Subwoofer Comparison

[Sancus]

Personally, I don't care about group delay anywhere other than where I intend to cross the speaker over to another speaker (mains, for example).

That said, I did provide it in my last review of the SVS PB-2000 (compared to the Monolith 12 THX, to boot):

I think he meant the cheap one which you also reviewed(Monoprice 9723), but previously stated you didn't have group delay readily available. However, you did note a resonance at 100hz and a port tuning somewhere around 35hz.

I do think there's a bit of a sample bias going on here. I think databass tended(past tense ) to measure only the cream of the crop. The manufacturers sending their subs in for testing tend to be the manufacturers that are confident in their sub's objective performance. You don't see a lot of the cheaper audiophile brand subs being tested, which may not show such excellent performance.

Subjectively, my Infinity R12 and Monoprice 12($99) subs do sound "slower" to my ears. It could easily be the room's they're in, though. I've never tried bringing them out into another room for testing.

I don't really think of SVS subs as the "cream of the crop", I mean the SB12-NSD was often on sale for $400... but they are certainly a step above the cheapest budget stuff. As I've noted previously, SVS seems to have a trend of having higher group delay, and yet I've never heard anybody say SVS subs are slow either. I'm not sure "x sub is slow" feedback tends to have ANY correlation with the properties of a sub at this point, rather than a correlation with particular room modes and how much a particular sub tends to excite them.

That said, the Monoprice 12(9723) is a $99 ported sub with a tuning well into the audible range. Definitely not what I would pick if I was even slightly worried about "slow sub syndrome", lol.

 

[Trdat]

Databass measured group delay, as well as a few other time related metrics which I think are sufficient for time related performance assessment. We don't hear time related bass issues well at all.

1. Room issues
2. Position issues (similar to room issues, but fixable)
3. Too much extension(lower extension will sound slower, because those frequencies are slower to develop).
4. Expectation bias (there's a lot of this, with companies like REL marketing their subs as such, which introduces expectation bias)

My post was written from a more measuring/testing perspective because after purchasing my SVS SB1000 I was absolutely heartbroken that an audiophile sub design can have such a high QTS driver in such an extremely high QTC alignment. Also, I would like to learn how to align subs in future or purchase a sub that gives me what I am looking for.

My room has a decay of about .2 .3(pretty good) and when comparing my DIY sub to my SVS SB1000, the SVS has literally double bass for the one bass note. Its clearly audible. But like you mentioned its a sub under a 1k. So perhaps that what you get for that price range.

If your sub(s) sounds too slow, I would:

1. Measure to see what your working with
2. Experiment with position, crossover, and EQ, and remeasure
3. If you've got multiple subs, make sure they're time aligned to you ears(impulse response is appropriate for this)

Ive time aligned, experimented with absolutely everything.

If your subs are time aligned you've got a neutral response, and it still sounds too slow, add a filter to remove everything under 30Hz. You'll lose a lot of the feel, but it will definitely sound faster, if that's what you want.

I have also tried this. Again, I understand that is what I paid for. I didn't expect that. I will check out and compare the impulse resonses and group delay for more expensive Subs, and perhaps over 1k they are all reasonable in results and equate to a non audible slowness like you said.

With my DIY sub I am more than happy.

 

[Trdat]

Well that would explain why it's not important, right? If every professional sub manufacturer is aware that they need to keep these measurements reasonable, and designing subs seems to be quite a lot simpler than designing multi-way speakers, then very few subs are going to have any issues in that area.

In fact that seems to be the case... data-bass.com shows impulse response, waterfall, and group delay for every sub they've measured, and just about every single one I've looked at from a significant manufacturer has no issues. When there is an issue, such as with the Danley DTS-10, it shows up clearly by measuring group delay. That would indicate that any time domain issues likely to be audible will always show up in group delay. So from the consumer perspective(not manufacturer) the other measurements/graphs don't seem to provide much useful information.

Great, Ill check out data-bass.com.

 

[Trdat]

Personally, I don't care about group delay anywhere other than where I intend to cross the speaker over to another speaker (mains, for example)

That said, I did provide it in my last review of the SVS PB-2000 (compared to the Monolith 12 THX, to boot):
https://www.audiosciencereview.com/...pro-12-inch-subwoofer-objective-review.18120/

Okay, I am not an expert but that blue line looks pretty bad I can only imagine how bad my SVS SB1000 graph would look like. My DIY sub is literally flat(ok slight exageration) in simulating software. The red looks like it more than acceptable. Please correct me if I am wrong. But if that blue line is anything similar to my SVS SB1000 then it might explain why my DIY sub with a flatter line sounds significantly more fast.

 

[richard12511]

My post was written from a more measuring/testing perspective because after purchasing my SVS SB1000 I was absolutely heartbroken that an audiophile sub design can have such a high QTS driver in such an extremely high QTC alignment. Also, I would like to learn how to align subs in future or purchase a sub that gives me what I am looking for.

My room has a decay of about .2 .3(pretty good) and when comparing my DIY sub to my SVS SB1000, the SVS has literally double bass for the one bass note. Its clearly audible. But like you mentioned its a sub under a 1k. So perhaps that what you get for that price range.



Ive time aligned, experimented with absolutely everything.



I have also tried this. Again, I understand that is what I paid for. I didn't expect that. I will check out and compare the impulse resonses and group delay for more expensive Subs, and perhaps over 1k they are all reasonable in results and equate to a non audible slowness like you said.

With my DIY sub I am more than happy.

As @Sancus mentioned above, and @hardisj showed above, SVS subs do show oddly high group delay for some reason(multiple times worse than competitors), so maybe that really is what your hearing.

 

[ernestcarl]

@Trdat

Don't you use any room correction software? If I'm not mistaken, something like Audiolense might be able to mitigate some of that delay -- by adding even more total system delay.

My room has a decay of about .2 .3(pretty good) and when comparing my DIY sub to my SVS SB1000, the SVS has literally double bass for the one bass note. Its clearly audible. But like you mentioned its a sub under a 1k. So perhaps that what you get for that price range.

I'd look at the T60M for the bass. Is this double bass note sound coming from only the sub itself in isolation (mains muted) or with the mains+sub combined?

 

[Haint]

Okay, I am not an expert but that blue line looks pretty bad I can only imagine how bad my SVS SB1000 graph would look like. My DIY sub is literally flat(ok slight exageration) in simulating software. The red looks like it more than acceptable. Please correct me if I am wrong. But if that blue line is anything similar to my SVS SB1000 then it might explain why my DIY sub with a flatter line sounds significantly more fast.

Wouldn't the SB1000, by virtue of being sealed, presumably have less group delay than the ported PB2000? Regardless, I'd say it's dubious there is any scientific support that 30Hz and below group delay is audible. I would caution that your intimate familiarity with these measurements (from your DIY designs) may be creating a confirmation bias that your brain is making a reality.

 

[Trdat]

Wouldn't the SB1000, by virtue of being sealed, presumably have less group delay than the ported PB2000? Regardless, I'd say it's dubious there is any scientific support that 30Hz and below group delay is audible. I would caution that your intimate familiarity with these measurements (from your DIY designs) may be creating a confirmation bias that your brain is making a reality.

Possibly, and I could be missing something or not understanding another variable at play. The only argument without measurements I can make is that each time I built a DIY sub going down a notch in QTC the slam and transients improved leaving my SVS sub on the bench or at least for movies and television.

There is also the music variable, most music you can't tell the difference its with dance music that it becomes more obvious. The last variable that it could be is the cabinet and its vibration at higher SPL, again this comes down to price. So yes, at low volumes its less noticable. My point is that there could some type of confirmation bias, I won't rule it out but the improvement in my DIY subs is noticable and can have nothing to do with slow bass but possibly from better cabinet structure and a better driver.

I can measure with REW but how much can that give us to figure out these variables? I understand the science and of course I haven't heard the big guns of subs and don't doubt them at all, but a high QTS driver needs a large cabinet right? A QTS of .55(SVS driver) in a 30 litre sealed cabinet seems small to me. If I drop in a driver in the same cabinet with a low QTC designed for small enclosures your telling me the difference will not be audible? I am really curious cause maybe I have had it wrong all this time. If there is no difference then it is cabinet and not slow bass or some other variable that I have missed but blamed the slowness.

 

[Trdat]

@Trdat

Don't you use any room correction software? If I'm not mistaken, something like Audiolense might be able to mitigate some of that delay -- by adding even more total system delay.

I'd look at the T60M for the bass. Is this double bass note sound coming from only the sub itself in isolation (mains muted) or with the mains+sub combined?

I feel audiolense makes it worse, leaving it with its natural roll off is better. Best is no convolution at all with subs that is. Of course I am a big fan of convolutions.

100% from the sub isolated.

 

[Trdat]

As @Sancus mentioned above, and @hardisj showed above, SVS subs do show oddly high group delay for some reason(multiple times worse than competitors), so maybe that really is what your hearing.

I think it's a possibility. But with many saying its inaudible now I am moving towards the fact that it is a cheap sub and that the same group delay in a better cabinet might in fact actually be inaudible.

 

[Sancus]

Wouldn't the SB1000, by virtue of being sealed, presumably have less group delay than the ported PB2000? Regardless, I'd say it's dubious there is any scientific support that 30Hz and below group delay is audible. I would caution that your intimate familiarity with these measurements (from your DIY designs) may be creating a confirmation bias that your brain is making a reality.

Confirmation bias is no doubt a significant problem in this area. That said, audibility below 50hz of any time domain issues isn't well supported by research, but I also haven't heard of any research below 40hz or so. I think it's just an assumption? I've only seen mention in a forum post of 15ms being a threshold at 40-80hz, but I couldn't find the referenced study(allegedly Aldoshina 1985, who is an AES-published researcher, but I can't find anything prior to the 90s).

There was additionally a long thread here where a claim was made that an addition of 20ms GD at ~45hz(?) was audible in abx.

There is no group delay test of the SB-1000 I've been able to find, but the SVS SB12-NSD did exceed those thresholds. However, data-bass said this wasn't audible.

In any case, as I note in my post below about SVS subs which I will just quote from its parent thread, sealed subs from many many other manufacturers stay below these thresholds, and of course ported subs have the typical increased GD around the tuning frequency, but for the better ported subs(read: ones I would actually buy) their tuning frequency is typically below 20hz, eg Rythmik's FV15-HP.

SB/PB-3000. What some might term "excessive" group delay is very common to sealed as well as ported SVS subs. For example SB12-NSD, PB-2000 Pro, etc. The reason for it is probably due to DSP they've chosen to use. Sealed/sealed-mode subs from every other reputable manufacturer(eg: JL, JTR, Rythmik, PSA, Hsu, etc) tend to have group delay well below 1 cycle at all frequencies. Of course, port tuning delay is unavoidable and well understood.

Would it be audible? I'll note that data-bass claims that the SB12-NSD's group delay wasn't audible, despite being high at >30hz. Although I might personally buy from a manufacturer with better measurements in this area, I do suspect all I would be doing is avoiding a psychological difference caused by looking at graphs I wouldn't buy ported subs with a tuning frequency in the audible range, either.

I haven't seen much good evidence regarding low frequency group delay audibility. Audioholics' summary page states group delay is only an issue above 50hz, where it should stay below 1 cycle. I found one poster mentioning a 1985 study but not sure which exact one it is, and even then, frequencies below 40hz weren't tested.

I think it's a possibility. But with many saying its inaudible now I am moving towards the fact that it is a cheap sub and that the same group delay in a better cabinet might in fact actually be inaudible.

If you think a time domain issue with the SVS is really the problem, you can test it yourself by buying a sealed sub from any of the manufacturers who show excellent GD(as listed above, but PSA, Rythmik, etc) and then A/B testing it after room correction.

Of course it won't be a perfect A/B, and there are so many potential frequency response issues with subs, especially if you don't have more than one using room correction, that is why I tend to think group delay is less important. It might be audible in a situation where you already have 4 subs and perfect DSP for them, but most people don't have that.

They have 1 sub and imperfect(if any) DSP, which almost always means they have frequency response problems that are much more audible.

 

[sweetchaos]

Improvements:

Added "High Pass Filter" column:
Also known as 'low-cut filter'. There are 3 methods of implementing a "High Pass Filter" (aka HPF).
A) Where the subwoofer manufacturer implemented a fixed HPF for RCA/XLR inputs/outputs at the typical crossover point of 80hz (sometimes close to it). Essentially, you send the signal to sub, the sub applies the HPF and sends the rest of the signal to the speakers. Often times, subs that were made for "studio monitors" have this option.
B) Where the subwoofer manufacturer implemented it's own fixed HPF below very low frequencies (say, between 12hz and 30hz). Modern non-DIY active subwoofers have it's own HPF filter for very low frequencies (say 10-30hz). You won't know about these, because manufacturers implement these in the crossover/DSP, but won't advertise that they did this.
C) Where the subwoofer manufacturer implemented a *variable* HPF, but only for very low frequencies (say, between 12hz and 30hz). The user can *selectively* apply their chosen HPF to cut some very low frequencies using the subwoofer's dip-switches/user-interface. Example: Arendal's subsonic filters can filter "Hz: 12,16,21,25,31 with dB/octave: 6,12 using on-screen-display."

Haven't filled out all subs yet, but started... ^^

On that note, I'm curious to the reason why SVS (and Revel and a few others) used to make subs with HPF at the typical crossover of 80hz, but no longer do and just use low pass filter now?

 

[Sancus]

Improvements:



Haven't filled out all subs yet, but started... ^^

On that note, I'm curious to the reason why SVS (and Revel and a few others) used to make subs with HPF at the typical crossover of 80hz, but no longer do and just use low pass filter now?

If I had to guess, it's because the vast majority of their sales are to HT people who have crossovers in their AVRs and weren't using the ones in the subs at all.

 

[MZKM]

Personally, I don't care about group delay anywhere other than where I intend to cross the speaker over to another speaker (mains, for example).

That said, I did provide it in my last review of the SVS PB-2000 (compared to the Monolith 12 THX, to boot):
https://www.audiosciencereview.com/...pro-12-inch-subwoofer-objective-review.18120/

20Hz is 50ms, so at 20Hz the SVS is over 2 cycles behind, that’s not super great. But again, is it even audible?

 

[ernestcarl]

I think it's a possibility. But with many saying its inaudible now I am moving towards the fact that it is a cheap sub and that the same group delay in a better cabinet might in fact actually be inaudible.

While I'm not completely dismissing the thought that GD differences might be contributing to some of this experience of yours, it is possible that it may be something else altogether like an audible resonance not present in your own subs -- only way to really show this clearly is with measurement comparisons between them using the same setup conditions as a control.

 

[Trdat]

Confirmation bias is no doubt a significant problem in this area. That said, audibility below 50hz of any time domain issues isn't well supported by research, but I also haven't heard of any research below 40hz or so. I think it's just an assumption? I've only seen mention in a forum post of 15ms being a threshold at 40-80hz, but I couldn't find the referenced study(allegedly Aldoshina 1985, who is an AES-published researcher, but I can't find anything prior to the 90s).

If it is inaudible, the problem here is that we have a cheap sub that potentially has other variables that might be resulting in a perceived slow bass. Ie. Resonances from the cabinet.

There was additionally a long thread here where a claim was made that an addition of 20ms GD at ~45hz(?) was audible in abx.

Fascinating, I wonder if there is more research out there.

I have cut off the lower frequencies and there is an audible difference. Previously when I said there wasn't any difference was with a convolution(perhaps time alignment wasn't perfected although with my DIY sub convolution makes it better), I just tried it without a convolution and reduced the lower freqencies with parametric EQ, it is better. Perhaps this helps us understand what is happening. In saying that, adding lower frequencies to my DIY sub doesn't cause any slowness.

There is no group delay test of the SB-1000 I've been able to find, but the SVS SB12-NSD did exceed those thresholds. However, data-bass said this wasn't audible.

Interesting.

Have we considered that it might be part of SVS design concept to provide slightly boomier bass to appeal to the mass market?

If you think a time domain issue with the SVS is really the problem, you can test it yourself by buying a sealed sub from any of the manufacturers who show excellent GD(as listed above, but PSA, Rythmik, etc) and then A/B testing it after room correction.

They have 1 sub and imperfect(if any) DSP, which almost always means they have frequency response problems that are much more audible.

So again potential bias here, but I went from the SVS to a DIY Dayton in a .75 QTC and the difference was audible, then I changed the Dayton to a .65 and I got improvement again. The jump from the SVS to the .75 QTC was insignificant but from the SVS to the .65 was significant. Then I went with the Dayton RSS315HO(designed for small enclosures) in a extremely large cabinet for its parameters 60litres and hit .41 QTC and even when using DSP to get a flat frequency till 30 hz I don't feel any slowness but with the previous subs I was always edging for a little tighter. Of course not A/B testing and I know this is all conjecture, I am not going against science just saying that there is one variable that I am noticing whatever it might be. And if we stick to science the most likely culprit is just the price tag of the sub. We can't expect miracles from a $500 dollar sub. But the potential for some audibility for slowness in the lower frequencies merits further research.

 

[Trdat]

And doesn't an impulse response show us how a sub woofer settles after a note? We are looking at group delay but I was under impression imulse response also can indicate the control over the woofer in the given enclosure.

 

[_thelaughingman]

SVS PB1000PRO came today, have a tall task of finding the right spot for it and redo the stereo placement.

 

[sweetchaos]

View attachment 118005

SVS PB1000PRO came today, have a tall task of finding the right spot for it and redo the stereo placement.

Niiiccceeeee! Enjoy!

 

[richard12511]

I have cut off the lower frequencies and there is an audible difference. Previously when I said there wasn't any difference was with a convolution(perhaps time alignment wasn't perfected although with my DIY sub convolution makes it better), I just tried it without a convolution and reduced the lower freqencies with parametric EQ, it is better. Perhaps this helps us understand what is happening. In saying that, adding lower frequencies to my DIY sub doesn't cause any slowness.

It very well may be a group delay issue, given that SVS generally show poor group delay performance. As mentioned, in the lowest frequencies, SVS subs are generally 2-3 full cycles behind other great sub brands.

My main subs are JTR RS2s. They're sealed dual 18" woofer subs. With them, I don't perceive any "slowness" whatsoever. Databass hasn't measured the RS2, but they did measure the S2, and the group delay performance is much better than the SVS subs I've seen. Here are the databass measurements of the S2. The RS2 is the S2's successor, and the main differences between the RS2 and the S2(from Jeff, the designer) is about 2dB more distortion limited output, and significantly less distortion below 25Hz. No idea what the group delay differences are between the RS2 and S2 are, but I hear no "speed" related issues with the RS2.

Have we considered that it might be part of SVS design concept to provide slightly boomier bass to appeal to the mass market?

Interesting question. For you, the lack of speed is obviously a negative, but do you think others may see what you're hearing as a positive?