Features:

• Large, high-precision meter-type display for stable tuning indication
• Supports tuning of seven-string guitars and six-string basses
• Sound Out function lets you produce a reference tone from the internal speaker.
• Auto Power Off function
• Bypass function

Editor Reviews:

Product Description:
The GA-40 is a dedicated, easy-to-operate guitar/bass tuner with automatic pitch detection. In Guitar mode it supports seven-string guitars (7B through 1E), and in Bass mode it supports six-string basses (Low-B and Hi-C). With the precision you expect from KORG, the GA-40 indicates the pitch quickly and accurately. The LCD needle-style display provides both the accuracy of an LCD as well as the easy viewing of a needle indicator, and the display has been enlarged for even better visibility. You can also use the built-in high-sensitivity microphone to tune an acoustic guitar.

Rating : - Perfect Little Tuner
Korg makes fantastic tuners. I used the GA-30 a lot before picking up this model. Both are fantastic. If you need your tuner to operate in-line, then this is a great choice. If you don't care that much, or really don't plan on using it in-line, just go for the GA-30. If you want to use a lot of non-standard tuning, I suggest model CA-30 or CA-40, both of which are chromatic tuners. They can tune to any of the 12 pitches across any octave (so far as I can tell). They don't include presets for Guitar or Bass, though, so you need to know which notes to be tuning yourself.

It is cheap enough for you to give it a try.