I’ve noticed that with my Brazos acoustic
guitar (model BA-50);
I tune the guitar as normal, using
a good chromatic tuner, but then
play a certain chord, and it sounds
a bit out of tune.
So, open strings tune fine, but
some fretted strings go sharp.
Do you know how, when you check
the tuning by hitting the low E string
on the fifth fret, and then the string below
it open (A), they should sound the same (be in tune)?
Well, I will tune the guitar to perfect tune with the tuner,
then go check it with that trick, and some pairs of strings
will be right on, and others will not.
So, I am assuming the intonation is off, but how do you
alter that on an acoustic? Electrics have screws to turn, etc,
but acoustics seem unalterable.
Also, the action on the guitar is a bit high, not sure
if that is related or not.
The guitar is from the late 1980's. I do not believe
it is worth much, so I'd rather not sink alot of money
into it if possible, although I really do like the guitar.
Yes, you do have an intonation problem. If you play the harmonic note at the 12th and compare it to the fretted note at the 12th (on any string) I bet the fretted note is a bit sharp? The high action is part of the issue because the distance that you need to push the string down in order to fret a note changes (shortens) the length of the string and alters (sharper) the pitch a little bit. If you lower the action a bit it is likely to improve. How high is the action, and how tall is the saddle? Do you have room to drop the action?
The other way to adjust intonation is to alter the shape of the saddle so that the break point of the strings is slightly further towards the end of the guitar (just like with the adjustment of an electric - but not so convenient). The reason why the saddle is sloped across the strings is to provide greater compensation to the bass strings than the treble ones. I would sugest that you fix the action first and see how the intonation works out. If it is still a problem the saddle will need some reshaping.
Finally, why is the action high? Is the bridge rotating or lifting, top bellying up, neck angle poor? These are the usual problems of a cheap guitar reaching middle age.
I played the harmonic on the 12th fret, low E string, and it
was in perfect tune. I then played the fretted 12th, low E, and
it was now sharp. You were correct.
Arthur, it sounds like it might be a case of needing a neck reset. Try this....with the neck as straight as you can get it, lay a good straight-edge on the frets so that the end of the straight-edge just touches the bridge. If the straight-edge intersects with the top of the bridge (not the saddle), then the problem likely lies elsewhere. But if the straight-edge intersects considerably below the top of the bridge, then a neck reset is inevitable.
If the guitar is a cheapie, it probably isn't worth the cost of the work. But Mark's right... first lower the action any way you can and see if the intonation improves.
Arthur - I will try to be gentle as I say this.
Do what Mike said. Put a straight edge along the frets and see if it points to the top of the bridge, or (likely to be the case) a position a bit south of there. If the latter is the case you have a few options:
1. Accept that this guitar will never again have playable action. Set it up for slide playing and get a new one as your main guitar.
2. If the high action seems to be because the bridge is a bit elevated (increased arch in the top behind the bridge, dip in the top betwen the bridge and the soundhole) you can rescue it by installing a "Bridge Doctor". See the Stewart McDonald site to buy one of these. They have been the saviour of many a poor guitar.
3. If you really love this guitar and you want to give it a new lease on life, get a good luthier to do a neck reset. Say goodbye to $500 bucks and enjoy your favourite guitar for another decade.
Sorry, but this is the reality of life for the owners of 1980s cheap guitars.
Very true, there may be a simpler issue, such as a needed truss rod adjustment. I also notice that too many guitars have saddles that don't actually match the radius of the fretboard, giving horrible action and playability. I'm sure this is an effect of buying a saddle off the rack without actually adjusting it to conform to the guitar.
You could always do the rather cheap alternative of cutting the heel and bolting it down again, the cheapo reset. It's not pretty, but effective. (I'm not finding instructions for this one, anybody?)
I took it to a local luthier, and he gave the truss rod a good turn,
and that was all it took. The action was high, caused by a bow in
the neck. The truss rod adjustment fixed the bow, and lowered the
action. Now with the action not crazy high like it was, the intonation
is correct. The action was so high, it was causing notes to go sharp
up the neck when fretted.
Thanks again to all for your advice.
Well, I spoke too soon. Seems the luthier over-adjusted the neck a bit,
and while the action is low now, there is alot of fret buzz, so, I have to take
it back to him for further adjustment. At least he did not charge me.
So, the saga continues...