Here is what Yamaha say...
'With a solid spruce top, the Yamaha APX700 projects a warm, mature tone with rich, ringing sustain both acoustically and amplified. The small body and slim neck ensure that, like all APX guitars, the performance experience is perfect.
The 1-way A.R.T pickup system in combination with the System 56 preamp delivers a clear, controllable sound thanks to its ultra-musical EQ and adjustable mid frequency control for precise tone shaping.
• Top: Solid Spruce
• Back & Sides: Nato
• Fingerboard: Rosewood
• Scale: 650mm
• Frets: 22
• Pickup: A.R.T. 1-way
• Preamp: System 56
• Controls: 3-band EQ, Volume, Tuner
• Tuners: Chrome
The unique A.R.T (Acoustic Resonance Transducer) pickup features a multilayer construction designed to provide the perfect balance between sensitivity and noise reduction. Designed exclusively for Yamaha acoustic guitars, the A.R.T pickup offers incredible dynamic range, outstanding feedback rejection and, thanks to its being mounted on the back of the guitar's top, picks up the natural resonance of the guitar to create exceptionally natural amplified tone.
Based on years of research, pickup placement in the APX was determined to within one-tenth of a millimetre. Having found the 'sweet-spot', Yamaha then re-designed the internal bracing of the guitars to allow for ideal placement while maintaining the tonal character of the guitars.
1-Way Configuration/System 56 Preamp
This configuration features one main pickup system consisting of two A.R.T pickups underneath the saddle. The 3-band EQ gives the ability to control the mid-range frequency for precise control and tonal flexibility. The preamp also features an onboard tuner.'