Grace M905 Reference Stereo Monitor Controller

New Firmware Supports Digital Speaker Control Via AES and S/PDIF Outputs

The is our second generation stereo monitor controller, engineered from the ground up to provide unrivaled sonic purity with a comprehensive and powerful feature set.

The m905 represents a new benchmark for audio playback quality. DAC performance is on par with the finest esoteric mastering equipment available. Our redesigned s-Lock™ PLL ensures ultra-low jitter clock regeneration. An asynchronous USB class 2 interface allows the m905 to act as the master clock of the computer’s USB audio buss, effectively eliminating interface induced jitter for computer audio playback. And finally, meticulous analog circuitry measures with outstanding numbers in dynamic range, distortion and noise performance, ensuring bracingly open, detailed and musical playback of any input source.

All main audio and power supply circuitry is housed in a 2U rack mount mainframe, while system control is managed by a sleek, ergonomic remote control unit. This new RCU is a combination of dedicated hardware and a color graphical LCD display. All primary monitoring features are accessed via hardware switches and a rotary encoder, while all system information is presented by the graphic LCD and illuminated switches. This hybrid design allows for the solid feel and function of traditional hardware with the added power and functionality of a graphical user interface.

Now supported is DSD 128x (5.6448MHz) via DoP v1.1 (DSD over PCM frames). DSD audio can be sourced from the AES3, S/PDIF or USB digital inputs. While still a niche playback format, DSD has held its ground over the years, and now more and more content is available via download. And playback is now supported by a number of players. DSD sounds stunningly natural, especially rendered through the rest of the playback circuitry of the m905. So If you’re the type to seek out this kind of fidelity, the m905 is a great way to enjoy it.

The GUI is designed so that any engineer unfamiliar with the m905 can use the system immediately and confidently. Then with a minimal time investment, advanced functions can be accessed and controlled with ease. Additional features include: naming individual inputs and speaker outputs, calibrating level offsets of any input and output, setting preset levels, and much more. The setup menus only ever drill down one level, so the main operating screen is always one button away. And when returning to any previously visited setup menu, its previous edit status is remembered, keeping redundant navigation and editing to a minimum.

The m905 offers the ability to transfer up to 10 channels of digital audio (8-channels of ADAT and two of AES3, or S/PDIF or TOSLINK) over USB to a computer, making the m905 capable of operating as a standalone USB audio interface. This is an advanced feature as there are clock issues to be aware of, but it works and is documented in the owners manual.

With stunning sonic performance and timeless design, the m905 is a mark of genuine progress in the pursuit of high quality audio production. Intuitive, reliable and beautiful, it is the perfect studio centerpiece – home base for your ears, eyes and hands.

M905 Analog Option (Analog Inputs Only)

The m905 Analog is now available without the built in DAC. This system is offered for users who already have an investment in DACs, whether stand-alone or built into their interface. System configuration is exactly the same, with all the same great monitoring features, except no digital inputs and an second pair of balanced analog inputs. The m905 Analog brings this world class performance into reach of almost any engineer or recording studio. Also, users can always upgrade their m905 Analog to the Digital version at anytime. NOTE: the analog only version incudes a simplified remote cable that does not carry headphone signal to the RCU. To enable the headphone output on the RCU, ask your dealer to upgrade to the premium remote cable.

Phono Preamp Option

The m905 phono module is a high performance RIAA preamplifier. This option is available on new and existing units, the latter requires the unit to be returned to our factory to be upgraded. If you are an overseas customer, please contact your Grace Design distributor for details.

Infrared Wireless Remote Option

Also now available is the m905 IR Remote Option, which is available on new or existing units (Digital and Analog). This feature allows wireless infrared remote control of a select set of monitoring controls via a legacy Grace Design Remote (discontinued), a standard Apple Remote, or with iOS and Android via the Logitec® Harmony Remote.

Features:

• Analog inputs – unbalanced (standard or the optional RIAA phono input), balanced (2nd pair balanced available on m905 Analog), CUE, talkback mic
• Digital inputs – 2x AES3 (Single or dual-wire), 1 S/PDIF, 1 TOSLINK, ADAT (selectable in 4 pairs, or 2 pairs in S/MUX), USB, DSD128 (5.6448MHz)
• Audio circuitry designed for completely transparent and musical playback performance
• Asynchronous Class 2 USB playback supports up to 24 bit/192kHz
• Mastering quality DAC circuitry with configurable de-emphasis filtering
• s-lock dual-stage Phase Lock Loop for ultra low jitter clock regeneration
• Hybrid RCU with hardware switches, large level encoder and graphical LCD
• LCD display shows input, level, output, SPL and DAC status plus a full calibration menu
• RCU includes built in microphone for talkback and onboard SPL meter
• SPL meter features include level, peak, fast and slow modes, A & C weighting
• Precision .5 dB step level control for speakers and headphones
• Reference headphone amplifier circuitry, with outputs on both the RCU and ACU
• Dedicated mono, dim, mute and sub mute switches
• Digital loop thru outputs that can be configured to pass incoming digital signals or as a digital speaker output when monitoring digital PCM sources
• Mono mode can be set to L+R summed, L only in both channels, or R only in both channels L solo, R solo, L-R and sub solo modes are available
• 3 available stereo speaker outputs, with two assignable mono sub outputs (or single stereo sub output)
• Multi-mode SUB/ DAC/ METER out
• SUB out mode for stereo or multiple mono subwoofer outputs
• DAC out mode for a fixed DAC output fed by the selected digital input
• METER out mode fed by selected input signal (digital or analog), configurable with a fixed level or to follow the monitor level
• Detachable RCU tilt base

color	Black, Silver
Brand	Grace Design
Condition	New

Analong I/O

THD+N at Maximum Volume, 1KHZ, 22HZ-22KHZ BW:

• +20dBu out: <0.0008%
• +10dBu out: <0.0008%
• 0dBu out: <0.002%

Intermodulation Distortion SMTPE/DIN 4:1 50HZ, 7KHZ:

• @+20dBu out: <0.002%
• @ 0dBu out: <0.0015%

Frequency Response:

• Balanced Inputs +/-3dB: 3Hz to 1.25MHz
• Unbalanced Input +/-3dB: 3Hz to 275kHz

Dynamic Range:

• 20-22kHz bandwidth: 118 dB
• 20-22kHz bandwidth and A weighting filter: 121 dB

Output Noise:

• 20-22kHz bandwidth, at -20dB gain: -99 dBu
• 20-22kHz bandwidth and A weighting filter, at -20dB Gain: -102 dBu

Phase Deviation:

• 20Hz to 20kHz: <10 degrees
• 10Hz to 100kHz: <19 degrees

Crosstalk Any Channel:

• 100Hz: <104dB
• 1kHz: <100dB
• 20kHz: <79dB

Balanced Input CMRR:

• 60Hz: <90dB
• 1kHz: <85dB
• 10kHz: <70dB

Gain Range:

• -104dB to +13dB

Channel Tracking Accuracy:

• Any channel: +/-0.1dB

Maximum Output Level:

• +26dBu

Maximum Input Level:

• Balanced Inputs: +29dBu
• Unbalanced Inputs: +21dBu

Impedances:

• Balanced Inputs: 88k Ohms
• Unbalanced Inputs: 53k Ohms
• Balanced Outputs: 300 Ohms
• Minimum load impedance: 300 Ohms

External Talkback Mic Preamp Gain:

• +7dB to +70dB in 1dB steps

Optional Phono Preamp Module

40DB:

• Gain @1kHz: 40dB
• Noise 22Hz-22kHz: -90dBu
• Noise A-weighted: -96dBu
• %THD+N 1kHz, 5mV IN: <0.0080%
• %THD+N 1kHz, 1mV IN
• %SMPTE/DIN 4:1 100/2kHz: <0.004%
• Max Input Level 0.1% THD+N: 110mV
• Sub Sonic Filter -3dB: 12Hz
• RIAA EQ accuracy: ±0.10dB

60DB:

• Gain @1kHz: 60dB
• Noise 22Hz-22kHz: -71dBu
• Noise A-weighted: -76dBu
• %THD+N 1kHz, 5mV IN
• %THD+N 1kHz, 1mV IN: <0.04%
• %SMPTE/DIN 4:1 100/2kHz: <0.003%
• Max Input Level 0.1% THD+N: 10mV
• Sub Sonic Filter -3dB: 12Hz
• RIAA EQ accuracy

Digital To Analog Converter Fixed Outputs

Output Levels:

• User selectable (0dBFS): -76dBu to +24dBu in 0.5dB steps
• Fixed output trim range (0.5dB steps)

THD+N:

• 1kHz, -1dBFS, (0dBFS = +20dBu), 20-22kHz bandwidth: 0.0006%

Dynamic Range:

• 20-22kHz bandwidth, 0dBFS = +20dBu (AES17 filter): 117dB
• 20-22kHz bandwidth, 0dBFS = +20dBu (A-weighted): 119dB

Input Lock Range:

• AES3/SPDIF:
• 44.1kHz +/-400Hz
• 48kHz +/-700Hz
• 88.2kHz +/-1200Hz
• 96kHz +/-1300Hz
• 176.4kHz +/-2000Hz
• 192kHz +/-2000Hz
• TOSLINK:
• 44.1kHz +/-400Hz
• 48kHz +/-700Hz
• 88.2kHz +/-1200Hz
• 96kHz +/-1300Hz
• ADAT LIGHTPIPE™: 44.1kHz +/-50Hz
• 8 Channels at 44.1kHz and 48kHz: 48kHz +/-70Hz
• 4 Channels at 88.2kHz and 96kHz (s/mux):
• 88.2kHz +/-50Hz
• 96kHz +/-70Hz
• USB Supported Sample Rates: 44.1, 48, 88.2, 96, 176.4, 192kHz, DSD64 2.8224MHz, DSD128 5.6448MHz

S-lock™ Capture Range:

• 44.1kHz: +/- 6Hz
• 48kHz: +/- 7Hz
• 88.2kHz: +/- 14Hz
• 96kHz: +/- 20Hz
• 176.4kHz: +/- 24Hz
• 192kHz: +/- 30Hz

Word Clock / Superclock Input:

• Impedance (switchable): 75 ohm / 1Meg ohm
• Minimum Voltage: 3V peak to peak
• Maximum Voltage: 5V peak to peak
• Word clock frequencies supported: 44.1, 48, 88.2, 96, 176.4, 192kHz

Power Supply / General:

• Power consumption: 60W
• Input Voltage 50-60Hz: 100VAC - 240VAC

Dimensions:

• Main chassis IEC 2U: 3.5" x 10.5" x 17"
• Remote control unit: 8.9" x 5.1" x 2.2"

Weight:

• Main chassis: 7.8lbs
• Remote control unit: 2.2lbs