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Cranborne Audio 500R8

USB Audio Interface, Analogue Mixer & 500-series Host
By Matt Houghton

Cranborne Audio 500R8

This most hybrid of devices does far more than just put A‑D/D‑A conversion into a 500-series chassis. In fact, it could even make you reconsider how you use your studio...

Launched last year, Cranborne Audio's Camden 500 mic preamp was a wonderful debut product: boasting stellar technical performance and some novel processing options, it prompted our Technical Editor Hugh Robjohns to conclude ( that "this is how I'd design and build a quality preamp." Announced at the same time as the Camden 500 were the 500R8 (reviewed here, and from hereon 'R8') and the 500ADAT, and these actually piqued my interest more, since both do something I've long wanted to see: they add A‑D/D‑A conversion to a 500-series chassis. As its name implies, the 500ADAT's digital interfacing is via ADAT, but the R8 adds stereo S/PDIF and multi–channel USB audio, as well as a low-jitter (Cranborne claim <0.5 picoseconds) master clock, to create an ambitious audio interface. But the digital side of things is only the start, as Cranborne have managed to pack much more into these devices, including a high-quality analogue summing mixer, monitor control facilities, and some novel analogue routing functions.


The R8 is a 4U-high, 19-inch rackmountable 28–in/30–out USB 2.0 audio interface with a built-in eight-slot 500-series chassis. Other than two TRS jack headphone sockets and the 500-series slots, all the analogue and digital connectors are on the rear. The first eight interface channels are assigned to the 500-series slots, whose XLR inputs and outputs are accompanied by a TRS insert point that sits between the module slot and the A‑D converter in the signal path. (Without a 500-series module, the XLRs can function as regular analogue line-level I/O, courtesy of a module bypass switch on the backplane). Two more interface channels access the stereo AES3-compatible coaxial S/PDIF I/O, and 16 are mapped to the optical ADAT streams — two pairs of Toslink connectors can carry 16 channels each way at 44.1/48 kHz, or eight channels via S/MUX at 88.2 or 96 kHz (192kHz support for four channels is planned in a firmware update in the near future). The remaining two USB inputs receive the analogue mixer's output, and the remaining USB outputs transmit two stereo DAW playback busses. The clock is accessed via the usual BNC connectors.

The idea of all that ADAT I/O is that you're able not only to hook eight 500-series modules up to your DAW, but also that you can connect a 500ADAT to an R8 to increase both the analogue I/O count and the system's capacity as a 500-series host. If you're happy with 44.1 or 48 kHz, it would be possible to add two 500ADATs, giving your DAW access to 24 channels of 500-series preamps, effects or processors with only a USB 2.0 cable and four ADAT 'lightpipe' optical cables. Alternatively, you could hook up any ADAT-equipped mic preamps or line-level converters to increase the analogue I/O count.

The possibilities don't end there, though. If you really wished — and had the financial means to make it happen — you could attach further 500ADATs (or other eight-slot 500-series chassis) to the system via the insert points on the first 'set', and start to construct something more akin to an analogue console, but one with the preamp, EQ and compressor stages of your choice on each channel.

The build quality seems very good. The powder-coated metal case is strong and remains rigid even before you screw in any 500-series modules. The back-panel connectors feel secure, and all of the switches and pots on the front feel suitably robust. That you can change the orientation of the rack ears for use as sturdy carry-handles is a nice touch, too, and will increases the R8's appeal as part of a location recording rig.

The 24V 5A power supply is an external 'line lump' switch–mode type, capable of accepting AC mains between 100 and 240 Volts. Each 500-series slot can draw 250mA, and there's a little headroom on top. I know some aren't fond of external PSUs but it's the right decision in this case. I mean 'case' quite literally, since there's no room inside this one to accommodate a PSU — that would have required a 5U or a deeper 4U chassis, and would have added weight to what, when fully loaded with transformer-balanced modules, is already rather a heavy device. The PSU's four-pin connector locks securely in the socket...

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Published September 2019