The 13DE7 is a 9-pin, single-ended, low-mu, medium-mu triode vacuum tube. It is known for its excellent linearity and musicality making it especially well-suited for use in audio amplifiers, preamps, mixers, and other audio applications. This tube is popular for its low microphonics and low-noise, making it beneficial for use in sensitive applications. It can be used in various different amplifier configurations such as single-ended and push-pull. Furthermore, it is also an ideal choice for high-gain circuitry.