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Conference napalm::guitar

Title:GUITARnotes - Where Every Note has Emotion
Notice:Discussion of the finer stringed instruments
Moderator:KDX200::COOPER
Created:Thu Aug 14 1986
Last Modified:Fri Jun 06 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:3280
Total number of notes:61432

86.0. "Intonation?" by UNCLE::GEORGE () Thu Nov 06 1986 16:56

    What is 'intonation' or, why does your guitar sound better than
    mine?
    
    I've got an electric Ibanez ??-200 that's about ten years old.
    I've made a few tapes with both the Ibanez and a D-18 and the
    difference between the two is painful.

    I can tune it to sound ok on chords in the first position, or
    tune it slightly differently for bar chords, but it's never
    really right.  The neck is true and, although the action is
    low, there are no dead zones or buzzes.  It's somewhat less
    noticable with heavier strings (currently Markley light/heavy's).
    
    I've been told that I should adjust the intonation.  OK, I'm game.
    The bridge is adjustable.  I've got access to an electronic tuner
    and a teeny screwdriver.  What next?

    Thanks,
    Dave    
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86.1BAXTA::BOTTOM_DAVIDThu Nov 06 1986 17:3433
    Ok a simple way to adjust intonation:
    
    1. plug in your tuner
    2. tune a string using the tuner so that the harmonic played at
    the 12th is in tune
    3. now play the note at the 12th fret
    4. if it is sharp move the adjustable bridge piece (saddle) away from the
    nut, if it is flat move the adjustable piece twords the nut
    5. go to next string. repeat above.
    
    1st fret                            12th fret
    |-----------------------------------------------------------------------
    |                                                                       
    |
    |
    |-----------------------------------------------------------------------
    
    ^
    |
    nut
     
    Note: as you adjust the bridge saddles the string will most probably
    require retuning.
    
    To play a harmonic (in case you dont know) lightly touch the string
    above the 12th fret and pick it pulling your finger away after the
    note is plucked, a soft tone will emit (theoretically, easy after
    a little practice) this note at the 12th fret should be the samme
    as the note played at the 12th fret.

    I do this to all of my guitars 3-5 times a year.
    
    dave
86.2Good...PARSEC::MELENDEZFri Nov 07 1986 10:017
    Ref .1)
    
    I did not asked for the information, but I would like to thankyou
    for it anyways.
    
    Miguel.
86.3OK on the practice, what's the theory?UNCLE::GEORGEFri Nov 07 1986 13:048
    I did ask for it, and I'd like to thank you too.  We'll give it
    a try this weekend.

    One more question, though.  Why is it necessary to redo the adjustments
    so often?  I'd think that the bridge for each string should be at
    some magical mathematical place based on string mass/tension/action
    height.  What changes to require a tune-up every 1000 songs?
    
86.4harmonic theory??HENRY8::MARSHALLFri Nov 07 1986 13:5360
    A whole smorgasbord of things can cause improper intonation. Here's
    a few that I can think of off the top of my head:
    	1) The quality of your guitar(i.e. how securely is your neck
    	   fastened to the body? I have problems with my 3 bolt Fender
    	   Strat neck all the time.)
    	2) Ambient temperature and humidity. As the air gets drier this
    	   time of year, the wood in your guitar may contract a bit.
    	3) Your playing style. Do you really wrench the neck around
    	   as you play? Does this alter the straightness of the neck??
    	4) Wear and tear. As you change strings and if you change them
    	   often, both the nut and the will wear a little causing string
    	   length changes.
    
    For those of you who are not aware of how this tuning system works,
    here are some pictures:

                  ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
    		 <                                               >
    		^ ''''''''''''''''''''''''''''''''''''''''''''''' ^
    		|                   \_string                      |
    	       nut					        bridge
    	when you pluck an open string, the whole string vibrates in
    	a loop.
    
                                       () -12th fret
                  ,,,,,,,,,,,,,,,,,,,,,  ,,,,,,,,,,,,,,,,,,,,,,,,
    		 <                     ><                        >
    		^ '''''''''''''''''''''  '''''''''''''''''''''''' ^
    		|                   \_string                      |
    	       nut	    			   	        bridge
    	As you just touch your finger to the string at the 12th fret,
    	you create a "node" in the string and subdivide it in two halves,
    	each half resonating one octave above the open string frequency.
    	It is here that the string length is measured for intonation.
    	This note you hear should be the same as the note played when
    	the string is fretted at the 12th fret. If the fretted note
    	is sharp, then the string is too short, send the bridge piece
    	out a little bit. And just the reverse if the fretted note is
    	flat.
    	

    				()- 7th fret
                  ,,,,,,,,,,,,,,  ,,,,,,,,,,,,,,,  ,,,,,,,,,,,,,,
    		 <              ><               ><              >
    		^ ''''''''''''''  '''''''''''''''  '''''''''''''' ^
    		|                   \_string                      |
    	       nut			    		        bridge
    	Another harmonic occurs at the seventh fret where the string is divided
    	up into thirds.

                             ()- 5th fret
                  ,,,,,,,,,,,  ,,,,,,,,,,  ,,,,,,,,,,,  ,,,,,,,,,
    		 <           ><          ><           ><         >
    		^ '''''''''''  ''''''''''  '''''''''''  ''''''''' ^
    		|                   \_string                      |
    	       nut			 		        bridge
    	And at the fifth fret, the string is divided into quarters where
    	it resonates two octaves above the open string frequency.

    rick    
86.5Real world intrusion into musical perfection19584::BECKPaul Beck, DECnet-VAXFri Nov 07 1986 16:1013
    Other factors include the size of your frets and the thickness of your
    strings. A string is neither zero diameter nor at infinite tension (your
    fingers will appreciate both). When you fret it, you are changing its
    length by stretching it. If you have high, fat frets (my recollection is
    that Ibanez guitars, for one, have large frets), and you fret hard, you
    bend the string over the fret, changing its length further. For reasons
    such as these, the absolute distance between nut and bridge is different
    for different diameter strings (ever wonder why the saddle isn't
    straight?). If you change from light to heavy strings on an electric
    guitar, I imagine you need to adjust the bridge. 
    
    A guitar is only an approximation. Technically, you can't make a guitar
    with perfect intonation, I believe. You come as close as you can.
86.6BAXTA::BOTTOM_DAVIDFri Nov 07 1986 16:4017
    One of the main reasons I do this so often is that I record alot
    and I'm VERY picky about tuning. Nothing hurts me more than some
    itiot in a bar that refuses to tune/intonate his guitar, I'll leave
    rather than listen to it.
    
    good luck
    
    dave
    
    re: three bolt fenders......I fixed the problems I was having with mine
    moving by 1) using rubber cement to help hold the neck in place and 2)
    shimming the neck in so tight that it requires a mallet to seat it
    properly (picks work great for this), on my Lead 1 with the kahler this
    was very difficult due to the shim kahler requres under the heel of the
    neck, that neck was very mobile at first but now doesn't move at
    all....even if I pull it sideways with all my might.