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. |
Onhwy61... Two signals, one at 30 Hz and the other at 20 Hz will yield a "beat" at 10 Hz. |
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. |
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). |
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. |
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. |
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. |
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. ;-) |
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] |
Pardon the grammar. That Akutek link has interesting info. Same link.[http://www.akutek.info/Posters/KG_Basses_on_Floor_Poster.pdf] |
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. |
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. |
Why the bottom octave?
Because it sounds so right, when done right. |
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. |
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. |
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 |
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 |
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. |
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! |
"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 |
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. |
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. |
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'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 |
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 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 |
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. |
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DUKES WIFE IS RIGHT ON "BIGGER IS BETTER" WHEN YOU KNOW HOW TO USE IT. |
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.
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