Why the fuss with subwoofer specs and brands?

[jsilvela]

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.

Great information, thanks.
> apparently haven't heard of DSP

I have the impression that this is down to "tribes" and brand loyalty. I think a lot of audiophiles still worship at the altar of "thou shalt not alter the signal between source and speaker".
I have noticed since starting to measure, that my bookshelf speakers are exciting a room mode at 44Hz or so, giving me "boomy" bass, and definitely DSP seems the way to go, as my bookshelf speakers don't have much placement freedom.

So, the prefix for the video should be "If you're unwilling to apply DSP, then do this".

 

[Sancus]

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.

Sure, I know all that, the oversimplification is intentional. I think those factors are of primarily academic interest to most buyers. Honestly, if you're only buying one small sub you have bigger real problems than distortion at moderate levels and hypothetical linearity issues above 100hz.

My experience is that bad limiters are very few and far between, even my ancient SVS SB12 NSD which spent more time with the clip light on than off would only exhibit audible issues in very specific home theatre edge cases. That is why I did mention cheap ported subs as they're by far the most likely to make bad noises when pushed. I think as long as you avoid anything with a port tuning in the audible range and stick with brands that have been through CEA2010 without the reviewer calling out any strangeness, you're fine.

 

[ryanosaur]

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.

I’m not advocating a furthering of the myth of musical vs HT subs. That is a red herring.
It is about how you are going to use a product that should determine what you look for. It is essentially a values driven decision.
My example of propping up a small standmount is just that, and no different than understanding how compression effects may hamper performance of a Tower. One may very well find themselves buying such a Speaker and thinking they are fine to 30 Hz when in fact there may be audible compression indicating a much higher crossover to a Sub.

Lose the mythology. You already commented that fast and slow characteristics in marketing shouldn’t be paid attention to. This is no different. Group Delay measurements will show you whether a Sub is suitable for any usage or should be looked beyond. Many ported Subs show excellent GD characteristics, for example, and shouldn’t be considered a poor choice just because they have a port.
That becomes a discussion for being able to see if there are any resonances due to the ports and more homework.

 

[sigbergaudio]

Great information, thanks.
> apparently haven't heard of DSP

I have the impression that this is down to "tribes" and brand loyalty. I think a lot of audiophiles still worship at the altar of "thou shalt not alter the signal between source and speaker".
I have noticed since starting to measure, that my bookshelf speakers are exciting a room mode at 44Hz or so, giving me "boomy" bass, and definitely DSP seems the way to go, as my bookshelf speakers don't have much placement freedom.

So, the prefix for the video should be "If you're unwilling to apply DSP, then do this".

But being unwilling to apply DSP in the low end of the frequency is just a bad idea if you want accurate sound reproduction. And I'm all for acoustic treatment of the room, the same speakers in two differently treated rooms actually sounds like the famous "night and day difference" (as opposed to just about any other change you can make), but you need incredible amounts to fix the low end. So I would recommend acoustic treatment and DSP. It's not either or.

 

[anotherhobby]

Great information, thanks.
> apparently haven't heard of DSP

I have the impression that this is down to "tribes" and brand loyalty. I think a lot of audiophiles still worship at the altar of "thou shalt not alter the signal between source and speaker".
I have noticed since starting to measure, that my bookshelf speakers are exciting a room mode at 44Hz or so, giving me "boomy" bass, and definitely DSP seems the way to go, as my bookshelf speakers don't have much placement freedom.

So, the prefix for the video should be "If you're unwilling to apply DSP, then do this".

Ideally, you would have no room influence in your bass response and not need any DSP to correct it (not reality). The video I posted bases their business on trying to get their customers as close to that ideal as possible (mostly for rich people and professional music), and isn't very interested in half measures. It's an extreme goal, but that doesn't make him wrong, and understanding the extremes is very helpful and informative. Room sound is lower quality than direct sound, and even if that's less impactful in the bass region, it's still true and it's part of the reason we treat rooms. My own more realistic goals are to reduce the room sound as much as possible within my budget and aesthetics before applying DSP, even if that's nowhere near what Acoustic Fields sells. The information he provides is very useful, even if not 100% directly applicable to my space (just like most things in acoustics). Shoving a sub in the corner will absoltely give you a boost, but that boost is all room sound.

 

[Chrispy]

booo ;P

Hey I used a smiley. Maybe true sub would be a better term....I suppose for an 8" it's fairly competent altho overpriced...

 

[sarumbear]

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.

He is not explaining why not, other than saying please don’t. Please you tell us why subs in a corner is bad. It will be good to hear an opposing explanation to Floyd Toole’s.

 

[sigbergaudio]

Ideally, you would have no room influence in your bass response and not need any DSP to correct it (not reality). The video I posted bases their business on trying to get their customers as close to that ideal as possible (mostly for rich people and professional music), and isn't very interested in half measures. It's an extreme goal, but that doesn't make him wrong, and understanding the extremes is very helpful and informative. Room sound is lower quality than direct sound, and even if that's less impactful in the bass region, it's still true and it's part of the reason we treat rooms. My own more realistic goals are to reduce the room sound as much as possible within my budget and aesthetics before applying DSP, even if that's nowhere near what Acoustic Fields sells. The information he provides is very useful, even if not 100% directly applicable to my space (just like most things in acoustics). Shoving a sub in the corner will absoltely give you a boost, but that boost is all room sound.

But he is saying in general terms "don't put subs in corners" and "don't use multiple subs". This is bad advice for almost everyone. He's not saying anything about "this is just advice for rich people who can have dedicated rooms with 1m thick false walls filled with insulation."

Your final sentence makes no sense. There's no meaningful difference between direct sound and room sound in the frequency range we are discussing.

 

[anotherhobby]

He is not explaining why not, other than saying please don’t. Please you tell us why subs in a corner is bad. It will be good to hear an opposing explanation to Floyd Toole’s.

From Toole, corner placement energizes all the room modes, which can be good or bad. Depends on the room and arrangement. In my case it's always been bad, but your mileage may vary. I'm not oppoosing Toole's explaination at all. You just have to try, measure, and test.

 

[FrantzM]

monkey

Great information, thanks.
> apparently haven't heard of DSP

I have the impression that this is down to "tribes" and brand loyalty. I think a lot of audiophiles still worship at the altar of "thou shalt not alter the signal between source and speaker".
I have noticed since starting to measure, that my bookshelf speakers are exciting a room mode at 44Hz or so, giving me "boomy" bass, and definitely DSP seems the way to go, as my bookshelf speakers don't have much placement freedom.

So, the prefix for the video should be "If you're unwilling to apply DSP, then do this".

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.

Others have already responded.
I'll add to those

Those are not good explanations. The man is selling some wares..

Happy holidays!
Peace.

 

[jsilvela]

Hey I used a smiley. Maybe true sub would be a better term....I suppose for an 8" it's fairly competent altho overpriced...

My emoji game is very limited; I had intended to respond with a

> it's fairly competent altho overpriced
I'll make do with this diplomatic response from one of the Knights of True Sub

 

[Chrispy]

My emoji game is very limited; I had intended to respond with a

> it's fairly competent altho overpriced
I'll make do with this diplomatic response from one of the Knights of True Sub

LOL I just type out the smilie, just noticed the emoji button....wonder how long that's been there, lol. But am curious what your reasoning was in buying that particular sub (or what your options were).

 

[jsilvela]

LOL I just type out the smilie, just noticed the emoji button....wonder how long that's been there, lol. But am curious what your reasoning was in buying that particular sub (or what your options were).

> or what your options were

Ah, see, that's key. Outside of the US, SVS, Rhytmik and such are a lot more expensive. I had been meaning to get a Rhythmik L12, but their site said they had basically stopped shipping, since overseas buyers generally backed out after seeing the price of transport.

I didn't have previous experience with subs. I had budgeted around 700 eur.
My options were REL, a Bowers & Wilkins, KEF 8b, and a Sunfire with dual 10" drivers that scared me a bit as the materials emphasized raw power and I did not see reviews/measurements for it.

I have to say REL are very canny in marketing to audiophiles who may not have AVR's or DSP or electronic crossover solutions at hand.
I also saw the one measured REL at Audioholics, and the response was pretty much just a driver, no DSP on top to flatten.
Seemed that integration of such a response with my bookshelf mains (Ascend Sierra-1) would be doable without an AVR.

Some of the comments I see on subs can get unhelpful. E.g. when told an 8" is not a true sub, I wonder, what am i missing with a small sub vs a 12" real sub?
There's scarcely consensus on music with content on specific low frequency bands.
Would be a lot more useful to hear something along the lines of "with a small sub, you'll be able to hear a bass guitar great, but pipe organ in Bach will get shortchanged".

 

[sarumbear]

Some of the comments I see on subs can get unhelpful.

Indeed. Some people don’t know that they don’t know but act like they are an expert.

E.g. when told an 8" is not a true sub, I wonder, what am i missing with a small sub vs a 12" real sub?

The only reality of a sub is to create the often missing bottom 1.5 octave to a level that matches the main speakers capacity. If you have a room the size of a ballroom even a “real sub” with an 18” driver, kilowatt amplifier with DSP will not be enough. However, if you listen at a bed sit an 8” subwoofer can be perfectly “real”.

 

[Chrispy]

> or what your options were

Ah, see, that's key. Outside of the US, SVS, Rhytmik and such are a lot more expensive. I had been meaning to get a Rhythmik L12, but their site said they had basically stopped shipping, since overseas buyers generally backed out after seeing the price of transport.

I didn't have previous experience with subs. I had budgeted around 700 eur.
My options were REL, a Bowers & Wilkins, KEF 8b, and a Sunfire with dual 10" drivers that scared me a bit as the materials emphasized raw power and I did not see reviews/measurements for it.

I have to say REL are very canny in marketing to audiophiles who may not have AVR's or DSP or electronic crossover solutions at hand.
I also saw the one measured REL at Audioholics, and the response was pretty much just a driver, no DSP on top to flatten.
Seemed that integration of such a response with my bookshelf mains (Ascend Sierra-1) would be doable without an AVR.

Some of the comments I see on subs can get unhelpful. E.g. when told an 8" is not a true sub, I wonder, what am i missing with a small sub vs a 12" real sub?
There's scarcely consensus on music with content on specific low frequency bands.
Would be a lot more useful to hear something along the lines of "with a small sub, you'll be able to hear a bass guitar great, but pipe organ in Bach will get shortchanged".

Yeah I'm spoiled here in the US with options. I just diy them for my last several now. Depends what your use of the sub is and the size of your room as well as your extension and spl goals. You have more sub options than that....depending. I use mine for more than just music, too....but to get 16hz with authority takes more than you've got.

 

[Prana Ferox]

EQ is good and should be used, but EQ consumes headroom in your amplifier stages and it reduces your driver margins to xMax and other power handling limits, also reducing your max SPL. Simply saying 'subwoofer frequency response doesn't matter' is not entirely fair. And you simply get to a point where if you want FR beyond a certain LF point at a minimum SPL, your selected subwoofer system simply can't cut it.

I understand we're generally talking conservatively designed commercial subs but port resonance and (especially with DIY bandpass designs, i.e horns) frequency response matters. It is certainly the case that predicting in-room response at the design stage (certainly for a non-DIY design) is impractical but starting from reasonably flat (in the passband) makes EQ a lot easier.

 

[ryanosaur]

Simply saying 'subwoofer frequency response doesn't matter' is not entirely fair

I know I didn't say that... don't recall if somebody else did. But as a metric for determining the "worth" of a Subwoofer, it is a misleading spec if relied upon too heavily/exclusively (which is an oft repeated crime). Hence, "silly."
Same with those who judge Subwoofers by Amp Power, alone, without knowing anything about the rest of the complex system, i.e. Driver Sensitivity (and Bl, Mms, Cms, etc), cabinet design and tune, Ports, etc. (Mind, I've never seen an ID Company share their Driver Specs or most other info needed to make Amp Power a worthwhile factor.)
Frankly, in that sense I'm more concerned by the Sub that requires an 8-10kW Amplifier than the one with the 1-2kW Amp. All things being equal, the requirement for that much Power on-hand screams inefficient design.

I do agree that when looking at (and understanding) the full system, all of these metrics come together for giving a technical snapshot of how a system may perform. Therefore, they all matter.
I think we agree.

(Soapbox moment:
I am tired of people that insist on sharing in-room measurements of their Subs, especially DIY Subs, and act that it is the end-all measure of success. I want to see somebody take their PSA or Dev or Marty or whatever outside and run a proper groundplane on it and show us what their money or efforts actually brought. THEN, show us what happens when you put it in your room. And then show us how you got it all dialed in.
I get it. This is not practical for most people to do.
It would, however, be a much more telling and revealing story about the interaction of multiple complex systems and the physics that tie them together.
Compare that to the REW warrior that knows how to do a sweep in their room and simply fix errors in the mix, as it were.

*steps off soapbox)

 

[Prana Ferox]

Would be a lot more useful to hear something along the lines of "with a small sub, you'll be able to hear a bass guitar great, but pipe organ in Bach will get shortchanged".

Subs aren't for bass guitar frequencies unless your mains are really wimpy. The fundamental (especially low E or lower) is a small part of the signal relative to the harmonics. The signal chain is quite frequently high-passed fairly high, what low frequencies are there tend to be rumble and mud; live amplification has the same problems as hi-fi reproduction, that very low frequencies eat amp power and ruin speakers, and you have even less control of room interaction. Effective highpassing at 80hz or higher is not uncommon. (Among other things this is why you don't use a bass guitar amp as a subwoofer amp, at least unless you can completely bypass the preamp section.)

Organ for organ weirdos, or keyboard / synth / any modern music where the instruments are pure virtual, are a different story. As are TV/movie SFX.

People also use subs to improve midbass kick, or free up their mains to do the same, i.e. have more headroom for transient response for real / simulated kickdrum beats (or various impact SFX)

 

[sigbergaudio]

???

Highpassing at 80hz is very uncommon. Both live and in the studio.

 

[Prana Ferox]

Your vintage sealed cabs roll off at 100hz or higher. The classic Ampeg fridge variants roll off anywhere from 55 to 80hz. Ported cabs go lower but frequently get farty until you turn the lows down. Then you have built in high-pass in the amp (preamp) which in old amps is usually fixed, in modern amps may be adjustable; A Mesa Subway adjusts from 30-125hz, for instance. Rarely do you get below 35hz - the old SWR amps that advertised to go down near to DC were notorious cab killers. The common Broughton high-pass filter pedal adjusts from 25-190hz or so, and center default is 80 hz. I have an fdeck pedal that adjusts from 35-140hz.

Keep in mind these HPFs are all cumulative, and live the FOH is dialing your lows out anyway if you don't beat them to it, because it's uncontrollable rumble.

People think bass cabs go low because they have big drivers (or they try to use sub drivers in a bass cab, with terrible results) but that's almost always for SPL and efficiency, not low extension. A bass cab built for sub frequencies would be as big and heavy as an actual (PA) subwoofer and no one wants to drag that thing in and out of a van. "Shouldn't my cab be able to reproduce the low E" is like the number 1 misconception for newer bass players and it's only worse for 5-string / BEAD types.

For more see for instance https://www.talkbass.com/threads/high-pass-filter-hpf-and-low-pass-filter-lpf-mega-thread.1333720/