I’m convinced that the electronic tuner is the robotic personification of Evil. Maybe that is over-stating it, but it has done a lot of damage to generations of music makers. Many folks, especially in rock and pop, have grown up with tuners and simply believe that if the tuner says it’s in, it’s in. Not so. Very pointedly not so. In fact, for guitars and basses if the tuner says it’s in it is guaranteed to be wrong. You can read a detailed and excellent technical explanation here
Reading that article, one might get overwhelmed by the complexity. However, you need not be a mathematician or scholar to tune your instrument well; all you need is your ears, and if you have been using tuners all along, you might be surprised to learn that your ears are excellent. Tuning by ear is where it’s at because ultimately it’s about what sounds good to you. Think of tuning as an integral an important part of the music itself, not just a chore to dispense with between takes. How you tune and intonate has a powerful emotional effect on the listener. For me, there is no empirical In Tune or Out of Tune; there is only what works and what doesn’t in a given musical context. Perhaps you want abrasive dissonant sounds to express abrasive feelings. If so, use it! But don’t use it by accident because you didn’t pay attention and have arbitrary intonation causing accidental sourness, use it because you want it that way and do it intentionally. On the other hand, if you want everything to sound mellifluous and soothing, know how to tune so that there is the least dissonance. Tuning creatively does not require a lot of time or esoteric training. I’ll talk about guitar and bass because those are the instruments I play best and because they are both very common. Tuning guitar/bass is not so intuitive because of the frets and parallel strings. Keyboard and wind instruments are pretty much set; you can tune them on the whole and make adjustments in your playing to compensate for problems, but with guitar and bass you need to do that for 6 or 4 strings simultaneously, compensating for the various voicings you are likely to use, and accounting for what interval is most likely played on that string.
Most styles of music have developed their signature sound precisely to accommodate the subtleties of tuning: Folk/Country and everything referencing that is tuned so that the third sounds good in at least two open guitar voicings. Metal and heavy rockers tune so that fifths sound perfect whether voiced on the two lowest strings or next higher. Jazz, or anything with lots of chord and/or key changes, requires tuning so that lets everything sounds a little off, kind of like a piano, but you can have the most flexibility with navigating chord changes. An adept player will know which intervals to leave out of a particular chord voicing in that case. Drone music, music with no chord changes, or most anything traditional Asian can be tuned to an untempered beautiful pure scale that is based on the naturally occurring harmonic series so that every note just sounds great with every other note. Blues or use of so-called blue notes beautifully takes advantage of the fact that thirds, flat sevenths, and fifths are so malleable, and the semitones around them are so evocative and powerful that they can be bent and massaged and stretched out against the tonic to cause all sorts of crazy emotional reactions. The list goes on but that covers most of what we encounter in all of pop. Understanding these things will allow you to tailor and temper your tuning for whatever music you’re working on and what effect you’re trying to produce. I tend to focus a lot on that sort of thing in production.
Step 1 is to intonate your guitar. It’s really very easy and you can definitely do it yourself. Until you do this everything else is pointless. The distance between the nut and bridge is what you adjust. First tune the open string; you can use a tuner or do it by ear if you have a reference. Then fret the octave lightly. If the fretted note is sharp, increase the distance between nut and bridge, if it’s flat, shorten the distance. When it’s right on you’re done. It’s even easier to hear if you play the 12th fret harmonic instead of the open string so that when you fret it is the same note in the same octave.* Note that pressing harder on the fret raises the pitch. This is something you have to deal with by fretting lighter or harder. This can be looked at as a problem but it can also help because it gives you the chance to make microtonal adjustments in your playing of various chord voicings. It’s as simple as that. Do it to each string and you’re done. Of course on an acoustic instrument you have to make a new bridge or have one made by a good luthier that compensates for intonation. They all know how to do it but make sure you get someone good because this is a big deal and is well worth the money.
Next you need to tune for the material you are going to play. There are many ways to do it but what I do is base everything on the tonic of the song and the main chord voicings I’ll be playing. For instance if it’s an acoustic guitar strumming in E I’ll tune the low, middle, and high E either to a tuner or any fixed reference such as a keyboard instrument that is on the particular track and cannot be adjusted. Then do the rest by ear. Start with the 5th in the position you will be playing and tune it against the E until it sounds beautiful, Then do all the other 5ths. Then do the same thing with the 3rd. This is trickier because if you’re playing the 3rd on the G string (G# fret 1) you can make it sound perfect – but when you change to a 1st position A chord the 3rd (C# fret 2 B string) the 3rd will sound bad. You have to either tune the G string a little flat or the B string and little flat or both. Then you can adjust by fretting those 3rd notes a little harder when you play them to adjust. What many people do is simply leave the 3rd out of the voicings that sound off. This leads us right into power chords and explains technically why they are so powerful and shows you how that style developed. If you want to hear that 3rd in one of the chords but don’t care as much about the other you can simply tune it so it sounds good on the chord you care about then not play it on the ones you care less about. It’s often good practice to leave 3rds out of rhythm parts and let the vocals or other lead instruments define how that very important voice reads. That way it gives room for the melodic voices or instruments to choose how flat or sharp they want to be. Problem solved. Another way to do it is to use bar chords to move around when certain notes in a chord don’t intonate properly. If you are tuned so that an open E or A chord sounds great you can slide it up and down to your heart’s content without compromising intonation – as long as the instrument was intonated to begin with as described above. A little experimentation with this will quickly show you how tuning and intonation literally defines the sound of various styles of music based on what chords sound good together on the guitar.
As you get into doing this you will find that it’s easy and with a little practice it will greatly improve the quality of your music and the sensitivity of your ears. It will improve your singing too because you sing what you hear! I strongly recommend getting this tuner. It will sound a note that you can set for the key of the song and tune to it. The note can be adjusted up or down by microtones as well. Leave it going and tune the 5th and 3rd to it as well. You’ll be mazed at how quickly you learn to hear intervals, not just unisons. Try tuning 2nds and 4ths and half steps too. It’s good. This tuner also has a metronome and humidity display. It is designed mostly for classical players as all this is elementary in that world. It also has a plug-in chromatic tuner so you can use it as a crutch on gigs. For the vast majority of live gigs, everything I said in this post is out the window. Just tune to the tuner and do the best you can. (I don’t use tuners on live gigs actually but I’m insane.)
* Using harmonics as a reference is problematic unless you are using and octave. The octave harmonics – two of them are very easy to get – will always be exact multiples of the fundamental frequency. If you use 5ths or other harmonics they may be quite far from where you actually want to be. Many bass players use this method and it can cause problems if you’re not aware of the discrepancy.