JMT45 Mk II (2)

Marshall (Brand), Marshall, J & T, (Musical Instruments) Ltd.; Hanwell & Bletchley

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  • Year
  • 1963–1966 ?
  • Category
  • Audio Amplifier or -mixer
  • Radiomuseum.org ID
  • 356651

 Technical Specifications

  • Number of Tubes
  • 6
  • Main principle
  • Audio-Amplification
  • Wave bands
  • - without
  • Details
  • Guitar Amplifier
  • Power type and voltage
  • Alternating Current supply (AC) / 230 Volt
  • Loudspeaker
  • - This model requires external speaker(s).
  • Power out
  • 45 W (unknown quality)
  • Material
  • Leather / canvas / plastic - over other material
  • from Radiomuseum.org
  • Model: JMT45 Mk II - Marshall Brand, Marshall, J &
  • Shape
  • Tablemodel, low profile (big size).
  • Notes

  • Introduced shortly after the initial JTM45 Offset release in 1963

    Key Changes from Original JTM45:

    • Wider input jack spacing
    • Elimination of the Bassman-style polarity switch on the front panel
    • "JTM 45 MK II" branding added to the front panel

    Front Panel:

    • Aluminium or white plastic construction
    • Controls (left to right): Presence, Bass, Middle, Treble, High Treble/Loudness 1, Normal/Loudness 2 (all labelled 0-10)
    • Four instrument inputs: two "High Treble" (channel 1) and two "Normal" (channel 2)
    • Chrome baton power and standby switches
    • Round amber indicator light

    Rear Panel:

    • Single speaker cable socket (for use with 16 ohms speaker cabinet)
    • Bulgin power cable socket
    • 2A fuse

    Circuit:

    • Two KT66 power valves (switched from original 5881/6L6)
    • One GZ34 rectifier valve
    • Three ECC83 preamp valves (including one phase splitter)
    • Radiospares RS De Luxe output transformer (30 watts maximum rated output)
    • 45 watts RMS power rating
    • Perforated Tufnell circuit board

    Chassis:

    • 2½-inch aluminum chassis with external cabinet anchors

    Cosmetics:

    • Black Tolex cover
    • Two-tone black-and-white "sandwich" front
    • Gold front strip
    • Metal "coffin badge" with red-on-silver capitalized Marshall logo
    • Four original black-plastic vee knobs
    • Leather handle

    Model Variants (introduced 1965):

    • PA version (model 1985)
    • Bass version (model 1986)
    • Lead version (model 1987)
    • Organ amplifier (model 1989, added later)

    Production:

    • Produced from 1963 to early 1966
    • Phased out with the introduction of 50-watt designs featuring EL34 power valves and solid-state rectification

    The JTM45 Mk II represented an evolution of Marshall's first amplifier, refining the design and establishing the foundation for the company's future iconic models.

  • Author
  • Model page created by Gary Cowans. See "Data change" for further contributors.

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