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Focusrite Clarett+ Octopre

Multichannel Mic Preamp & A-D/D-A Converter By Matt Houghton
Published July 2022

Focusrite Clarett+ Octopre

Twenty years on, the Octopre concept remains as strong as ever.

I can hardly believe it’s almost two decades since I first acquired an Octopre! I’ve used several of its successors too and have been broadly happy with all of them. The few small niggles of the earliest models were soon ironed out and the last one I tried, the Clarett Octopre, sounded wonderful and boasted some great facilities. Still, Focusrite clearly felt there was room for improvement: their new Clarett+ Octopre improves further on the specs of its predecessor, offering better converters and analogue stages boasting lower distortion, greater dynamic range and a frequency response that’s as near as damn it flat from 20Hz up to well beyond the limits of human hearing (within ±0.05dB between 20Hz and 20kHz).

Grand Tour

The Clarett+ Octopre is a 1U 19‑inch rackmount device with an attractive red front panel and a black chassis which extends about 24.5cm behind the rack ears. Inside the review unit box were the Octopre itself, an IEC lead, four stick‑on, anti‑slip rubber feet, and fold‑out multilingual safety instructions. There’s no hard‑copy manual, but the downloadable PDF one is worth reading if you’re new to ADAT and clocking. Register, and you also get licences for a range of high‑quality DAW plug‑ins from the likes of Focusrite, Brainworx, Softube, Antares and XLN Audio — this could potentially save you a pretty penny in subscription fees!

There are eight analogue input and output channels, along with A‑D/D‑A conversion. On the rear are inputs for six of the eight channels, each with a mic/line Amphenol combi socket, and the eight balanced line outs share a DB25 D‑sub connector. Each channel also has a TRS jack insert point. Inputs 1+2 are on the front panel, again on combi sockets, their jacks being switchable to become high‑impedance JFET instrument inputs. ADAT digital connectivity is via two pairs of Toslink ports, the second pair enabling support for higher sample rates through the S/MUX protocol. The word‑clock input and output are on BNC connectors, and the input is suitably terminated. Mains power (100‑240 V AC, 50/60 Hz) is delivered to the switch‑mode power supply via a rear‑panel IEC inlet, and I was pleased to note that there’s a front‑panel on/off rocker switch.

The Clarett+ Octopre not only acts as a bidirectional analogue‑to‑ADAT converter, but also boasts insert points for every channel.The Clarett+ Octopre not only acts as a bidirectional analogue‑to‑ADAT converter, but also boasts insert points for every channel.

Each channel has its own input gain pot, and this applies whether you’re working with mic, line or instrument sources. These felt pleasingly firm to me and I didn’t notice any annoying gain bunching. Each pot has an overload warning LED, while a display with six‑segment LED meters informs you of the signal level at the A‑D converters. This meter’s uppermost three LEDs (red, yellow, yellow) indicate 3dB steps down from 0dBFS, and the next two (green) are in 6dB steps, with a greater leap down to the last LED (green), which effectively indicates ‘signal present’.

For the mic amps, 48V phantom power is switchable in two banks of four channels. Some people might grumble that they’d prefer these to be individually switchable but this arrangement offers plenty of scope to use mics that require phantom power alongside those which are particularly sensitive to it, and I regard it as a sensible design choice. Beneath each pot is a dual‑purpose switch with indicator LED which operates relays to engage/bypass the insert return and the in‑built Air process, of which more later; a pair of buttons near the meter determines which of those facilities is being switched, and the channels’ indicator LEDs change colour to reflect that. Further buttons allow you to set the sample rate and clock source — the Octopre can be set to its internal clock, in which case other devices must be set to follow it, or to follow the clock embedded in the ADAT signal, or word clock.

In Use

My system comprises an RME MADIFace USB and standalone converters which double up as MADI‑ADAT converters. So to get the Octopre working required me to sync three devices. Doing so was pretty easy, and required me only to hook the Octopre up using a pair of ADAT ‘lightpipe’ cables (there are none provided). Word‑clock sync worked fine for clocking as well.

I tested the preamps on a range of sources: sung and spoken‑word male and female vocals, close‑miked kick and snare, some acoustic guitar miked a bit further back, and synths and DI’d electric guitar and bass. I have to say, the sound of this thing is wonderful: clean and clear, with low noise and no discernible hint of distortion. There was always ample gain on hand (and with up to +57dB available there will be for all but the most demanding applications), and I had no problems accommodating the signal from a sensitive mic used close up on a snare drum. The line inputs sound similarly clean, and the JFET DI stage feels nicely responsive and ‘lively’; I could get the latency on my system plenty low enough to play DI guitar and bass through amp sims in my DAW software too. I’d happily describe the conversion as ‘transparent’.

Air adds a seductively smooth, bright sheen to the signal, which often helps to help bring a part ‘forward’ in a mix.

The Air process puts icing on this cake. It’s a combination of an input impedance change and two high‑shelving EQ boosts (creating, in tandem, a 4dB boost), and it’s intended to emulate the ISA 110 preamps of the legendary Focusrite Studio Console. Air adds a seductively smooth, bright sheen to the signal, which often helps to help bring a part ‘forward’ in a mix, without ever straying into ‘aggressive’ or ‘brittle’ territory. It sounded great on my own vocals, drawing out those breathy frequencies nicely, and on female vocals and acoustic guitars it’s generally a pleasing effect. You do have to tread a little carefully on some sources, though. Obviously, you can’t bring everything forward at once: good mixes require both light and shade! It will tend to emphasise any HF noise/hiss in a source too so, for example, if working with tape or noisy guitars/amps/pedals and you plan on using compression, you must listen out for this. But it is a lovely effect.

Should you want to do more to shape the sound while recording, you can connect outboard gear to the insert points. The return is switchable in/out of circuit but the send, like the line and ADAT outs, is always active, so the Octopre could be used as an eight‑channel three‑way splitter. You cannot route ADAT signals to/from the insert points, though; these can be routed only to the line outputs. More routing options would mean more components and higher cost, of course, but as things stand if you wish when mixing to access devices that you’ve patched in as inserts for recording, you’ll need to repatch things. And if you plan on rackmounting this unit (not everyone will!) the combi connectors make repatching fiddly, since you can’t connect both the line and mic inputs up to a patchbay. You could ‘bodge’ it using the line outs and insert returns, but there’s room for improvement. For example, duplicating the line inputs on a second DB25 would make connection to a patchbay easier, and the ability to route ADAT to the insert points would be better still. Still, on the whole I reckon the switchable inserts are a big plus; more interfaces and preamps should offer them.

I was surprised to find no polarity inversion on board, particularly given that Focusrite’s website claims that this device is “ideal for multitracking drums.” I always end up ‘flipping’ at least one signal when using multiple mics on a drum kit, and it’s essential if using top and bottom mics on a snare. This won’t bother everyone, though: you can invert the signal polarity in your DAW or audio‑interface software, and possibly on your main interface’s preamps too. But having the facility on one or two channels would be an improvement. While there are no pads or high‑pass filters either, this is less of an issue. As I’ve mentioned, sensitive mics on loud sources weren’t problematic, and high‑pass filters are generally less critical during tracking (although they could be useful at the start of an insert signal chain).


Despite a few tiny caveats, then, I was very impressed with the Clarett+ Octopre. Indeed, I regard it as a great all‑rounder preamp: it sounds superb, can handle pretty much any source, and any facilities it lacks will usually be catered for by your audio interface or DAW. The Air facility is seductive, the insert points are welcome and it’s great that it can be used as a splitter. I’d be very happy to have one in my studio or for location/live recordings, and am just as happy to recommend it to anyone looking to add eight mic preamps to their ADAT‑capable interface.


Focusrite’s best‑sounding and best‑performing Octopre to date, the Clarett+ model should prove a great addition to any ADAT‑equipped audio interface — as long as you’re prepared to use your interface or DAW software for functions such as polarity inversion and high‑pass filtering.


£699.99 including VAT.

Focusrite Audio Engineering Limited +44 (0)1494 462246


Focusrite Group US Inc. +1 310 322 5500.