Curious about subwoofer/low frequency "tightness"/musicality. What does it even mean? What do YOU look for?

[Jiraya369]

I've been researching subs and i've been learning more and more, at first I thought i'd be happy with just a specified loudness at 20 hz, meaning it goes as deep as i'd want it to. But as i looked more and more I started seeing differing opinions on stuff

I see people talking about things in the title all the time and dismissing ported subwoofers or SVS subwoofers because they're "laggy" and sound "horrible". But then these same people go ahead and say that their speakers are far tighter. How is that the case? If we even take a look at the Blade Two Meta and Erin's group delay measurements, it measures worse than a 300 dollar RSL Speedwoofer 10e under 70 hz (Based on audioholics's measurements). Or if we look at something like the Genelec 8331A, it's just worse under 100 hz altogether.

Then there's some ported subs like the Klipsch RP-1600SW, it puts out group delay measurements that embarrasses most sealed subs. So at that point, i don't think a Genelec sub is really putting out anything better or worse, especially at these frequencies under 100 hz where IMO as long as the sound isn't completely easily horrible in terms of compression and distortion, it doesn't matter THAT much I think.

I'd like some insight into this. What do YOU guys think of/look for in a sub? A decent loudness capability that matches your room size/preferences alongside less than 20 ms group delay at less than 70 hz ought to be more than good enough I think.

 

[dlaloum]

Personally I think the focus on loudness and infrasonic performance over the last 20 years to the detriment of low distortion, has been severely missplaced.

I think that the THD (and resonances) leads to subwoofers being localisable, when playing frequencies that should not be localisable (below 60Hz) - thereby negatively affecting imaging and immersion.

With more recent setups like the D&M AVR's with 4 location specific subs being offered, the localisation of the sub becomes an issue - which means you need lower THD subs.

Also the use of Dirac ART, would I assume also have some performance limitations driven by THD... and would be more effective with low THD designs.

Currently subs with 10% THD are considered pretty good... in full range speakers, that would never be acceptable (let alone electronics)

We are, I think, on the cusp of a major rethink of subs....

 

[Jiraya369]

but is 10% THD even that bad when it's <50 hz? And like the SVS PB4000 Pro, although not the best in terms of group delay, does stay under ~2-6% THD at around 20hz based on Audioholics's review. Something like the JTR Captivator RS1 does ~20 hz at 102 db with ~6% THD. I mean Amir seemed pretty happy with the Genelec 8361 and the Neumann KH420 despite the horrendous distortion at those frequency levels.

I just think that under 60 hz it's just all so much difficult to distinguish that our rooms are going to be a bigger factor than the sub as long as it's better than the Speedwoofer 10e.

 

[Keith_W]

First things first: ignore any reviewer who does not back up their claims of audibility with measurements. This is ESPECIALLY true for subwoofers. Half of a subwoofer's performance depends on factors beyond the designer's control - where it was placed in the room, and how well it is integrated with the mains. Even a VERY GOOD subwoofer will sound "unmusical" or "flabby" (or just plain bad!) if the owner is ham fisted / ignorant.

That said, subwoofers are designed for different priorities. IMO, the best subwoofer is one that is designed to be as linear as possible down to 20Hz with as little group delay as possible. That means no ports, since ports sacrifice group delay in exchange for bass extension. That is my personal pet peeve - I hate ports. I would personally prefer to spend more money and get more subwoofers. Others are designed for small size, high SPL, low budget, etc. etc. You always have to give something up, and the question is what you want to give up. See Hoffman's Iron Law - small size, bass extension, high efficiency: pick two.

"Flabbiness" and "musicality" are subjective terms that have no clearly defined meaning. It is better to avoid terms like those and speak of objectively measurable phenomena.

 

[Curvature]

What @Keith_W wrote. Sub tightness is a function of 1 and 2 below, where I've listed everything else in order of descending importance along with how to achieve it.

1. Flat response (room position, EQ, multisubs).
2. Low decay (room design and treatment, Diract ART impulse response correction, Trinnov Waveforming or other source-sink method).
3. LF Extension (room position, sub size, although EQ can do a lot).
4. High SPL (room position, sub size).
5. Resonances (design competence).
6. Nonlinear distortion (sub size, design competence).
7. Group delay (sealed subs, although the measurements I've seen don't show audible GD in ported subs; it's possible GD can be a problem where the designer is not competent).

Servo mechanisms in subs work well, although I think they aren't necessary anymore because of the performance of new optimized sub drivers. Could be wrong, though.

 

[DVDdoug]

Curious about subwoofer/low frequency "tightness"/musicality. What does it even mean?

Who knows? ...Typical subjective review language which is useless without an explanation and/or without measurements to back-up whatever they are saying... or trying to say.

Here's another quote from Floyd Toole:

The NS-10M was admired because of its "tight" bass, a consequence of the deficiency of bass fundamental frequencies.

I see people talking about things in the title all the time and dismissing ported subwoofers or SVS subwoofers because they're "laggy" and sound "horrible".

You can make a good speaker either way. But, it's easier to foul-up a ported design.* Or sometimes one-note bass is intentional because "the kids" like a boomy-resonant woofer and you can get "more bass" cheaply and easily. Or it may be OK for movies (explosions and other non-musical "effects").**

There are some general characteristics of ported and sealed designs. I saved a link to this post which shows the trade-offs. The ported speaker has a lower cut-off frequency but a steeper slope. So at some point the curves cross and the sealed port is putting-out more.

A lot of home theater subs are small active sealed enclosures with EQ (analog or DSP) and lots of wattage to flatten and extend the bass.

Ported speakers that go down to 20Hz (with useful SPL) are rare and usually huge! And EQ doesn't work very well because at lower frequencies (below the tuning/cutoff) you mostly end-up with the woofer flopping around without putting-out much sound.

Pro subs used for live music and in dance clubs are usually large and ported and they typically they go-down to around 40Hz. These compromises allow for a loud-efficient speaker that can fill a large space with bass you can feel in your body. (The lowest note on a standard bass guitar is about 40Hz.)

I took the "pro PA" approach with my DIY subs. I built a pair of 15-inch subs in big ported boxes. They are "tuned" to go down to the 30Hz range with a slight 1-2dB "bump" to lower the -3dB cutoff frequency. (This was all modeled, not measured, but they can "rattle the walls" and they don't sound boomy or "bad".) They are passive because I had an extra amp.

What do YOU look for?

Smooth, deep, strong bass.



* Early "bass reflex" speakers in the 70's and 80's got a bad reputation. Bad designs are not that common these days. After the Thiele/Small research, and once computers became ubiquitous, it became easer to make a good speaker with less trial-and-error. I assume that bad reputation is why they changed the name to "vented" or "ported".

** The original subwoofers used in the movie Earthquake (1974) were just reproducing triggered low-frequency noise because the optical soundtracks at the time didn't support deep bass.

 

[Jiraya369]

First things first: ignore any reviewer who does not back up their claims of audibility with measurements. This is ESPECIALLY true for subwoofers. Half of a subwoofer's performance depends on factors beyond the designer's control - where it was placed in the room, and how well it is integrated with the mains. Even a VERY GOOD subwoofer will sound "unmusical" or "flabby" (or just plain bad!) if the owner is ham fisted / ignorant.

That said, subwoofers are designed for different priorities. IMO, the best subwoofer is one that is designed to be as linear as possible down to 20Hz with as little group delay as possible. That means no ports, since ports sacrifice group delay in exchange for bass extension. That is my personal pet peeve - I hate ports. I would personally prefer to spend more money and get more subwoofers. Others are designed for small size, high SPL, low budget, etc. etc. You always have to give something up, and the question is what you want to give up. See Hoffman's Iron Law - small size, bass extension, high efficiency: pick two.

"Flabbiness" and "musicality" are subjective terms that have no clearly defined meaning. It is better to avoid terms like those and speak of objectively measurable phenomena.

ok thanks for the fan-friggin-tastic answer

i had a feeling before but this confirms it and i have an idea now. Basically what i think happened is that, those blokes tried out a sub that was TOO powerful, and along with the room, the sub just became bloated. On the other hand, the sealed subs they use obviously give less output than ported ones, as a result the sub output was lower and the "lagginess" was also lower. Therefore allowing them to focus more on the upper frequencies, making it "musical"

I'm curious though, what's wrong with ported subs? The Arendal V subs or the Klipsch 1600SW show better performance than 90% of sealed subs, if not 95%+ of sealed subs. Well at least based on audioholics's measurements. I mean even Genelec subs are ported i think. What would you say is a good sub and what would you say is a bad sub as examples? curious

I think audio in general is improving in such a drastic rate that older ideas are starting to fade away, the Speedwoofer 10e, a 300 dollar sub, gives extremely good measurements in all aspects. The problem being the size mainly. Which lines up with Hoffman's law. Honestly I think size is the least problematic thing as long as expectations are realistic, for example people expecting 20 inch sub outputs from a cheap 10 inch one

 

[Jiraya369]

What @Keith_W wrote. Sub tightness is a function of 1 and 2 below, where I've listed everything else in order of descending importance along with how to achieve it.

1. Flat response (room position, EQ, multisubs).
2. Low decay (room design and treatment, Diract ART impulse response correction, Trinnov Waveforming or other source-sink method).
3. LF Extension (room position, sub size, although EQ can do a lot).
4. High SPL (room position, sub size).
5. Resonances (design competence).
6. Nonlinear distortion (sub size, design competence).
7. Group delay (sealed subs, although the measurements I've seen don't show audible GD in ported subs; it's possible GD can be a problem where the designer is not competent).

Servo mechanisms in subs work well, although I think they aren't necessary anymore because of the performance of new optimized sub drivers. Could be wrong, though.

ooh nice im a bit curious

what is nonlinear distortion? is it like THD or something?
When would group delay become a problem for you? Like do you have an idea of "oh yeah this sounds bad!" or something? Like what do you look for when looking for a sub? Oh and how is room design related to decay? So that you "trap" all the lingering frequencies so that the produced frequencies start and end faithfully?

 

[Jiraya369]

Who knows? ...Typical subjective review language which is useless without an explanation and/or without measurements to back-up whatever they are saying... or trying to say.

Here's another quote from Floyd Toole:





You can make a good speaker either way. But, it's easier to foul-up a ported design.* Or sometimes one-note bass is intentional because "the kids" like a boomy-resonant woofer and you can get "more bass" cheaply and easily. Or it may be OK for movies (explosions and other non-musical "effects").**

There are some general characteristics of ported and sealed designs. I saved a link to this post which shows the trade-offs. The ported speaker has a lower cut-off frequency but a steeper slope. So at some point the curves cross and the sealed port is putting-out more.

A lot of home theater subs are small active sealed enclosures with EQ (analog or DSP) and lots of wattage to flatten and extend the bass.

Ported speakers that go down to 20Hz (with useful SPL) are rare and usually huge! And EQ doesn't work very well because at lower frequencies (below the tuning/cutoff) you mostly end-up with the woofer flopping around without putting-out much sound.

Pro subs used for live music and in dance clubs are usually large and ported and they typically they go-down to around 40Hz. These compromises allow for a loud-efficient speaker that can fill a large space with bass you can feel in your body. (The lowest note on a standard bass guitar is about 40Hz.)

I took the "pro PA" approach with my DIY subs. I built a pair of 15-inch subs in big ported boxes. They are "tuned" to go down to the 30Hz range with a slight 1-2dB "bump" to lower the -3dB cutoff frequency. (This was all modeled, not measured, but they can "rattle the walls" and they don't sound boomy or "bad".) They are passive because I had an extra amp.


Smooth, deep, strong bass.



* Early "bass reflex" speakers in the 70's and 80's got a bad reputation. Bad designs are not that common these days. After the Thiele/Small research, and once computers became ubiquitous, it became easer to make a good speaker with less trial-and-error. I assume that bad reputation is why they changed the name to "vented" or "ported".

** The original subwoofers used in the movie Earthquake (1974) were just reproducing triggered low-frequency noise because the optical soundtracks at the time didn't support deep bass.

awesome comment my friend!

im wondering though, what is "strong" bass? or "useful" spl for you? the speedwoofer 10e is a 20x20x20 inch 300 dollar sub that goes down to 20 hz at 94 db with 18.6% THD So usable loudness ought to be 85-90. Add room gain and it's a capable one no? Or is it still not a useful spl?

 

[mhardy6647]

Y'all do understand that the typical manifestation of "THD" (principal harmonic component of the 'distortion') is doubling, yes? E.g., 20 Hz in to the transducer results in "lots" of 40 Hz out into the room/listening position relative to the level of of the desired 20 Hz output. It's not unpleasant, it's just wrong -- when and if reproduction of the 20 Hz 'fundamental' is the desired outcome. Is that bad? Depends. Formally, sure. Practically? meh.
You get what you get.

 

[dualazmak]

Using Adobe Audition's 3D Time(x-axis)-Fq(y-axis)-Gain(color-scale) color spectrum (soundprint analysis), you can objectively and visually observe the tightness and cleanliness of the low Fq sound (rectangular 8-wave, 3-wave, 1-wave tone burst signals) played by sub-woofers and woofers.
If you would be interested, please visit my posts on my project thread.

- Measurement of transient characteristics of Yamaha 30 cm woofer JA-3058 in sealed cabinet and Yamaha active sub-woofer YST-SW1000: #495, #497, #503, #507

- Precision measurement and adjustment of time alignment for speaker (SP) units: Part-1_ Precision pulse wave matching method: #493
- Precision measurement and adjustment of time alignment for speaker (SP) units: Part-2_ Energy peak matching method: #494
- Precision measurement and adjustment of time alignment for speaker (SP) units: Part-3_ Precision single sine wave matching method in 0.1 msec accuracy: #504, #507

- Reproduction and listening/hearing/feeling sensations to 16 Hz (organ) sound with my DSP-based multichannel multi-SP-driver multi-amplifier fully active stereo audio system having big-heavy active L&R sub-woofers: #782

- A nice smooth-jazz album for bass (low Fq) and higher Fq tonality check and tuning: #910, #63(remote thread)

This independent thread hosted by myself would be also of your reference, I assume:
An Attempt Sharing Reference Quality Music Playlist: at least a portion and/or whole track being analyzed by 3D color spectrum of Adobe Audition

 

[Oddball]

ok thanks for the fan-friggin-tastic answer

i had a feeling before but this confirms it and i have an idea now. Basically what i think happened is that, those blokes tried out a sub that was TOO powerful, and along with the room, the sub just became bloated. On the other hand, the sealed subs they use obviously give less output than ported ones, as a result the sub output was lower and the "lagginess" was also lower. Therefore allowing them to focus more on the upper frequencies, making it "musical"

I'm curious though, what's wrong with ported subs? The Arendal V subs or the Klipsch 1600SW show better performance than 90% of sealed subs, if not 95%+ of sealed subs. Well at least based on audioholics's measurements. I mean even Genelec subs are ported i think. What would you say is a good sub and what would you say is a bad sub as examples? curious

I think audio in general is improving in such a drastic rate that older ideas are starting to fade away, the Speedwoofer 10e, a 300 dollar sub, gives extremely good measurements in all aspects. The problem being the size mainly. Which lines up with Hoffman's law. Honestly I think size is the least problematic thing as long as expectations are realistic, for example people expecting 20 inch sub outputs from a cheap 10 inch one

While some think there is a problem with ported subs, some don't. Always good to have options.

It has already been noted what to look for in a solid sub, thus no need to repeat. What I will say it that one can't really expect (in most rooms) that a single sub will do a great job. Two or more subs are generally needed to get the best of the low end.

I thought I knew a lot about the bass and had plenty of great resources to reproduce it in spades and with lots of headroom to spare. But then, 4 weeks ago D&M released Dirac ART on their upper tier AV gear. After ART experience, I do think I understand the bass a whole lot better. Sub is a foundation, but then it is all in the room or EQ system. Double bass arrays and recently Trinnov wave-forming are also examples of tools that are taming the room - the worst enemy of even the greatest subs.

 

[Curvature]

what is nonlinear distortion? is it like THD or something?

Nonlinear distortion is when additional unwanted frequencies are created by the device. THD is an example of a measurement of one kind of nonlinear distortion with a single tone as the input signal. It is not very relevant for music or our hearing.

When would group delay become a problem for you? Like do you have an idea of "oh yeah this sounds bad!" or something?

GD is more of a theoretical problem as far as I can tell. I don't know that I've ever heard it in isolation as an issue. Josh Ricci of Data-Bass used to measure it: https://data-bass.com/systems/5ba943ca7cbbd6000447f8b5 Not much came from those efforts other than confirming that it doesn't seem to be an issue.

Like what do you look for when looking for a sub?

I look for the biggest and most powerful sub I can afford, that fits my space, has CTA2010 measurements, has XLR inputs.

The bigger issue is integrating subs with mains and making the frequency response even:

• The majority of audible improvement is even frequency response.
• To do the above, you need a measurement microphone, some way to EQ, and some way to introduce an LPF for the sub, and HPF for the mains.
• If you have money and room and willingness for more, then multiple subs.
• Low frequency treatment is good, and works, but is very large and heavy and expensive. Probably impractical for most people.
• If you have more money, buy an AVP with Diract ART.

Oh and how is room design related to decay

In rooms the dimensions and materials determine bass response. You can calculate it in advance with some accuracy just knowing the dimensions. The calculations will be off to some degree because of material properties of walls, which are a little too complicated to cover (the short version is that even the most solid of materials flex, which introduces phase shifts to the reflected waves).

Bass behaviour in rooms causes areas of big peaks and dips, different per frequency. The idea is to find a place for your sub where the response is the most even, relatively speaking. It will never be completely flat unless you invest a house's worth of acoustic reconstruction into the room. All of the same stuff applies to your listening position. And if you are sitting in a peak, that frequency will have a long decay.

See below for a real-room measurement from a 2001 Genelec paper on bass EQ for rooms. The timescale is in seconds. https://www.genelec.com/publications

Thankfully, with a little measurement and EQ you can even out the response decently well, even if you can't move the sub or your listening position very much because of how the furniture is arranged or other reasons.

 

[Jiraya369]

t

Nonlinear distortion is when additional unwanted frequencies are created by the device. THD is an example of a measurement of one kind of nonlinear distortion with a single tone as the input signal. It is not very relevant for music or our hearing.

GD is more of a theoretical problem as far as I can tell. I don't know that I've ever heard it in isolation as an issue. Josh Ricci of Data-Bass used to measure it: https://data-bass.com/systems/5ba943ca7cbbd6000447f8b5 Not much came from those efforts other than confirming that it doesn't seem to be an issue.

I look for the biggest and most powerful sub I can afford, that fits my space, has CTA2010 measurements, has XLR inputs.

The bigger issue is integrating subs with mains and making the frequency response even:

• The majority of audible improvement is even frequency response.
• To do the above, you need a measurement microphone, some way to EQ, and some way to introduce an LPF for the sub, and HPF for the mains.
• If you have money and room and willingness for more, then multiple subs.
• Low frequency treatment is good, and works, but is very large and heavy and expensive. Probably impractical for most people.
• If you have more money, buy an AVP with Diract ART.

In rooms the dimensions and materials determine bass response. You can calculate it in advance with some accuracy just knowing the dimensions. The calculations will be off to some degree because of material properties of walls, which are a little too complicated to cover (the short version is that even the most solid of materials flex, which introduces phase shifts to the reflected waves).

Bass behaviour in rooms causes areas of big peaks and dips, different per frequency. The idea is to find a place for your sub where the response is the most even, relatively speaking. It will never be completely flat unless you invest a house's worth of acoustic reconstruction into the room. All of the same stuff applies to your listening position. And if you are sitting in a peak, that frequency will have a long decay.

See below for a real-room measurement from a 2001 Genelec paper on bass EQ for rooms. The timescale is in seconds. https://www.genelec.com/publications

View attachment 486123

Thankfully, with a little measurement and EQ you can even out the response decently well, even if you can't move the sub or your listening position very much because of how the furniture is arranged or other reasons.

thank you

 

[Curvature]

Nonlinear distortion is when additional unwanted frequencies are created by the device. THD is an example of a measurement of one kind of nonlinear distortion with a single tone as the input signal. It is not very relevant for music or our hearing.

GD is more of a theoretical problem as far as I can tell. I don't know that I've ever heard it in isolation as an issue. Josh Ricci of Data-Bass used to measure it: https://data-bass.com/systems/5ba943ca7cbbd6000447f8b5 Not much came from those efforts other than confirming that it doesn't seem to be an issue.

I look for the biggest and most powerful sub I can afford, that fits my space, has CTA2010 measurements, has XLR inputs.

The bigger issue is integrating subs with mains and making the frequency response even:

• The majority of audible improvement is even frequency response.
• To do the above, you need a measurement microphone, some way to EQ, and some way to introduce an LPF for the sub, and HPF for the mains.
• If you have money and room and willingness for more, then multiple subs.
• Low frequency treatment is good, and works, but is very large and heavy and expensive. Probably impractical for most people.
• If you have more money, buy an AVP with Diract ART.

In rooms the dimensions and materials determine bass response. You can calculate it in advance with some accuracy just knowing the dimensions. The calculations will be off to some degree because of material properties of walls, which are a little too complicated to cover (the short version is that even the most solid of materials flex, which introduces phase shifts to the reflected waves).

Bass behaviour in rooms causes areas of big peaks and dips, different per frequency. The idea is to find a place for your sub where the response is the most even, relatively speaking. It will never be completely flat unless you invest a house's worth of acoustic reconstruction into the room. All of the same stuff applies to your listening position. And if you are sitting in a peak, that frequency will have a long decay.

See below for a real-room measurement from a 2001 Genelec paper on bass EQ for rooms. The timescale is in seconds. https://www.genelec.com/publications

View attachment 486123

Thankfully, with a little measurement and EQ you can even out the response decently well, even if you can't move the sub or your listening position very much because of how the furniture is arranged or other reasons.

Oh, and I should add that with even frequency response, the decay times will even out to some degree as well and be less obvious. In general humans are not very sensitive to bass decays, so if shortening them is not practical through treatment or other means, then don't worry about it.

 

[Oddball]

Oh, and I should add that with even frequency response, the decay times will even out to some degree as well and be less obvious. In general humans are not very sensitive to bass decays, so if shortening them is not practical through treatment or other means, then don't worry about it.

To that point it seems that most people in ART threads are bedazzled with reduction in decay times, that as you say, goes to some extent hand in hand with the more even frequency response.

We are starting to see a ruler flat sub response at 1/6 smoothing - not something I would ever hope to see from a system that is not in 6 figures and not installed by the elvish kind. Decay will go up with SPL but still way better than what we were used to.

 

[sigbergaudio]

I'm curious though, what's wrong with ported subs? The Arendal V subs or the Klipsch 1600SW show better performance than 90% of sealed subs, if not 95%+ of sealed subs. Well at least based on audioholics's measurements. I mean even Genelec subs are ported i think. What would you say is a good sub and what would you say is a bad sub as examples? curious

There's nothing inherently wrong with a ported subwoofer that is designed properly. But they are generally much larger than a sealed subwoofer - and many people today would not like a super large sub.

 

[HalSF]

My subjective take on this discussion, as with most advanced sub discourse, is that it’s being directed specifically at me, and it’s telling me, “You idiot with your single SVS subwoofer instead of two or more, calibrated without microphone and room software and room treatments, why are you even alive, your happy audio world is nothing but delusion and darkness, your listening room with its soggy bass is a peat bog of stupidity, know FUD and tremble in fear.”

 

[Oddball]

My subjective take on this discussion, as with most advanced sub discourse, is that it’s being directed specifically at me, and it’s telling me, “You idiot with your single SVS subwoofer instead of two or more, calibrated without microphone and room software, why are you even alive, your happy audio world is nothing but delusion and darkness, your listening room with its soggy bass is a peat bog of stupidity, know FUD and tremble in fear.”

I would not go that far. Would trade lots of hardware for more music and movies that I would love to hear/see but are not out there. While it is obviously important how we enjoy the content, the content is by far more important.

 

[Jiraya369]

My subjective take on this discussion, as with most advanced sub discourse, is that it’s being directed specifically at me, and it’s telling me, “You idiot with your single SVS subwoofer instead of two or more, calibrated without microphone and room software and room treatments, why are you even alive, your happy audio world is nothing but delusion and darkness, your listening room with its soggy bass is a peat bog of stupidity, know FUD and tremble in fear.”

lmao

im of the side that a subwoofer, if it's a half competent one, is going to be always better than not having one. So you having an SVS one already puts you in the top 50% of audiophiles as imo a full range response is more important than just having a 9k usd+ setup that's pristine till 80-120 hz. Need muh bass