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I have a vintage Gibson K2 mandocello that I thought was all set up and ready. I pull it out tonight and discover that something's wrong with the C course: suddenly both strings buzz a lot and have almost no volume. It was professionally set up when I bought it and definitely wasn't having this problem a few months ago.
What might have happened?
Process of elimination.
Check all aspects of set up: neck bow, string height at nut, string height at bridge, etc.
Check the bridge for damage or other problems.
Check bracing to see if anything has come unglued.
Check the strings themselves.
Tailpiece, tuners... heck, check everything.
Hm. Well, it's a 1912 and has what I think is the original 1-piece bridge with removable ebony saddles that sit in a slot running the length of the bridge ... and it looks like there's a bit of a gap under the C saddle.
1- Check inside the soundhole on the bass side to see if the transverse brace under the bridge may have popped loose.
2- Ship it down to the southeast this week and watch the whole action swell up 2" off the fingerboard from all the rain and humidity we've been getting!
I did check the brace and it doesn't seem amiss. But it has been mighty warm by Pacific Northwest standards and the action does seem to have climbed up a bit.
Check the brace again and check all of your seams.
If you've got D'Addario off the shelf 'cello strings with .074" C strings and .048" G strings on there, get rid of them right now and lighten up your gauges. Their set will pull an old Gibson to pieces, and a change in sound might be the first sound of something going awry.
I don't have exact gauges worked out for a 'cello, but I would buy some singles and start experimenting. I would start around 16 plain-26 or 28 wound - 40 or 42 - 60 or 62 and go up cautiously if necessary. That'll put you in the neighborhood of 18 to 21 lbs. per string, or ~180 lbs. for the whole instrument, which I believe to be reasonable for a 100 year old Gibson.
The D'Addario set will put somewhere around 240 to 250 lbs. tension on your instrument, which would be a stiff load on a modern 12 string guitar.
Maybe if the saddle was loose. Just maybe it might of been switched out to another spot. Check the groove width on the saddle.
I don't know exactly what gauges are on it, but I'll get the calipers out and measure. I have most gauges sitting about up to .056, but after that the next heaviest I have is .070.Quote:
Originally Posted by rcc56
The tension of an .074" string tuned to C on a 24.75" scale instrument is about 28 lbs. An .070" string is 25 lbs., an .062" is 20.3 lbs, and an .060" is 18.6 lbs.
Since the courses are doubled, that yields 56 lbs. on your instrument for just the C strings if you use 74s, as opposed to 37 to 41 lbs. if you use 60s or 62s. These figures are for nickel strings. Phosphor bronze strings of similar gauges will have about 10% higher tension.
For comparison, the tension of an .038" tuned to G on a 13.875" scale Gibson mandolin is 21.5 to 23.7 lbs; depending on the alloy, a .040" will run 23.6 lbs. to 26.1 lbs. I can't speak for anyone else, but I won't put anything heavier than a 40 on an old oval hole Gibson mandolin.
I don't like to put much more than 180 lbs. total tension on an older instrument of any kind. And things such as old flat back mandolins are better off with less.
I hope you figure out what is causing your problem, and that it is not serious. My reasons for posting the exhaustive figures above are that I've seen the heavy modern 'cello sets wreak havoc on the old Gibsons. The same goes for some of the mandola sets.
Well, I used the D'Addarios on a 1917 K1 for a number of years with no problem, but this '12 might be more delicate. I use 70-46-32-20 on my Steve Andersen but it has a truss rod.
hi
I have a 1916 K2, has quite a bow in the neck which I have never fixed because I love the sound and don't want to mess with it. I changed from the D'Addario set to Thomastik (they are a bit expensive but I don't change strings much)
They are a lighter gauge and I noticed improvement in the bow. Plus the sound is great and easier to play. (I read online that some people feel they ruin the sound of the low strings, I don't find that at all) Also they are flatwound and polished so there is no more squeak .....
Yes, I can make up a flatwound set with D'Addario chromes and use .065 for the C strings -- but I think I'll experiment with phosphor bronze roundwounds first; they are cheaper.
Having had a lot of experience in the past with pre-1921 Gibson K-1 (& K-2) mandocellos (think I have owned three of them in the past) I am going to say most likely you are starting to get top "sinkage" on the bass side of the top. This is very common on those mandocellos. Sometimes the sag does not happen immediately after you string it up but some times happens slowly and you find what appears to be a well set up mandocello one day is suddenly "thuddy" and lifeless a few weeks later. I had one 1936 K-1 that would experience severe top sag but then spring back to normal contour a few days after tension was removed and then sag again within 1 - 2 weeks after being brought back up to tension. The transverse brace on that one remained glued down the problem was that the brace and the top board combined were too weak to support the strings (I used D'Addario J-78s). Somewhere on the builders section there is a long string that explains how I did the Frank Ford fix on that K-1 by taking the back off and adding a second spruce transverse brace directly under the bridge. It worked perfectly -- no more top sag. Even better the mandocello --if anything - sounded better than before the fix. The second brace seemed to transfer the vibrations all across the top and it was a real boomer.Quote:
Originally Posted by mrmando
Well, I can confirm it was strung with either suspension-bridge cables or the D'Addario set, take your pick. I'm going to go 56-42-32-20 and maybe let it sit a day or two before bringing it up to tension.
It's certainly worth a try. The 56's may be a little bit floppy, but at least you'll get some idea of how the instrument will react to a lighter set. I hope it works out well.
I can certainly procure something in the range of 60 or 62, but 56 is what I have in the building at the moment.
Suddenly my idle mind realized that this thread needs a scroll reference. We would perhaps all be enlightened from reading it then.
(It's just my obscure sense of humor, carry on...)
Does it buzz open and on all frets? find where the buzz starts. lighter strings vibrate more back and forth and may make it worse.
Tuned up with lighter strings and the problem is gone! Nonetheless, Paul the luthier will check it out. He may lower the action at the nut. As predicted, 56s are somewhat floppy when tuned to low C (although they still sound better than the 74s did). If Paul can't come up with some 60s or 62s I'll find them myself.