MB845 MkIIm mono blocks

110w of Pure Triode Power

Designed in Leicester by David Shaw, founder of Icon Audio. 845s the ultimate power triode!  The RCA 845 valve dates from about 1931 when the only way to get higher powers was to make valves bigger and run at higher voltages. The later EL34 and KT88 types are far more efficient but do not sound the same.

When first released in the UK the MB845s were greeted with great acclaim by the hi fi press and customers, for power and value, but above all their unique sound quality. They have become THE reference valve amplifier for Hi Fi World magazine.

Many other 845 amplifiers use 4 stages, often using 300B valves, this more complicated design does not give the speed and clarity of the MB845s, or give the maximum output of 115w useful if your speakers need a lot of power. But the power is secondary to the large bandwidth and low distortion available.

For some people only a large triode valve like the 845 can give the golden warm tone which is so pleasing, with its feeling of air and space and sense of realism. The MB845 MK I has truly become a legend in the UK, but hi fi fans were soon asking if there was more that could be done to improve the performance. With the MB845 Super, Icon Audio have used all their expertise to create the ultimate amplifier.

Surprisingly from such big amplifiers is how well they perform at low powers. Their agility and detailed texture of strings and vocals is quite astounding. Modern recordings demand low noise amplifiers. The MB845s will give you an “ink black silence”

A special feature of the  MB845s is the high and low sensitivity. This enables MB845s to work with both “Passive” and conventional pre amplifiers. This is not done by attenuation which reduces quality, but genuinely changes the gain of the input.

Specifications and Features

•  Improved Tertiary winding output transformer

•  Improved dual 6SN7 high current driver circuit

•  Choke regulated power supply

•  All hand wired point to point

•  No printed circuit board to ‘colour’ sound

•  Class A, all Triode front end

•  2x 845B precisely matched for best performance

•  1x 6SL7 first stage gain valves

•  2x 6SN7 driver valves, choke loaded plates

•  845 AC heating for max life and max reliability

•  30.5V (approx) output at clipping point 8 Ohms*

•  Giving approx 20 Watts of Pure Class A

•  Can be used with passive or active pre-amp

•  450mv (high) & 1000mv (low) input sensitivity.

•  Signal to noise level -90db* (approx)

•  Hum and noise 0.5mv (low sensitivity)*

•  6SL7/6SN7 DC heater circuit for minimum hum

•  Freq response -1db points= 6Hz 27khz

•  Freq response -3db points= 6Hz-57kHz

•  Source impedance 0.7Ω (8Ω taps, low sensitivity)

•  Damping factor 13

•  Gain 67 (high) 30 (Low)

•  THD typically less than 0.1% @ 1w. 0.14% @ 8w (1kHz)

•  4 & 8 ohm loudspeaker taps

•  Custom hand-wound mains/output transformers using Japanese special long grain iron and low oxygen copper Attractive valve cover included in the price

•  High quality 2W metal film, & wire-wound resistors

•  Solen audio capacitors (or optional Jensen Copper foil)

•  Silver PTFE audio cable

•  Ceramic valve holders for minimum leakage

•  Gold plated Input & speaker terminals

•  220/240volts (115 v adjustable)

•  Comprehensive manual supplied

•  Full instructions for DIY valve change included

•  Power consumption: 180w quiescent, (290w max sine wave) each

•  Size in cm W24, D57, H28 mm ( inc cover), 33kg each

(Allow space for connections and ventilation)

•  Carton 2x 66x35x38cm + 1x 57x31x32 Total 84kg

(Specifications subject to change, errors & omissions excepted August 2011)

 

MB845 MkII Leaflet