The Korg CA40 Chromatic Tuner with Output Jack (Folding Stand) wide range that covers A0 (27.50 Hz) - C8 (4186.01 Hz), you can tune a variety of instruments with the Korg CA-40, including wind, string and keyboard instruments. The pitch and range are detected quickly and accurately. You can use the built-in high-sensitivity microphone to detect the pitch of an acoustic instrument without the need for any other equipment. Alternatively, you can use the separately sold CM-100 contact microphone to send the vibration of the instrument directly to the tuner, so that you can tune accurately without worrying about other sounds in the environment. An output jack (bypass) has been added to this digital tuner, making it easy to check the tuning even while you perform.