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An alternative theory for Pirastro string roll

Discussion in 'Strings [DB]' started by swingingoodtime, Oct 5, 2013.

  1. swingingoodtime

    swingingoodtime Supporting Member

    Mar 19, 2009
    Sydney, Australia
    Hi all,

    So, I finally got to try a (second hand) set of EP Weichs on my bass. They're pretty cool and I'm trying to work out whether they will replace my Spiro Mittels. However, they have a bit of the dreaded string roll but I noticed that, before I put them on, they had a spiral-twist down their length (ie, laying one flat would be like looking at a coil spring, albeit one with very few coils in it). I think this develops due to a twisting motion that occurs when winding a string onto the peg. It's like pinning one end down (ie, at the tailpiece) and then repeatedly twisting the string from the other end (the action of the turning tuning peg); I once had some guts that effectively unwound down their length somewhat due to this problem.

    I reckon that the Pirastro synthetic core eventually adopts this twist permanently due to plastic 'creep', so when I detected the string roll when they were on the bass, this got me thinking: Perhaps the roll is due to the twist, rather than the 'loose core' problem that people talk about with Pirastro strings (particularly Obligatos). I think that initially the twist is tight (like winding a coil spring tighter), but as the material gives, it loosens up and ends up acting like a long spring of low coil tension which you can roll it along its length.

    In the case of these strings on my bass, I think that my tuners may have a different number of turns (fewer) required to bring the strings up to tension compared to the bass of the string's previous owner. Either that, or my tendency to prewrap the string around the peg before pinning the end in the peghole has effectively reduced the number of twists introduced by the winding motion.

    If this is correct, then it means the solution to string-roll is to remove and restring (without prewrapping).

    What do people think of this theory?
  2. swingingoodtime

    swingingoodtime Supporting Member

    Mar 19, 2009
    Sydney, Australia
    I guess another way to phrase all of my blabber above is that I think that winding a string onto a bass induces a twist into the string that resists a natural tendency to roll; one way to test this would be to place a new string under playing tension using a method that doesn't twist the string and see if it rolls any and then see what the tendency to roll is like after winding on to a bass (hypothesis is that it would be less for the latter).
    The ability of some synthetic core materials to stretch & creep into a new 'at rest' state means that, after being wound onto a bass, they stretch/creep towards the untwisted-under-tension state, hence the increased tendency to roll.

    Thoughts? Am I barking up the wrong tree?
  3. Hey I had a set of obligatos that has lots of twisting under the bow as well as pizz. Bought them used and had them on several basses for quite a while. I've got a set of EP solos that I bought new but had them on on and off several basses as well. No twisting that I would've noticed on these ones. I must admit here that obligatos and EP are so different to my ear and fingers that I would not compare them. EP are much twangier and thinner under the bow. This may be the breaking in problem but I've had them for quite a few months before I started to worry and they never broke in

    - sasha
  4. swingingoodtime

    swingingoodtime Supporting Member

    Mar 19, 2009
    Sydney, Australia
    Thanks Sasha, makes me wonder if the EP's have a different core to the Obligatos (it would make sense from a product difference point of view). Also, Solos are lower tension, so perhaps the problem doesn't affect as much as regular EP's? Interesting!

    My A string had the worst roll, so I rewound it from scratch but also put a few twists into the string in the opposite direction of the roll first (had to make sure that the ball-end didn't rotate). This worked quite well; there's significantly less roll now. I also noticed that the twists I put in are in the same direction as that of the metal wrap's coil; possibly coincidence (or maybe they deliberately designed the coil in that direction), but this could be helping to reduce the roll and it's good to know that I've not loosened the wrap in trying this.

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