The magnificent Russian GU81 has superb audio qualities and is tremendously robust. We were so inspired by the prototype we decided to have a limited edition production in response to customer requests.


The MB 81 has seemingly unlimited vigour and drive and is capable of reproducing large orchestral works and rock music in a vivid 3D soundstage in vivid warm natural colour.

The result is probably the most amazing amplifier we have ever made.


Following our work with other big triodes, we wanted to build an amplifier that would deliver plenty of power to drive the largest inefficient speakers with ease in pure triode mode, in very large rooms. For example although large speakers are generally efficient their complex crossovers full of capacitors and inductors often present a difficult load for an amplifier, especially if it is running with less than ideal power. It is a curious thing that speaker companies say very little about the amplifiers that their speakers are designed for, yet the intimate synergy between the two is crucial to “make or break” a good sound system.


Have an audition you will not be disappointed!

Icon Audio MB81 Mono Block Valve Power Amplifier (Pair)

  • Specifications and Features

    • 250w (45v) @ 8 Ω continuous, @1Khz, 2% THD
    • THD 0.5%@100w, 0.1% @8w
    • Pure Class A, pure Triode front end
    • All hand wired point to point
    • Built in “Easy Bias” Meter
    • 1x 6SL7 first stage valves
    • 2x 6SN7 output driver valves
    • 2x EL34 output driver valves (in triode mode)
    • Signal to noise level -100db
    • Damping factor of 3
    • Frequency response 12hz-28kHz -1dB @8v
    • Suitable loudspeakers 4Ω to 16Ω
    • *Low Distortion Tertiary” wound output transformers
    • Solen/SCR Hi Fi quality audio capacitors, upgrades available
    • Jensen copper PIO caps on request
    • Silver plated pure copper PTFE audio cable
    • Gold plated Input & speaker terminals
    • Attractive Plexiglas valve cover supplied
    • Sensitivity: 0.65v (0dB FB), 1v (3.7dB FB), 2.7v (12.4dB FB)
    • No printed circuit board, easy to service
    • Input impedance 100 kΩ
    • 220/240/115 volts 450watts typical, 750w max
    • W31.5, D66, H38.5cm (40 inc cover), 50kg
    • Packed 2 of 49x81x45cm. 1 of 85x43x46mm Total 136 kgTypical Figures @ 235v Provisional specifications subject to change
    • (Overall dimensions exc cables, allow for good ventilation)

    200w“Goliath” triode PP power amplifiers for very large
    Modern speakers in a large room, for someone who wants very large valve amplifiers at no expense spared

Looking for more information? 
Contact our expert sales team now! 01334 570 666