Moon 850P Dual-Mono Reference Pre-Amplifier

SKU 850P

Moon 840P Dual-Mono, Dual-Chassis Reference Pre-Amplifier



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The MOON 850P is the most advanced MOON preamplifier to date. Extensive research and development, coupled with recent advancements in electronic parts have provided us with the foundation to design what may very well be the transparent, quietest, most accurate and uncolored preamplifier. Targeted to the discerning listener who desires uncompromising musical reproduction, the 850P features numerous proprietary technologies.

Our M-Octave Damping damping system that eliminates the sonically degrading effects of microphonics by mounting the main audio circuit on an 8-point floating suspension. The result is a more natural, liquid and lifelike sound. Since listening environments are typically loaded with acoustically induced vibrations that originate from the loudspeakers, we use M-Octave to isolate the 850P from these microphonic-causing vibrations, allowing you to hear more music, exactly the way it was recorded.

Other in-house technologies include (i) i²DCf power supply voltage regulation, (ii) M-Ray volume control, with a phenomenal 530 steps, allowing for an extremely precise level adjustment, (iii) SimLink and (iv) M-Lock, just to name a few, as well as an RS-232 connection, IR port and 12 Volt triggers for custom-install environments. Finally, a plethora of user selectable cosmetic options are available at the time of purchase.

850P Technical Features

· 2-chassis design with one chassis housing the power supply, digital controller circuitry and software processing. The other chassis contains the audio circuitry
· The preamplifier’s audio section is located on its own dedicated circuit board, which is mounted to the chassis with our M-Octave Damping system
· A dual-mono oversized power supply using 2 toroidal transformers in conjunction with 6 stages of DC voltage regulation and extensive choke filtering
· M-Ray volume control based on the R-2R resistor array configuration using metal film surface mount resistors with 0.1% tolerances, resulting in no sonic degradation of the audio signal, regardless of the selected volume setting
· Power supply voltage regulation includes i²DCf (Independent Inductive DC Filtering); There is one inductor dedicated to each integrated circuit type component (DAC, Op-Amp, etc.) in the audio circuit’s signal path; 40 stages in all
· Fully differential, no global feedback circuit topology, using absolutely no capacitors anywhere in the audio signal path
· M-Lock for “user selectable” maximum volume setting lock-out for each line input
· “Gain offset” for each individual line input with a ±10dB range
· Each line input is fully configurable to be “home-theater ready”, where the gain section of the 850P is bypassed
· RS-232 port for (i) full unsolicited bidirectional feedback and (ii) firmware updates
· IR input for external control
· 12 Volt trigger output for remote operation
· SimLink™ controller port for 2-way communications with other compatible MOON components
· 4-Layer printed circuit boards with pure copper tracings for a much shorter signal path; This results in greater sonic accuracy and a dramatically improved signal-to-noise ratio
· Ultra rigid chassis construction to minimize the effects of external vibrations
· Accurate matching of the very finest quality electronic components in a symmetrical circuit design
· Includes FRM-3 remote control.

850P Detailed Specifications

Type Solid State
Configuration Dual-Mono / Fully Balanced
Power Supply Transformers 2 x 150VA (audio);   1 x 10VA (controller)
Power Supply Capacitance 50,000µF
Circuit Topology Open Loop
Balanced Inputs   (XLR) 3 pairs
Single-ended inputs   (RCA) 4 pairs
Input Impedance 11,000Ω
Input Sensitivity 200mV – 4.0V RMS
Monitor Loop 1
Balanced Outputs   (XLR) 2 Pairs
Single-Ended Outputs   (RCA) 2 Pairs   (variable & fixed)
Output Impedance   (RCA / XLR) 50Ω / 100Ω
Volume Steps 1 dB from 0-30 and 0.1dB from 30-80
Gain Control M-Ray   (fully discrete R-2R)
Gain 9dB
Signal-to-noise Ratio   (20Hz – 20kHz) 130dB
Maximum Output Voltage – XLR 15 Volts
Maximum Output Voltage – RCA 7.5 Volts
Frequency Response 5Hz – 100kHz   (+0 / -0.1dB)
Crosstalk @ 1kHz -130dB
IMD unmeasurable
THD   (20Hz – 20kHz) 0.0005%
12 Volt Trigger Output Operation Direct Logic (0V = off, 12V=on) using a 3.5mm
mono jack with an output impedance of 1000Ω
and current requirement of 12mA
SimLink™ Port 1 input + 1 output each on 1/8″ mini-jack
RS-232 Port 9-pin female DB connector
IR input 1/8″ mini-jack
Remote Control FRM-3 All-Aluminum Full Function
Display Type 8 character dot matrix LED
Power Consumption @ idle 25 Watts
AC Power Requirements 120V / 60Hz   220-240V / 50Hz
Fuse Replacement   120V   /   220-240V 400mA short slow blow   /   200mA short slow blow
Net Weight 72 lbs / 32 Kgs
Shipping Weight 147 lbs / 67 Kgs
Dimensions – Preamp   (w x h x d) 18.75 x 4.1 x 16.81 in.   (47.6 x 10.4 x 42.7 cm.)
Dimensions – Controller / Power Supply 18.75 x 4.1 x 17.3 in.   (47.6 x 10.4 x 43.9 cm.)


32.0000 kg
Analogue Inputs

4 Pairs






Two Tone Black & Silver

Depth (mm)


Height (mm)



Moon 850P



Width (mm)


xlr inputs


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Moon specialises in custom home audio solutions, from custom handmade cables to headphone modification services.