Results 1 to 11 of 11

Thread: A string intonation weirdness

  1. #1

    Default A string intonation weirdness

    Hi all,

    I've got a Samick F style mandolin (I believe it's a MF1) and I've been having some intonation issues on the A string.

    Here's what I'm seeing when I tune the open A string:

    - A#,B,C and C# are all noticably sharp
    - D and up tuning is acceptable, almost all the way to the octave

    My first attempt at fixing the problem was to file the nut to bring up the open A but I destroyed the nut in the process so I replaced the nut. The new nut has the exact same problem.

    I replaced the straight bridge with a compensated bridge from another instrument but that didn't fix the A string problems.

    All the other strings are pretty good. I don't play high on the fret board very much so I'd be happy with a solution that improves intonation on the first 7 frets.

    I can't quite explain how a single string could have this problem, does anyone have an explanation and a proposed fix?

    Thanks,
    Andrew

  2. #2
    Middle-Aged Old-Timer Tobin's Avatar
    Join Date
    Mar 2009
    Location
    Kerrville, TX
    Posts
    4,004

    Default Re: A string intonation weirdness

    Is it possible that the frets are worn so much that the groove has shifted the position of the fretted string slightly? By that, I mean when a fret gets a groove worn into it from lots of playing, it no longer has a crowned surface. The deeper the groove, the wider the surface the string is being pressed down on. So it's possible that the distance between the bridge and the contact point of the fret has shrunk a little bit, due to the groove getting down into the wider portion of the fret wire. This might explain why it's only happening on the first 4 frets, where you play the most. And it would explain why the notes are slightly sharp.

    I always find the A strings wear the frets faster than other strings, which might also explain why you're seeing this only on the A course. It might be time for fret dressing.

  3. #3

    Default Re: A string intonation weirdness

    Thanks for the reply.

    Quote Originally Posted by Tobin View Post
    Is it possible that the frets are worn so much that the groove has shifted the position of the fretted string slightly?
    I had that problem early on so I doubt it's a wear problem.

    Quote Originally Posted by Tobin View Post
    I always find the A strings wear the frets faster than other strings, which might also explain why you're seeing this only on the A course. It might be time for fret dressing.
    Thanks, I'll keep that in mind. Maybe the frets aren't worn but were bad from day 1. It's not a very high end instrument but I really like the sound so I'll consider replacing or fixing the frets.

  4. #4
    Registered User Tom Wright's Avatar
    Join Date
    Jun 2010
    Location
    Rockville, MD
    Posts
    1,919
    Blog Entries
    7

    Default Re: A string intonation weirdness

    Two possibilities: A is too high in the nut slots, or you have too much bowing in the neck. Either case makes for too much clearance in the low frets, and too much tension increase when fingering that can't be compensated at the bridge. Since you say the effect drops away after the first few frets I would guess it is the nut.

    The string is very reactive to the tension increase caused by pushing it down to the fret, and much more sensitive than guitars with their larger distance to the first fret. The A is probably higher tension than the E and D, so would react more.

    One way to check is capo at the first fret and then see if the next couple of frets behave. I check this visually by observing how far the string deflects downward when I fret from open to fret #1, and compare how it looks going from fret #1 to fret # 2. You will see that the string gets pushed down only slightly when going from #1 to #2, but the deflection from open to fret #1 will likely be noticeably larger. I find the nut has to be essentially identical in clearance to that between frets.

    You need to either buy or make proper nut slotting files, or go to a shop that can improve your setup. In my experience all mandolins are extremely touchy about this issue. Get Rob Meldrum's setup e-book, email him at rob.meldrum@gmail.com .
    Bandcamp -- https://tomwright1.bandcamp.com/
    Videos--YouTube
    Sound Clips--SoundCloud
    The viola is proof that man is not rational

  5. #5

    Default Re: A string intonation weirdness

    Thanks, good tips. Will try your suggestions tonight.

    Quote Originally Posted by Tom Wright View Post
    The string is very reactive to the tension increase caused by pushing it down to the fret, and much more sensitive than guitars with their larger distance to the first fret. The A is probably higher tension than the E and D, so would react more.
    I noticed that I can compensate a little bit by using less pressure on the first few frets so what you're saying makes a lot of sense.

    The nut is an off-the-shelf replacement so I'm sure I could improve the situation a bit. Good excuse to get a set of files.

    Andrew

  6. #6
    Registered User pfox14's Avatar
    Join Date
    Sep 2009
    Location
    Holiday, FL
    Posts
    1,152

    Default Re: A string intonation weirdness

    Are you using a tuner to determine if the pitch is off? Sometimes your ear can fool you. Given the fact that it's only one string and only certain notes on that string, leads me to believe that it's not a structural issue like the nut or frets. If the fret spacing was off, then all the strings would be out of tune. A very puzzling problem.
    Visit www.fox-guitars.com - cool Gibson & Epiphone history and more. Vintage replacement mandolin pickguards

  7. #7
    Mando-Accumulator Jim Garber's Avatar
    Join Date
    Mar 2003
    Location
    Westchester, NY
    Posts
    30,753

    Default Re: A string intonation weirdness

    How old are these strings? Have you tried changing strings to new ones? What kind of strings are you using?
    Jim

    My Stream on Soundcloud
    Facebook
    19th Century Tunes
    Playing lately:
    1924 Gibson A4 - 2018 Campanella A-5 - 2007 Brentrup A4C - 1915 Frank Merwin Ashley violin - Huss & Dalton DS - 1923 Gibson A2 black snakehead - '83 Flatiron A5-2 - 1939 Gibson L-00 - 1936 Epiphone Deluxe - 1928 Gibson L-5 - ca. 1890s Fairbanks Senator Banjo - ca. 1923 Vega Style M tenor banjo - ca. 1920 Weymann Style 25 Mandolin-Banjo - National RM-1

  8. #8
    Registered User
    Join Date
    Oct 2002
    Location
    san diego
    Posts
    1,267

    Default Re: A string intonation weirdness

    Sometimes mandolins just do not tune up right no matter what. I took an expensive F5 type once to a respected instrument repairman here in San Diego and he told me that mandolins many times will not note in pitch up the neck. He told me that that's just the way they are. He also said that most mandolins get that "hump" on the fingerboard near the bridge. I just think mandolins are not an exact science. Guitars seem to be better.
    ntriesch

  9. #9

    Default Re: A string intonation weirdness

    Quote Originally Posted by pfox14 View Post
    Are you using a tuner to determine if the pitch is off? Sometimes your ear can fool you. Given the fact that it's only one string and only certain notes on that string, leads me to believe that it's not a structural issue like the nut or frets. If the fret spacing was off, then all the strings would be out of tune. A very puzzling problem.
    Yeah, definitely using a tuner. My ear is okay but not good enough to keep up with some of the people I play with so I'm dependent on a tuner.

    Quote Originally Posted by Jim Garber View Post
    How old are these strings? Have you tried changing strings to new ones? What kind of strings are you using?
    Hmm, good question. Strings are pretty new d'Addario but I don't remember exactly what kind they are. I think the red ones with gauges 11-15-26-40. That's what I usually buy. In the light of what Tom Wright say maybe I should go lighter.

    Quote Originally Posted by Nick Triesch View Post
    Sometimes mandolins just do not tune up right no matter what. I took an expensive F5 type once to a respected instrument repairman here in San Diego and he told me that mandolins many times will not note in pitch up the neck. He told me that that's just the way they are. He also said that most mandolins get that "hump" on the fingerboard near the bridge. I just think mandolins are not an exact science. Guitars seem to be better.
    Agree, it's pretty tough to keep them in tune but I'm hoping I can do a little better. My pitch recognition isn't that great and I can tell it's a bit off.

    By hump do you mean the neck getting a bend where it's attached to the body?



    Thanks for all the tips,
    Andrew

  10. #10
    Registered User
    Join Date
    Jan 2009
    Location
    S.W. Wisconsin
    Posts
    7,507

    Default Re: A string intonation weirdness

    I fought the same thing with a '22 Gibson, finally i was ready to pull all the frets, fill the slots and refret. While measuring for scale length i discovered the spacing from the first fret to the nut was the same as the first fret to the second. Added a shim at the end of the fingerboard and the nut and it plays in tune all the way up the neck. I have seen several '22 Gibsons with this problem since.
    THE WORLD IS A BETTER PLACE JUST FOR YOUR SMILE!

  11. #11
    Mando accumulator allenhopkins's Avatar
    Join Date
    Mar 2006
    Location
    Rochester NY 14610
    Posts
    17,378

    Default Re: A string intonation weirdness

    Quote Originally Posted by Nick Triesch View Post
    ...a respected instrument repairman here in San Diego...told me that mandolins many times will not note in pitch up the neck. He told me that that's just the way they are. He also said that most mandolins get that "hump" on the fingerboard near the bridge. I just think mandolins are not an exact science. Guitars seem to be better.
    ?????

    I would think this wouldn't be true for properly fretted and set-up mandolins. Never heard that improper intonation was "just the way [mandolins] are."

    Can't find examples of the "'hump' on the fingerboard near the bridge" (? -- mandolin fingerboards don't get very near the bridge, do they?) on any of the 15-20 mandolins I own. Maybe I just got lucky…?

    There are pretty well-documented examples of improperly fretted Gibsons from the 1920's, when the fretting jigs Gibson used got worn, or out of kilter, for a period of time. But the idea that mandolins are generically un-intonate-able, and usually develop "humps" in their fingerboards, is new to me. None of the repair techs with whom I work here have ever told me that.
    Allen Hopkins
    Gibsn: '54 F5 3pt F2 A-N Custm K1 m'cello
    Natl Triolian Dobro mando
    Victoria b-back Merrill alumnm b-back
    H-O mandolinetto
    Stradolin Vega banjolin
    Sobell'dola Washburn b-back'dola
    Eastmn: 615'dola 805 m'cello
    Flatiron 3K OM

Tags for this Thread

Bookmarks

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •