collapse expand iconDescription

The Octal-Plex Series is a family of guitar amps based on Marshall plexi circuits adapted for octal preamp tubes. Modern features and a menu of optional features and circuit variations make it easy for you to create your own signature amp.

Like all BC Audio amps, the Octal-Plex Series are meticulously hand crafted in true point-to-point fashion, and employ 6SL7GT octal preamp tubes for their rich, warm tone and power-tube-like breakup.

Includes optional footswitch-controlled Gain Boost, optional footswitch-controlled Volume Boost, custom dual footswitch and optional tube-buffered Effects Loop with Send and Return Level controls.

Based on the classic late '60s 50w plexi. Even more aggressive, mean and in-your-face. Earlier breakup, more gain, with a thick, meaty crunch. Tighter response, less sag. Cuts thru the mix.

JMP50 circuit: EL34 power tubes, silicon diode rectification, split V1 cathodes, smaller bright channel coupling cap, large bright cap, large mix resistors, later tone stack, bypassed V2a cathode, small PI coupling caps, less negative feedback, lower B+ voltage particularly in the preamp, heavy B+ rail filtering.
BC Audio JMX50 Octal-Plex Series 50W Tube Guitar Amp Head
BC Audio JMX50 Octal-Plex Series 50W Tube Guitar Amp Head

collapse expand iconSpecs

  • Power: 50W (tube)
  • Tubes: three 6SL7GT octal (preamp); two EL34 (power amp)
  • 100% All-tube signal path
  • True point-to-point wiring
  • Many options available
  • Bright and Normal channels
  • 3-band EQ
  • Volume boost
  • Gain boost
  • Presence and Depth
  • FX loop
  • Impedance selector for 4, 8 or 16 ohm speaker
  • Built in the USA
  • Weight: 34 lb.

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