The Fender Princeton Chorus is a classic amplifier and both the Red Knob and Black Knob versions are well-regarded by guitar players.
The main difference between the two is the look and feel of the amplifier, as the Red Knob version was produced in the 80s and the Black Knob version was produced in the 90s.
In terms of sound, both versions of the Fender Princeton Chorus have a clean and versatile tone that is suitable for a wide range of playing styles.
They both feature a 12-inch Celestion speaker and a built-in chorus effect that provides a shimmering, wide stereo sound.
Ultimately, the choice between the Red Knob and Black Knob versions comes down to personal preference and whether you prefer the look and feel of the older or newer version. Both amplifiers are well-regarded and will provide a high-quality tone.