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Bass frequency/waterfall plots: what they mean to rigs

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

  1. greenboy

    greenboy

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    greenboy designs: fEARful, bassic, dually, crazy88 etc
    I've got a rather extreme visual example of bass guitar output here, showing frequencies of the fundamental and overtones across the plot, and the timeline starting where the note is just struck at the back, leading to the front as it sustains and decays. You can see each partial of significant energy as its envelope changes.

    [​IMG]



    Why is this example extreme? Well, for starters it's a very dark fretless bass/strings combination taken at F1 - 43.65 Hz fundamental - where the first fret would be. Also the sample was taken with both pickups blended about 50/50, which because of phase differences cancels a fair amount of energy above the fundamental and octave overtones until you get to the higher content.

    That's that scooped sound one hears when blending two pickups on many basses. So. The area where the graph is truer green leading to aqua, from around 125 Hz to 350 Hz or so is diminished in output. If this was a fretted and brighter bass you'd still be seeing this, but there's be a lot more upper frequency content at the start of the note leading up to the 16th partial at 698.4 Hz, and some stuff up above there even for a brief period.

    Another important factor here is that the pickups are Q-Tuners, which seem to reproduce a lot more fundamental content and less exaggeration through the spectrum than a lot of conventional wound pickups. The result is that yellow fundamental actually is a lot bigger with this example than it would be on most basses. And still, compared to the first overtone an octave above, it exhibits maybe just over half the energy on the average. Notice that octave overtone too: how it blooms a little after the inital attack, then during a period of over a second-and-a-half smoothly loses some output, to plane out even with the fundamental, before doing a nice big slow bloom to again dominate the mix.

    I'll get to what all this means for rigs in a second post, but I want to first allow people some time to check this out and think about it, and to thank Passinwind for supplying me with the data I wanted, and understanding what I was after.
  2. bongomania

    bongomania Gold Supporting Member

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    owner, OVNIFX and OVNILabs
    I always dig seeing plots like that. It really helps to understand what is actually going on in the sound.
  3. kesslari

    kesslari Supporting Member

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    Lark in the Morning Instructional Videos; Audix Microphones
    Very interesting - gonna keep watching this thread.
  4. zac2944

    zac2944

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    I'd love to see this bass compared to something like a fretted Fender Jazz as a benchmark or sorts. This type of data would be interesting to consider when designing a custom cab. Thanks for posting, can wait to read your follow up.
  5. Passinwind

    Passinwind Charlie Escher Supporting Member

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    If someone wants to send me a brief .WAV file of a Fender 4 playing low F I'll make it happen. I don't own a fretted bass...:cool:
  6. zac2944

    zac2944

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    I could make that happen, but I don't want to hijack GB's thread.
  7. greenboy

    greenboy

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    greenboy designs: fEARful, bassic, dually, crazy88 etc
    Make sure there's some data about pickups, strings, and all that, too. Charlie's got a well-calibrated system for not only taking measurements, but for gathering samples, BTW. Could send him a bass ; }
  8. greenboy

    greenboy

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    greenboy designs: fEARful, bassic, dually, crazy88 etc
    Here's a EUB (electric upright bass) sample on the same note, F1. The EUB has a 42 or 43" scale, so I think that gives a clue about what scale length can do. The particular sample was chosen as indicative of the type of sound you get when you are using your hand technique to sound deep - there's not a lot of thump or snap here which would be indicated by more fast-decay content in the aqua range.

    [​IMG]

    Compare it to the fretless bass:

    [​IMG]
  9. paganjack

    paganjack

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    yay science! that graph is quite informative. i look forward to reading more of this thread! It's nice to see a visual representation of how all the frequencies stack up.
  10. Gastrok

    Gastrok

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    greenboy - what sort of equipment and/or application did you use to do this?

    VERY interesting!
  11. Passinwind

    Passinwind Charlie Escher Supporting Member

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    Good point. On further review, I should probably just borrow a fretted Fender to keep the methodology completely consistent.
  12. DudeistMonk

    DudeistMonk

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    This is really interesting....I'm regretting not hung out in amps[BG] till now.

    Subscribed.
  13. Passinwind

    Passinwind Charlie Escher Supporting Member

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    I actually did the graphs. I used an EMU 1820M sound card, my DIY tube line driver, which measures ruler-flat, as the front end, and WaveLab 4.0 to do the waterfall graphs.
  14. JB696

    JB696

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    Whereabouts do the bass "tweeters" come into play? Somewhere over in the purple? ;)
  15. Kael

    Kael

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    To facillitate the usefulness of those graphs in understanding how your EUB and fretless differ in the frequencies they produce and how those frequencies sustain/decay, you really ought to show them using the same time scale. I think that you are mainly concentrating on what frequencies each instrument emphasizes, but I still think that using the same time scale would be beneficial.

    Safe assumption that the EUB was plugged in? Piezo or magnetic p/ups.
  16. greenboy

    greenboy

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    Frankly I see a bunch of people wanting to rush to see their bass instead of just getting what this is really about, and why I mentioned that the examples were rather EXTREME. And why it's in the AMPS section in the first place instead of strings or pickups or basses or whatever.

    It has special pertinence to low-tuners - people who downtune or have a low B string or lower. I think cab design is largely predicated on the 4-string bass still, but just adding a fifth string, the B, takes that content down:

    - from a predominant energy from 81.4 Hz and maybe an octave above and a fundamental at 41.2 Hz -

    - to a predominant energy from 61.74 and a fundamental at 30.87 Hz.

    Driver design for woofers suitable for this have been long in coming, but we are finally getting there. But still, many cab designs are recipes for blown drivers or less than stellar low note body ; }
  17. Passinwind

    Passinwind Charlie Escher Supporting Member

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    Another good point. But since the plucking mechanism (me) is pretty poorly calibrated, sounds like a lot of work...;) Greenboy asked for something over 2 seconds, so that's how I did the BG graph. I've posted the EUB graph a few times before, and he thought it would be cool to include it here for general discussion. I can take a stab at making a longer one tomorrow though. I just made these from snipped sound clips that were kicking around on the 'puter.

    The EUB is a 4 string BSX 2000, individual piezo pups per string, built into the bridge. Same signal chain that I posted above.
  18. svtb15

    svtb15

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    Endorsing Artist:Alleva-Coppolo| MESA |Genz-Benz R.I.P.|REDDI|Westone
    I am beginning to wonder what the exact physical characteristics would be as well as what the visual aspect and correct/proper dimensions would be for a great 1x12 .. it would not have to be ruler flat. ... In other words what would a great 1x12 that can handle a 5 string bass look like.. what would it look like and how large would it be? I know there may be a million variables as well as speaker selection... and is there anything on the market that does that or comes close these days...
    I wish i could see a sketch of what that might look like.. just for the fun and education part of it...

    That graph shows alot
  19. davio

    davio

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    http://www.talkbass.com/forum/showthread.php?t=508659
  20. greenboy

    greenboy

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    The EUB samples is one Charlie did before I decided to pursue this topic, which really is not about specific basses as much as it is about tendencies that electric basses possess and how that SHOULD pertain to modern cab design. One thing I've noticed is that on lower notes on lower strings from most pickups, there actually isn't as much fundamental content as one would suppose.

    But as one adds a B string or even an F#0 string it becomes a lot more obvious that a huge majority of bass cabs manufactured today often don't even represent the octave overtone of those lower notes very well, sometimes the cabs are really starting to come on strong only by the octave-and-fifth overtone.

    Then throw in the ear's huge lack of sensitivity at lower frequencies into the equation:

    [​IMG]

    Notice that a low conversational level of 80 phons (SPL at 1K Hz) actually requires around 110 dB at 30 Hz just to seem equal!

    So, it's more about how does a cab designer or company best deal with this for various player profiles like

    1) solo performer and has low tuning (no band)
    2) never PA support and has low tuning
    3) sometimes PA support but often abysmal
    4) good PA support

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