Sealed versus Ported Bass, can the difference be measured?

[3ll3d00d]

I see group delay as envelope-distortion that warps any audio waveforms within the range of frequencies it spans. Nothing to do with timing, one frequency vs another.

Isn't that the same thing? it reads like it. You look at a spectrogram and see it smeared over time or look at a waveform and note it's all stretched/distorted, just 2 sides of same coin.

 

[Sokel]

My experience is that many of the really impactful sounds (like percussion) are quite wideband, so you need both the low-end and the range all the way up to 500hz in order.

I also swear to sealed subs, but recently ended up designing our full range loudspeaker to be ported to get enough capacity in the bottom end. And tuned to 28hz I'm hard pressed to say that it sounds any less tight and punchy than the sealed subs if I'm honest (which I try to be).

Good test about it here:

Bass: the Physical Sensation of Sound

Ever wonder why you can feel bass? We take a look behind the science of bass waves and the tactile sensations that they cause. Our bass experiments were quite revealing but don't try them at home.

www.audioholics.com

 

[Koeitje]

There is little convincing evidence anywhere of group delay audibility in low frequencies. I have always presupposed that the perceived ‘tightness’ people hear from sealed subwoofers is really just from the absence of very low frequencies that, by nature, rumble in a way that doesn’t sound tight.

SVS even has an article about sealed vs ported and group delay audibility (scroll down to "What about music?") on their website: https://www.svsound.com/blogs/subwoofer-setup-and-tuning/75367747-sealed-vs-ported

 

[morillon]

SVS even has an article about sealed vs ported and group delay audibility (scroll down to "What about music?") on their website: https://www.svsound.com/blogs/subwoofer-setup-and-tuning/75367747-sealed-vs-ported

we don't learn anything new there....neither original....
just marketing

 

[Koeitje]

we don't learn anything new there....neither original....
just marketing

The sealed section is some marketing bs, but the graph and its explanation is accurate.

 

[gnarly]

What do you think the limits of group delay audibility are? I am not trying to be sarcastic but as far as I can tell there is not much study that has been done, just some "rules of thumb" i.e. 1.5 cycles or 2 cycles which make some sense at high frequency but not so much at 20 Hz.

What I've been trying to say, although not very well, that I don't think we can judge group delay audibility based on number of cycles.
I see group delay as not having any real time component, but only having an 'apparent time' component. This apparent time has become viewed as real time through historical convention, it seems. So any mapping of it into number of cycles is just another form of historical convention.
Anyway, I'm hoping to put together something to explain the view better. I ask for a little patience in the meantime, thx !

 

[gnarly]

Isn't that the same thing? it reads like it. You look at a spectrogram and see it smeared over time or look at a waveform and note it's all stretched/distorted, just 2 sides of same coin.

Yep, may well be. I need to look deeper into REW's spectrograph capabilities. I haven't been using REW much lately preferring to use proaudio Crosslite+, but I see REW has wavelet, Morlet wavelet, and another type i haven't heard of.

 

[Paul McNeil]

I started this post, "Sealed versus Ported Bass, can the difference be measured?"I

I knew I would not do this measurement again, since all I had was old REW measurements to compare my new system (all sealed) to the previous (all ported). I would not, as suggested, be willing to stack up 3 Klipsch THS 120 for this, to remeasure (too old at 72, and not motivated).

The frequency responses of the ported and sealed system were very similar but one respondent thought the small difference could explain my preference for sealed. I posted GD and Phase responses from the older ported responses, which yielded no comments in explanation.

Others suggested that the ported went lower (it did not) and that I was put off by the lower registers of the ported system.

REW, I summarize from these posts, will not readily measure the difference, which would have been in my measurements (posted).

I wonder, because this is suggested by many comments, can one actually hear the difference between sealed and ported subwoofers, of excellent design?

 

[ryanosaur]

I wonder, because this is suggested by many comments, can one actually hear the difference between sealed and ported subwoofers, of excellent design?

The argument I tend to agree with is no, you should not hear a difference between equally capable Ported or Sealed Subs. What we hear as differences most likely falls into the category of differing distortions, be it in harmonic, compression or resonance. Flashing back to the old myths, it was the old Ported designs which were the "bogeyman." As Driver and Cabinet design improved, so did Ported Sub performance. Now you are more likely to see very low distortion, near-to-textbook compression, and more advanced DSP to help balance things out. (Not in every case, but designers are getting there.)

Even to that last point, look at Hsu and the fact they are still not using DSP in their Plate Amps, yet his latest sub is fairly impressive.

Hsu Research VTF-TN1 15" Subwoofer Review

The VTF-TN1 is the newest flagship subwoofer that boasts a 15" driver and 600-watt amp from Hsu Research. Read our review to find out what Hsu Research did to pull off this minor miracle.

www.audioholics.com

 

[Paul McNeil]

The argument I tend to agree with is no, you should not hear a difference between equally capable Ported or Sealed Subs. What we hear as differences most likely falls into the category of differing distortions, be it in harmonic, compression or resonance. Flashing back to the old myths, it was the old Ported designs which were the "bogeyman." As Driver and Cabinet design improved, so did Ported Sub performance. Now you are more likely to see very low distortion, near-to-textbook compression, and more advanced DSP to help balance things out. (Not in every case, but designers are getting there.)

Even to that last point, look at Hsu and the fact they are still not using DSP in their Plate Amps, yet his latest sub is fairly impressive.

Hsu Research VTF-TN1 15" Subwoofer Review

The VTF-TN1 is the newest flagship subwoofer that boasts a 15" driver and 600-watt amp from Hsu Research. Read our review to find out what Hsu Research did to pull off this minor miracle.

www.audioholics.com

Does this review measure the possible difference between ported and sealed, based on the approaches posted above. Or is ti subjective and REW frequency response? I'll have a look...thanks.

 

[Keith_W]

REW, I summarize from these posts, will not readily measure the difference, which would have been in my measurements (posted).

I wonder, because this is suggested by many comments, can one actually hear the difference between sealed and ported subwoofers, of excellent design?

REW WILL readily measure the difference provided that the measurement was done properly. However, you replaced 3 stacked Klipsch ported subs with one sealed SVS sub and posted a screenshot. As has been pointed out many times, it is impossible to specifically answer your question about the difference being due to group delay. BUT we can probably tell you if the new setup is better than the old one.

Please do this: copy all your measurements into one MDAT. Clearly label the measurement "before" and "after". Zip the MDAT and upload it to ASR.

 

[Paul McNeil]

REW WILL readily measure the difference provided that the measurement was done properly. However, you replaced 3 stacked Klipsch ported subs with one sealed SVS sub and posted a screenshot. As has been pointed out many times, it is impossible to specifically answer your question about the difference being due to group delay. BUT we can probably tell you if the new setup is better than the old one.

Please do this: copy all your measurements into one MDAT. Clearly label the measurement "before" and "after". Zip the MDAT and upload it to ASR.

Yeah, that was not my question, whether my present system is better than the previous. Or to compare apples to oranges. But about whether sealed versus ported differences are measurable. OK, many here say they are, and I believe I can hear them. I'm happy!

 

[ryanosaur]

Does this review measure the possible difference between ported and sealed, based on the approaches posted above. Or is ti subjective and REW frequency response? I'll have a look...thanks.

No it does not directly compare Sealed v. Ported. I linked to support my comment that even today a quality Sub can be had without leaning on DSP to fix what ails its design.

Also, I like to geek out and compare measurements from time to time and this one came to mind. Also also, I think that even a DIYer would be hard pressed to build 1 capable sub at this price point, and perhaps not even at multiples of subs which is where the real value proposition of DIY exists... but that is outside the bounds of this conversation: just a tangent to touch upon.

 

[ryanosaur]

I'm happy!

This is what matters. At the end of the day, it is your system and your home. If you are happy with it then be happy and enjoy!

 

[DVDdoug]

I started this post, "Sealed versus Ported Bass, can the difference be measured?"

The question can't really be answered because 2 different speakers will ALWAYS sound different and measure different. You can make a good speaker either way.

So you could say YES. The differences between different speakers CAN be heard and measured. But there are lots of things that go into speaker design and one is not always better than the other.

Simply plugging the port will make a difference in sound and in the measurements but it's not a "fair test" because if there is a port the speaker wasn't optimized as a sealed design.

With measurements you MIGHT be able to make a good guess if it's ported or not.

But, NO. You can't tell if a speaker is ported or sealed by listening.

...My DIY 15-inch subwoofers are in large ported cabinets.

Here is something Amir posted:

I don't know why people are so fascinated with how some speaker/headphone is made. What matters are the results.

 

[3ll3d00d]

here's an example of comparing ported and sealed and what you can actually measure

sealed - https://data-bass.com/systems/5b11dab8a201f10004e39d72
ported - https://data-bass.com/systems/5b11bfe651412e00047d6693

same driver, box/port sized in some reasonably sensible way (albeit not optimised, it's still a test box), both fed with plenty of power

you can see how distortion profiles vary, how much more output the ported sub has down to tune and how much more that driver can take, how compression varies (and also how group delay varies but that is surely the least consequential part of the story)

 

[Paul McNeil]

Well, your are still comparing apples to oranges (because even though the drivers and amps may be the same, DSP is involved), but a pro measurement comparison of the SVS Ultra SB-17 to the PB-17 would be interesting. Of course, so would a blind listening test at equal volume levels!!!

 

[3ll3d00d]

Well, your are still comparing apples to oranges (because even though the drivers and amps may be the same, DSP is involved), but a pro measurement comparison of the SVS Ultra SB-17 to the PB-17 would be interesting. Of course, so would a blind listening test at equal volume levels!!!

there's a protective high pass filter in place as you'd expect for a competently designed ported sub. Ported vs sealed is *inherently* apples vs oranges, you use a port because you need a port, if you don't need the output from a port, don't use one, the end

 

[terryforsythe]

REW, I summarize from these posts, will not readily measure the difference, which would have been in my measurements (posted).

Have you tried measuring the step response and impulse response (time domain measurements)?

If you drive a woofer directly from a low output impedance amplifier (without a passive crossover), the (EDIT) properly damped acoustic suspension (sealed) configuration typically will exhibit quicker rise and decay times. However, a passive crossover introduces impedance between the amplifier output stage and the woofer, which lowers the damping factor. Thus, when passive crossovers are used, especially if the DCR in series with the woofer is relatively high (e.g., in a 3-way speaker with a low woofer crossover frequency), the difference in rise and decay times between sealed and ported may be subtle as compared to directly driving the woofer from the amplifier.

I removed the passive crossovers from my 3-way bookshelf speakers and plugged the ports, using DSP for active crossovers. The bass is much tigher now. I use a subwoofer, so the reduced low bass frequency extension is not an issue with my setup.

 

[terryforsythe]

Here is a video I just came across today that discusses ported vs sealed woofers: