Changing strings on an acoustic bass

[LowEnder2112]

Hey, i just bought myself an acoustic bass, fairly decent; it's the Micheal Kelly Firefly 4 string acoustic bass. And the strings they came with were pretty old, so i bought my self some d'addario acoustic bass strings (long scale, medium). And i know how to change strings on an acoustic guitar, and an electric bass, so i figured, might as well put some new strings on. But after i just put on the E string, it's up to tension, the action is very low and the fret buzz is unbearable. so im thinking; what did i do wrong for it to buzz so much? it wasn't like that when i got it with the bad stock strings...so help is much appreciated. I haven't put on the other 3 strings, just incase i mess those up too.

[obaka-san]

sounds like you need a truss-rod adjustment, there's plenty of guides in the setup and repair forum.

Before you change anything though, put all the strings on the bass and bring it up to tune, it can make quite abit of difference to the overall action of the bass.

[Parabolic Box]

Maybe the original strings were a heavier gauge than the ones you put on.

[Lokire]

If you just have the E string on and no other strings, then that's normal. Without the tension of the other 3 strings, the neck will have more of a backbow than usual resulting in low action and fretbuzz. Put the other 3 strings on and then tune it up. Should be closer to normal then