Marshall JCM 900

The Marshall JCM 900 (Model 4100 Dual Reverb / Model 2100 Master Volume) is a legendary all-valve amplifier head introduced in 1990 as the successor to the acclaimed JCM 800 series. Designed to meet the demands of late-1980s and 1990s rock and metal guitarists, the JCM 900 introduced significantly higher gain capabilities directly from the front panel, eliminating the need for external overdrive pedals.

Featuring two switchable channels (Channel A for clean/crunch and Channel B for high-gain overdrive), independent gain and reverb controls, a shared 4-band EQ section, an integrated spring reverb, and a switchable power mode (Pentode/Triode output reduction), the JCM 900 head became a cornerstone of touring rigs throughout the 1990s and beyond.

Technical Specifications

• Amplifier Type: All-Valve / Tube Amplifier Head
• Power Output: 100 W RMS (switchable down to 50 W via High/Low Pentode/Triode mode switch)
• Preamp Valves: 3 x ECC83 / 12AX7
• Power Amp Valves: 4 x 5881 (or 4 x EL34 depending on production year/reissue model)
• Channels: 2 (Channel A: Clean/Crunch, Channel B: Lead/Hi-Gain)
• Dimensions (Width x Height x Depth): 740 mm x 310 mm x 215 mm (29.1 in x 12.2 in x 8.5 in)
• Weight: 18.8 kg (41.4 lbs)
• Speaker Outputs: Dual 1/4″ jack outputs with selectable 4 Ω, 8 Ω, or 16 Ω impedance settings