The CP-400 was one of the three "Classic Popular" lineup by Yamaha.

Made in Japan in 1978, It was the second-best hybrid guitar.

Yamaha combined the acoustic guitar with the classical guitar.

This is my loose translation from their brochure in Japanese: "The CP series combines the beautiful looks of a folk (acoustic) guitar with the ease of play and the warmth of a classical guitar.  It has an excellent tonal balance which is both warm and crisp.  This series is suitable for both acoustic and classical music."

The guitar is essentially a classical guitar, hence is smaller and easier to hold than an acoustic dreadnaught guitar.

The string action (height) is in between that of an acoustic and a classical guitar.

The basses have a nylon core and produce deep yet warm tones, while the treble strings have a steel core with a nylon outer layer and produce a bright yet pleasing tonal combination of steel and nylon.

Enhancements:

1. I have improved the bracing to make it more resonant and responsive.

2. I have tuned the soundboard to the notes of A and E, so the guitar sounds more music and musical.

3. I set it up to be easiest to play across all playing styles.  The action allows for the broadest dynamic range without sacrificing playability.  In other words, it is easy to play with no string buzz.

4. I Have installed the trans-acoustic system, which amplifies the guitar without using an amplifier.  The system also has built-in effects, eliminating the need to carry pedals and power supplies to gigs.  The system is powered by a good quality 18650 rechargeable lithium-ion battery which can last for many hours.  The system has two pickup sources: 1. high-quality piezo-electric pickup under the saddle and a condenser microphone to capture the warmth of the acoustic sound as well the percussive sounds for loop-pedal players. 

The processed sound (wet signal) can be fed back to the guitar and/or sent to the output jack to an amplifier or P.A. system.

Specifications:

Top: high-grade solid spruce top

Back and sides: Brazilian rosewood

Neck: Mahogany

Fretboard: Ebony

Bridge: Rosewood

Binding: Plastic protective binding around the body, neck and headstock.

Tuners: brand new golden tuner

Scale length: 65cm

Nut width: 52mm

Pickups: One piezo-electric and one condenser microphone

Control knobs & Effects: Volume, On/Off, Room reverb, Hall reverb, Chorus, Delay, Tone knob, Pickup & Condenser microphone blend knob, USB-C charge port. 

Please check out the sound demo video.

I am happy to answer any questions you may have.

Regards.