher frequencies. But the coils in sealed design's have to move way more to achieve the same SPL, and this means much more distortion. It also means much more compression and a lot less headroom. In this respect, sealed designs are less linear and less accurate than ported designs, all other things being equal. And what's more, they are more inaccurate in a way that is more readily perceivable.

 

[VonMagnum]

@shadyJ - So what you're really boiling it down to is that sealed designs have less output and therefore more distortion if pushed past a certain point, which all in all congeals with the aforementioned idea that ported boxes produce MORE OUTPUT, MORE EFFICIENTLY (at the cost of group delay distortion, however inaudible it may be).

Thus, you need a larger sealed sub with more power to achieve the same output levels with lower distortion as a ported box. But a sufficiently large sealed sub will always outperform the ported sub in basic design (i.e. group delay) as that flaw is inherent to the design of the ported sub and cannot be removed no matter how much money you put into a ported design. In other words, money no object, you'd still wanted sealed for the lowest possible overall distortion because there is no way possible to overcome the one flaw of a ported design, which is the delay induced by the back wave of the driver.

If cost, power requirements and/or space issues are a serious impediment you would likely have to consider a ported design for such constraints and generally speaking those are the only reasons to consider a ported design in the first place.

Would you say those are accurate statements?

 

[shadyJ]

@shadyJ - So what you're really boiling it down to is that sealed designs have less output and therefore more distortion if pushed past a certain point, which all in all congeals with the aforementioned idea that ported boxes produce MORE OUTPUT, MORE EFFICIENTLY (at the cost of group delay distortion, however inaudible it may be).

Thus, you need a larger sealed sub with more power to achieve the same output levels with lower distortion as a ported box. But a sufficiently large sealed sub will always outperform the ported sub in basic design (i.e. group delay) as that flaw is inherent to the design of the ported sub and cannot be removed no matter how much money you put into a ported design. In other words, money no object, you'd still wanted sealed for the lowest possible overall distortion because there is no way possible to overcome the one flaw of a ported design, which is the delay induced by the back wave of the driver.

If cost, power requirements and/or space issues are a serious impediment you would likely have to consider a ported design for such constraints and generally speaking those are the only reasons to consider a ported design in the first place.

Would you say those are accurate statements?

I would agree with those statements. One thing that shouldn't be understated is how much more clean headroom that a ported sub offers over a sealed sub around port generated output. Let's take a look at an example:

Compare the huge headroom advantage that the port gives the ported operating mode over the sealed operating mode at port tuning. It can be as much as 12 dB and with less distortion. That means you would need four of the sealed mode subs to equal a single port mode sub at 16 to 25 Hz. Keep in mind that is just talking about dynamic range limitations and nonlinear distortions. Ported can also have an advantage in linear distortion as well, because it can hold a flatter response shape over a greater range.

You might say that there is no reason not to go full sealed in an all-out cost-no-object system, and I might agree with that. But the very moment that other criteria enters the picture regarding performance, ported can become a viable alternative, even in a pricey system.

 

[Matthew J Poes]

The video is kind of right. Ported subs will have more group delay in port generated output. However it is almost exactly 1 cycle behind the driver signal, so it really sounds matched to the driver output. The only way it would ever sound unmatched is if the signal changed so drastically that one cycle is entirely unlike the next cycle. That doesn't really happen very much, and our ability to discern group delay and phase distortion at low frequencies is not very good as it is. So a cycle of delay centered around a really deep port tuning frequency like say 25 Hz is just fine. It's more of an issue in port tunings in upper frequencies where our hearing is far more acute. In fact this is where ported subs get a bad reputation for sound quality, its from crappy bandpass subs that come in HTiB sets with port tuning around 50 Hz. A GOOD ported sub sound is as sharp as a tack.

And a qualitative disadvantage regarding sealed designs that is only mentioned once and glossed over by the video is the toll taken on the driver from trying to reproduce low frequencies in a sealed design. In a ported design, at port resonance, the driver's motion actually lessens, so the coil stays in a very controlled region within the motor. So ported designs can be seen to lower in distortion as they approach the port tuning frequency from higher frequencies. But the coils in sealed design's have to move way more to achieve the same SPL, and this means much more distortion. It also means much more compression and a lot less headroom. In this respect, sealed designs are less linear and less accurate than ported designs, all other things being equal. And what's more, they are more inaccurate in a way that is more readily perceivable.

James you have to be careful with this point. The motion decreases yes, but power Input remains high. There is a lot of heating in the coil without the normal motion to cool it. Harman has a port paper that I’ve sent you before that examined the myth that ports improve cooling. Found they do quite the opposite.

I’d also say that the audibility of group delay is a big unknown. There is not good research showing it’s inaudible. There is some showing it to be very audible and certainly not enough to draw conclusions. I forgot to show you the dissertation I have on that, but it included rigorous listening tests that showed LF group delay was audible to far below 1 cycle. While we both found that hard to believe, we can’t dispute their findings without replicating the study.

I also don’t think a subs frequency response, specifically it’s flatness is necessarily important or a good thing. I mean, without knowing much about the room I’m not going to say other shapes are better, but I think in general a rolled off response below 80hz leads to a flatter response in room. Even if we prefer or desire bass that rises as it goes lower, I’d still prefer a rolled off shape. Sealed is great for that and they tend to measure much flatter in room. Ported can too, like in a QB3 alignment, which I prefer. I find subs that measure very flat down to port tuning don’t always measure as nicely at around the port tuning. If tuned to 20hz or below maybe we don’t care. If tuned to 25-30hz it can lead to a bump at that frequency.

Ports are also not exactly nice. Their is no such thing as a linear port, just better versions of non-linear flawed ports. All ports make noise, compress, and add distortion. The key is ensuring their advantages outweigh their disadvantages. I agree that for a lot of modest subs or even crazy max output subs, a good port has advantages that can outweigh the disadvantages. However, all else being equal, my ultimate sound quality subs would probably still be sealed. My view is mains should be sealed. I rather subs handle the bass, and it’s a lot easier to integrate mains when they aren’t ported.

 

[shadyJ]

James you have to be careful with this point. The motion decreases yes, but power Input remains high. There is a lot of heating in the coil without the normal motion to cool it. Harman has a port paper that I’ve sent you before that examined the myth that ports improve cooling. Found they do quite the opposite.

I’d also say that the audibility of group delay is a big unknown. There is not good research showing it’s inaudible. There is some showing it to be very audible and certainly not enough to draw conclusions. I forgot to show you the dissertation I have on that, but it included rigorous listening tests that showed LF group delay was audible to far below 1 cycle. While we both found that hard to believe, we can’t dispute their findings without replicating the study.

I also don’t think a subs frequency response, specifically it’s flatness is necessarily important or a good thing. I mean, without knowing much about the room I’m not going to say other shapes are better, but I think in general a rolled off response below 80hz leads to a flatter response in room. Even if we prefer or desire bass that rises as it goes lower, I’d still prefer a rolled off shape. Sealed is great for that and they tend to measure much flatter in room. Ported can too, like in a QB3 alignment, which I prefer. I find subs that measure very flat down to port tuning don’t always measure as nicely at around the port tuning. If tuned to 20hz or below maybe we don’t care. If tuned to 25-30hz it can lead to a bump at that frequency.

Ports are also not exactly nice. Their is no such thing as a linear port, just better versions of non-linear flawed ports. All ports make noise, compress, and add distortion. The key is ensuring their advantages outweigh their disadvantages. I agree that for a lot of modest subs or even crazy max output subs, a good port has advantages that can outweigh the disadvantages. However, all else being equal, my ultimate sound quality subs would probably still be sealed. My view is mains should be sealed. I rather subs handle the bass, and it’s a lot easier to integrate mains when they aren’t ported.

Thermal compression is a different animal, and it doesn't affect output nearly as much as mechanical compression caused by tensed suspensions or coils out of the gap, so long as the coils don't burn out.

While there may be some cause for reassessing the conventionally held views of audibility of group delay at low frequencies, we also have to keep in mind the severity of it. Look at the group delay of a sub that is tuned to 20 Hz. Most of us here with ported subs have them tuned at 25 Hz or lower. Even if group delay is audible in lower times than 1 cycle at these very low frequencies, how much does that impact the sound vs sealed? In my experience, I couldn't tell you the difference, but I could tell you the difference caused by sealed subs reaching their limits. In complex content, I doubt anyone could tell the difference of these time domain issues in such low frequencies. Maybe we can devise a test where the difference is audible, perhaps a gap test of some sort, but I doubt very much that the phase distortion caused by ports is as intrusive as the output compression that sealed subs run into in low frequencies.

I agree that the ideal system would likely be sealed, but ideally we would also be picnicking in the garden of Eden with Unicorns and fairly godmothers and there would be no war or poverty and Optimus Prime would be president of the United States.

 

[Matthew J Poes]

Thermal compression is a different animal, and it doesn't affect output nearly as much as mechanical compression caused by tensed suspensions or coils out of the gap, so long as the coils don't burn out.

While there may be some cause for reassessing the conventionally held views of audibility of group delay at low frequencies, we also have to keep in mind the severity of it. Look at the group delay of a sub that is tuned to 20 Hz. Most of us here with ported subs have them tuned at 25 Hz or lower. Even if group delay is audible in lower times than 1 cycle at these very low frequencies, how much does that impact the sound vs sealed? In my experience, I couldn't tell you the difference, but I could tell you the difference caused by sealed subs reaching their limits. In complex content, I doubt anyone could tell the difference of these time domain issues in such low frequencies. Maybe we can devise a test where the difference is audible, perhaps a gap test of some sort, but I doubt very much that the phase distortion caused by ports is as intrusive as the output compression that sealed subs run into in low frequencies.

I agree that the ideal system would likely be sealed, but ideally we would also be picnicking in the garden of Eden with Unicorns and fairly godmothers and there would be no war or poverty and Optimus Prime would be president of the United States.

There are reasonable ways to achieve a sealed sub with no material limits to be concerned with. It doesn’t have to be fairy land.

You have the SI 24 and the Mach 5 32, both of which have so much displacement that they wouldn’t reasonably hit their limits, even at very low frequencies. I would have one of each by now but you told me I can’t build any more subs I can’t lift by myself.

 

[ryanosaur]

@shadyJ , @Matthew J Poes
That was beautiful. And I think I just got smarter, too.

 

[ryanosaur]

You have the SI 24 and the Mach 5 32

@shadyJ
Please, kind sir... Do tell.

 

[shadyJ]

@shadyJ
Please, kind sir... Do tell.

Mach 5 WOW-32
Stereo Integrity HS-24 mkIII
Both would need gigantic cabinets for optimal performance, the 32" especially. These subs would be hundreds of pounds, so what Matthew says reasonable, maybe he means for guys like Gene and Hugo, but not everyday mortals. You can get lots of displacement with sealed subs in reasonable form factors, like just take a bunch of 15"s and put them in separate sealed enclosures. The problem is that they would need a ton of wattage, so now you need a lot of amps and a lot of electrical circuits.

 

[3db]

No. I run PSB T45s in the front L/C/R, PSB B15 for front heights, side surround, side surround #2, PSB S50 for top middle, PSB X1T for rear surround and PSB CS500 for rear height. The only Def Tech is the subwoofer. I do have a pair of Def Tech BP2 surrounds I use in an exercise room (they used to be the surround speakers when I used the Carver AL-IIIs as the mains (Energy brand center) at my old house. I did try them in the front with the Def Tech sub, though for awhile (before I got the AL-IIIs in).



I have the T45s (which can play to 35Hz) set to SMALL at 80Hz.



No, it's all the Powerfield sub. The bathroom is the really crazy spot, it's something like 10dB louder in there than in the main room at the lowest frequencies (turns the room into a little sub box).

As for the comments on "doesn't rattle", rattling is a result of the walls, furniture, etc. responding to high levels of excitation. If the SVS sub isn't rattling anything, either the room is well damped or it's not putting out high levels. I do run my subwoofer +4dB higher than the mains (more bass just sounds/feels better), but that's not what I'd call excessive (I'll turn it up even more for some bass anemic recordings).

Nice to see another PSB fanboy here All three of my systems are built around PSB and one pair of RBH in ceiling speakers.

 

[Matthew J Poes]

Mach 5 WOW-32
Stereo Integrity HS-24 mkIII
Both would need gigantic cabinets for optimal performance, the 32" especially. These subs would be hundreds of pounds, so what Matthew says reasonable, maybe he means for guys like Gene and Hugo, but not everyday mortals. You can get lots of displacement with sealed subs in reasonable form factors, like just take a bunch of 15"s and put them in separate sealed enclosures. The problem is that they would need a ton of wattage, so now you need a lot of amps and a lot of electrical circuits.

See James takes all the fun out of my subwoofer projects.

I was really teasing. These are Goliath subs capable of massive swept area and as such can be used in a sealed box and achieve levels of sub-sonic bass that is just unreal. Large ported subs with lesser drivers often barely keep up if at all. On the other hand, you can use those other subs in multiples for far less total money and likely exceed the Goliath sub.

Still, isn’t it just cooler to say you have 32” subs in your room? It’s comically large!

 

[ryanosaur]

massive swept area

as in they clear everything out of their path and you don't have to dust or vacuum where they fire?

Still, isn’t it just cooler to say you have 32” subs in your room?

Indubitably.

Truth is I am fascinated by Stereo Integrity and Deep Sea. Also JTR. I don't see myself ever buying their product though (DS or JTR) but could see myself doing an SI build.
If I keep my small listening room over the long haul, I think I might do a full sealed build... 15x11', high sloped clerestory ceiling, ~2000'3. They lady would have to be on board for setting up a separate rig in the greatroom, but it would be a fun experiment.

 

[Matthew J Poes]

as in they clear everything out of their path and you don't have to dust or vacuum where they fire?


Indubitably.

Truth is I am fascinated by Stereo Integrity and Deep Sea. Also JTR. I don't see myself ever buying their product though (DS or JTR) but could see myself doing an SI build.
If I keep my small listening room over the long haul, I think I might do a full sealed build... 15x11', high sloped clerestory ceiling, ~2000'3. They lady would have to be on board for setting up a separate rig in the greatroom, but it would be a fun experiment.

Like the JTR Noesis 212RT’s here.

I don’t know what everyone’s issue with JTR is, that’s a totally normal sized speaker (for reference the wood wave panel is 24” square and the blue absorber is 50” tall).

I wish I had taken a pic of the Klipsch RP-8000f’s next to them. A large tower on their own that looked like little babies.

 

[VonMagnum]

Still, isn’t it just cooler to say you have 32” subs in your room? It’s comically large!

Comically large? Like this?

 

[Matthew J Poes]

Comically large? Like this?View attachment 29272

Is that actually functional or just a prop? That is pretty comically large.

 

[Sef_Makaro]

Comically large? Like this?View attachment 29272

There’s historical evidence that one chord on a guitar connected to this would launch you across the room.

 

[VonMagnum]

Nice to see another PSB fanboy here All three of my systems are built around PSB and one pair of RBH in ceiling speakers.

I don't know if I'd go as far as fanboy (as in I'm not opposed to other brands per se). I originally was listening to speakers in the $2000 or less range in college and narrowed it down to the Carver AL-III dipole ribbon speakers or the PSB Stratus Gold. I went with the Carver ribbons, but I remembered how neutral sounding the PSB speaker was and when I moved to another house I decided to go with PSB for the home theater. Well, I was already invested in PSB so when I went from 6.1 to 17.1 (11.1.6), I kept going with PSB (that nice neutral clean sound means all the speakers play nice in every direction around the room, more like one giant sound field than individual speakers.

 

[VonMagnum]

Is that actually functional or just a prop? That is pretty comically large.

Well, I am out of control with movie props lately (https://www.therpf.com/forums/threads/magnatron-home-theater-room-with-movie-props.301549/), but that's not mine (looks like a prop display to me, though).