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tension/tailpiece?

Discussion in 'Setup & Repair [DB]' started by JAS, May 6, 2002.


  1. JAS

    JAS

    Jul 3, 2001
    California
    what is the relationship between string tension (boyancy) and the tailpiece? A friend has a little piece of wood (or some other hard material) under the tailpiece (where the wire meets the bass). This seems to be making his strings be more boyant and have less tension. I also have a piece of wood there, but it isn't as big. Just to see what would happen, I rolled a paper towel up and cut it to size and placed it under the wire to raise the tailpiece up a little. I raised my strings up a little too and it seems like there is less tension on the strings and they are more boyant. should i get a new (wood?) piece put under the tailpiece to raise it up if i like how this feels and sounds? How much would something like this cost?
     
  2. anonymous0726

    anonymous0726 Guest

    Nov 4, 2001
  3. JAS

    JAS

    Jul 3, 2001
    California
    So, if I had the saddle raised causing the tailpiece to be higher, it would decrease the tension? How much would this cost?
     
  4. anonymous0726

    anonymous0726 Guest

    Nov 4, 2001
    I've never had it done, but I don't think it's astronomical.
     
  5. JAS Me Blues:
    Let's stay clear on the difference between string tension, measured longitudinally (Wow. Did I say that?), and what was called "pressure" or "force". referring to the bridge feet pressing down on the bass top. While the string tension remains the same, the pressure is reduced when the saddle is raised. That's what you meant, right?
     
  6. JAS

    JAS

    Jul 3, 2001
    California
    i think so. I'm talking about the strings being more flexible. Less tension on the strings so that they are less stiff even if there is slightly higher action.
     
  7. JAS

    JAS

    Jul 3, 2001
    California
    Is this what you are talking about? Bassically, I like how the bass feels and sounds with the strings tuned down somewhere in between a half step and a whole step. How can I achieve this and still have the strings raised up a bit? I already have strings that are pretty low tension.
     
  8. anonymous0726

    anonymous0726 Guest

    Nov 4, 2001
    Get your hands in shape. The more you play, the higher/stiffer you'll like your strings, up to a certain point, so that you can feel like you can dig in without getting the thing rattling.
     
  9. Chasarms

    Chasarms Casual Observer

    May 24, 2001
    Bettendorf, IA USA

    I have gone from solos tuned to standard pitch to orchestra-guage spiros in only five months.

    If you play regularly, your hands will get in shape pretty fast. At least mine did.

    It is true that low tension makes the bass easier to play, but once you realize the huge gains you get in tone clarity and sustain, you learn to deal with the heavier strings.

    Although I am glad I started with the solos, I think helped prevent me from getting discouraged by the abuse your hands take in the beginning.


    Chas
     
  10. JAS

    JAS

    Jul 3, 2001
    California
    I have had spirocores on the bass before and I learned to adjust to them and i liked them. Personally i have grown to like the sound and feel of a lower tension, more flexible setup. I think it is better to play music when your body is more relaxed and you can play without straining your body. Plus i think my bass actually is louder and has a nicer sound when it is set up in this way.
     
  11. This thread still bugs me, so here are the results of my actual physical experiments concerning raising the rear of the tailpiece. (on my newer plywood, with a really expensive bridge with wooden wheels) After a bit of a rant. JAS, I too was convinced that the "buoyancy" of the strings would change if the rear of the tailpiece was raised releasing some of the "tension" from the top. Sooo.. instead of doing the actual raising of the back of the tailpiece suggested by master luthier Jeff B. I went with a bungie cord hooked to a work bench and the other end hooked to my bridge and then I leaned back and forward over and over playing my favorite songs. Results? As I leaned back to let the bungie take some FORCE off the top the bass got a little quieter. As I leaned forward, back to no "tension" taken off the top it got louder, it's normal sound. But the strings felt exactly the same "buoyancy" (your word) Then I sat in front of the bass and would push on the bridge to add FORCE to the top, again it simply muted the sound, with the strings staying exactly the same "tension" but the"pitch" changing slightly. So I figured the force to my top was just about right. If your looking for "looser" tension (like Jimi Hendrix tuning down a half step) new strings or as Pete O. said, resetting the neck angle is the only way. (ahhhnold also)

    I'm not recommending anyone else try this. Just my own observations!
     
  12. anonymous0726

    anonymous0726 Guest

    Nov 4, 2001
    There's one big flaw in your experiment. By using the bridge to adjust tension on the top the way that you have, it will always sound best when unmolested as pulling on or pushing the bridge will dampen the the bridge -- the only way for vibrations to make it to the body of the bass. Adjusting the height of the bridge, if you have adjusters, or swapping higher and lower bridges, would give you better results of pressure changes to the bass due to string height changes. The only way to test the effect of the change of the height of the tailpiece would be to change the height. When you change the bridge height, you change both of the angles of the string as it breaks over the bridge, but when the saddle is raised or the neck angle changed, you only change one angle.
     
  13. let's get the terminology and the physics straight, to continue this discussion. (See, when you said "I'll never need this sh*t" in school, your teacher was right after all :p )

    As Don explained above, "tension" is the pulling force in direction of the string. "Bridge force" or "pressure" is the pressure applied to the top of the bass through the bridge's feet. The former determines the pitch of your string. The latter affects the "voice" of the bass, by allowing the top plate to vibrate more or less easily. The two ARE related, but there is an additional factor, which is the angle between the string and the bridge.

    For those you are not terrified of a little mathematics, it is the cosine of the angle that matters. Remember the cosine? that's the one whose value is "1" at an angle of 0 degrees, and which gradually decreases to a value of "0" at an angle of 90 degrees. The total force downward through the bridge = (tension on the G string above the bridge * cosine of the angle between G string and Bridge) + (the tension on the G string below the bridge (should be same as above) * cosine of the angle of that length of string with the bridge) + .... and so on for all strings.

    Simply put, when you widen the angle between strings and bridge, either above or below, (say, by raising tailpiece or reducing the bridge height) you reduce the pressure on the top. When you narrow the angle, you increase the pressure. But as long as the pitches remained tuned the same, the string tension doesn't change.

    Going further, does reduced pressure always mean more sound, and increased pressure, less sound ? This is what Wellspal found, but it is NOT necessarily always the case. Every bass probably has an optimal top pressure where it will speak up the best, according to your taste. But by further widening the angle below the bridge by raising the tailpiece, thus reducing the top pressure, you might go right on past your bass's optimal top pressure and start losing sound. Worse, change your strings, your soundpost, your climate, or any of a hundred other variables, and the "optimal" top pressure will certainly change also.

    As for "tension" on a given string, there's only one way to change that: with the tuning machine ! Tension and pitch have a direct relationship to one another. Math is simple: Pitch = a constant * tension / length. (The constant factor depends on the string's weight and flexibility. Change to a different type of string, and you'll need a different tension to tune to the same pitch. And guess what? A different string tension means your bridge pressure will change also.)

    I think what you guys are talking about with the word "bouancy" is the feel of the string under your left or right hands or bow. Tension will contribute to that feel, and of course so will the height off the fingerboard and the string's construction. But if your chosen brand G string on a 41.5" mensure requires 50 lbs of tension to be tuned to a G, it is always going require that same 50 lbs, regardless of what angle you set between tailpiece string and bridge. Raising or lowering the tailpiece won't make the string up where you play it "feel" any different physically under your fingers, but will probably make the bass's sound respond differently, again owing to the affect of top plate pressure as explained above. Raising or lowering the bridge itself can make the string physically feel different, but that is only due to the change in distance to fingerboard. Of course, changing bridge height can also impact sound, but because it changes those angles a bit, not the tension at pitch. Remember, for a given string at a given length, tuned to a given pitch, the tension is fixed.

    Hope this clarifies things a bit a bit.

    BTW, Wellspal, if you think your bass spoke better with less pressure on the bridge, an easy change would be to use lower tension strings. Consult the string tension guide on Gollihur's site. Remember, leaving tailpiece and bridge, and thus all the angles the same, using lower tension strings will translte directly to lower pressure on your top plate, just as your bungie pulling did. Of course lower tension strings will have a different feel, which you may or may not like, and will certainly introduce a different set of partials into the tone, which could result in a timbre you like less. But you'll only know if you give it a try.
     
  14. There are a lot of folks who would disagree with you about this.
     
  15. Well ok Pete, I disagree and I agree. We should probably avoid falling into a debate about the semantics of what "feel" means here, or on psychoacoustics and cognition. But what the h*ll. I'll see if I can I find a way to reconcile your view and mine.

    I did say of course that changing tailpiece angle can affect the acoustic response of the bass. After a change in the tailpiece or other parts of your setup, a given movement and pressure of the hand will probably produce a different sonic response, which provided it is sufficiently different from before, should be percieved by the brain. Or put the other way around, to produce a identical sonic response after such a change as compared with before, you might need to use your hands slightly differently. So in the brain, comparing hand gestures to sonic response, in this sense, yes, the bass will definitely feel different. But this is an interpretation of "feel" which involves both the hands and the ear, and of course the brain.

    What I meant was a cruder sense of "feel", hands only, not involving any cognitive reference to the heard sonic result. In this more basic sense, I still assert that no matter what you do with your tailpiece, if your string length, string composition, and string pitch are all unchanged, then string tension (as I defined it above) will also be exactly unchanged. Any physics text will bear me out on this. So, the string physically will have the same physical "give" or "bounce", left hand or right. If also string height is unchanged, the string will require the same force to depress to the fingerboard at a given pitch. So in this direct, basic sense, no change in feel.

    But I'll now hedge a bit even here, if it helps us establish a common ground! (Big conflict of my life. I'm a bloke with strong opinions, but I also treasure agreement and interpersonal harmony.)

    I'll agree with you that in addition to the ear/hand sense of "feel", some very experienced and sensitive players can perceive acoustic activity through their hands directly, without reference to the input they're getting from their ears. In fact, this is probably easier through the chest or belly. In the hands, it is probably easiest through the bow. If you blocked a good player's ears completely, he/she can still tell when the bow is at the optimal sounding point or bow speed for a given pressure and desired timbre, just by the way the bow buzzes in the hand. If a change in tailpiece angle then changed the bass's acoustic properties fairly dramaticly, yes, perhaps one could percieve it directly through the bow.

    I would think direct perception of acoustic properties through the left hand, whilst not non-existant, is far more difficult, and probably below a level of sensitivity which could tell whether the tailpiece had been changed. I'm rather sure its all but impossible through the pizzed right hand, 'cause the hand is off the string by the time it sounds.

    Okay - agree or disagree, I enjoy thinking about all of this, and I hope this stuff is interesting to some of you!

    :D :D
     
  16. I didn't say that I disagreed, just that some others disagree and swear that raising the saddle makes the strings play softer.
    It makes some sense to me that if the string breaks at a sharper angle, it doesn't stretch as easily.
    I don't worry about it. I get strings that sound good to me and set the bridge and saddle to where it sounds good.