scale length?

[4-string-thing]

Just bought a 3/4 bass from a fellow basschatter (hi ben) and whilst wiping the dust off and having a quick look around, I noticed some marks in the finish near the bridge which makes it look like the bridge may have been moved. As I'm a newcomer to double bass I was wondering what the scale length should be ? I don't want to start moving the bridge around without knowing what I'm doing. . .

[TheRev]

The scale length will vary slightly from bass to bass, but the bridge should line up with the notches on the f-holes.

[FLoydElgar]

If you move your bridge do it flat on the ground or your soundpost will fall over!!

[4-string-thing]

Ah, thanks for the advice both!

The bridge seemed to be about an inch or so closer to the neck than it should be (going by the f hole slots) so after laying it flat, I loosened all the strings, moved it and retuned. This seems to have lowered the action a bit too, is that likely? Or is that just wishful thinking?

Incidentally, I know double basses have a soundpost and it needs to stay put, but can you tell me what it does, and how? Excuse the silly question, but I really am a complete novice! (Despite having played electric bass for well over 30 years)

[fonzoooroo]

Yes, the action will have gone down.

The innermost F hole nicks should point at the centre line of the bridge.

The soundpost should be about 1/2 the thickness of the bridge foot lower (toward the endpin) than the bottom edge of the bridge foot.

Basically, the soundpost is a support. It is positioned at a node point of the front, so doesn't actually transmit vibration to the back (as is often thought!) ... Inside the front on the bass side, there is the bass bar, which spreads the load of the bridge (string tension/pressure) over a wide area of the front, and transmits the vibration further into the most active parts of the front of the bass.