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Bass frequency/waterfall plots: what they mean to rigs

Discussion in 'Amps and Cabs [BG]' started by greenboy, Jan 27, 2009.


  1. rbonner

    rbonner

    Sep 25, 2008
    Alex that is SO UNTRUE, and you keep hammering at this. If you had ZERO content at 31 Hz but only had content at 62 you would not have B0 at all. You NEED this content to tell your ear you have low B. The brain can't make up something that isn't there. This is not even logical.

    Now what we have here is a weaker fundamental signal which is obvious in the waterfall as compared to the second harmonic. Much of the ENERGY is in the second harmonic, but that doesn't mean we don't need the fundamental to hear the B0.

    The problem we have here in Bass Guitar is reproducing 40Hz and lower at any power. That is why our cabs FART out. It isn't because 62 hz is causing the cabs to over extend themselves. Its the fundamental.

    Whether we can amplify this loud enough to hear it well or not is irrelevent. We have to MAKE it in the first place. We have come to expect a note to have content at harmonic frequencies. But that is just the information that provides character to the note.

    Now, human hearing. Unless your hearing is shot, you can detect 17Hz or some of these other low tones. I had my hearing tested many many times in industrial settings and for flying. I believe the lowest in those tests was 25Hz.

    Like has been said, playing with a signal generator is a real eye opener. But we're making music here.

    We as Bassists have accepted that it is tough to reproduce the low notes and that it takes special equipment to reproduce the serious low notes at any volume. Just because of that it is irresponsible to BLOW OFF the fundamental or say it is not important.

    Here we have some of the cream of the crop of bassists around the world, discussing the reproduction of low notes.

    And Charlie, don't be afraid of pulling out your EUB waterfalls, as we have to understand the comparisons and benchmark to understand the Electric Bass also.

    We are discussing this in the correct forum, but we need to understand the nature of the signal before we can amplify it. We nknow low notes are there, its the reproduction and amplification thats the trouble.

    I wish my PhD was more in this area, I am out of my realm a bit as it is in Physics of RF energy instead of sound. The two do have common properties. Especially harmonic content. In RF we attempt to eliminate harmonic content.

    We know our brothers in Professional Sound have been working on better bass reproduction for decades and there are professional subs capabile of producing energy down to 8Hz and regularly generating content at 18Hz. This is some of Bag End's work.

    We just really haven't a clue as to what happens as we improve the propogation of our fundamental. There's almost 200,000 bassists on TB, and here we are pushing the envelope. I think we'll see some good coming from this. BUt its going to take some of the falacies that have been throust on us over the years and thinking beyond current limitations. BOB
     
  2. greenboy

    greenboy

    Dec 18, 2000
    remote mountain cabin Montana
    greenboy designs: fEARful, bassic, dually, crazy88 etc
    You really need to expand your reading before asserting this. I've seen some researchers and scientists assert this is true, oh, ever since the days of the first telephone grid maybe ; }

    I will say this: because the number of harmonics DOUBLES as you ascend each octave, the SPACING alone will tell the ear/mind what the fundamental is.
     
    Will_White likes this.
  3. Aye, Psychoacoustics. Love it! :hyper:

    Great thread people, very interesting :)
     
  4. greenboy

    greenboy

    Dec 18, 2000
    remote mountain cabin Montana
    greenboy designs: fEARful, bassic, dually, crazy88 etc
    I'm going to talk to myself here just to save time.

    This is a good one, because the proof is all around us. We've all experienced it since the first time we ever used a phone.

    I am not one to contend we can get rid of those pesky low fundamentals completely. There is more to feel, and greater richness for the ear, when the fundamental is there. I just believe it helps to truly understand all the issues and what the tradeoffs are.
     
  5. synaesthesia

    synaesthesia

    Apr 13, 2004
    UK

    -1. The sonic signature of an electric bass signal is what it is, as it is for an EUB piezo signal, and as it is for DB, mic'ed or un mic'ed. There are some similarities in them, and the fundamental is not as strong as the higher harmonics. This is what distinguishes the sonic signature of the string bass family, acoustic or electric from say a tuba, euphonium, kettle drum, pipe organ or for that matter a sine wave.

    The discussion so far as been about direct measurements, in the context of everyday musical consumption, you can be assured that the recordings you listen to, even of pipe organs, have had some low end cut off electronically, largely due to the imperfection of the transduction processes (mic'ing and reproduction). With electric bass guitar, most of the recordings you hear have very little content below 50 - 60 hz.

    DBX manufactured the boombox to generate synthetically subharmonic content that was generally filtered out in the recording and pressing process, it had some popularity with classical music audiophiles wishing to recreate the atmosphere of a cathedral where a pipe organ exists, for example. For want of better analogy, it is basically an octave box.

    For the electric bass guitar, the natural sonic signature of its sound is what it is, it is the nature of the beast - forced mathematical parity of the fundamental to the higher harmonics would be artificlal.
     
  6. alexclaber

    alexclaber Commercial User

    Jun 19, 2001
    Brighton, UK
    Director - Barefaced Ltd
    It is not untrue at all and it is entirely logical. Please google "restoration of the missing fundamental".

    Also see page 43 of "This is your brain on music" for an example of a barn owl being played "The Blue Danube" using tones from which the fundamentals had been removed yet electrodes placed within the owl's brain detected that the firing rate of the neurons was that of the fundamentals, not the overtones.

    If you really needed to hear the fundamental to ascertain the fundamental pitch, why would anyone bother with tubas and double basses in orchestras?!

    Alex
     
  7. greenboy

    greenboy

    Dec 18, 2000
    remote mountain cabin Montana
    greenboy designs: fEARful, bassic, dually, crazy88 etc
    Nope, not always true. In fact often we get by without high pass filters in spite of having enclosures that are tuned rather high simply because those lower notes aren't making much energy at the fundamental. If that fundamental was "tall" more drivers would be "toast".

    Here's an old comparison graph of two woofers, each shown with two box tunings. Note that one of them has a big crescent scoop for both of its plots. That my friend, is the Fart Zone. And for lower bass notes, it's right in the range of the first couple harmonics.

    CiareEm10.
     
  8. rbonner

    rbonner

    Sep 25, 2008
    Sure GB, use caution, now getting int omy area of expertise.

    We limit the bandwidth and compress it for telelphone and voice radio communications. Voice can be limited easily down to 500-2900Hz and still get all the information passed, this is not music however.

    When we were using telephones to move AM radio station studio to transmitter links we had to use high bandwidth lines generally these were 8Kz bandwidth phone lines.. We still didn't have much bass content and you can really tell if you remember any of those old radio signals.

    FM required the STL radio links and T-1 digital lines to get the job done as the bandwidth is much greater.

    With RADIO and TELEPHONES and electronic media, FAX, Teletype and things like that you can compress the information in a tighter bandwidth and reexpand the information to get the original content returned with very little degradation to the signal.

    They are doing that today with digital encription. This also allows scrambling, compressing multiple phone calls on digital bandwith and also placing music on a compact disc.

    This doesn't mean we have audio happening there. So really that is a bad example.

    The transmission of RADIO TELEGRAPH, we can get 100% information content down to a bandwidth as low as 100 hz and still move the information as fast as you can speak.

    Music is music and sound in its purest form. If we never needed to amplify we'd not be having this discussion, however when we amplify we need to take the original content and reproduce it in as pure a form as we can. I'd say when it comes to the lows we're still lacking technology to reproduce it as good as we can. This discussion is how can we do it better, not should we do it better, or we don' tneed to do it better.

    Thats like the guys in the amps forum saying why do you need an amp that big? BOB
     
  9. greenboy

    greenboy

    Dec 18, 2000
    remote mountain cabin Montana
    greenboy designs: fEARful, bassic, dually, crazy88 etc
    Bob, much of what you said was superfluous. Your original contention was that the fundamental had to be present to identify the pitch. But clearly in bandwidth-limited communications we can hear that mom isn't a baritone and that dad isn't a soprano. In my family anyway.
     
  10. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    +100. Point of fact, not only do you not need to hear the fundamental to identify pitch, you cannot identify pitch purely from the fundamental until that fundamental lies in the directional frequencies, above roughly 80Hz. This isn't physics, it's biology. Pitch identification relies on the same mechanism as directional location. The distance between our ears and the attendant processing power allocated by our brain places the lower limit of same to about 80 Hz. Those who think they hear 30 Hz from the fundamental alone may do so only if they happen to be a pachyderm.
    I doubt if one in a thousand members here, including those who claim to hear pitch information below 80 Hz, have ever heard a pure tone in that range. Those who have know that without harmonic information the pitch of those tones cannot be distinguished. OTOH the harmonics alone that would normally occur along with said fundamental tones when present at the same ratio and amplitude as would occur when the fundamental is present do provide not only the pitch information but also the illusion that the fundamental is present. Why? Haas Effect. When a 30 Hz note is played since the 30 Hz portion of the note is more than 10dB below the average level of the entire signal you equate the harmonics as being representative with what a 30 Hz note sounds like, and not the 30 Hz itself.
     
  11. [​IMG]

    The is a Fender P with DiMarzio DP146 Will Power Middle installed, fresh set of EXL-220 rounds.

    The sample was E1 (41 Hz) accumulated over 4 seconds.
    Please take note of the amplitude at 41 Hz.
     
  12. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    What would be more revealing would be to overlay this plot with one playing the same note through your favorite amp/speaker with the tone set where it sounds perfect to you. What the signal content is where it enters the amp and what it is when you're actually listening to it in most cases will be markedly different.
     
  13. greenboy

    greenboy

    Dec 18, 2000
    remote mountain cabin Montana
    greenboy designs: fEARful, bassic, dually, crazy88 etc
    Also, and the reason I wanted to start this thread with waterfall/3D spectrum analysis instead of time slice plots or averaged long-term plots is that one can see over time what the harmonic balance is doing... In long-term averaged cumulative plots the fundamental can actually average high because a majority of the upper harmonics decay fairly quickly after the initial attack, and only a few harmonics typically hang around for any length of time.
     
  14. OldogNewTrick

    OldogNewTrick

    Dec 28, 2004
    Germany, EU
    with all my sampling, the fundamental was always the same strength as the first harmonic. My technical execution of the sampling process was amateurish, I find Passinwind's and bgavin's plots far more revealing.

    What confuses me is that earlier in the thread was stated by some, that the energy level of the fundamental is much lower than that of the harmonic content. However here it appears to pretty much the same... What am I not understanding here ? :help:

    What pertinence this has to rigs (thread topic) is an entirely different issue.
    To live (backline) rigs, the reproduction of the natural level of fundamental seems to be more of a nuisance than a benefit, harmonic being more responsible for the pitch recognition (and the brain making up for the missing fundamental).
    In a studio / recording setup, IME, this is different, here I would like to see (hear?) an as faithful as possible setup.

    But, what do I know.... :bag: :D

    Still great thread, looking forward to learn how this all really works :)
     
  15. greenboy

    greenboy

    Dec 18, 2000
    remote mountain cabin Montana
    greenboy designs: fEARful, bassic, dually, crazy88 etc
    If I said that without using the word "typically" as a qualifier, I apologize. Not meaning to slight your earlier post either, olddog. I've seen a lot of plots (wish I still had some from my old Mac studio days when digidesign was beginning to take off with sampling tools and hard disc recording), and there can be a lot of variation in basses. Which is why I felt it necessary to post a couple times trying to say that there is no one typical electric bass - only a string's set of natural harmonics really providing tendencies and limitations.

    This does however lead me to mention something I was going to mention anyway: that if we are to have a clear picture of any passive bass, it should be sampled in conditions similar to those with which it would be recorded or performed with. And with passive basses, that means similar loading conditions. Preamp input spec, etc.
     
  16. greenboy

    greenboy

    Dec 18, 2000
    remote mountain cabin Montana
    greenboy designs: fEARful, bassic, dually, crazy88 etc
    I'd also posit for an open string that narrow aperture pickups (such as Bruce's P bass example) in certain placements closer to the neck and with some body and neck woods would have a greater chance at a preponderance of fundamental content.

    That's one reason why on my basses I have the "neck" Q-Tuner pickups set to narrow aperture. That way on either bass, the neck pickup is not so dissimilar to what the COSM-massaged GK pickup/V-Bass seems to typically deliver for spectral balance.
     
  17. OldogNewTrick

    OldogNewTrick

    Dec 28, 2004
    Germany, EU
    I've done a series of plots trying to show the difference in pickup position and plucking style/position.

    While in general the results with regards to strength of fundamental vs harmonics were what you would expect (picking over bridge pickup with bridge pickup engaged vs. picking near neck with neck pickup engaged) both permutations* were really blurred in their results.
    (Edith says: shifting plucking position, keeping pickup constant / blending pickups from one extreme to the other, keeping plucking position constant)

    Reason I'm not posting those is that without a mechanized plucking finger which plugs consistently at the same angle, with the same attack and strength, results simply vary too much in shape and amplitude of the harmonic content to provide an interpretable plot.

    That is one methodical reservation I do have to compare any plots. To keep the other stuff constant (passive/ active etc.) is fairly easy to achieve.
     
  18. greenboy

    greenboy

    Dec 18, 2000
    remote mountain cabin Montana
    greenboy designs: fEARful, bassic, dually, crazy88 etc
    Are we dealing with noise floor issues here, or noise from plucking/striking technique perhaps? I've seen some plots where the gak intruded so bad you couldn't clearly see even the more predominant harmonics standing apart. Also, settings for building the interpretive plot have some bearing, methinks.

    I guess my take on that is that the electric bass is an expressive instrument, and as such, different hand technique makes for spectral/envelope variations. But a number of samples should at least allow one to grasp the spectral tendencies of that bass/pickup.
     
  19. Passinwind

    Passinwind I Know Nothing Supporting Member Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    Caffeine...must have......caffeine! :cool:

    I found some pretty interesting examples of that last night. I'm especially interested in the BG samples that showed marked subharmonic content.

    I'm going to take a stab at neck vs. bridge vs. blended for the bass in the first graph, then hopefully a fretted Fender (thanks for yours Bruce), and my scary Travis Bean, a very bright fretless but also one with a neck PU at the 24th fret position.

    I downloaded a demo version of Spectra Plus last night to double check my results in WaveLab. They looked OK, so I'll carry on with WL unless someone points out a fatal flaw in my methodology so far.

    Thanks to everyone who's contributed to this thread. Feel free to keep the requests coming.
     
  20. OldogNewTrick

    OldogNewTrick

    Dec 28, 2004
    Germany, EU
    no, noise floor wasn't at all the issue.
    I used the my BassPodxt's unmodeled signal via USB into my laptop, bypassing the build-in soundcard. Noise floor level adjustable in the software. No problems here.

    My finger is the problem... :bag: Percentage of meaty part ve. calloused tip with a bit of occasional fingernail, even though they're pretty short.... all that, plus the plane the finger makes the string oscillate in, made a significant difference to the harmonic content displayed in the waterfall plots ....