I installed a trans system preamp on a YAMAHA APX. This preamp can output a more powerful and louder sound than a YAMAHA trans guitar. It's possible to have a mini-concert without a guitar amp in a small room. Neck, nut, and saddle adjustments. After adjusting to the best condition with fret leveling, I installed DOUBLE OS1. This will change the conventional wisdom of acoustic guitars. ⭕️Search for DOUBLE S1 OS1 on Youtube 【Preamp】 ⭕️Trans function: The condenser microphone and piezo pickup pick up the vibrations of the guitar and strings, and the preamp applies effects, sending the signal to the actuator (vibrator) installed on the back plate, making the body resonate. The sound of the natural sound and the effects are mixed and come out of the guitar. You can enjoy the effect sound from the sound hole without connecting anything. Also, when connected to a guitar amp via line out, you can play it as a regular electric acoustic guitar. ⭕️Effects: You can apply mic blend, delay, chorus, and reverb all at the same time. ⭕️AUX: A function not found in other preamps. You can connect via Bluetooth, import sound sources from an iPhone, etc., and play along with them. ※ You can also enjoy music as a Bluetooth speaker by hanging the guitar on the wall. ⭕️The power source is a rechargeable battery with a C-terminal cable for charging. 【Features】 ◯APX series top single-plate. Sides and back are resin using wood that is resistant to howling. ◯The 4-piece saddle picks up the single notes of each string, resulting in a well-defined arpeggio. 【Condition】 ◯Fret leveling, neck, nut, and saddle adjustments for a low string height of about 2.5mm at the 12th fret, 6th string. ◯There is no fret wear, and it is polished with steel wool and is shiny. ◯The original preamp holes on the side are not intentionally closed as monitor holes to deliver the sound directly to the player. ◯The oval rosette, which is a feature of the APX, is also in a beautiful condition. 【Specifications】 ◯Color: White ◯Top: Spruce single-plate ◯Sides/Back: YAMAHA original resin ◯Neck: Nato ◯Fingerboard: Rosewood ◯Bridge: Indian Rosewood ◯Nut width: 42mm ◯Scale: 650mm ◯Body thickness: 75mm - 85mm ◯Pegs: Replaced with new silver chromatic pegs ◯Accessories: Preamp instruction manual and charging cable