String Tension

Discussion in 'Basses [DB]' started by Dave Irwin, Dec 21, 2002.

  1. Are there factors other than length, mass, and height that go into string tension. (at least perceived tension)?

    I played 2 basses, both with Helicores at the same height.
    1 bass had a 41.5" string length and the other had a 42.5" string length.
    I would have thought the longer string length would have meant more tension to tune to the same note but the 7/8's (with 42.5" str len) actually seemed less stiff with less tension on the string.

    The bass is more resonant as well

    Do the strings on a less resonate bass feel more stiff?

  2. anonymous0726

    anonymous0726 Guest

    Nov 4, 2001
    If the bass isn't sounding good, either because of the bass, the room, or my ears, it'll feel awful. In my experience, anyhow.
  3. Francois Blais

    Francois Blais Supporting Member

    Dec 11, 1999
    Québec, Canada
    The height of the strings at the nut is also very important!
    Also, the fingerboard's scoop.
    One FB with a smaller scoop will feel easier to play (with equal string heights at the end of the FB).
  4. anonymous0726

    anonymous0726 Guest

    Nov 4, 2001
    I used to do some guitar setup, and I found that it's a balance between scoop and string height.

    If the scoop is too great, the strings will feel high no matter what you do. If the relief is too shallow, you have to get the strings up to a certain height so that they won't buzz, and you have stiffness again. The relief ultimately has to correlate to the movement of the strings. Lighter or floppier strings require more relief. Heavy or stiff strings require less.
  5. Dave Irwin wrote:

    You are correct, these are the only factors which determine string tension per se . The formula is:

    Tension = Pitch x Mass x Length (x a constant)

    Pitch is in Frequency. Mass is per unit of length. The constant term is simply to get everything to work right, and will depend on what units the other terms are measured in.

    Thus it is accurate to say that it will take more tension to get a longer string (of consistent guage and materials) up to pitch.

    But this is the calculation for the tension, or force, in the linear direction of the string only. You are getting more to the operative point, Dave, when you mention "Perceived tension". In the left hand, this will depend on a lot more factors, in particular, nut height, string height at the end of the board, and fingerboard scoop, as Ray and others explained above. I also agree that there can be a real difference in perceived tension depending on acoustic response of the bass. If you have to work harder to get a given loudness or projection, to me, a bass feels "stiffer". Strictly speaking, this sensation is really due to the bass overall, but we may perceive it as mainly in the string, through the right hand.
  6. Since the difference is noticed playing open strings as well, I'm thinking it's not nut hieght or scoop.

    It really seems to be the resonance of the instrument. It's really amazing that a 42.5" string length could feel so "loose" and easy.

    Thanks for the details. I knew it was length, mass, and pitch but I could never remember the actual formula.

  7. I find it easier to remember this formula rearranged this way:

    Pitch = Tension / (Mass x Length)

    This way it all seems pretty intuitive to me. Tension, well, every time we crank a tuning machine tighter, the pitch rises, so it's easy to remember that these two are proportional. On the other hand, pitch is inversely proportional with both mass (per unit length) and length. These can be seen to be pretty intuitive also. Length is easy, we stop the string at shorter lengths to raise the pitch whenever we play. Mass is maybe slightly less obvious. I just try to recall that lower pitched strings are made in a heavier guage so that they'll produce a lower pitch at the same length and at (more or less) the same tension as the higher strings. (In fact, depending on the string brand and model, when tuned to normal pitch the four strings are not always at exactly the same tension, though I believe they try to design them so that they are in at least the same ball park.)