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intonation weird thing I never seen

Discussion in 'Hardware, Setup & Repair [BG]' started by Dredmahawkus, Oct 29, 2013.

  1. Dredmahawkus


    Nov 4, 2012
    Ok now let me start by saying I still have to get a good tuner...just have the d'addario clip on and a snark.

    So I set my intonation to 12th harmonic yesterday and I could tell it sounded out of tune down there on the G string. anyway the 12th harmonic sounds and reads perfectly in tune but if I play a fretted 12th fret G it sounds and is way out of tune almost a half note! how can the 12th fret harmonic be in tune and the 12th fretted note isnt? should I set the intonation to the 12th fretted note?
  2. megafiddle


    May 25, 2011
    It is the 12th fretted note that you should be adjusting the intonation of.

    The 12th fret harmonic will always be in tune with the open string (on a good string).

  3. Dredmahawkus


    Nov 4, 2012
    ah ok I always thought it was the harmonic.....glad I asked!!!!

    my saddles are messed up...its a 75 AVRI the old fender bridge...the screw starts coming out of the saddle and I have to pull the saddle to get it to go up.....do they all do that? I never seen that on my other basses.
  4. megafiddle


    May 25, 2011
    Do you mean that the screw backs out the tail of the bridge when you try to move
    the saddle towards the neck, instead of the saddle moving forward?

    Thats normal. You just need to keep pressure on the screw head to hold it against
    the bridge tail while adjusting it.

  5. Dredmahawkus


    Nov 4, 2012
    ok cool thanks! I am going to adjust all my basses now! I cant believe I thought it was the harmonic!
  6. megafiddle


    May 25, 2011
    Glad to help.

    It's understandable. There are (or were) at least two websites that described adjusting
    the harmonic.

    I started writing a procedure which may help also. Will post it here as soon as it's finished.

  7. megafiddle


    May 25, 2011
    The basic intonation procedure adjusts the pitch of the 12th fretted note in relation to the open string.
    The 12th fret pitch is set to be precisely one octave higher than the open string. When the 12th fret
    has been adjusted, the other frets will normally be acceptably in tune also.

    Many use the 12th fret harmonic instead of the open string as a reference for setting the 12th fret note.
    This is possible because the 12th fret harmonic is always in tune with the open string. You can use
    either the open string or the 12th fret harmonic as a reference. The 12th fret note is then set to be in tune
    with that reference.

    The procedure is to first tune the open string. Then the tuning of the 12th fretted note is checked. If the
    note is flat, the saddle needs to be moved towards the neck. If the note is sharp, the saddle needs to be
    moved away from the neck.

    You don't want to try to read the tuning while you are moving the saddle. It's not like tuning an open string,
    where you watch the tuner while adjusting the tuning key. You first determine which way the saddle has to
    move, and then move the saddle a small amount, like 1/16".

    Then you retune the open string, and check the 12th fretted note again. If it's still off, you move the
    saddle again a small amount. Then retune, check again, adjust saddle again, etc.

    This first procedure is commonly used:

    1. Tune open string.
    2. Check 12th fret note. If flat, saddle needs to move towards neck. If sharp, saddle needs to move away from neck.
    3. Move saddle small amount in required direction, about 1/16".
    4. Repeat 1, 2, and 3 until 12th fret note is in tune.

    This procedure is done by ear and doesn't require retuning after each adjustment:

    1. Tune open string.
    2. Adjust saddle until 12th fret note is in tune with 12th fret harmonic.
    3. Retune open string.

    Also, when checking intonation, use the same fretting pressure that you would use when playing.

  8. 96tbird

    96tbird PLEASE STAND BY

    Or you can say: just tune the string, then fret the 12 and check. If flat move saddle toward neck. If sharp move it away.

    That harmonic mistake you made is a regular mistake mentioned around here by neo's. i think it stems from long convoluted explanations that confuse novices.
  9. Dredmahawkus


    Nov 4, 2012
    I noticed I couldnt pluck the 12th note and try and tune it while moving the saddle and hold the note at the same time....so I was already checking to see if the 12th was in tune move the saddle....retune the string then check the 12th again.

    I have a bunch of basses and always checked the 12th harmonic....and didnt notice how off they were until I changed the strings on one yesterday and it was way off. I would play a song and instead of a G on the 12th it was actually playing a Ab. I would check the harmonic it would be fine.....I was like these strings suck! I have noticed that before using other basses of mine that that song sounds off when I play the 12th fret G...so I have other basses I have to check today that I know are off that I thought were just the strings.

    I decided I like lighter strings since I just traded for a bass with lighter strings on them. are they harder to tune? I was having a hard time getting the E string to tune yesterday. it was reading all over the place with brand new strings I was putting on.
  10. lundborg


    Apr 8, 2008
    Changing to different strings may affect intonation, especially if the new strings are a different brand.

    Changing to a different gauge will most definitely require adjustment of the intonation.
  11. megafiddle


    May 25, 2011
    That's true. It can also stem from just plain wrong information:


    I like knowing why things are done and so tend to provide such information. Good to know, I think.
    I also provided the 4 numbered steps. I think those are as simple as possible, while still being complete.

    I mentioned the retuning because I have seen some move the saddle, check the 12th fret, move the saddle, check the 12th fret, etc.
    Of course, while they are doing that, the open string is going more and more out of tune.

    New strings have stronger overtones (harmonics) which can confuse an electronic tuner.
    Did it sound ok?
    Try rolling back the tone.
    Also try picking or plucking at a different spot on the string.

    If the 12th fret note is varying, lighter strings are more sensitive to fretting pressure. Use just enough
    pressure to get a clean note.

  12. :p Nice!

    Yes. Tune open string. Check at fretted 12th. Adjust saddle. Retune open string. Check fretted 12th again. Adjust saddle if necessary. Lather. Rinse. Repeat. :)
  13. bassbenj


    Aug 11, 2009

    Think about this. If you tune the open string and then play the 12th fret harmonic the string is NOT pressed down to the fret. When you play the NOTE at the 12th fret it is pressed down. That STRETCHES the string and changes the tension and hence changes the note being played! Thus, all the instruction here of tuning the OPEN string and then intoning the FRETTED 12th fret note. That takes care of a lot of things automatically.

    And another reason you can't tune to harmonics is that a harmonic is only an integer frequency to the open string (2x 3x etc) for IDEAL strings. Normally music wire strings (top strings on a guitar) are pretty ideal. But the WOUND strings on a bass are NOT ideal and that means the harmonics DO NOT track the open string note. And it's worse than that! The amount of non-ideal harmonic shift varies with the size of the string. Just look at the saddles on a properly intoned bass. Note that they are at an angle! That is because the amount of harmonic shift and shift of the 12th fret note changes with string diameter. Thus the string length for proper intonation is different for each string.

    Yeah, it's all confusing to a noob, but just intonate so the fretted 12th note matches the open note and most things are taken care of.

    PS. Complicated aside: The non-ideal character of strings shows up yet another way. If you have a 24 fret bass and you check intonation between 12th fret and 24th fret you'll usually find that they won't be the same! Usually intoning the 12th fret works best, but if you really intend to USE those upper notes, sometimes you have to find a compromise intonation between 12th and 24th fret notes.

    I presume this long convoluted explanation has confused noobs. :bag:
  14. Hopkins

    Hopkins Supporting Member Commercial User

    Nov 17, 2010
    Houston Tx
    Owner/Builder @Hopkins Guitars
    The simple answer is, if its sharp at the 12th fret you make the speaking length of the string longer. If its flat you make it shorter. Most of the time when doing setups, especially first setups, the 12th fret is sharp.
  15. Zooberwerx

    Zooberwerx Gold Supporting Member

    Dec 21, 2002
    Virginia Beach, VA
    Just a reminder: make sure the other parameters are set correctly prior to tweaking intonation, including:

    *New strings, if necessary, properly installed with adequate break angles and witness points.

    *Optimal relief, usually .012-.014".

    *Nut slot depth, usually .003-.005 at the 1st fret with 3rd fretted.

    *Optimal string height...YMMV.

    *Hold instrument in normal playing position when checking clearances.


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