Why the obsession with the lowest octave

Another good way to appreciate "full range" in the real world is listening to a locomotive freight train live and up close.

If your home has a slow rolling locomotive freight line nearby and you stop close to the safety rails, step out of your vehicle and listen. The sheer depths from its' massive front engines, steel wheels, bearings, horns, multiple car connectors, brakes, steel rails and substructure noises, and fully/partially loaded freight cars can be a very powerful and moving experience. The sub-sonic vibrations feel abundant and natural in your feet, legs, while your ears process all the upper bass, mids and highs. The "soundstage" is true and naturally phenominal.

When I listen to a well-recorded freight train through most sound systems, the live, full-range experience sounds better in every way. I'm making this comparison because it's so easy for many to fully appreciate it while reading. Subharmonic sounds on musical recordings open up much the same way with a smooth and strong bottom end.

I'm using a Behringer DEQ 2496. After equalizing both fronts, they roll off starting at 50 Hz. I crossed over my SVS Ultra 13 sub at 63Hz - with a roll off below 25 Hz to remove the lowest recording artifacts and help protect the sub driver.

Musical listening experiences, like standing close to a locomotives' massive main engines and freight cars rolling by, can be greatly enriched by the naturally occuring lower octives.

The set-up trick or goal is reproducing a full range natural balance. I'm certainly not putting down limited musical systems. I enjoy music from many systems with lower octive limits very much. A natural sounding full range system simply adds those enjoyable subharmonic structures without excess artifact or being "muddy".

Carefully "pressurizing" a listening room, noted earlier, is a really good way for me to think about it, too. It seems to be everywhere, yet, sounds right.

DUKES WIFE IS RIGHT ON "BIGGER IS BETTER" WHEN YOU KNOW HOW TO USE IT.

"then perform..."

I wonder if Ecruz' experience is due to removing (filtering)deep bass from the main speakers and the bass/midrange drivers so they are actually performing better since the heavy burden of producing the deepest bass is removed from the main speakers - the drivers than perform better with lower distortion.

I agree, it's not possible in a crossover. I'd need a cap as big as a house. I'm going to implemnt a line level high pass filter and see how that experiment works out for me.

Thanks

Bob, implementing this highpass in a post-amp crossover will require some really large values. To design this correctly would take knowledge of the drivers and the network in use. It would make sense for a poll that low in frequency to look to an active line level crossover solution. There are good ones for a couple hundred bucks.

I'm actually trying to find an answer to a technical problem along these same lines (please don;t ask why, it's complicated). I need to apply a change to my passive crossover to begin rolling off my speakers at 40Hz so that they are down quite a bit at 30Hz.

Anyone have a schematic or an explaination of how to implement this on my crossover?

Thanks,
Bob

I am in agreement with the Elizabeth camp. It reminds me of terms as accentuated or exaggerated, as unnaturally occurring (bass). I am VERY happy with my Beauhorn Virtuosos w/ Lowther dx4. No added sub or tweeter needed here. They are powered by 45 or 300b amps. If I DO need a bass fix... Sunn 2000s amp @120watts w/cerwin vega 18" cab. Plus, the standard Fender (tweed) champ @ 3.5 watts w/volume knob which goes to "twelve"! No macho-ness here.

I completely agree with Vlad. I hooked up the SA last night for the first time. Another brick in the wall never sounded better. The bass was tight, clean and detailed, providing a concert atmosphere. The bass could even be felt at lower listening volumes as the low frequencies pressurized my large living room. What bothered me was just as I had the SA dialed in for one cd, the next either was bass overload or not enough. Hoping to find a middle-ground setting soon.

The big problem I think is the idea that really low bottom octave bass sounds muddy blurred smeared etc. I happen to think it does also. Maybe I get that impression from the wretched super subs installed in that SUV 5 cars away annoying the living S**t out of me.
That being said I am curious to know what it is that I am missing out on, when these low sounds are properly reproduced. I am very curious how Duke's systems work. Yes I too was a bass freak as a kid. I grewout of it quickly and purchased Klipsch Heresys for my first real system in 1976.
At that time people really liked Cerwin Vegas for rock because they had such loud bass. I don't think any of us even knew what a subwoofer was. Maybe they weren't invented except for Bud Fried's "Coffin" system.
The new wave of music that was the thing at that time included Punk which was pretty much a distorted wall of sound played really loud. The Heresys didn't dissapoint.
The specs on my Klipsch clearly showed no bass below I think 50Hz. In real life I think they didn't make much bass below 60Hz unless you put them directly on a non carpeted floor. That's what I did. Later I used them as BookShelves really on shelves.

"a THERORETICAL -3db, who cares what you guess a system will do." - Acoustat6

Theory is not the same as guessing; it's what designers use in the design stage.

Duke
speaker designer

I haven't read all the replies, but what you miss with the lowest octave is not only bass, but especially the ambiance cues of the original site that makes a recording sound "real" and complete. Then you can talk about soundstaging and imaging. As they say, you don't know what you're missing until you get it!

Why the obsession with the lowest octave?
It could also bestated;
Why the obsession with the highest octave?

I like pipe organ.So of course it is necessary. Yes, most music is in the midrange. Press both your tweeters in and tell me after a week if you miss the very highest frequencies. There's hardly any music there anyways.

Duke said, "I'd choose quality bass down to 40 Hz ballpark over somewhat muddy extension down into the bottom octave. An honest 40 Hz is pretty darn deep anyway.

That being said, recently I built a semi-custom four-piece subwoofer system for a customer, and this set is theoretically -3 dB at 16 Hz after room gain. Yes, it does add something that was missing before, and my wife wants me to build us a set. How cool is that - she's actually encouraging me to put BIGGER subs in the living room!"
Duke

I for one am not impressed, a THERORETICAL -3db, who cares what you guess a system will do. Measure it and post a picture of the response and we can all be wowed.

How about a system that does +15db at 20 hz and is then extended to 13hz before it starts to drop off.
If you would like to see an ACTUAL measurement of it go here;

http://www.hometheatershack.com/forums/rew-forum/27565-my-new-room-response.html

An "honest" 40hz really is not low, don't fool yourself.

Bob

I'd choose quality bass down to 40 Hz ballpark over somewhat muddy extension down into the bottom octave. An honest 40 Hz is pretty darn deep anyway.

That being said, recently I built a semi-custom four-piece subwoofer system for a customer, and this set is theoretically -3 dB at 16 Hz after room gain. Yes, it does add something that was missing before, and my wife wants me to build us a set. How cool is that - she's actually encouraging me to put BIGGER subs in the living room!

Duke

If you understand the physics of sound production with musical instruments you might understand better the "obsession" for the lowest octaves. Although one may not be able to hear a very low frequency bass tone the fact that the speaker can produce low frequencies and may be vibrating at a low frequency sets up the mid range and high frequencies within the harmonic series to produce a more resonant quality. Musicians choose instruments with this quality and tune their instruments to tap into this harmonic structure so the instrument sounds better. These vibrating harmonics, even if they are too low to hear, bring out upper harmonics to add color to the quality within the speaker and accoustically in the room air. Some musical instruments are better than others by just they way they are made and I imagine speakers are the same, some good, some not so much. Walk over to a piano (any piano but a grand piano demonstrates better) and push down slowly on a middle C so the hammer doesn't strike but is off the string and hold it down. Then, while continuing to hold down the middle C strike a C in one of the real low registers for 1 second and release to dampen that note. The middle C will be vibrating when you release the low note and it was never struck due to resonating harmonics from the lower portion of the harmonic series. Bottom line is a speaker that has a great low frequency quality will make the entire spectrum and system sound better.

If it was there when the music was recorded, why not have it there in your room when it's played back? The hard part is doing it right.

Why the bottom octave?

Because it sounds so right, when done right.

I've found it interesting that while the OP ask about the "lowest octave", which would commonly be defined as 20-40 Hz, so many replies have commented on bass in general or if specific, reproduction above 40 Hz.

But for the general value of a decent subwoofer (or bass extension), I had a learning experience similar to Ecruz. Many years ago I visited a well-respected dealer for a sub-woofer demo. The main speakers he chose were Spendor BC-1s (that may hint how long ago this happened) with an excellent mid-range reputation but known for low frequency limitations. But to my surprise, for the music demo he used a solo violin. Even with such a limited low frequency range of the instrument, it was very obvious when he switched the sub system in and out. That forever sold me on the value of extended bass (again in general, I'm not identifying a specific frequency) for a fuller musical experience.

Good point that even instruments do not have a single sound. It is a function of the environment played in (ie the venue) and the sensors used to detect the sound (ie your ears, microphones, etc) that create the variations.

Facts like these are the reason why while can appreciate the value of a good venue, I always have to chuckle when it is suggested the room you listen in has to be effectively neutralized completely to get the correct sound.

The fact is the room in which the music is recorded and the room in which the music is played are both factors in the resulting sound in a home system, as much so and often even more so than the system played on.

Practically, the goal should be to optimize the resulting sound to sound good to you, not to achieve some perceived standard of perfection that does not even exist and cannot practically be achieved at any cost.

That thinking is good for the vendor though! It keeps everybody chasing the carrot and draining their funds indefinitely to achieve an impossible goal.

Pardon the grammar. That Akutek link has interesting info. Same link.[http://www.akutek.info/Posters/KG_Basses_on_Floor_Poster.pdf]

How much bass comes from the concert hall reinforcing bass from the instruments? When the instruments are measured, they are probably done individually in a room that may have no influence on the sound. No room reinforced bass may be the case. Anyway, something to think about. Resonance of the hall and surroundings. That may be some of the reason for bass being there, good or bad. We here it live, and can miss it at home. Here is a link to look at.[http://www.akutek.info/Posters/KG_Basses_on_Floor_Poster.pdf]

Thanks for the correction, Eldartford and Kihanki! I am mixing myself up. The fundamental IS the lowest sinusoid. I'm sounding like Irwin Corey again. ;-)

I have OHM 5 series 3 near full range floorstanders that do well down into the 20-30hz range and Dynaudio Contour 1.3mkII monitors that I would estimate do well into the 40-50 hz range on the same system.

That extra low end makes a big difference on most everything play!

I had the monitors first to see if I really needed the low end I knew was not there. I do to be totally satisified, though the Dyns do a ver satisfying job with the low end UNTIL you compare with the others that plunge the depths way better by design.

i relate to what ecruz said.

the first time i hooked up subs it totally baffled me how the soundstage expanded.

also the perception of low level detail.

Mixing two different tones is another story but the lowest frequency is called root and the rest are overtones that are higher. When you play instrument with complex harmonic structure (typical for percussion instruments) like piano - each key produces tone and overtones. There is no sub-overtones. The same is with guitar and many other instruments. Some things like bells produce subharmonics but for the rest of the instruments it is not common. You can obtain subharmonics with violins using special techniques (not very common) but you won't get it from the piano's individual keys.

Dan_ed... I don't believe that you can call modulation below the fundamental a "harmonic".

Consider a violin string. It is fixed at each end. and sounds a fundamental tone. But, by soft placement of a finger in the middle of the string you can immobilize that point of the string so that each section (end-to-middle and middle-to-other-end vibrate at a higher frequency because the length of sting is shorter. I don't see any way to make the string vibrate at a lower frequency (other than by loosening it up).

Yeah, and a snare drum whack is maybe an even better example of the very complex sounds we listen to.

I think what sometimes happens is we read the definition where is says that the harmonics are "integer multiples" but we forget that there is a negative integer series that fills in below the fundamental and we get that bell curve shape around the fundamental. This is in the frequency domain.

Onhwy61... Two signals, one at 30 Hz and the other at 20 Hz will yield a "beat" at 10 Hz.

On 1/21 Dan_Ed wrote:

To ignore the range from 20 to 40 Hz is to deny the FACT that there are harmonics down in that range that do affect realistic music reproduction.

and on 1/22 Arj wrote:

adding on to Dan_ed's post, from what i could figure out the fundamental at 40 Hz has a subharmonic at 20 Hz as well as overtones at 80 /160

If I understand these statements correctly, then a harmonic overtone series is produced both upwards and downwards in frequency from the fundamental frequency. That's just not my understanding of harmonic overtones. With very rare exceptions acoustic instruments produce only higher frequency overtones. Am I wrong? Can someone please explain the math.

Dan_Ed, good point about cymbal and bass content. Large cymbals are basically enharmonic and their frequency spectrum can go from 30Hz to 60+kHz. The bass content shouldn't be that surprising since the cymbals in question are 11" diameter and greater. They are the size of large woofers.

FWIW, I'll share my experience on this.

I once heard a demo at a local shop. It was a recording of an acoustic guitar. Nothing else. Don't remember exactly what speakers I was listening to. I listened for a while, it sounded very nice. The dealer then said," I'm going to switch things up a bit and let you listen to the same recording, same speakers, same amp. Tell me what you think". I listened again, wow! It sounded more real, deeper soundstage, more immediate, etc. Like the notes were floating out there instead of coming from the speakers. I asked if he switched cd players? "Nope", he said, "I turned on the REL sub in the corner over there".

There's definitely information that we process, even if we don't exactly "hear" it.

Excellent comments and observations!

My experience(s) grew me into the desire for 20hz to 30hz bass. I use Merlin TSM-mme stand mount speakers. They are amazingly musical and love the sound. The bass is very good but not so deep (mid 40's in my room).

I purchased JL fathom subwoofers and very carefully adjusted them and blended them with the Merlins. I much perfer the full deep bass. On Ray Browns Moonlight Serenade I could hear all the notes pleasingly. But, with the JL's I can hear and feel the low 'E' just vibrating away.

I also listen to pipe organ works and enjoy the subwoofers in the system. I am convinced I need and desire bass to about 20hz.

I have learned a lot from my Behringer DEQ2496 which has a spectrum analizer function, 61 frequency bands, 1/3 octave. The internal wide bandwidth noise signal is a good representation of music, but you can also look at externally generated signals like a sine sweep.

And, after you understand your problem you can fix it with the EQ function. $350 including mic. What a deal!

Dan,

Yes, the resolution of the analyzer I used was limited, but you still got a decent picture of how the music was distributed across the audible frequency spectrum, so that was educational albeit an approximation that does not relate all the details

I'm sure there are some good analyzers out there these days if one is interested, maybe more on the professional gear side.

Mapman, that kind of sa probably uses frequency bins but may help show what is going on. The issue people forget is that we're not dealing with simple sinusoid signals. A single note from a musical instrument is a very complex sinusoid. That is how the same note from a sax and from a trumpet sound different, or at least they should or our system is really crap.

"Hook up a spectrum analyzer."

Good idea!

I had one (Audio Control I think?) years ago. The spectrum analyzer was a display mode on the equalizer as I recall. It is quite educational to see what is really in the sounds you hear frequency-wise, both coming over the wire and as detected in room using a microphone!

:-) Hook up a spectrum analyzer. It would probably shock you to think that there is sometimes bass content in some cymbal whacks.

A device called a "Subharmonic Synthesizer" can be used to create tones which are not there but which "ought to be" based on what is there. It can sound better than trying to record real tones in the extreme low range.

So Dan_Ed, how about an explanation of your mathematically derived harmonic content?

Can't say for others but I "get" the harmonic content from mathematics. You guys are all free to believe what you want and setup your systems any way you see fit.

Of course, having the ability to deliver very deep and powerful bass is a big advantage. I just think that, given the usual constraints of size, power requirement, and BIG dollars, there are tradeoffs involved. There are tradeoffs for ANY aspect of speaker performance. The choices one wants to live with depends on taste, type of music, etc.

For example, unless one is talking about a very well engineered active biamp or triamped system, trying to achieve really deep bass using low-powered tube amplification is extremely impractical (look at some of the as-big-as-a-room bass horns of some Japanese systems). But, if you have heard what a really good SET amp can do, trading off some bass capability might be your preference; it is a matter of taste.

I actually have speakers capable of reasonably deep and powerful bass (it has two 12" drivers per channel), but, my chosen amp really cannot deliver room shaking volume. What this combination offers is doing almost everything else right at a comfortable volume level. It is a big system, with a "big" sound, just not a super loud system. I don't use it for home theater, so I don't need things to shake when it plays.

I have heard many speaker systems with full range bass capability (e.g., Wilson MAXX 3), and certainly they do deliver in that respect, but, I have heard few that, on balance, I would prefer over what I have (and those were also not particularly big in terms of bass performance).

"Having a tweeter than goes well above the audible frequency range just allows a better reproduction in the range that you can hear"

Not necessarily - it might distort more at few kHz range.

Another thought with a full range speaker is that if the speaker is capable of reproducing extrememly low tones (the same goes for the extreme high tones as well) then the vast majority of music doesn't require the speakers to work at the max capacity. I think this is applicable to just about all audio equipment. You wouldn't want an amplifier to be driven maxed out. This would only apply to a subwoofer in the sense that it can reduce the low frequency requirements on the mains. Having a tweeter than goes well above the audible frequency range just allows a better reproduction in the range that you can hear.

Where are people getting this sub-harmonic talk. Yes, string instruments can produce sub-harmonic sounds, but it is not a commonly used technique and it's virtually never written into compositions. Harmonic overtones are always present in acoustic music, sub-harmonics are not.

"Grandma's Hands" was recorded on a suspended wooden floor which is being excited by the foot tapping of the singers. It's a common effect in recorded gospel music. It's debatable if those sounds are part of the performance or are they in the class of falling mic stands, A/C rush, passing subways, page turning and fret scrapping, in other word noise. Although on tunes like the Supremes "Where Did Our Love Go" the floor effect is prominently featured as part of the rhythm track.

adding on to Dan_ed's post, from what i could figure out the fundamental at 40 Hz has a subharmonic at 20 Hz as well as overtones at 80 /160. it is a combination of all of these which give the flesh/timbre to the tone.
Any graphic equalizer using a digital out (eg i used a DEQ2496) shows a surprising amount of music in the 20-25hz region in many peices. the most surprising revelation has been "GrandMas hands" by Livingston Taylor. supposed to be an Acapella but has a consistent 20-25 hz bass content which is not heard in anything but a fullranger OR with subs and once you hear it that way can never ever listen to it without that bass fabric!

There is 40hz bass and then there is 40hz ATC active 100's bass. Real 40hz isn't all that bad.

Elizabeth, LOL and then there was the woman on Jeopardy who was shown a picture of a bird and asked "What is a Booby?" Well if she doesn't know, then who would?

The ability to fully and faithfully reproduce the lowest octave adds considerable realism to music reproduction.
However, I do not think it is best accomplished by a "full-range speaker." This is expensive, and leads to compromises in other areas of the speaker's design.

Reproduction of the bottom octave is what good subwoofers are for -- as in my Velodyne DD-18.

It took me years to achieve it, but now my best recipe or great bass for reasonable cost are newer OHM series 3 or X000 series Walsh speakers driven by a good 500w/ch Icepower AMP. MIT networked ICs seem to work well in this combo.

Set this up well and use decent gear around it and you have some mighty tasty and hard to fault bass that hangs with the best.

And the rest is right up there as well.

However, this experience cannot be replicated in a home system, no matter how good it is, or how low the bass goes - unless you happen to live in the concert hall. You have to buy a ticket to experience that kind of truly deep bass.
Learsfool

That's always been my way of thinking about bass. Never been much of a sub fan even when I had my Spendor Classic Series speakers which aren't known for bass, but their mid-range. My current speakers go lower and the bass is more extended and very satisfying for home listening. To me trying to get bass to sound like it does in a well designed concert hall is a bit like a dog chasing it's tail. I'm sure it can be done, but at what cost? If I need to hear more bass I'll go to a concert.

Martykl, not referring to you earlier. Someone else linked T. Rex foot falls and human hearing. BTW, I think your 1/21 post is very accurate.