Korg CA-40 Chromatic Tuner is the successor to the popular Korg CA-30. This little workhorse, about the size of a deck of playing cards, is an excellent basic electronic chromatic tuner. As a chromatic tuner, it can tune all the pitches in a chromatic scale. This makes it more useful than some dedicated guitar tuners. Korg CA-40 is all many musicians need, though it has some limitations.
Useful features are the ability to play the pitch through the integrated speaker, as well as a 1/4" output jack for an amplifier. The CA-40 also accommodates an external microphone with a 1/4" jack, for example the Korg CM-100L Contact Microphone. While the internal mic is OK for quiet environments, we strongly recommend an external mic, preferably a contact mic that will be less likely to be confused by ambient sounds. CA-40 can also be calibrated so that if, for example, the piano in the band is a few cents low and cannot be tuned, the Korg CA-40 Chromatic Tuner can be adjusted to match, then be used to tune the rest of the band. The display is large, and has colored lights that also indicate sharp, flat or in tune. The tuner also detects the closest pitch automatically and adjust the display so that the operator does not have to press buttons to tune a different pitch.
Korg CA-40 Chromatic Tuner lacks some features that users with more rigorous tuning needs may require. The LCD display needle lacks the fine resolution of a genuine analog needle. In most cases, it's fine, but those seeking precision may find the jumpiness of the needle as it flicks from one set of LCD crystals to the next frustrating. While the tuner will detect the closest pitch automatically, it does not display the numerical value of the actual pitch being played; the pitch number displayed is that to which the tuner is calibrated.
Korg CA-40 Chromatic Tuner specifications say the tuner will work with A0 through C8, the entire range of a piano. In practice, we find that it is not as effective with hearing the pitches of higher and lower octaves, especially when used with the built-in mic. Using the Korg CM-100L Contact Microphone to get as close as one can to the instrument helps with this, but once again as a basic tuner it is not going to be as effective in unusual circumstances as a better tuner.
Bottom Line: Korg CA-40 Chromatic Tuner is excellent for the majority of musicians' needs for gigs and practice. But for technicians or other situations where pitch values are critical, or deep bass or high soprano instruments are tuned, this value tuner may not be the best choice. For a chromatic tuner with more features and a wider range of uses we recommend the Korg OT-120 Orchestral Tuner.