New double bass strings may include a short and thin (about 1 centimeter long) section of a plastic tube. It's the D string which goes through the tube. What is it, the tube? What is one supposed to do with the tube when installing the strings?

enter image description here

The tube shown on the detail of a tailpiece arrived with this same (new) instrument already stringed with these same Spirocore strings, but by that time, it was placed within the bridge groove of this same D string, as if saying "I'm not properly setup, take me to the luthier."

1 Answer 1


This was posted by Bob Gollihur of Gollihur music, a reputable bass dealer in the US on a bass forum:

Got an official response from Thomastik on the other board: Re: Plastic on Thomastik I love learning new things every day! Here's today's funfact: The tube on the D string is used for reaching a "less metallic" sound. In fact it cuts off high frequencies, this might reduce the sustain a little, especially the sustain of higher harmonics. Most of the players do not use this tube or they install it just because they think they should. It is not needed. Sorry for taking so long getting back to you but my knowledge is a bit limited when it comes to the bowed line of TI. I'm learning, though... This info comes straight from T.I. HQ in Vienna...

Bass strings do not cut into a bridge like a high E violin string does. Even if they did it would not be logical to put one only on the second thinnest string. The red silk windings at the tailpiece are an identifier of Thomastic Spirocore strings.

  • Thomastik's answer still doesn't really explain why it needs to go specifically on the D string only, and I'd have thought there's not much string movement behind the bridge (may be wrong there).
    – Tim
    Commented Oct 25, 2022 at 8:58
  • Thank you. That page also contains evidence that the tubing on the D string was present as early as in 2001 and that it used to be black whereas now it is white. So its inclusion, while not essential, is neither accidental nor experimental. Commented Oct 25, 2022 at 8:59
  • 1
    @Tim - I suspect that it might have to do with the fact that a double bass is used to produce melody, a lot of the melody comes from the G string, or from quick transitions between G and the next lower string. In the latter case, harmonics on the D string and harmonics on the simultaneously sounding G string could produce some muddiness. Whether the tube can indeed reduce this effect, I will try to experiment with. Thomastik suggests that the reduction of higher harmonics happens when the tube is placed in the groove of the bridge, whereas the position shown in the picture does nothing. Commented Oct 25, 2022 at 9:13
  • 1
    @Tim I have not used Thomastic strings I’m many years but I used them literally for decades without ever knowing their reason for the little rubber tube (I assumed it was for slightly raising a string at the bridge or nut if needed and that’s what I used them for). Thomastics are very bright sounding and if memory serves the D string was particularly so, thus the inclusion of the little plastic sleeve. Commented Oct 25, 2022 at 16:21
  • 1
    @JirkaHanika The tubes may even predate 2001, I can’t say for sure. I probably bought my first set around 1980. They originally were red, not clear and a little longer. Commented Oct 25, 2022 at 16:23

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.