Tube chart · Guitar amp

Tubes for Marshall JCM800 (2203 / 2204)

Era: 1981–1990Power: 50 W or 100 W

The JCM800 single-channel master-volume Marshall — the entire 1980s hard-rock and metal canon ran through 2203/2204 heads. EL34 power section is critical; swapping to 6L6 changes the entire midrange. Rolling 5751 in V1 cleans up the gain stage for blues use.

Complete tube line-up

Every socket in the JCM800 (2203 / 2204), with stock tubes, direct-swap alternatives, and rolling notes. Tube names link to dedicated specification pages.

  • Preamp gain stages × 3
    12AX712AX7 / ECC83
    Alt:ECC83, 7025, 5751 (less gain)
  • Phase inverter
    12AX712AX7 / ECC83
    Alt:ECC83
  • Power tubes × 2
    EL34
    Alt:6CA7, KT77, 6550 (re-bias)
  • Rectifier (solid-state)
    Solid-state (no tube)
Important: bias before you swap

Power tube swaps almost always require rebiasing — running a new quartet of EL34 cold or hot will shorten tube life dramatically and can damage the output transformer. See the biasing guide and the troubleshooting guide before rolling tubes.

Related amplifiers