Svs sb2000 or pb2000

[KEW]

Human hearing does not hear impulse responses. Human hearing does not hear what Q is outside of its effect on the frequency response. I am beginning to think its time to expand on the 'myths about subwoofer' article.

What? That's crazy!
I have definitely heard impulse responses!

 

[shadyJ]

What? That's crazy!
I have definitely heard impulse responses!

Are you sure you don't mean impulsive responses? Very different thing.

 

[Andrein]

You don't seem to understand how enclosures work with ported subwoofers. They do have a lot of backspring pressure. You might look this fact up or better yet ask the guys at SVS about it, if you want to appeal to their authority. And when I say the phase delays that were are discussing is not audible, I am not talking about just my own experiences. I do so based on the available research, and I have been through much of it. Luckily for us, one of the most comprehensive studies done in this area is freely available online.

Note how carefully SVS is in wording the ostensible advantages of sealed subs: "described by enthusiasts." They won't make that claim themselves, nor will they stand behind it, because it nonsense and they know it. In that same article they go on to reject that nonsense by explaining how the frequencies that have the cycle of delay are too low to matter.

I would say that ported is better for music that has actual deep frequency content. Driver motion in ported can stay in linear operating range far better at deep frequencies than sealed, which can see an eruption in very audible distortion from the driver flying past its linear excursion.

Please concreate quotes. No time to read 100 pages full of formulas now. I hope you read it yourself. So far you and another ported sub supporter did not provide any evidence and even graphs you threw in in another thread contradicted your own point.

 

[Steve81]

What? That's crazy!
I have definitely heard impulse responses!

To offer a couple cents on impulse response as it relates to subwoofers, I'll simply point to a couple posts from Josh over at AVS:

http://www.avsforum.com/forum/113-subwoofers-bass-transducers/2754489-many-subs-dsp-optimised-factory-these-days-should-they-3.html#post51162649

http://www.avsforum.com/forum/113-subwoofers-bass-transducers/2754489-many-subs-dsp-optimised-factory-these-days-should-they-4.html#post51192105

Any change to the response bandwidth or response shape and this includes the signal used, will show up in the measurement. Unless nearly everything is the same in the comparison including the frequency response of the two systems the impulses are of course going to be much different. The problem is some seem to be relating a shorter more abrupt impulse to a better controlled or more well damped subwoofer. What it actually means is the response that was measured for that sub contains a lot more high frequency energy and less actual low bass. Any EQ you make will change it, placing it in a room will have huge effects, the typical 70-100Hz low pass filter has a huge impact.

 

[Pogre]

I've had both and prefer ported, though it's not really apples to apples going from 2 SB1000's to 2 VTF-3 MK5's...

 

[shadyJ]

Please concreate quotes. No time to read 100 pages full of formulas now. I hope you read it yourself. So far you and another ported sub supporter did not provide any evidence and even graphs you threw in in another thread contradicted your own point.

I have read it and also the major papers that it cites. The bottom line is that phase distortion is very difficult to hear unless it is extreme. In the tests that guy did, phase distortion was only found to be slightly audible on some test tones, and only then in a very tightly controlled laboratory setting using high-end headphones. Phase distortion was not generally audible using loudspeakers. Given that so much of the sound we hear is reflected, if phase distortion was a serious nuisance, everything would sound like gibberish all the time. It is a very good thing that human hearing is so oblivious to phase distortion. The phase discrepancy caused by the ports being a cycle removed from the driver motion in a ported sub is nothing compared to the damage that is done to phase integrity by room reflections- yet these subs can still sound fine, ported or sealed. Humans are generally insensate to phase until it starts to impact the frequency response.

 

[shadyJ]

To offer a couple cents on impulse response as it relates to subwoofers, I'll simply point to a couple posts from Josh over at AVS:

http://www.avsforum.com/forum/113-subwoofers-bass-transducers/2754489-many-subs-dsp-optimised-factory-these-days-should-they-3.html#post51162649

http://www.avsforum.com/forum/113-subwoofers-bass-transducers/2754489-many-subs-dsp-optimised-factory-these-days-should-they-4.html#post51192105

That is a really good find, Steve. I hope those who continue to use impulse response as though it were some kind of group delay measurement read through that whole thread.

Along those lines, here is an extreme example of how shaping the frequency response affects the impulse response: this is the SB16-Ultra, with the low-pass filter off (green curve) vs the filter on and set to 30 Hz (blue curve):

Whoa dude! The SB16-Ultra is so much more tighter than that other sub, the SB16-Ultra! Uh-oh, my mind is blowing- everyone run for cover!

 

[KEW]

Human hearing does not hear impulse responses.

Seriously, why do you believe humans hearing cannot detect an impulse response?
I know I hear the sound my speakers make when I get a graph of impulse response from my Omni-mic system. It measures FR at the same time, if that is relevant.

Are you sure you don't mean impulsive responses? Very different thing.

Clever, but looks like a dodge of a question to me!

 

[shadyJ]

I've had both and prefer ported, though it's not really apples to apples going from 2 SB1000's to 2 VTF-3 MK5's...

A single VTF-3 mk5 is probably on the order of 3 to 4 times more powerful than a SB-1000, and probably even more than that at port tuning frequencies. If you want to do a more fair comparison between ported and sealed, just plug the ports on your VTF-3.

 

[Pogre]

A single VTF-3 mk5 is probably on the order of 3 to 4 times more powerful than a SB-1000, and probably even more than that at port tuning frequencies. If you want to do a more fair comparison between ported and sealed, just plug the ports on your VTF-3.

I have. I much prefer the output with both ports open. They're a lot more tame plugged.

 

[lovinthehd]

I have. I much prefer the output with both ports open. They're a lot more tame plugged.

You sure they're not just tighter and more musical?

 

[shadyJ]

Seriously, why do you believe humans hearing cannot detect an impulse response?
I know I hear the sound my speakers make when I get a graph of impulse response from my Omni-mic system. It measures FR at the same time, if that is relevant.

You do not hear sound as a waveform from an impulse response measurement. You might hear a click from the speaker, but aren't going to be able to put together a impulse response graph based on what you heard. Humans hear amplitude over frequency, but we can use binaural phase differences to sense location.

 

[Steve81]

One other bit on impulse response from Bill Fitzmaurice that's important to keep in mind:
http://www.avsforum.com/forum/113-subwoofers-bass-transducers/1478581-how-important-impulse-response.html#post23464901

What the impulse mainly shows is how quickly inertia is overcome and the cone returns to rest after a single cycle pulse is applied. We don't listen to single cycle impulses, we listen to a continuous stream of impulses, and the inertial force is totally dwarfed by the electro-magnetic force provided by the motor. If the impulse response was really bad you'd hear it, but the frequency response would also point out the speaker deficiencies, and it would do so far more obviously. The main use of impulse response is to help identify what might be causing a really poor frequency response.

 

[KEW]

You do not hear sound as a waveform from an impulse response measurement. You might hear a click from the speaker, but aren't going to be able to put together a impulse response graph based on what you heard. Humans hear amplitude over frequency, but we can use binaural phase differences to sense location.

Might?
In what situation would you not hear it? And why not?

At this point, I'm thinking you made a mistake and said we cannot hear Impulse responses when you meant to say that it is unlikely to hear the difference between "fast" and "slow" responses.

If that is wrong, I want to learn more.

If that is right, just be straight forward and state what you intended to say.

Right now, my OCD tendencies are conflicted between learning "how could you not hear an impulse response" if your statement is correct vs "this statement is not correct and will misinform many readers" if you did misstate the situation.

 

[shadyJ]

Might?
In what situation would you not hear it? And why not?

At this point, I'm thinking you made a mistake and said we cannot hear Impulse responses when you meant to say that it is unlikely to hear the difference between "fast" and "slow" responses.

If that is wrong, I want to learn more.

If that is right, just be straight forward and state what you intended to say.

Right now, my OCD tendencies are conflicted between learning "how could you not hear an impulse response" if your statement is correct vs "this statement is not correct and will misinform many readers" if you did misstate the situation.

An impulse response is an acoustic measurement (in this case acoustic, but the principle is used in other mediums as well, like electronics). You can hear the tone, but you can not measure it without the right equipment. I don't know that you could hear the difference between a 'fast' response and 'slow' response. I suppose you could hear a difference in extreme cases. I don't think that would occur in any competently designed loudspeaker or electronics. In either case, it is something that has to be recorded and analyzed. The information of interest in an acoustic response measurement is not going to be audible itself. It will only ever sound like a click.

 

[KEW]

As to sealed subs with eq to bring up the low end, are you talking about further increases with additional eq or just as provided by the sub designer? That they're audible at all times (rather than say being further boosted by the user) I think is a conclusion of yours rather than reality....

I think this post by ShadyJ actually captures exactly what I have experienced:
https://forums.audioholics.com/forums/threads/looking-for-a-sealed-sub-under-1500-to-pair-with-kef-ls50.109137/#post-1212043

So, right now, I am thinking it (the difference I perceive between a sealed and ported subwoofer) is either:
1) frequency response (after room gain) or Impulse response.
2) Q, but it seems like the end effect of this would show in the measurements.
3) Something measured that I have overlooked
4) Something which the Data-bass measurements do not reveal.

Now, I am thinking it is all about FR!

Given the info provided but Steve and ShadyJ, I think I can rule out Impulse response being relevant since it is essentially a "subset" of the FR.
Q may be a major factor, but since the Q value is not usually revealed and hopefully should be reflected one way or another in the measurements of the end subwoofer system, it is probably not the best place to get traction.
That only leaves something not measured by Josh and I figure if there is something significant he (and the people he may have collaborated with) missed, it is not easily forthcoming. ...So I'll consider that a dead end for now.

So at this point, I'm going with FR as the problem I perceive with ported subs.

To that end, the Klipsch SW-310 is about the only ported sub (passive radiator) I have had in my home (I had ruled ported subs out before I moved here). It is the same as the SW-311 Ricci reviewed here, less room EQ and 100Watts (same box, drivers and passive radiators).

http://www.audioholics.com/subwoofer-reviews/sw-311-subwoofer-review/sw-311-measurements

Here is the basic FR:

Here is in-room response (and the result of ARC roomEQ)

Admittedly, he chose this location as the worst of three possibilities to demonstrate the result of ARC, but you can imagine how muddy this would be with a ~10dB hump next to the generally depressed output between 40 and 80Hz.

Unfortunately, my room offered a similar problem (probably not that bad, as I was running a pair) and Audyssey XT 32 could not mitigate it.

So the next thing I should do is see if using miniDSP to flatten in-room response will get clean sound out of a ported sub in my room!