The bottom octave

[Mal]

I would be interested in the thoughts of others regarding the significance of the bottom octave in music/speakers.

"music rarely has extremely deep, under-50Hz bass, and most speakers with 5-inch (127mm) or larger woofers can muster 50Hz bass in small or midsize rooms."

The case against subwoofers for music

For home theater and games, sure, subwoofers can provide deep bass oomph that speakers alone can’t match.

www.cnet.com

Do you even need as much as 5 inches? Bass on my KEF LSX sounds quite good. Reports on the Sonus Faber's bass response are quite positive. Going up to five inches may be problematic for me as I like listening in the very close near field and using small bookshelf speakers as computer speakers. But I do like to hear the bass instruments in classical orchestral music.

"54Hz at -3.8dB is quite an accomplishment from a single 11.5cm coax driver."

KEF LSX Review (Wireless Speaker)

This is a review and detailed measurements of the KEF LSX "Wireless" speaker. It is on kind loan from a member and costs US $1,250 from Amazon including Prime shipping. In every way KEF could nail the look and feel of the speaker, it has done so: Not only is the iconic coaxial driver...

www.audiosciencereview.com

 

[Plcamp]

Seems the thread that postulates “your woofers are not big enough” is probably correct.

Is bass headroom the single most common defect for faithful reproduction…both from a speaker’s ability to deliver spl, and the user’s ability to integrate properly with their room?

 

[Sokel]

It's just another general preference that may or may not work in a particular case.....altho I've not had the experience with a 60 hz crossover to be localizeable. I generally don't cross that low, tho. YMMV.

One reveling test I do with my friends who use subs is this:

The Subwoofer Kick Drum Test

Give your subwoofer a kick (or two... or six).

www.audiocheck.net

I find the "background" explanation sensible and in many cases can reveal the "wrong" feeling one has with improper paired subs:

 

[anibal66]

Thanks for interesting post and comments.
A question, within the situation of a condominium, where neighbours must be cared of: What would be the effect of EQing down the first octave and EQing up the second octave in order to try to preserve the energy balance of the recording as much as possible? How to do it properly?

 

[GaryH]

I ended up choosing 120Hz for mine. It was to get rid of most of the bass dips caused by the room, and also because I ended up preferring to stuff the ports of my speakers. I did try 90Hz with open ports and ended up with an almost identical measured curve at listening position, and then when A/B'ing 90Hz open ports vs 120Hz closed ports I decided I liked 120Hz closed ports better, I made a note that the bass sounded clearer as well as the areas above the bass. Following was 90Hz open ports vs 120Hz closed port measurements compared at listening position, so basically identical:

The sub is behind & inbetween my two speakers, and I've not had any localisation issues with that high crossover frequency. Sub is time aligned (delay in miniDSP based on distance of sub behind mains) and phase aligned through help of measurements, phase aligned in terms of choosing a phase degree value in the sub that provides the largest most consistent measured frequency response at crossover.

Yeah it seems if the sub is placed between the speakers localisation occurs at a higher frequency compared to at a side wall or corner. Your perception of cleaner bass is likely due to less distortion as your speakers aren't having to output as much sub-bass where their distortion is likely highest. (By the way your image isn't showing up.)

 

[teashea]

In my experience:
Speaker makes it to ~75 Hz and then drops like a rock (36 dB/oct) = oh crap, there's a lot missing.
Same speaker, but EQ'd to maintain a decent level into the mid-50s with slow dropoff starting at ~70 Hz = good for general purpose / casual listening, a bit missing at the bottom but nothing dramatic.

By the time you make it well into the mid-40s (and I mean flat), music generally tends to be covered very well. Might be why you often see that as a lower limit even in larger monitors. Keep in mind that the limit at -6/-10 dB is just one parameter, and the exact shape of the bass response is not unexactly unimportant either. Given the same -10 dB point, something that is flat and then drops like a rock (say 36 dB/oct, i.e. 6th order) would have more bass than a system with a 2nd order dropoff throughout.

Clearly, while the bottom octave should have some priority in a no-compromise music playback system, it's the one that I could do without first. Now not having 50-80 Hz, that would really suck.

Good information.

 

[teashea]

It does seem that the type of music / genre makes a big difference. From the various references here to music with low frequency content it seems that specialized music genres have content below 40 hz. I have seen no reference to much in pop or rock with content down there. From my involvement with recording studios and various recording forums, it is more likely that the recordings purposely have no content below 40 hz.

 

[fpitas]

I Linkwitz Transform my woofers flat to about 20Hz, but it's not real noticeable vs the natural 37Hz -3dB point without the transform. Maybe a little more body feel of the bass.

 

[Multicore]

Clearly, while the bottom octave should have some priority in a no-compromise music playback system, it's the one that I could do without first. Now not having 50-80 Hz, that would really suck.

This is a better summary of how I feel about it than I have managed to say myself.

 

[Robbo99999]

Yeah it seems if the sub is placed between the speakers localisation occurs at a higher frequency compared to at a side wall or corner. Your perception of cleaner bass is likely due to less distortion as your speakers aren't having to output as much sub-bass where their distortion is likely highest. (By the way your image isn't showing up.)

I edited my previous post now to attach the actual file rather than just copy & paste the picture (I could see it, but maybe now others will see the graph now).

Yeah, re placement of sub between the speakers I noticed in the post (research) you quoted that if inbetween speakers then it was up to 140Hz as ok without localisation, so I guess that makes sense re me finding 120Hz ok re not able to localise the sub.

About cleaner bass (as well as cleaner in rest of frequency range), the sub doesn't actually measure that low in distortion when I measure it in my room, but it is supposed to be a low distortion sub - my theory for the clean sound is reduced IMD in the main speakers by having the sub do more of the work, and perhaps plugging the ports of the speakers also reduces some dirtiness. I would like to get a second sub just to reduce the distortion in the sub, but £600 is quite a spend. Here is the distortion of the sub & speakers at 84.5dB at 1kHz at 3.8m listening position (following graph) - which is about the loudest I use it. I'm giving the sub about 10dB of boost around 68Hz to combat a dip, which is paired down to less than 10dB after the roomEQ kicks in - so we can give the sub a let off for that peak at 68Hz, it does like some distortion at 20Hz though, but I've removed a 3dB boost at 20Hz since doing this distortion graph, so it's a little better down there now, but not totally flat in frequency response down to 20Hz now.

 

[GaryH]

my theory for the clean sound is reduced IMD in the main speakers by having the sub do more of the work

Yeah that's what I meant by less distortion from your speakers (mains)

 

[DVDdoug]

20Hz (or even) lower is great if you have the budget and space for "big" speakers/subwoofers, and amplifiers, etc. But often there are compromises. Most pro subwoofers used live or in dance clubs are tuned to go-down to about 40Hz. That's low enough for bass you can feel in your body (as long as it's also loud enough). If you design them to go lower you start to loose efficiency and you need a lot more amplifier power and more or bigger woofers to get the same loudness at 40Hz and above.

It's "easier" to get deep bass at home because you don't have to fill a large space with strong-deep bass. Home theater (and studio) subs are often tuned to go lower.

There is also an issue with music production. Our ears are not as sensitive to low bass and low-bass requires more amplifier power so if you release a recording with lots of strong-deep bass, that energy has to come from the rest of the spectrum and overall it won't be as "loud" and even the bass might not sound as "loud". When the "average listener" turns-up the volume they can easily drive their amplifier or speakers into distortion with frequencies that their speakers can't reproduce and that they can't hear. I sometimes get that problem with my Honda car stereo. A recording with "good bass" can cause distortion and I have to turn it down. In this case it's not necessarily super-deep bass. The regular bass on those speakers (and amplifier) is wimpy. My other vehicle has a "killer" sound system! But it's not perfect either... It's got some kind of bass resonance that sometimes shows-up with male vocals, and that's something I might work-on someday...



...I built my (home) subwoofers (ported, 15-inches, in fairly-large cabinets) for somewhere in the 30Hz range. I don't remember exactly and I haven't measured them but they can easily shake the floor in my mobile home! I don't often "take advantage" of them because I don't want to annoy the neighbors. But, I needed a sub when I set-up my home theater and I was always unhappy with the bass from my main speakers (also DIY).

 

[hege]

It does seem that the type of music / genre makes a big difference. From the various references here to music with low frequency content it seems that specialized music genres have content below 40 hz. I have seen no reference to much in pop or rock with content down there.

How is this a mystery? Dance oriented genres have more bass by nature etc, but there's nothing "specialized" about electronic, hiphop etc, which have easily over billion listeners. Soundtracks is a very popular genre too. And what does "pop" and "rock" even mean with their dozens of subgenres and different eras? Of course stuff from 70's have less subbass than say modern pop like Billie Eilish or Beyoncé, which is full of it.

I even posted a spectrogram of your own pop(?) song, I was curious about what you have to say about that? Did you not know it has content under 40hz, or was there a purpose for it? It even has a cliché sine sweep down to 5hz.

Fact is that 30-40hz is very common, under 30hz less so. Feel free to go roaming Youtube for example, and analyze yourself.

 

[gnarly]

It is a common misconception that bass management cuts off at 80Hz like a brick wall filter. Far from it. Whether the most common 12dB/octave slope or even at 24dB/octave, there's still a TON of energy outside the high pass filter and the low pass filter to the speakers and subwoofers, respectively. So, a main speaker with capability below the cutoff has significant advantages in (a) allowing the filters to function properly in blending the outputs of both the main and the sub through the crossover frequency "range" (not just at 80Hz,) and (b) in headroom, the ability to play loudly and cleanly below and above cutoff across the entire crossover frequency range.

Very good points imo.

A subwoofer localization test I like is to have a single sub the only thing playing (with its processing, xover in place).
It's dang hard not to localize it then.

I've found I can still localize the L or R sub using full-bandwidth pink noise low passed as follows:
with 100Hz 96dB/oct,
with 80Hz 48dB/oct,
and with 40Hz 24dB/oct !!!!!!!!! YIKES!

I could not localize 80Hz using a near brick-wall low pass.

Admittedly, this is with pink noise which should be easier to localize than music. (I'll rerun the test with music someday.)
And there is also the fact that the main speaker can/will mask higher frequency content the sub puts out.

But still, sub alone is so easily localized with pink, that 96 dB/oct is my default sub-to-main xover.

 

[bodhi]

Fact is that 30-40hz is very common, under 30hz less so.

Yeah, I don't understand why this has to be argued on in 2022. I mean people demand results from electronics that far surpass human hearing, but losing a lot of information in music because of inadequate extension of their speakers is OK and valid hifi?

Same is true also for subjective audiophiles: friend of mine had small Harbeth monitors (and fancy vintage electronics) in a big living room 1,5 meters from front wall. He refuses to even discuss frequency response ("I know it's all there"), measurements or, yuck, subwoofers. Well, we don't talk about it so we don't get into an argument.

 

[hege]

Yeah, I don't understand why this has to be argued on in 2022. I mean people demand results from electronics that far surpass human hearing, but losing a lot of information in music because of inadequate extension of their speakers is OK and valid hifi?

I do get it. Cost, WAF, lack of DSP, difficult subwoofer integrations yadda yadda. Or just dedicating your life to 70's rock or something where you "don't need it".

An informed decision to skimp on bass is fine. But you really need to hear a good setup first to appreciate (or not appreciate) low bass. I think it's the same with higher SPLs too, it's easy to dislike if you never heard a well tuned setup (but I completely understand if you just want to protect your hearing).

 

[Sancus]

From the various references here to music with low frequency content it seems that specialized music genres have content below 40 hz. I have seen no reference to much in pop or rock with content down there.

Hip hop is literally more popular than rock now, and I hope I don't need to show you how many hip hop songs have sub-40hz content(it's even sort of a meme, there are songs ABOUT subwoofers). And is DSOTM not "rock"????

You can keep narrowing your definitions to avoid the point but the reality is that 20-40hz is an important part of the audible spectrum and is used in many genres of modern music, including both popular and niche ones.

 

[bodhi]

I do get it. Cost, WAF, lack of DSP, difficult subwoofer integrations yadda yadda. Or just dedicating your life to 70's rock or something where you "don't need it".

Just found out about Marting Logan Dynamo 800X: it's a small pretty box for 1k€ with built-in room correction.

It would be fun to smuggle that to my friends house and set it up somewhere out of sight.

 

[Robbo99999]

Very good points imo.

A subwoofer localization test I like is to have a single sub the only thing playing (with its processing, xover in place).
It's dang hard not to localize it then.

I've found I can still localize the L or R sub using full-bandwidth pink noise low passed as follows:
with 100Hz 96dB/oct,
with 80Hz 48dB/oct,
and with 40Hz 24dB/oct !!!!!!!!! YIKES!

I could not localize 80Hz using a near brick-wall low pass.

Admittedly, this is with pink noise which should be easier to localize than music. (I'll rerun the test with music someday.)
And there is also the fact that the main speaker can/will mask higher frequency content the sub puts out.

But still, sub alone is so easily localized with pink, that 96 dB/oct is my default sub-to-main xover.

I think that's all irrelevant, listening to music is what matters in terms of you localising it. (Although I appreciate that you're playing safe).

 

[DavidMcRoy]

I think that's all irrelevant, listening to music is what matters in terms of you localising it. (Although I appreciate that you're playing safe).

I chased down and corrected my highly localizable 80Hz room node specifically because I COULD easily localize it in music and movie soundtracks, even on male voices that were tracked with excessive bass content. (And there's a lot of that, accidental and intentional.)

As an as aide, solo human voices are my first (but not only) go-to test track because there's no distracting music or SFX in the mix to give a place for noise, distortion and frequency response issues to hide.