snip I don't have the OT-120, but its predecessor the MT-1200 snip
The MT 1200 is programmable, and has octave stretching (for pianos and some fortepianos). The MT1200 is more accurate than any of the Korg models. It is truly good to half a cent, which is pretty good. However, due to the input microphone sensitivity it is less suitable for tuning lutes by most sorts of microphones, including the little clip on "microphones". It is superb for tuning by ear, using the built in sound. Make sure you calibrate the tuner, the tuner includes a reference tone which you then match to the little trim pot with a small screwdriver. Most professional tuners do not use the mic input, so the MT1200 is the gold standard for tuners under a grand. When you think about it, a ten dollar mic that cost Korg 50 cents to make is perhaps not the most accurate of devices. Some newer Korgs, including the "orchestra" tuner (as if it would be used to tune an orchestra) have a variable speed input for different types of instruments. That is because pluckies and bowies have amplitude detuning, at the widest arc of the string the notes go sharp. On either a bowed instrument or a plucked instrument the pitch will rise as you pluck the string harder or bow harder. To tune accurately you must learn the average deviation for each string and learn to repeat the pluck consistently. Players routinely pluck the string harder when tuning, so the end result is that some notes are slightly flat. Anyway, you have a great tuner, so learn to tune using the built in sound. Play the sound, play the note, one after each other (do not play them at the same time). This will train your ear as far as unisons. Hear better; play better. Unfortunately, the korg does not do Gerle, Dowland, Arnaut, Ordinaire, Niedhardt, Handel's temperament, etc, so those tuning are rarely used nowadays. Bach's so called temperament is pretty much Neidhardt, but it doesn't do that either. On the MT 1200 you can program a pretty good equivalent to most temperaments. Another way to tweak the tuner is using the calibration button. You can lower or raise the thirds by manipulating the reference tone. Last and most important perhaps is the reference tone itself. The MT 1200 allows you to set the core tone for any temperament. Basically, without going into all the details, if you like the built in meantone in A major, and you want exactly the same sound in G major, you set the temperament reference tone a tone lower. Normally, people use the factory setting, but this setting has about a twent five percent chance of being optimum, unless, of course, you only play in F major. I think Korg realized that the MT 1200 was too complicated, so subsequent models had fewer features. But that is its charm. I find the thirds in the built in "korg" meantone to by very slightly too pure for the lute or the harpsichord. They sound great on the organ. A cent or two higher or lower, you get a kind or frisson of color in the sound. That is just taste. Similarly, when tuning a piano, the unison strings are very slightly out of tune to creat a sparkle, or shimmer in the sound. Otherwise they sound kind of dull. The precise function of the tuner is to apply a layer of uniformity to tuning which never existed historically. I have a box full of tuners, can't live without em--I use them in the orchestra because the orchestra is playing so loud I can't hear the notes. So I plug in a contact mic. Hey maybe it is an orchestra tuner after all. In this scenario, in the pit so to speak, I just have memorized the spots on the dial for the different tunings, I don't bother with the presets, usually. If you set your second fret low, you can pull the octaves and fifths into tune by twisting your fingers while you play. That's the best I can do without tastini, and it isn't meantone, but it is not too bad. Nice thirds. You can also find some pieces that are missing a note or two, they sound quite beatiful in meantone. But most lute music--most early music--has an F sharp and a B flat. After you have tuned your lute, play all the octaves. Play all the fifths, and so on. That will give you a sense of the temperament. Your octaves will not all be in tune, but a temperament is a choice, not a perfect system. Normally people go for the thirds, but historically it is much more likely that the fifths and octaves would have been considered more important in the hierarchy. A difference, however, is that on the organ it is important to allocate the beats more carefully; you don't hear the beats as strongly on the lute, unless you use wire strings. Enjoy your MT 1200--it is a great tuner. I learned to tune with a wristwatch! I once saw a colleague tuning with a watch, and someone in the audience asked where the korg was. When the tuner replied that they were tuning by ear (using the watch to set the key fifth) the other person was shocked and said they had never seen such a thing. dt To get on or off this list see list information at http://www.cs.dartmouth.edu/~wbc/lute-admin/index.html
