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Double Bass crack in back under soundpost...

T

tbassist4

Aug 21, 2005
614
24
Boulder, Colorado
#1
I was just wondering about the severity of a crack in the back of the bass directly under the soundpost. The school's bass has developed one, either from being a brand new instrument and settling in, exposing weaknesses in contruction, or from it falling off my back (as opposed to me dropping it. This was due to a faulty case strap, but either way, I should have been more careful, considering that I knew the strap was faulty, and didn't give it as much care in holding it as usual...).

I did check it, and it seemed fine at the time. My teacher was mostly worried about the neck, and that was fine. It just seems unlikely that it would crack there from that type of fall (it wasn't down a flight of stairs or something, haha). I didn't even catch the crack until later.

Anyways, the school will pay for the repair. I do know this is a serious thing, but I was wondering how extensive the repairs will be. Is this an easy fix? Or is this something very, very dangerous to the instrument, and cost a lot to fix? This is just an interesting place to have a crack, and I'd assume that since it is where the soundpost is placed, special repairs will have to be made.
 
#2
hopefully some of the many people who are more knowledeable than me will reply soon, but it seems to me that's quite a bad crack. The strings are always putting pressure on the sound post, and over tme--mayeb very quickly--that crack will get worse, ad I assume the top will start to sink as well. I maye be wrong, but think that should be addressed right away
 
#3
I am no luthier, but it seems that it could be any of your mentioned causes or simply the fact that the post is not fitted well. It's possibly too long or on edge.

Even if the post is not the initial cause of the crack, the fact that it as developed under the post is of particular concern as it does assert a great deal of pressure at a concentrated point. Plus, we are approaching winter. The bass is going to draw up a bit as the humidity drops. The situation has a chance of getting much worse.

I would drop the tension on the strings and knock over the post until a luthier can look at it.
 
#4
Tbassist4,
Noticing that my soundpost had just begun pushing out the back plate of my cheap ply, a luthier placed a 4" disc of thin model airplane plywood between the soundpost and back successfully stopping the process. Hope yours is at this early stage. Good luck!
 
#5
A soundpost crack in the back of a carved instrument is unfortunately one of the worst single cracks one can have. It is worse than a top soundpost crack in that a top one tends to want to stay closed due to the pressure of the strings but a back crack will forever desire freedom via the posts insistence. To properly repair it on a school bass will be prohibitively expensive. The instrument needs to come apart and have a soundpost patch installed in the back. If this is a carved bass then I would say it is likely that the crack will become worse over time.
 
#7
I'd also doublecheck the neck, it may not be broken but it doesn't take much ( from bitter, personal experience) to break the glue in the neck block. Everything seemed fine until I took tension off the strings and the neck started wobbling around...
 
#8
ooo...that really is unfortunate. It's an expensive laminate instrument, not carved. I really hope this will be alright. The school will pay for it though, as I attend a private academy and they greatly appriciate the arts programs. What kind of numbers am I looking at for a cost? It's held very well so far...The crack was, and still is very small, it hasn't opened any further, at least as far as I can tell. I didn't notice it for a really long time, so it's been doing very well. Anyways, what is the expected total?
 
#11
I bought a cheap Cremona about three years ago to bang around with, about a year later I noticed I had a crack in the back of the bass under the sound post.

I was originally worried about it, but forgot as other things came up in life.

I noticed the other night that it hasnt gotten any larger (the crack).

I can only assume that it being a plywood bass is what kept the problem in check...
 

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