Double Bass String change has put my intonation all over the place.

[DoubleMIDI]

Whenpressing strings down you make them longer. The more the higher the action is. Depending on the core material, construction and thickness, the force to press down the string is different. The higher tension due to the elongated string rises the pitch. More for a core that needs a lot of force to be stretched by a certain amount like steel, less for gut or synthetic core strings.
The aging of strings might also have an influence, since strings stretch over time and get a bit less tension.

 

[jazzyvee]

The new strings feel much less tight and much easier to finger. I don't know what the old strings are but they have red silks and the guy i bought the bass from had not changed the strings. I was aware he had the bass since 2013 when i bought an electric bass from him. so they are at least 8 yrs old. What is the normal period for string changes?

 

[Francois Blais]

They probably were Super-Sensitive Red Label strings.
Solid-core, very rigid.
The period to change strings depends on the brand. Spirocores can last a full decade or even more.
Depends if you like when they sound bright or dark.
All strings will mellow and get darker with age and use.
Many players will change their strings after one or two years, also depends how often you play them.

 

[DoubleMIDI]

If you give us a photo of the ball ends we can tell you if these are red labels or Spirocore Medium.

 

[jazzyvee]

Thanks will do that later. Post a pic of each set so maybe you can tell what they both are.