851

Mono Power Amp

The Boulder Amplifiers 851 Mono Power Amplifier represents the next evolution in high-fidelity amplification, bringing the revered performance and engineering pedigree of the acclaimed 861 Stereo Power Amplifier into a dedicated monoblock format. Designed for audiophiles and professional installations that demand pure, uncompressed power, the 851 Mono delivers 100 watts of continuous output into 8 ohms with phenomenal control, transparency, and musical authority.

At its core, the 851 Mono Power amp improves upon the proven amplifier design of the original 861 Stereo Power Amp, including ultra-wide bandwidth response, extremely low distortion, and robust protection systems. By simplifying the signal path, dedicating each chassis to a single channel, and implementing the ground-breaking Smart Current Technology Output Stage; Boulder’s engineers have extracted every bit of resolution and dynamic nuance from the design while enhancing headroom and channel separation.

Features

  • The first amplifier in the 800 Series to implement the all new Smart Current Output stage.

  • Along with assembly and testing, every circuit board and piece of metalwork is produced in-house at Boulder's dedicated facility for unparalleled quality assurance

  • Boulder's traditional in-house 0.25" (6 mm) thumbscrew binding posts for secure speaker cable connections and optimal sound quality

  • Space saving design is the same footprint (width and depth) as the 812 DAC Preamplifier, and 808 Phono Preamplifier

  • The only Class-A amplifier in the 800 Series.

  • 100 W Continuous Power into 8-Ohms

  • Sophisticated protection circuitry to prevent any potential damage to your system

  • Software updates to the internal control and housekeeping systems available as needed with automated online downloads or manual USB port installation

  • 150 W Peak Power into 8 Ohms

Specs

851
Mono Power Amp

  • Continuous Power, 8 Ohms

    100W

  • Peak Power, 8 Ohms

    150W

  • Continuous Power, 4 Ohms

    200W

  • Peak Power, 4 Ohms

    250W

  • Peak Power, 2 Ohms

    350W

  • Balanced Analog Inputs

    1 pair balanced via 3-pin XLR

  • Outputs

    .25" (6mm) Binding posts

  • Distortion, THD

    .002%

  • Equivalent Input Noise (EIN), 20 kHZ

    2.6 μV

  • Input impedance

    100kΩ Balanced

  • Frequency Response, 20 Hz to 20kHz

    +0.00, -0.04 dB

  • Frequency Response, -3dB

    0.015 Hz, 150 kHz

  • Maximum Analog Gain

    26 dB

  • Power Requirements

    100V, 120V, 240V 50 - 60 Hz

  • Power Consumption

    550W Maximum

  • Dimensions

    12" x 12" x 3.5"

  • Weight

    22 lbs