Bulge under bridge?

Is it normal for there to be a slight bulge underneath the bridge? Noticed the Martin OXK I got recently has a slightly raised area. Normal or cause for concern? Thanks!

It's normal enough for ukuleles and guitars to have slight bellies/bulges between the saddle and the bottom of the instrument. Just what is normal though and what is too much has been the subject of many a thread for time immemorial.

I have a couple of luthier-made tenors that have a very slight depression under the center of the bridge. Both builders separately reassured me that it is normal and allows the top to move a tiny amount without threatening the seam between the two halves, or the sides.

They also said that a very slight belly or ripple can form between the bottom edge of the bridge and the bottom edge of the top.

It is primarily due to the changes in the humidity and to a lesser amount to the temperature. Often happens if too much humidity is experienced by the uke.

Neither affects the sound of the instrument unless it gets severe and causes separation from the braces on the back of the sound board.

If it is slight, then that is quite normal. No cause for concern.

John Colter

40mm - Thanks for asking, I had a similar question a few days ago.

Thanks for the replies, very helpful.

In my case, I was seeing a bulge between the bridge and the bottom edge. When I first noticed it, the bulge was occurring under load of "hard tension" strings. I changed strings to a "medium" set, and I'm still feeling the bulge (it's barely noticeable by sight). After a quick consult with another member who has a tenor version of my uke, I'm not worried about the bulge turning into something damaging.

Thanks for the responses folks. Any other OXK owners with the bulge under the bridge? Also is the thinking that if I were to take all tension off the strings that body would lay flat again, or is the bulge now shaped into the "memory" of the laminate. Hope that makes sense.

If you take off the string tension, I would not expect the body to become flat again. It is all quite normal, if only slight.

John Colter

Excellent! Thanks so much. Really like this Martin OXK so I'm glad it's not an issue. The bulge is definitely only very slight.

ukantor said:

If you take off the string tension, I would not expect the body to become flat again. It is all quite normal, if only slight.

John Colter

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