Double Bass Open strings go sharp

[Puzzler5]

So my spirocore D and G get about 1/2 step sharp if I play and hold an open string! I had old evahs on before and the D was also going sharp but that was my experience with old guts and I assumed they were dead. But with red spiros? Is it a set up issue or are my strings really old and used? The spirocores I put on are like a few months old but they sound great so I’m a little confused.

 

[BassinCT]

Did you purchase the Spiros new?
I have only experienced this phenomenon with very old strings or cheap knockoffs that go sharp with faster bow speed + weight

 

[GretschWretch]

Your nut on those strings may be cut too high. Too much space between the fingerboard and the bottom of the open string can make the string go sharp when depressed. Check the depth of the string notches all across the nut.

 

[jj.833]

How do you 'hold an open string'?

 

[john m]

How do you 'hold an open string'?

Don’t touch it.

 

[Puzzler5]

Did you purchase the Spiros new?
I have only experienced this phenomenon with very old strings or cheap knockoffs that go sharp with faster bow speed + weight

Spiros were new.and it definitely happens when I bow fairly quickly or strike the string particularly hard.

 

[Puzzler5]

Your nut on those strings may be cut too high. Too much space between the fingerboard and the bottom of the open string can make the string go sharp when depressed. Check the depth of the string notches all across the nut.

I think I will bring the bsss in because the A and E are ok. Also the action has gotten particularly low on the D and G

 

[jj.833]

Would you care to send some pics? Nut, from the fingerboard towards the bridge, and also whether the soundpost is alright?

 

[AGCurry]

Spiros were new.and it definitely happens when I bow fairly quickly or strike the string particularly hard.

It's normal for the pitch to be a little sharp on a hard attack or with heavy bow pressure... but a half step sharp is not normal.

 

[Francois Blais]

Maybe there's a wolf on that note, or harmonic?

 

[Don Hergert]

What is your double bass's mensure? What tension Spiros are you using, and are you using 4/4 or 3/4 Spiros?

You may be finding your double bass mensure combined with these particular Spiro strings and your playing style produces too much excursion when you pizz or arco the strings. Try a very light touch with an electronic tuner to get in tune, then as you play normally, if you're getting more than 30 or 40 cents difference high or low on the electronic tuner when the string is in action, you may need higher tension Spiros on that double bass -- you could try to develop a permanent lighter touch, but higher tension Spiros would be easier.

Also, if this double bass was setup for fat/low-tension strings (guts, synthetics) before the Spiros, you may be dealing with setup differences with the nut and bridge slots and/or with fingerboard relief. In that case a luthier setup might be appropriate, and you may want to also have the luthier check the sound post for the best tone with Spiros.

 

[Derek Kay]

It's easier to play an open string more vigorously than a stopped note.
I will often avoid them as they can sound odd.

They will begin sharp and drop to the correct tune as the amplitude decreases

What does a tuner show?

 

[Don Hergert]

What does a tuner show?

Typically a tuner shows the note and how close you are to it, often measured in increments of 10 cents on a small screen. So if I'm over-playing an open string that is in tune, I can watch how it varies back and forth around the actual note. More than 40 cents off in either direction and you're getting within the range of the next half-tone. As you over-play less, your string stays closer to the note it's tuned to.

Low tension strings are more prone to this than high tension strings because of increased excursion. Higher tension strings tend to stay closer to the tuned note when over-playing.

Note: Aside from having an electronic tuner on my DB, I use gStrings tuning software on my (Android) phone and pad. In the "Auto" mode this software demonstrates the above description very nicely on a larger screen.