You are here

Page 2: Cranborne Audio 500R8

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

USB Interface

The whole ensemble hooks up to your computer via USB 2.0 (no USB cable is included — to reduce waste, as most people will have suitable cables already). For Windows systems, you'll need to install Cranborne's ASIO driver (as used by Hugh for his technical performance tests — see box) but if you're on a Mac, as I was during the review period (2018 MacBook Pro running MacOS 10.14.1, connected via a Mokin USB-C hub), or iOS, it's recognised automatically as a Core Audio device, and configuration is via the OS's Audio & MIDI Settings app. (Speaking of which, the only I/O I've so far failed to mention are the rear-panel MIDI in and out, on the usual 5-pin DIN sockets.)

The USB interface will, as set out above, offer access to 28 inputs and 30 outputs in total. I say "will", because on this review unit the S/PDIF hardware had been fitted but was not yet accessible; a firmware update will implement this functionality soon (hopefully by the time you read this). Similarly, as mentioned earlier, 192kHz S/MUX support for ADAT will arrive soon.

Using the R8 as an interface with my Mac was a breeze. The channel layout is intuitive, with the first eight channels corresponding to the eight 500-series slots, for example, and the main stereo DAW output being suitably named by default.

The converters sounded really nice to my ears — very clean, with good stereo imaging. The latency performance was subjectively good too, and that impression was again backed up by the measurements in Hugh's 'Technical Performance' box. (I managed to achieve stable performance on my Mac with a 32-sample buffer at 48kHz.) Of course, for many users the latency question will largely be moot, since they can use the analogue mixing and monitoring facilities when tracking; it will be of more interest to those who play virtual instruments 'live'.

Getting Hands On

While my daydreams inevitably considered how I might build a 500-series console out of the R8 and a number of 500ADATs, in the real world I settled for experimenting with accessing a few different module setups from my DAW over the course of the week-long review period.

I created different recording chains comprising separate preamps, EQs, compressors and saturators; I tried filling the slots with 'mojo' processors (to borrow Cranborne's term) that I could use to process four stereo group busses with 'external plug-ins' in my DAW; and I created a four-stage stereo-bus chain, with an IGS stereo EQ, a Serpent bus compressor, a couple of Roger Mayer's new tape-emulation modules, and a pair of Cranborne's Camden 500 preamps —whose Mojo circuit sounds seductive on pretty much anything when set to 'Thump'!

I found the 500R8 really fun to use, which might strike you as a little odd for something as mundane as an audio interface. Largely but not exclusively, I think it's because it encouraged me to play more with my 500-series modules than I typically do, particularly while mixing. Whatever anyone says about the quality of plug-ins these days, I just find it so much more engaging using knob-per-function hardware like this, and it's a way of working that's just so easy to embrace when both the modules and the monitor controls are there at your fingertips — rather like on an analogue console. So yes, I think 'fun' is the right word!

It really is such a versatile system and, given that you can buy real mic preamps and other modules in this format for very little more than the price of some software models, it left me wondering why no-one's attempted it sooner. Still, I felt it my duty as a reviewer to search for niggles. Happily, I could find nothing that truly bothered me, but I should perhaps mention that the summing mixer controls feel a touch crowded; particularly when the unit was on my desktop rather than racked, I found myself knocking adjacent controls — but then I couldn't see a better way to arrange things in the available space. Also, I found myself wishing that there was a convenient way to process the analogue stereo mix bus with two 500-series channels before recording to the DAW — so you could mix through 14 channels of R8 and 500ADAT, into a stereo bus compressor on the remaining two, and record it in one pass. You can achieve that by patching the mixer outputs into two input channels, but I suspect most people would instead choose to hit the compressor in a second pass.


The bottom line is that this melting-pot of an interface is a genuine triumph — and it's all the more impressive given what a mish-mash of compromises might have resulted from jamming so many different ideas together. Everything sounds good and feels as effortlessly integrated as I think is realistically achievable. Whether you're looking to build a high-quality tracking system, a hybrid-mixing coloration box, an analogue mastering chain, or something on a grander scale, there's definite potential to be explored. And Cranborne have managed to deliver excellent technical performance too — so they have a right to be very proud of this flagship product.

What's more, I think the 500R8 offers great value. Yes, you'll want to budget for mic preamps if you don't already have some, but that's true of many high-end interfaces — and you can offset some of that with savings in terms of the 500-series chassis and cabling. To put it another way, consider the price of a high-quality eight-slot 500-series chassis, an analogue summing mixer, and a monitor controller, and subtract the total from the price of the 500R8. That's a seriously impressive price for a multi–channel interface whose converters compete with the best!


Nobody has taken 500-series integration as far as Cranborne. The only other company I know to have offered 500-series hosting in an audio interface is Aphex, whose four-slot device was nowhere near as ambitious as this and has been discontinued. Emanate Audio announced an ADAT-equipped 500-series chassis a few years ago, but I don't think it made it to market. Meanwhile, other manufacturers offer on–board mixers (Heritage Audio), headphone amps (Radial), a patchbay (Black Lion), and even USB remote control of modules (Wes Audio) in their stand–alone 500-series chassis — but they all lack the audio interfacing and the degree of expandability offered by the 500R8.

Technical Performance

Technical Editor Hugh Robjohns: I ran a standard set of bench tests on the 500R8 using an Audio Precision test set, primarily to check the performance of its internal converters. The AP's analogue inputs and outputs were connected to slots 1-2 and 3-4, respectively, while its AES3 digital I/O was converted to and from the ADAT format through an RME ADI-4DD connected to the 500R8's ADAT ports. Signal routing was performed in a SADiE DAW via the USB connection running the Cranborne ASIO driver for Windows OS. All DAW signal paths were set to unity gain and all tests made with the system running at 44.1kHz and a 64-sample buffer (the lowest stable setting I could operate in my system). The system clock source was selected appropriately for each test between the USB and ADAT options.

Testing the A‑D converter, I confirmed that the analogue-digital alignment is +4dBu = -20dBFS, this being the standard SMPTE alignment. So a full–scale digital signal requires +24dBu at the analogue inputs.

The high end of the frequency response is obviously determined by the sample rate, while the low end measured -1dB at 7Hz, and the -3dB point was around 3Hz — although I suspect the true figures are actually a little lower, because this was running up against the limitations of my AP test set; Cranborne claim -1dB at 2Hz and -3 and 1.2Hz.

Total harmonic distortion measured an excellent 0.00027 percent (ref +4dBu), while the THD+N figure was 0.0014 percent (same reference), which equates to -99dB A-weighted and is the same as the signal-to-noise figure (96.6dB unweighted). Here again, I was brushing against the limits of what is measurable with my AP system! Intermodulation distortion measured 0.0018 percent using the SMPTE format, while crosstalk measured an impressive -115dB at both 1kHz and 10kHz. Assessing the A‑D converter's dynamic range performance using the AES17 method delivered a result of 119.4dB A-wtd —that's a good result, on a par with the Prism Lyra 2, Eventide H9000, and Apogee Symphony.

Moving to the D‑A side of things, the analogue/digital alignment is the same (-20dBFS = +4dBu), of course. The THD figure came out at 0.0003 percent (ref -20dBFS), while the THD+N figure was 0.0014 percent again — these figures are the same as for the A‑D. IMD measured 0.001 percent (SMPTE) and the signal-to-noise ratio came out at 97.8dB. Crosstalk was fractionally poorer, but still excellent at -105.3dB for both 1kHz and 10kHz. The AES17 dynamic range figure was even better at 120.7dB A-weighted, placing it against the likes of the RME ADI-2 (DAC and Pro), the Lynx Hilo, and the Antelope Eclipse 384. Again, the high end of the frequency response is set by the sample rate, but the low end measured -1dB at 2Hz.

The monitor section headphone driver was able to deliver a maximum output level of +22dBu (9.9V RMS), and there is enough gain in the system to achieve that with a -20dBFS return from the DAW, so there's plenty of headphone volume available! At full blast, headphones like the Sennheiser HD650s or AKG K702s would be putting out about 124dB SPL.

I also took the opportunity to measure the latency from analogue input to analogue output via the DAW. With the ASIO buffer set to 64 samples at a 44.1kHz sample rate this was 5.64ms. This broadly agrees with the driver's own calculations, which gave the input latency as 130 samples (2.95ms), and output latency as 110 samples (2.49ms).

Overall, then, the 500R8 measures extremely well: this is a very impressive set of specifications which is easily on a par with the best standard USB interfaces currently on the market.


  • Impressive technical specs, and it sounds great too.
  • Good build quality.
  • CAST system looks very promising.
  • Mix and monitoring facilities can be expanded.
  • Clearly designed with real-world applications in mind.
  • Good value, considering the functionality and convenience on offer.
  • Includes MIDI ports.


  • Processing can't easily be applied to the analogue mix bus.


The 500R8 could easily be the centrepiece of any serious recording/mixing setup: it's a top-notch audio interface, a capable 500-series host chassis, an expandable analogue summing mixer, and more besides. While you'll clearly need to budget for 500-series modules if you're to make the most of it, it offers great value for money.


500R8 £1599; 500ADAT £1399. Prices include VAT.

Sound Technology +44 (0)1462 480000

500R8 $1699; 500ADAT $1499.

Cranborne Audio +44 1707 656500.

Published September 2019