FiiO CP13 Portable Cassette Tape Player with 3.5mm Earphone jack, Ultra-low Wow&Flutter, Powered by Type-C or lithium battery (Red/Silver) CP13 is a portable stereo cassette player, and it is currently the thinnest and most stable cassette player in production. It supports playing Type I to IV tapes. To ensure a stable movement, a customized large pure copper balance wheel with a diameter of 30.4mm and a thickness of 4mm is selected. Additionally, a high-voltage drive motor powered by 4.2V is carefully chosen to maintain an extremely low oscillation rate, resulting in a more stable sound output. In the pursuit of superior quality magnetic heads, meticulous screening processes have been implemented to ensure stringent control over the entire production of CP13 magnetic heads. The aim is to minimize the disparity between the left and right channels, surpassing the current standards of mass-produced models available in the market. Additionally, a balanced differential circuit design has been adopted for the acquisition of magnetic head signals, resulting in more stable signal transmission, higher signal-to-noise ratio, and lower distortion. The CP13 is meticulously crafted with a dual-tone aluminum alloy shell, featuring a seamless design with no visible screws on the body. The buttons are treated with a hardened oxidation process, ensuring durability and resistance to wear and corrosion. The volume knob of the aluminum alloy is designed with a large-volume analog volume potentiometer, which is more stable and reliable in quality compared to the flat potentiometers used in ordinary cassette players, providing a better tactile feel for adjustment. Featuring the renowned JRC5532 operational amplifier. 1800mAh lithium cobalt oxide battery, providing over 13 hours of continuous playback for extended listening sessions.