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Cranborne Audio 500R8

An Interface, Summing Mixer, Monitor Controller and Rack

The 500R8 is the first Cranborne Audio product that I’ve had a chance to try, but it certainly won’t be the last. As they would say in the UK—where Cranborne Audio is located—this is one impressive piece of kit.

You can put up to eight 500 Series modules in the 500R8, and use the level and pan knobs at the bottom for controlling monitor or summing mixes.

Its many roles include USB audio interface, monitor controller, 500 Series rack and summing amplifier. But rather than being a jack of all trades, master of none, it does everything really well. Despite such broad functionality, it’s surprisingly user-friendly and intuitive, not to mention reasonably priced.

The 500R8 is a 4RU unit contained in a robust metal casing. It comes with rack ears that can be detached and turned into a carrying handle.

The vast majority of its front panel area is open so that you can populate it with up to eight 500 Series processors. The stock 500R8 does not come with any built-in preamps—except one for the talkback circuit. On the review unit they lent me, the Cranborne folks included a couple of their own Camden preamps. But on a stock 500R8, you’ll have to supply your own.

Populating your 500R8 with 500 Series units will obviously add to your total cost, but you don’t have to do it all at once. Even if you only fill a couple of slots initially, you can configure each of the eight analog input channels to accept line-level signals, making it possible to connect external preamps as long as they have line outputs.

Eventually, if you want to get the most from the unit, you’d fill it with a variety of preamp types, and swap in and out compressors and EQs as needed, too.

In the back of each of the unit’s eight input slots is a switch that lets you bypass the 500 Series wiring, allowing you to use the input for an external line-level source. The switches are on the inside top of the unit and a little hard to see. I had to use my phone’s flashlight to find them the first time.

You can chain the 500 Series slots together, with the signal going from left to right. If you have, say, a compressor or EQ that you want in the recording chain, you can connect one channel to the next with the flip of a switch, and the signal will follow (flowing left to right).

On the far right of the panel are the other controls. These include two 1/4-inch TRS headphone jacks—one for the Monitor bus and one for the Aux bus—and a power switch. You also get two, 14-step LED meters for the main left and right outputs. There aren’t individual channel overload indicators, but presumably those would be on the 500 Series preamps you’re using.


The eight channel-line inputs are on rear-panel XLR jacks. Each channel also features a 1/4-inch TRS insert. When you’ve connected the 500R8 to the computer over USB (2.0), channels 1 through 8 on the hardware correspond to those same channel numbers in your DAW. The main stereo outputs from your DAW appear on Channels 9 and 10. The unit is USB class-compliant on a Mac, but requires drivers on Windows. I tested it on a Mac Pro.

An additional analog 1/4-inch input pair on the back of the unit is labeled DAW 2. It’s a separate circuit that you can monitor with a flick of a switch. Cranborne suggests using it to get signal into the unit when connecting from external converters.

Alternatively, you could also use DAW 2 for inputting a reference track when mixing. Both the Aux and Monitor output buses have a source switch that toggles between DAW 1 and DAW 2, so you could quickly flip between your mix and a reference track.

On the output side, you get eight XLR Module Direct outputs, two independent speaker output pairs (speaker-pair A is on XLR jacks and speaker-pair B on 1/4-inch), which you can switch between on the front panel. You also get an XLR Mix output-pair and a 1/4-inch Aux output-pair.


In addition to a USB 2.0 jack, you get connectors for MIDI In and Out, Word Clock In and Out, one pair of S/PDIF I/O on RCA jacks, and two optical ADAT I/O ports. If you connect two ADAT-compatible interfaces, you can get up to 16 additional channels at up to 48 kHz sampling rates. If you want to record at 96 kHz, the max is eight channels, and at 192 kHz, four channels.

The rear panel is also home to five C.A.S.T ports. C.A.S.T stands for Cat5 Analogue Signal Transport. It’s Cranborne’s proprietary audio distribution system, which carries analog signals on standard Ethernet cables. The four jacks are labeled A, B, C and D, and correspond to channels, 1-2, 3-4, 5-6 and 7-8.

Each of those C.A.S.T ports carries two channels in and two channels out. You can connect it to optional C.A.S.T. expander boxes such as the N22, a snake and breakout box; and the N22H a snake, headphone amp and breakout box. Cranborne plans to release more C.A.S.T. Expander units in the future.

The fifth one, labeled C.A.S.T. Link, is designed to connect to Cranborne’s 500ADAT, which is an ADAT expansion unit. It also has eight channels, and eight 500 Series slots. When combined with a 500R8 over C.A.S.T, you get double the number of inputs and summing mixer channels.

All the controls for the unit are on the front panel. Each channel has its own Mix Level and Pan knobs, plus a three-way input source switch. The switch allows you to independently set each channel to receive USB (audio coming back from your computer), analog or C.A.S.T. audio.

The right side of the front panel is home to the monitor-section controls, which include a SPKR A/B switch; Mono, Mute and DIM switches, and a Talkback switch with a Level knob. There’s no built-in mic for talkback; you need to connect your own to the jack on the back. You can use either a dynamic or condenser mic. If the latter, phantom power is automatically applied.


Also, on the front panel are level knobs for the Aux and Monitor buses. Cranborne recommends using the Aux bus to feed the headphones of the talent and the Monitor bus for the control room or engineer’s headphones. Each has a level knob and a DAW/Mix knob. The latter allows you to adjust the balance between what’s coming back from the DAW and what’s coming through the inputs.

It’s unusual to see a high-quality interface like this using a DAW/Mix knob. Most units in this price range offer mixer software for controlling levels and setting up cue mixes. The Cranborne folks see the lack of mixer software as a good thing. In the manual, they correctly point out that software-mixer applications tend to be complicated and user-unfriendly. And the DAW/Mix control gives zero latency.

There’s no built-in reverb for monitoring, but the manual suggests a couple of different ways to connect an external reverb processor with it returning through the DAW 2 inputs.

You can use the Aux and Monitor headphone outputs, which go through the unit’s powerful built-in headphone amps, for sending monitor mixes to the talent. If needed, you could also feed headphone amps from the Mix and Aux outputs on the back panel.

The architecture of the unit is such that you’re limited to two different monitor mixes. While that might be problematic in some ensemble recording situations, for most personal studio applications it’s sufficient.


Another powerful feature of the 500R8 is its built-in summing mixer. If you send out stems from your DAW, distributed over the various input channels or channel pairs, depending on how you want to do it, the unit will sum them to both its Mix output and back into your DAW through USB onto input Channels 9 and 10.

For my workflow, I’d probably leave all the channel mix level knobs at a default position and do all the level mixing inside my DAW. I would want to be able to recall the mix easily, which, if you use the onboard knobs for level setting, would require recall sheets. I do wish the volume knobs had at least a center detent, so you could set them to precisely to the original spot when doing a recall.

One of the advantages of using a 500ADAT expander unit connected via the C.A.S.T. Link jack is that it allows you to sum all 16 channels of the two units together in the 500R8.

After using the 500R8 as my interface for several weeks, I came away with a couple of main impressions: First, between the design, the converters, the internal clocking and the general quality of the components, the sound quality is stellar. Second, the folks at Cranborne Audio did a great job of designing its feature set that’s both practical and comprehensive.

I would recommend the 500R8 to anybody who wants a versatile analog front end for their DAW. The only limitation I see is that two monitor mixes might be problematic for people who do a lot of ensemble recording.

But otherwise, if you’re putting together your studio or replacing your interface, the 500R8’s combination of quality, versatility and expandability make it an excellent centerpiece to build around. Considering all that it does and what you’d have to buy hardware-wise to equal that functionality, it’s very reasonably priced.

Now that I’ve had a chance to get familiar with the 500R8, I’m eager to see what the Cranborne Audio folks come up with in the future.


COMPANY: Cranborne Audio
PRICE: $1699
PROS: Excellent sound quality; can house up to eight 500 Series modules; channels can be switched to accept outputs from external preamps; easily create 8-channel summing mixes; module direct outs for each channel; MIDI I/O; ADAT ports for expansion; C.A.S.T. ports for connecting to other Cranborne gear; can be paired with 500A8 for 16-channel input and summing mixes; excellent monitor control features; powerful headphone amps; summing mixes can be mixed to external gear or over USB to DAW; DAW 2 input adds lots of connection options; easy to use
CONS: Only two monitor mixes at a time; no detents on channel Mix Level knobs