f-hole corner sinking. Problem?

[mheintz]

The f-hole on the treble side of a fully-carved, 16? year old, bass is no longer even. The inside, upper portion is sinking below the outside upper portion. I don't see a drastic change in the top curvature, but obviously the wood near the f-hole is sinking a bit. I have a winter soundpost in (it's starting to get chilly) and I'm hesitant to change to a tighter soundpost. I don't see a bump on the top from the soundpost. Is this normal? Suggestions?

[el_mariachi]

I was kinda wondering the same. I have a romanian laminate and it does the same thing on both F-holes. the string sides are curved inwards. it was like that when I bought it. I had it inspected by a luthier before I purchased it and he didn't say anything about it. I'm eager to see what some of the more knowledgeable members here have to say.

[KSB - Ken Smith]

The outer side of the FFs can warp upwards as well. Also, look at the Back of the Bass from top to bottom and see if the Back is bulging at all where the Soundpost is.

The Bass sort of adjusts itself throughout its life. Sometimes major repairs/restorations are needed to correct sinking Tops from under the Soundpost, Bassbar or both.

[CPike]

Mine sinks a tad on the post side as well. maybe 1.5mm at the most - is it advisable to correct this with a longer post or would that stress the instrument too much?

Chris

[KSB - Ken Smith]

Originally Posted by CPike

Mine sinks a tad on the post side as well. maybe 1.5mm at the most - is it advisable to correct this with a longer post or would that stress the instrument too much?

Chris

I discussed this in another thread but I will touch on it briefly here with some pics. If the outer feet of your bridge are set wider than the upper inner f-hole eyes, the tension of the Bridge can push the FFs down especially on the G-string side where there is no Bassbar to support it. There is some leeway with this but not much. The sinking of the FFs is often a serious sign of something wrong. The longer you wait to have it corrected, the more permanent the damage can be.

Bridge feet too wide, damaging the Top;



Bridge feet just inside the line of the upper eyes (This is the Top of a c.1830 John Hart Bass of London was sunken in and just had a massive restoration;



Bridge feet just 'outside' the upper eyes of a perfectly healthy Top. This is a master grade Forster School Cello model Bass by Samuel Gilkes, 1814 London with the shoulders cut c.1870-1880. The Top has never split yet in its 193 years! With a Top so perfect, we can move the feet slightly wider for a bit of a deeper sound;



On this old Northern European Bass (France/England c.1775, +/- 50 years), the FFs are so far apart on this full sized Bass that the Bassbar is actually inset quite a bit. The eyes measure well over 180mm (as I recall) but the Bridge width will be well under that at about 165mm after its restoration. The Scars from the older 170ish/mm Bridge are obvious by the varnish wear;



Note: On this last and very large instrument, the Top has never sunken in. The FFs are perfectly aligned within its original arching.

[el_mariachi]

I suspect my bridge might have *some* part in it. I plan on getting a new one anyway as it is a nasty Glaesel bridge (the ones with the pivoting feet that automatically adjust to the contour of the top).

[CPike]

Thanks Ken for the great info and pics. I'd like to elaborate and clarify my sinking situation. The F hole wings are fine, its the region above and below the G foot of the bridge that concerns me. The part over the bass bar side is perfectly shaped, but on the other side you can see the bridge foot has sunk slightly with the area above and below clearly higher by about 1.5mm or so. This bass is 30 yrs old and has been like that for a while - do you think it could be corrected with a longer post pushing the table back up level with the bass bar side?

I was thinking about achieving this gradually over the next couple of years: putting in a very slightly longer post every 4 months or so to give the wood a chance to relax and settle instead of jacking it up too much all at once. Any thoughts?

Chris

[mheintz]

Thank you so much, Ken. It looks like a trip to Gage is in order.

[mheintz]

So I took the bass to David Gage today. Simon and David took a look at it. They adjusted the soundpost a bit and moved the bridge slightly. They said it's something to keep an eye on and perhaps in the future may require a patch to reinforce the top. It turns out the top is a bit thin. It sounds great, so I'll just monitor the situation.