The ‘Universal Converter’ UC1 solves all your monitoring needs. It has outputs for analog and digital destinations and offers analog and digital loops with reference quality converters.
Key Features:
- 18 channel back USB & 2 channel front USB
- 4+2 analog outputs, 4 analog inputs
- 4 digital outputs, 4 digital inputs
- Versatile monitoring features
- Ultra-low jitter clock with hybrid PLL
- Hybrid PLL : fast lock, high jitter suppression
- HP specification : Max 15 dBu -- 30mW -- into 600 Ohm
- High performance phones output
- Foldback for latency free monitoring
- Sample rates from 44.1kHz up to 192kHz
- Word clock in- and output
There are many USB audio interfaces on the market but few of them are designed with both the sound quality and the specific use case in mind. The Grimm Audio UC1 has a different approach: it is a USB interface and monitor controller in one. The UC1 is an ideal match with the Grimm Audio LS1 or PMC digital monitoring systems, but it works great with analog (active or passive) loudspeakers too. Add a pair of secondary loudspeakers and headphones, and all your monitoring needs are covered with the flip of a switch.
Present day use cases have been the premier focus from the first UC1 sketches onwards. This led to an unusual design with remarkable flexibility. When mixing and mastering, not all inputs and outputs are equal. The UC1 offers 18 channels of USB I/O of which some are dedicated to monitoring and others to re-recording. With the second USB ‘i-put’ on the front there is no sample rate and word length restriction when using your iPad or iPhone. The i-put also serves as a convenient stereo USB input for laptops.
The Grimm Audio UC1 is a Universal Converter. And a headphone amp, pre-amp and master clock. To give an idea. As a dac chip Grimm Audio has deployed an AKM 4396VF. And there are three in there (one per stereo pair). The ADC is a wonderful TI PCM4202. Internally we see, of course in a seperate housing, some famous clock crystals with circuitry. The extra housing ensures both thermal stability and it prevents resonances (the crystal is encapsulated by the way. In this FLIR-picture we do not see the clock glowing, but a heatsink doing its job. The heatsink is between the shunt regulators and the bottom plate. Thus, the UC1 is passively cooled and therefore quiet.
At its heart, the UC1 is a 20‑channel (10x10) line‑level USB interface (there are no mic preamps) with integrated monitor control functions. Housed in a 1U rackmount chassis extending about 210mm behind the rack ears, it is an elegant‑looking device with a rich padauk (tropical hardwood) front panel. Set into this joinery is a small colour display which shows I/O signal levels, the selected monitoring source, the current volume setting, and the prevailing sample rate. The same display is also used to navigate the configuration menus, controlled through a rotary encoder and a couple of soft buttons.
Also set into the woodwork are two quarter‑inch TRS jack sockets, providing a powerful headphone output and an unbalanced stereo analogue input; both have volume controls. A second USB connection called the ‘i‑put’ is intended for stereo USB sources like a laptop or smart device. Although there are no mic preamps, the unbalanced input can accept instrument sources, as it presents a 1MΩ input impedance!
The rear panel is absolutely crammed with socketry, starting with a universal IEC mains inlet with an integrated on/off switch, accepting 90‑240 V AC. A power LED sits as the dot above the ‘i’ of ‘Grimm’ on the front panel. There’s a 3.5mm remote‑control socket, too, although this facility hadn’t yet been implemented at the time of writing. Audio connectivity is arranged with digital I/O to the left and analogue I/O across the middle, all on XLRs.
Ten physical inputs can be routed to a DAW over the primary USB port on the rear panel. These inputs comprise two rear‑panel balanced XLRs, two front‑panel unbalanced inputs on a quarter‑inch stereo TRS socket, four digital inputs on two more AES3 XLRs, plus the i‑put USB stereo input on the front‑panel.
On the output side, a DAW can send 10 separate output signals into the UC1 over the primary USB connection. General purpose outputs comprise four analogue balanced XLRs and one AES3 stereo digital XLR output, so there’s sufficient analogue and digital connectivity to connect a piece of outboard hardware (a compressor, for example) and to route signals to and from the DAW, which is what the handbook references to ‘loop’ connections are all about.
Another pair of analogue balanced XLRs is intended for a secondary monitor speaker pair but can also be allocated as artist cue outputs. The front‑panel headphone output always duplicates the signal being sent to these outputs. The powerful headphone amp is designed to work well with higher‑impedance headphones (up to 30mW into 600Ω).
The main (bespoke digital) stereo speaker outputs appear by default on an Ethercon‑style RJ45 connector, but this connection is not Ethernet and isn’t compatible with any of the common AoIP formats. Instead, it carries a proprietary combination of AES3 audio and MIDI control data for Grimm Audio’s own LS1 digital speaker system — the data element controlling volume and muting functions directly in the monitor speaker.
However, a menu function allows the data format at this connection to be configured to PMC’s own proprietary digital speaker interface standard, extending the UC1’s application and versatility considerably. And if Grimm Audio LS1 or PMC active speaker systems aren’t available, the main monitor speaker signal can be routed internally to either the first two analogue or the AES3 digital outputs instead, with volume and muting etc performed inside the UC1.
All analogue outputs operate with a nominal level of +4dBu, which equates to a digital signal level of ‑14dBFS, corresponding to the standard EBU alignment (0dBFS = +18dBu). As shipped from the factory, the same alignment also applies to the analogue inputs, although a menu option recalibrates the A‑Ds to accept +24dBu, if necessary.
Basic traffic‑light sample‑peak metering for all inputs and outputs is normally displayed on the main volume screen, showing green for signals above ‑60dBFS, yellow at ‑14dBFS (the analogue reference level) and red at ‑1dBFS. Larger meters can be viewed by holding the top soft button for a couple of seconds, after which pressing the top button cycles between all inputs, all outputs, or everything, while the bottom button resets the peak‑hold function. The rightmost pair of meters in the output set show the main monitor output level (and name). The bar‑graph meters in this display mode have no scaling marks but the same colour scheme is used, although in this mode the ‑1dBFS red bar is almost invisible!
Clocking is normally controlled from the DAW, but external word‑clock in and out are also provided on BNCs (both 75Ω terminated), and either of the AES3 digital inputs can be used as a clock source, if desired. Supporting all sample rates from 44.1 to 192 kHz, the UC1’s internal clocking system is derived from the company’s master clock products and features extremely low intrinsic jitter (less than 0.6 picoseconds).
The primary USB interface is class‑compliant and supported natively by Mac OS, Linux and, in theory, Windows 10. However, an ASIO driver is needed for Windows 7 and Grimm Audio also recommend using it for Win 10 systems — that’s what I did throughout this review. At the time of writing, firmware updates could only be applied from a Windows computer (the review unit was running v1.1.3).
In the Box:
- Converter
- Manual
