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Why the fuss with subwoofer specs and brands?

jsilvela

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I've been doing a lot of learning since discovering ASR recently. When it comes to subwoofers, I find a lot less data (at ASR and in general), and more of brand-loyalty or brand-shaming than for other areas at ASR. Even in the subwoofer comparison thread by sweetchaos, the frequency response data is sparse. A lot of the models listed don’t have any frequency measurements.

Learning more, in any case: in mid-sized or smaller rooms, for low frequencies, the response is heavily influenced by the room, and clued in people like ASR readers are probably going to apply some EQ, either rolling their own or with Audissey/Dirac etc. Some will do multi-Sub to tame room modes with physics.

There was also a presentation by Floyd Toole shared by NTK on “Getting the bass right”.
A few jewels from that:
  • corner placement for subwoofers is highly recommended, and gives the signal a 6dB boost, to, em, boot
  • woofers are minimum-phase devices, and fixing their frequency response “fixes” their time-domain response
  • so, talk of “fast” and “slow” subs is misleading
EDIT: also relevant is this terrific video by Amir on "Music: how loud is loud?". To wit: human hearing is not equally sensitive to all frequencies. Sub-bass frequencies require a lot more SPL than midrange frequencies to get equivalent "loudness".

So, the thing is, if many (most?) people are getting a subwoofer for a mid-size or small room, and are going to place it on a corner with the extra 6dB amplification, and (ASR readers at least) are going to apply EQ to correct room response, does the subwoofer brand make such a difference? Do we really need top-of-the-line specs?
Is recommending 12-inch SVS’s to people with a small room akin to recommending 4-wheel-drive vehicles with high horsepower to urbanites?

I’ve started taking measurements with REW and a UMIK-1, and my recently purchased REL T/5x is doing fine, easily giving more than enough punch at 20Hz. I had been feeling embarrassed about the purchase until I started measuring.
 
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anotherhobby

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I don't like subs in corners for all sorts of reasons, but that wasn't your question.

As for top of the line specs on subs — yes, you may need them depending on room size, the speakers you pair them with, and your desired output levels. I have a pair of JL Audio e112's, which I think would fall into your category of higher end subs at $2500 each. However, they are in a pretty large space (>1000 sq/ft) and they start to compress around 105 dB below 30 Hz. I'm okay with that, but I'm also not reaching THX spec of 115 dB. If I wanted/need that in my life, I'd need to either get bigger or more. Little cheap subs aren't going to get that done. That said, you could probably pull off the same levels with 15-18" Dayton Ultimax subs that you built yourself for cheap, but the fit and finish will be limited by your skills.

SVS is a very popular recommendation because it's a reasonably well made affordable internet direct brand.
 
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anotherhobby

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I’d be curious about those reasons… I’m pretty new to subs
I think the video below explains the problems with subs in the corner pretty well. Also, in the last 4 rooms I've set up subs in, I've gotten better native room response from my subs when placed along the wall away from the corners. Too much "room sound" would be the primary problem I have with corner subs.

 

DVDdoug

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does the subwoofer brand make such a difference? Do we really need top-of-the-line specs?
I don't care about the "brand" (and I don't trust manufacturer's published specs..

But I'm sure you've heard car stereos (and maybe some home stereos) with annoying one-note boomy bass. The quality and performance of the sub is important. And although the bass is heavily influenced by the room, you still might be concerned if the sub can't reproduce the lowest frequencies. Usually bass is a compromise and it's often a trade-off between strong bass or deeper-smoother bass that's less efficient (requiring more power for the same overall bass).
 

ryanosaur

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I'll add this:
FR is silly with a Subwoofer. Most subs now are already DSP controlled and the Sub, out of the box, should likely show a pretty smooth response.
What becomes significantly more important are Long Term Compression and Distortion measurements. Even the CEA-2010 Bursts don't tell the whole story. So when you are shopping for Subs, you have to really know what your goals are, short term ("I want MOAR Bass!") to long term ("I want clean and linear Bass"). Along with that, how are you using the Subs (Music:Movies, Classic Rock or Orchestral, Jazz or Pipe Organ, Acoustic Folk or Jungle D&B)? How loud do you listen? And most importantly, HOW MUCH TOTAL OPEN ROOM VOLUME is the Sub going to be exposed to?

Myself, I love Pipe Organ. So I am chasing a very clean and linear SQ down to 16Hz. Not that 16 is all I care about, but that's the main goal for my system. I'm in a small irregular room about 2000cu.ft, and only 11x15'.
I'm going to look for Subs that perform as cleanly down to 16Hz as possible with minimal distortion and Compression as possible. I'm going to weigh what happens below as well, but that is less important than what is achieved from 16Hz and above. I also value Headroom and will likely use these for Movies as well, so considering my listening level of ~70-75dB I also know what my Sub will need to do in order to hit Reference level for a movie though I may not push it that hard.
On the other hand, If I only wanted to prop up some Standmounts for Music listening alone, I might look for something more efficient from 25Hz and up rather than chasing Infrasonics.

Learning how to understand the full measurements that you might see on AH and DataBass is very important and helpful. James Larson even wrote a series of articles over at AH breaking down how to interpret and understand the different measurements and what they mean. This is a very good place to start.

Placement and Acoustics is a whole other battle. You have to not only understand Room Acoustics but also how Low Frequecy Wavefronts work. If you have a regular rectangular closed room, Corner Loading all four Corners and/or symmetrically placing pairs of Subs is one way of approaching the problems. This is well defined by Todd Welti. Another approach is defined by Earl Geddes and requires strategically placing Subs asymmetrically around the room and away from the front wall. He also utilizes the Mains in this process if they are capable Full Range Speakers.
In the end, every room is different, and nothing can really be taken for granted without taking measurements and moving things around until you hit the right recipe.
 
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jsilvela

jsilvela

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I don't care about the "brand" (and I don't trust manufacturer's published specs..

But I'm sure you've heard car stereos (and maybe some home stereos) with annoying one-note boomy bass. The quality and performance of the sub is important. And although the bass is heavily influenced by the room, you still might be concerned if the sub can't reproduce the lowest frequencies. Usually bass is a compromise and it's often a trade-off between strong bass or deeper-smoother bass that's less efficient (requiring more power for the same overall bass).
Right, I hear what you're saying and I agree. But it's quite a fuzzy statement. How can I verify "the quality"?
What does one need to look for then? A minimum SPL at 20 Hz? A relatively flat response? Good controls for phase?
E.g. I saw Erin's comparison of budget subs. He recommended the two with the highest SPL, *not* the flattest response.
 
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jsilvela

jsilvela

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I think the video below explains the problems with subs in the corner pretty well. Also, in the last 4 rooms I've set up subs in, I've gotten better native room response from my subs when placed along the wall away from the corners. Too much "room sound" would be the primary problem I have with corner subs.

Thanks. I'm going to try out different locations esp. along the wall as you suggest. Now I have REW + a mic, I feel less blind.
But the video goes against the presentation by Floyd Toole and his book on Sound Reproduction which showed research on multi-subs.
Plus the message is "don't buy into multi-sub, buy into room treatment", so it's hard to know who to trust.
And that's part of the issue i see with subs: there are significant disagreements on the basics.
 
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jsilvela

jsilvela

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I'll add this:
FR is silly with a Subwoofer. Most subs now are already DSP controlled and the Sub, out of the box, should likely show a pretty smooth response.
What becomes significantly more important are Long Term Compression and Distortion measurements. Even the CEA-2010 Bursts don't tell the whole story. So when you are shopping for Subs, you have to really know what your goals are, short term ("I want MOAR Bass!") to long term ("I want clean and linear Bass"). Along with that, how are you using the Subs (Music:Movies, Classic Rock or Orchestral, Jazz or Pipe Organ, Acoustic Folk or Jungle D&B)? How loud do you listen? And most importantly, HOW MUCH TOTAL OPEN ROOM VOLUME is the Sub going to be exposed to?

Myself, I love Pipe Organ. So I am chasing a very clean and linear SQ down to 16Hz. Not that 16 is all I care about, but that's the main goal for my system. I'm in a small irregular room about 2000cu.ft, and only 11x15'.
I'm going to look for Subs that perform as cleanly down to 16Hz as possible with minimal distortion and Compression as possible. I'm going to weigh what happens below as well, but that is less important than what is achieved from 16Hz and above. I also value Headroom and will likely use these for Movies as well, so considering my listening level of ~70-75dB I also know what my Sub will need to do in order to hit Reference level for a movie though I may not push it that hard.
On the other hand, If I only wanted to prop up some Standmounts for Music listening alone, I might look for something more efficient from 25Hz and up rather than chasing Infrasonics.

Learning how to understand the full measurements that you might see on AH and DataBass is very important and helpful. James Larson even wrote a series of articles over at AH breaking down how to interpret and understand the different measurements and what they mean. This is a very good place to start.

Placement and Acoustics is a whole other battle. You have to not only understand Room Acoustics but also how Low Frequecy Wavefronts work. If you have a regular rectangular closed room, Corner Loading all four Corners and/or symmetrically placing pairs of Subs is one way of approaching the problems. This is well defined by Todd Welti. Another approach is defined by Earl Geddes and requires strategically placing Subs asymmetrically around the room and away from the front wall. He also utilizes the Mains in this process if they are capable Full Range Speakers.
In the end, every room is different, and nothing can really be taken for granted without taking measurements and moving things around until you hit the right recipe.
Thank you. This is great information and I will look for the James Larson articles.
What seems strange though, is the differentiation by music style. For "regular" bookshelf speakers, one looks for flat on-axis, good directivity etc.
I see e.g. Genelec monitors being recommended freely at ASR with a link to the review, with no caveats on the type of music.
My take-away from what I've read so far, is that low frequencies are far from a "solved problem".

One does see a difference between movies an music in that for movies, it's the LFE Kaboom that is sought.
So the one thing I know to do is look for subs that advertise for music ... but that means somewhat believing marketing materials.
 
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jsilvela

jsilvela

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Forgot to add this terrific video by Amir on "Music: how loud is loud?".
It's easy to forget that human audition is differently sensitive to different frequencies, and for low frequencies, we require A LOT more SPL for equivalent perception.
Doing tests recently, it's easy for me to get room-shaking bass that does not seem at all loud to my ears.
I mention this because until I saw that video I assumed "I just need my sub to do 70-80 db at 20hz".
 

HarmonicTHD

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Right, I hear what you're saying and I agree. But it's quite a fuzzy statement. How can I verify "the quality"?
What does one need to look for then? A minimum SPL at 20 Hz? A relatively flat response? Good controls for phase?
E.g. I saw Erin's comparison of budget subs. He recommended the two with the highest SPL, *not* the flattest response.
Next to linearity, the distortion over frequency at certain (often 96dB) SPL levels is a good indication if a speaker can play loud without distorting. Erin and Amir measure this. Manufacturers not so much unfortunately.
 

amirm

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Thanks. I'm going to try out different locations esp. along the wall as you suggest. Now I have REW + a mic, I feel less blind.
But the video goes against the presentation by Floyd Toole and his book on Sound Reproduction which showed research on multi-subs.
Plus the message is "don't buy into multi-sub, buy into room treatment", so it's hard to know who to trust.
And that's part of the issue i see with subs: there are significant disagreements on the basics.
I watched his videos a while ago and I definitely would go by what Dr. Toole would say. :)

Acoustic products are simply not an effective solution to frequencies below 100 Hz. Equalization is a must and works superbly (as does positioning, multi-sub, etc.).
 

Waxx

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I watched his videos a while ago and I definitely would go by what Dr. Toole would say. :)

Acoustic products are simply not an effective solution to frequencies below 100 Hz. Equalization is a must and works superbly (as does positioning, multi-sub, etc.).
You can fix room issues in the sub region, but it's very hard, expensive and rather intrusive in your room to do that. It's done in a lot of recording and mastering studio's, but know that acoustics is often the biggest part of the cost of setting up a studio, and it cost a fortune to do. The last time i was involved in that the budget was 30K€ for acoustics for a relative big music listening room, and that was not going all the way, only fixing the biggest issues, and involved an acoustician study the room and a fully rebuild of the internal space of that room (the basic structural concrete box was there, the rest is redone).

With DSP processing you can do 95% for way less money (even using the most expensive dsp arround), and the multisub theorie (both version) both can help a lot when done right. So I would also go that road and get some (at least more than one) decent subs (FR not to ragged, distortion low) that can get as loud and low as you want, and use dsp and placement in the room to fix the rest of the issues.
 

sigbergaudio

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I think the video below explains the problems with subs in the corner pretty well. Also, in the last 4 rooms I've set up subs in, I've gotten better native room response from my subs when placed along the wall away from the corners. Too much "room sound" would be the primary problem I have with corner subs.


This guy is

A) selling acoustic treatments, but using this to properly smooth the response below 100hz is next to impossible, and literally impossible in any regular, multi-purpose room.

B) apparently haven't heard of DSP which as opposed to acoustic treatments is very effective at smoothing the response below 100hz.

C) He claims adding additional subs at best improves / smoothens out the response with 1-2dB. This simply is not true.


In summary: This video is full of misinformation. Corner placement could be problematic before DSP, but are now (post DSP) usually a good placement. As always this is individual for each room, so the best way to find optimal placement is to experiment with all locations that are practically available to you.
 

Sancus

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Thank you. This is great information and I will look for the James Larson articles.
What seems strange though, is the differentiation by music style. For "regular" bookshelf speakers, one looks for flat on-axis, good directivity etc.
I see e.g. Genelec monitors being recommended freely at ASR with a link to the review, with no caveats on the type of music.
My take-away from what I've read so far, is that low frequencies are far from a "solved problem".

One does see a difference between movies an music in that for movies, it's the LFE Kaboom that is sought.
So the one thing I know to do is look for subs that advertise for music ... but that means somewhat believing marketing materials.

Frequency response is much less important for subs because they're 100% omnidirectional, so there's no difference between on-axis and off-axis response. This makes them very simple to EQ, and they are simple to construct in general(compared to speakers) since they don't have any crossovers. These factors cause commodification of subs, other than price, output, and distortion there's not really any other performance variables. Of course there are variables in terms of aesthetics, size, etc.

In addition, room effects are so strong in bass that they completely overwhelm any minor differences in sub FR. The result of all this is that subs are mostly interchangeable and it doesn't really matter which one you buy, so you might as well buy the cheapest one that has sufficient output for your use case. I say mostly because yes, there are crappy subs out there, especially in the sub-$500 ported category, but the usual suspects like Rythmik, SVS, PSA, JL Audio, etc have that stuff down.

Is recommending 12-inch SVS’s to people with a small room akin to recommending 4-wheel-drive vehicles with high horsepower to urbanites?

A 12-inch SVS sealed sub is closest to the smallest size that you can justify calling a subwoofer. People usually underestimate how much bass output is actually useful. At 20hz, 100dB sounds like 40dB at 1khz. It's fairly common for bass peaks to hit above 100dB, or even 105dB at an average listening level of around 75dBA. I've measured way higher than that on bass-heavy organ music or EDM. But any half-decent modern sub will compress silently, so even if the sub can't handle it, you generally won't notice that something is missing unless you're familiar with the correct sound.

It's usually better to have multiple small, reasonably priced subs like the SB1000 or even 3000 Micro than a single one, even if it's larger.
 
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jsilvela

jsilvela

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Frequency response is much less important for subs because they're 100% omnidirectional, so there's no difference between on-axis and off-axis response. This makes them very simple to EQ, and they are simple to construct in general(compared to speakers) since they don't have any crossovers. These factors cause commodification of subs, other than price, output, and distortion there's not really any other performance variables. Of course there are variables in terms of aesthetics, size, etc.

In addition, room effects are so strong in bass that they completely overwhelm any minor differences in sub FR. The result of all this is that subs are mostly interchangeable and it doesn't really matter which one you buy, so you might as well buy the cheapest one that has sufficient output for your use case. I say mostly because yes, there are crappy subs out there, especially in the sub-$500 ported category, but the usual suspects like Rythmik, SVS, PSA, JL Audio, etc have that stuff down.



A 12-inch SVS sealed sub is closest to the smallest size that you can justify calling a subwoofer. People usually underestimate how much bass output is actually useful. At 20hz, 100dB sounds like 40dB at 1khz. It's fairly common for bass peaks to hit above 100dB, or even 105dB at an average listening level of around 75dBA. I've measured way higher than that on bass-heavy organ music or EDM. But any half-decent modern sub will compress silently, so even if the sub can't handle it, you generally won't notice that something is missing unless you're familiar with the correct sound.

It's usually better to have multiple small, reasonably priced subs like the SB1000 or even 3000 Micro than a single one, even if it's larger.
Fantastic answer, thanks so much!
 

sigbergaudio

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Frequency response is much less important for subs because they're 100% omnidirectional, so there's no difference between on-axis and off-axis response. This makes them very simple to EQ, and they are simple to construct in general(compared to speakers) since they don't have any crossovers. These factors cause commodification of subs, other than price, output, and distortion there's not really any other performance variables. Of course there are variables in terms of aesthetics, size, etc.

In addition, room effects are so strong in bass that they completely overwhelm any minor differences in sub FR. The result of all this is that subs are mostly interchangeable and it doesn't really matter which one you buy, so you might as well buy the cheapest one that has sufficient output for your use case. I say mostly because yes, there are crappy subs out there, especially in the sub-$300 ported area, but the usual suspects like Rythmik, SVS, PSA, JL Audio, etc have that stuff down.

This is an oversimplification. An unlinear sub due to issues with the enclosure or the driver isn't necessarily just EQed flat without consequence, and in general especially boosting will massively increase distortion (if even possible). So native low end response is not inconsequential. Many subwoofers also roll-off and/or become unlinear quite quickly above 100hz, while others are linear to several hundred hz. Whether that matters depends on the use case of course. How hard subwoofers can be pressed without audible issues also varies. Some have well implemented limiters, some have none at all. Finally some subwoofers have significant distortion even when driven at moderate levels, which is not presented through the traditional CEA2010 tests. There are lots of subwoofer drivers with weak motors and various problems that aren't immediately apparent just based on published specs.

This being said I agree that purchasing subwoofers from the well-known and respected brands (for instance those mentioned) you can likely feel pretty confident that you get a well designed sub.
 
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