"a" string suddenly goes flat

[Jon Hall]

My mandolin is a 1999 Weber Absaroka. A week ago, during a performance, one of my "A" strings went suddenly flat. I mean really flat as if I had knocked the tuner. It only did that once during the gig but since it was when I was taking a break it was a little unnerving. I thought that I might have not wound the strings around the posts enough times so when I changed strings this past week I made sure that I made three wraps around the posts. It happened again last night during band practice. As best as I can tell it happened when I picked the A strings. I was digging in with some down strokes.
I had practiced a total of about two hours earlier in the day but without having this problem. I'm sure I wasn't picking as hard during practice as when I was playing with the band.

I would appreciate your opinions and suggestions.

[Dale Ludewig]

Jon, first place I'd check is if you have a binding nut slot. That's classic behavior. Did you change string gauges recently?

[Rodney Riley]

If string size the same, maybe some gunk dried up in the nut slot. Maybe just clean it with a soft cloth and water. Rub a little pencil lead in the slot. Make sure tuner screws have not loosened any.

[Tobin]

I had that happen once. It had nothing to do with the tuner. The winding at the loop end had actually slipped, making the 'noose' a little tighter. You might check there and see if it looks different than your other A string.

Supposedly, this is why the old-style tailpieces had the double hooks for the A and E strings, so they could be made to bend around one set of hooks and reduce the slippage issue. The claim is that modern strings are wound better at the loops, negating any need for this, but I have found that occasionally it does still happen.

[jshane]

If it happened on 2 different sets of strings, I'm betting that the nut bound the string, and the extra "digging in" was enough force to pop it free. I suppose if the tuner gear is worn badly, it could have slipped a tooth, but that seems pretty extreme.

[Dave Hicks]

I use Nut Sauce lube on saddles and nut on electric guitars. What might it do to an ebony bridge?

D.H.

This stuff:

http://www.bigbends.com/nutsauce/agora.cgi?product=Nut Sauce

[Jon Hall]

I did begin using a different set of strings a few months back. The "A"s are .016 instead of the 015 I was using. It doesn't happen all of the time, obviously, but I'm guessing the string is binding in the nut slot. I'll take it to technician that can check the slots and file if necessary. In the meantime I'm going to rub a little graphite in those slots. I appreciate all of the replies.

[Willie Poole]

Jon, a lot of people just install strings and never stretch them a few times and then when they pick them with a little force they stretch and go flat, try pulling on them just a bit until they won`t stretch and go flat any more...I do this and very rarely ever have to tune during a performance...

Willie

[AlanN]

I do what Willie does whenever I change a string. I pinch it between thumb and forefinger and gently but firmly yank it uo to the sky 2 or 3 times. Gets rid of the slop.

[Mark Wilson]

I had practiced a total of about two hours earlier in the day but without having this problem. I'm sure I wasn't picking as hard during practice as when I was playing with the band.Nut binding for me never takes long to slip out of tune even with light playing. Maybe take Tobin's suggestion to check the loops to see if they are same size now.

[sunburst]

I always pull the strings too.
Does your tailpiece have smooth round attachments for the string loops? If so, it might be the loop tightening like a noose at the tailpiece as someone mentioned. If the attachments are squared or otherwise kink the loops a little, strings slipping at the tailpiece is pretty rare.
Basically it pretty much has to be the tuner, the nut or the tailpiece. We've already gone over the low chance that it is the tailpiece, the tuner is not likely unless it is badly damaged, and that leaves the nut as the most likely culprit. Rather than try to lube a poorly fit nut slot with pencil lead or whatever, it's best to fit the slot to the string.

[Tobin]

I did begin using a different set of strings a few months back. The "A"s are .016 instead of the 015 I was using. It doesn't happen all of the time, obviously, but I'm guessing the string is binding in the nut slot. I'll take it to technician that can check the slots and file if necessary. In the meantime I'm going to rub a little graphite in those slots. I appreciate all of the replies.
If the string were binding in the nut slot, it would have more tension between the nut and tuner than between the nut and saddle. Any forceful playing action that caused the string to relieve this tension difference in the nut slot (i.e. even out the tension on both sides of the nut) would cause the string to go sharp, not flat*. So I'm not seeing how nut slot binding could possibly be causing the string to lose tension suddenly when playing. It has to be losing grip at the tuner or tailpiece. If you've checked your tuner to make sure the gear is not defective/worn, and you have enough winds around the post, then my money is on the loop end slipping at the tailpiece hook.

*edited to add: this is true only if you're tuning up to pitch, not down to pitch. You always tune up to pitch, right???

[Jon Hall]

I always tune up to pitch. I took the tail piece cover off and the 4th string (the A nearest the center of the bridge) has a loop that appears to be 2-3 mm longer than the other three un-wound strings. That would explain why this hasn't been a regular occurrence since I started using these strings. I stretch my strings when I change them.

[allenhopkins]

Possibilities:

1. Loop in the A string deforming.

2. Tailpiece prong bending.

3. Tuner post slipping/rotating.

4. String binding in the nut slot, strenuous picking puling an extra length of string through the slot, which could lower the pitch of the string even though the string might be at higher tension (i.e., "sharp") between the peg and the nut.

Something has to be operating to lower string tension. Possibly some other very-low-probability causes, but these seem the most likely.

[Tobin]

I always tune up to pitch. I took the tail piece cover off and the 4th string (the A nearest the center of the bridge) has a loop that appears to be 2-3 mm longer than the other three un-wound strings. That would explain why this hasn't been a regular occurrence since I started using these strings. I stretch my strings when I change them.

Just to clarify, did the loop get longer, or is there just a longer length of winding? When I had the loop slip before, the very end of the winding (where the wire terminates) stayed put where it grabbed the string, but that portion of the string had jumped forward (towards the bridge). But the lower part of the winding stretched out and had gaps between the winds. The actual loop got smaller, but the length from the end of the loop to the termination of the winding got longer, if that makes any sense.

Is this what you're observing?

[sunburst]

...the 4th string (the A nearest the center of the bridge)...

...the longest unwound string from nut to tuner post, and the most likely to pull through the nut slot from hard picking. Another piece of evidence in favor of the problem being the nut slot.