The Science of Quack

Discussion in 'Telecaster Discussion Forum' started by teerjerker, Feb 6, 2008.

  1. teerjerker

    teerjerker Tele-Meister

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    Where does “quack” come from?

    I'm getting a sound fairly close to strat quack with my MIM '69 Thinline RI.

    I don’t hear it while using the neck pickup and I don’t hear it when using the neck pickup but put the switch in the middle and there it is. I suppose some kind of filter is created by combining the two pickups but I am hoping someone can fill me in on the details. I’d also like to know in what frequency range “quack” lives.

    Thanks. Inquiring minds want to know.
     
  2. BillyG

    BillyG Tele-Holic

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    I think of quack as the 2 & 4 positions of a Strat (Robert Cray tone) and personally, I don't care for it at all. I don't think that a 2 pickup Tele can approximate the sound (thank God).
     
  3. w0odman

    w0odman Tele-Meister

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    teles do more of a "cluck" I would say. Although the strat quack has its place for me as well.

    Maybe Terry Downs can provide some science for us?
     
  4. teerjerker

    teerjerker Tele-Meister

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    Yeah, cluck might be a better description. Whatever it is, it seems related to what strat players can get using a certain combination of pickups. I found that it is more pronounce through my tube amp than through my el cheapo ss amp. The tube amp is probably accentuating the frequencies that this sound lives in.

    At some point in this thread, I"d like to ask the question: "How do I decrease the cluck/quack without changing my pickups?"

    Well, looks like I just did...

    You see, I really like my pickups by themselves. I think I should tackle this through a change in my amp. Maybe by changing the bypass cap, perhaps?
     
  5. J-man

    J-man Doctor of Teleocity Ad Free Member

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    Try adjusting pickup heights.:cool:
     
  6. yegbert

    yegbert Poster Extraordinaire

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    Is quack the result of some frequencies getting cancelled out?
     
  7. Dacious

    Dacious Poster Extraordinaire

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    What you are hearing is two things: pickups in phase and parallel produce a lower impedance. This produces a milder sound in itself. Also, as noted, the combined sine wave coming off the two different positions is causing some phase cancellation.

    If you pluck up near the neck pickup you get a bassy tone. If you pluck or strum down near the bridge, you get a sharp trebly tone. The Tele pickup positioning does some phase cancelling but likely not as much as a Strat.

    This seems more pronounced in a Strat because the pickups are closer and the individual sound they are producing is also closer together.

    A way of getting more cluck out of a 2-pickup Tele is to go to one of the five way switching scheme with capacitors on some positions a la the Donohue switching pattern which will knock some freqs. out of one or the other output.
     
  8. tdowns

    tdowns Former Member

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    It is all about pickup position. When a string vibrates, there are places across its length that are antinodes where there is no movement. If the pickup had a sensing point that was infinitesimal, there would be great nulls in the sound of certain notes. Lucky for us, the magnets in pickups that "pickup" (that's a verb) the string velocity have a wide sensing section along the length of the vibrating string. This lessens the nulls.

    When you add another pickup to the mix, the location of it relative to the other pickup can result in cancellation of big chunks of the frequency spectrum. But is depends on the frequency of the note that is played.

    However, if it were as simple as phase cancellation, you could buy a 30 band equalizer and turn a Tele into a Strat instantly (which you almost can). The difference is, the harmonic content of the string is quite high when first plucked, but then settles out to a pure sinusoid near decay. Since the harmonic content varies so much around a plucked string with 2 pickups that are placed apart by a certain amount....quack is born.

    Here is a quack experiment of mine...
    The Blue Tele
     
  9. tdowns

    tdowns Former Member

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    Also the info on the Brent Mason guitar shows my analysis on its pickup spacing and the applicable spectral plots.

    Brent Mason Guitar Info [PDF file]

    Page 10 is most applicable.

    I hope this helps.
     
  10. igorBG

    igorBG Tele-Holic

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    Correct me if I am wrong. But the big part of Start tone comes from vibrato springs also. They create some sort of reverb chamber which is why Strat has so mush air in its sound. Maybe someone who has played hard tail Strat could put comment on this
     
  11. yegbert

    yegbert Poster Extraordinaire

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    Thanks for your splainin and your spearmint too, Terry. You have a way with words and a way with your playing! When I see all those bumps in the graph, it's very easy to just get confused. But I could just drift away in the beauty when you pluck that thang.

    I installed a Tele single coil bridge pickup in my Squier Standard Tele Special (came with bridge HB) with just the absolute minimum wood removal, and that pickup by itself sounds quacky. I measured and found out it has the HB bridge pickup rout a little farther from the bridge end of the strings than even my Squier VM Tele Custom (also HB rout in bridge); and given my minimalist install of the Tele bridge pickup, it is also farther from the bridge end of the strings than my other Teles with their SC bridge pickups in the standard spec position.

    I don't like the quack of this one of mine, but I'm also not that fond of Strat quack in general. But you make that Tele of yours sound really good with its quack.
     
  12. guitarzan13

    guitarzan13 Friend of Leo's

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    Nope...

    Robert Cray quacks big time.... he plays a hardtail......
     
  13. tdowns

    tdowns Former Member

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    Noo. thank YOU for being YOU!

    Yes, indeed. You mess with the Tele pickup position and slant relative to the bridge and a big change will occur in the sound.

    Here is one of the plots of two pickups creating quack.
    [​IMG]

    • The Y axis is amplitude
    • The X axis is frequency (pretend you are looking at a mic frequency response plot)
    • It is the 1st string played open
    • 2 pickups, with their distances from the bridge shown
    • Both pickups are the same volume level
    • The pickup magnetic field width is estimated at 1 inch
    • The yellow line is the fundamental frequency of the note
    • The red bar is the range of fundamental frequencies of that string played up to the last fret

    Notice the big notch at ~3kHz. It is > -40dB !!! That notch moves around with different notes. This is affecting the harmonics of the string.
     
  14. teerjerker

    teerjerker Tele-Meister

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    Thanks, Mr. Downs, for posting this information. It was a big help.

    So, where is the Institute of Advanced Quack Research located, anyway? ;)
     
  15. tjalla

    tjalla Friend of Leo's

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    From the thread title, I thought this was about the Mythbusters episode proving that a duck's quack does echo!
     
  16. dogn4u

    dogn4u Tele-Meister

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    where?

    Quackow, Poland.
     
  17. tdowns

    tdowns Former Member

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    Oh I forgot to mention a very important part.

    Those plots are only the magnitude of the pickup output due to the velocity of the string. It doesn't include the response of the guitar electronics like the resonance of the pickup inductance with the cable/amp/tone control capacitance.

    The real output of the guitar would be the plot above multiplied by an electrical response of the guitar electronics below (typical).


    [​IMG]

    I've been very busy, but I plan to work toward an analysis that includes the pickup position COMBINED with the response of the electronics. I don't know if anyone would care, but it is a personal goal of mine.

    I have always been curious how Leo determined the Tele bridge position and slant. I'm sure it was experimentation. It is definitely a "sweet" spot. I bet he would flip out to know we humans could simulate that with a computer today. Not that looking at plots would tell you if it sounded good!! It's just an academic exercise.
     
  18. tdowns

    tdowns Former Member

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    I'm glad it helped.

    My liddo computer is in Wylie TX.
     
  19. chabby

    chabby Friend of Leo's

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    Maybe Fender shoulda named them Stratoquackers instead of Stratocasters.
     
  20. yegbert

    yegbert Poster Extraordinaire

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    I would love to see the results of that analysis.

    No, looking at plots wouldn't tell you if it sounded good. But I think it would quantify some of the characteristics that make up the timbre, and timbre is often a factor that affects our perceptions how good it sounds. A musical instrument designer that can figure out how to alter the timbre in predictable ways can better target his designs. A guitar tech / hobbyist that can figure out how to alter the timbre in predictable ways can better target his work repairing or modifying guitars. A musician that can figure out how to alter the timbre in predictable ways, and can assimilate that into his song writing and playing, can better "say what he means" musically. And some musicians will have things to say musically that sound good to some listeners.
     
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