I’m a fanboy of Grace Design's gear, so when they announced the m701 interface at the NAMM Show in January, I immediately got in touch with Michael and Eben Grace to ask if I might be able to review it when it became available. Now that I’ve had a beta unit here in my studio for a few months, I can confidently say that these are the converters of my dreams, and the hardware ecosystem they have created will make this a very enticing product for many studio configurations and installations.
Now that I’ve given away the conclusion in my opening paragraph, how about some details? The m701 is based around a 2 rack space frame with a built-in dual redundant power supply. The digital I/O of the base unit includes eight channels of AES/EBU, eight channels of ADAT, and stereo S/PDIF. It will work at any 1x, 2x, or 4x sample rate between 44.1 kHz and 192 kHz. The front panel has a large 800 x 480 pixel color LCD display for metering and configuration controlled via a large encoder dial and navigation buttons. After turning the m701 on for the first time, I was able to dive through the pages and settings without any documentation. That may seem impressive, but what’s even better is to connect your computer to the m701 via the Ethernet port on its back panel and use what they are calling GraceNet to access the brains of the unit from any web browser; this provides for real-time programming of the routing and metering, and offers the ability to save/load different workflow configurations from your computer. It’s brilliant and ironclad.
As an interface, you’re going to need ways to get audio in and out of the m701, right? The beauty of this system is in its modularity. There are eight card slots that can be any combination of 8-channel DAC or ADC modules utilizing the latest design of Grace’s converters. There’s also a new 4-channel mic pre card. Any combination of these modules can be installed, or swapped out later if your needs change. These cards all incorporate DB-25 connectors, making for quick and easy integration into an existing patchbay or for cabling directly to other hardware. There’s another panel for additional expansion: A 24-channel AES I/O board (also on DB-25). Other modules are planned for the future. Finally, there are the two interface slots reserved for computer connectivity. As of this writing, DigiLink (for connecting to an Avid HDX system), Dante, and RAVENNA/AES67. Future expansion plans include a USB card with 32 channels of driverless, class-compliant I/O – two of these interface cards will be able to run up to 64 channels of I/O simultaneously.
I have been using the m701 in my studio connected via either DigiLink or Dante. For my Pro Tools setup, I used the primary port on the DigiLink module in the m701 to connect to an HDX card running in Avid’s Pro Tools | HDX Thunderbolt 3 Chassis. The m701 then appears as two 16-channel interfaces in Pro Tools; the configuration was instant and seamless. To connect via Dante, I used both the NTP Technology DAD Core 256 Thunderbolt 3 interface, as well as the brand new Focusrite RedNet TNX [Tape Op #169] interface. These are both effectively a Dante PCIe card in an external enclosure with Thunderbolt 3 connectivity to the computer. If you are familiar with Dante networking and configuration, the setup is a no-brainer. I was also able to route via Dante to my Grace Designs m908 [Tape Op #152] for monitoring, thus keeping the signal digital as long as possible.
The ADC and DAC cards are likely going to be the most commonly used I/O modules for the m701 to get signals in and out of a computer in the studio. The operating level of these converters can be toggled between +18 dBu and +24 dBu on a per-channel basis. The line level gain on both AD and DA converters is also adjustable per channel, +/-20 dB in 0.1 dB steps, should one need to calibrate for compatibility with finicky outboard. The dynamic range of the converters is greater than 120 dB. If you want to get even deeper with the tweaking, the ADC cards can be set to any one of four oversampling filter types, and the DAC to those same four, plus two additional ones. Depending on the headroom you need, as well as the types of frequencies most prevalent in what you are tracking/monitoring, these options can help reduce pre-ringing and overshoot in the conversion process.