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Review: Audient iD22 USB Audio Interface & ASP880 Microphone Preamp ADC

Audient’s desktop interface and preamp rack combo is closer to the company’s console heritage than it looks.

By

19 September 2014

The iD22 is the first of a new line of Audient audio interfaces. The English-designed, Chinese-built new kid quietly honours the company’s near 20-year heritage in console design and manufacture. On face value the two-in, six-out interface seems like an understated addition to a sector of the market offering plenty of choice. At $999 its price alone suggests there’s a little more going on. Supporting multiple flavours of Windows and OSX (10.6.8 or later), the USB 2.0 device relies on the included 1.5A 12VDC wall wart for juice. A desktop design, the chassis is built like a tank and favours a layout placing monitor control at the heart of operations. 

I.D. THANKS, KID

The top panel provides control over two channels of Audient Class A mic preamp (a +/-15V version of their console pres) with switches for polarity, HPF (-12dB/octave at 100Hz), +48V phantom and a -10dB pad. On the rear of the unit two combo connectors offer both mic and line access to these channels with channel two boasting a 1MegΩ discrete Class A JFET DI. Both analogue input paths feature balanced insert pairs prior to the ADC; the first time I’ve seen this in such a model. Two stereo output pairs are delivered via TRS and a third is available via the headphone jack. Both analogue paths and conversion is really impressive and bring some classic console character to a format that often sounds relatively bland. Optical I/O expands the iD22’s capabilities, supporting both stereo S/PDIF and ADAT (eight channels at 44.1/48k, four channels at 88.2/96k via SMUX), making it a viable option for both musicians and small recording setups. During testing I did experience some sync problems when clocking to and monitoring from an external ADAT source at sample rates >48k. It proved to be an unreported Windows specific bug but within a few days a new beta firmware version had been provided to rectify the issue.

GET ON BOARD

A 32-bit on-board monitor mixer is accessible via the desktop application incorporating channels for all inputs and the first six software outputs for the creation of one master and two cue mixes with approximately 1.6ms roundtrip latency. These mixes can then be routed to any of the hardware outputs via a matrix of radio buttons. The remaining eight software outputs, relating to the digital interface, have been omitted from the mixer and I missed them when tailoring monitor mixes using an extended combination of input, playback and effect return channels. Limited DSP power means the iD22 cannot compete with those offering full channel strips and auxiliary effects within their software mixers while the iD22 matrix currently overlooks loopback, mirrored routing and hardware output calibration options that can be very useful. There is however a full complement of monitor switching options that will suffice for most applications, and configurations can be stored in presets. With no current support for iOS/Android or TouchOSC control, the iD22 isn’t optimised for standalone operation. It will remember your most recent mix when you disconnect the USB but if you need to change any settings, including sample rate, you’ll need to access it via the desktop app. However, with the right configuration it can add two standalone mic pres, and six channels of ADAT DAC to any studio; and even moonlight as a powerful ADAT driven monitor control centre. This is valuable multitasking from a portable interface.

The audio performance of the iD22 is worthy of interfaces more than twice its price, but as the first in a new family of products there’s room for the software and interface implementation to grow. At the lowest buffer settings the interface delivers only average stability when placed under serious processing load but it’s certainly not alone here and is simply less suited to live use. At this point OSX seemed to deliver performance improvements against the Windows installation, which has been a more recent development. In practise, I didn’t have any problems when recording and the low latency DSP mixer meant I could back off the buffers if things got edgy without any impact to the monitoring experience.

NEED TO KNOW

Audient iD22 USB Audio Interface &
ASP880 Microphone Preamp ADC
  • PRICE

    iD22: $999
    ASP880: $1899

  • CONTACT

    Innovative Music: (03) 9540 0658 or info@innovativemusic.com.au 

  • PROS

    • Both preamps & conversion sound great
    • iD22 delivers a full-featured console master section
    • Inserts on all input channels
    • ASP880 ADC & preamps capable of independent operation

  • CONS

    • Room for refinement in iD22 DSP mixer/matrix
    • iD22 digital outputs absent from DSP mixer
    • Just average low latency performance under load 

  • SUMMARY

    The iD22 has some fairly serious competition in its class. Low latency performance and the flexibility and power of its DSP mixer/matrix falls short of the best but its signal path and master section is formidable. The ASP880’s dual digital interface and modular hookup options make it a viable addition to myriad recording setups. Its preamps offer tone and dimension rivalling those many times its price; and while you wont always use all of its features, they’re nice to have.  

In Control

Volume controls on the iD22 are made using its large custom-milled aluminium master knob and applied digitally in 1dB increments within the DSP mixer application. Audient Technical Director Tom Waterman expands: “The volume control is scaled such that dynamic range isn’t compromised significantly when at typical output levels and loudspeaker SPL. The benefits to doing it digitally include perfect stereo matching, its output can be assigned wherever you need it, and it’s very cost effective.” Despite the digital control, the pot has end points and isn’t replicated in the software interface, so storing and recalling preferred level settings isn’t available.

As You Like It

The iD22’s three user-assignable function buttons provide direct access to many DSP mixer monitor functions, including: Talkback, Mono Sum, Polarity reverse (used in combination with Mono Sum for mid/side monitoring), and an Alternative speaker send with it’s own trim control. These compliment the dedicated Dim and Cut switches located below the master volume control. Additional settings for Mono mode, Cue mix preview, and global mixer presets are presently only available from within the iD Mixer desktop application. Button modifier combinations are strictly reserved for in-house development functions… for now.

3 kΩ HIGH & FALLING

ASP880 mic preamps feature three selectable input impedance options (Hi: 2800Ω, Med: 1200Ω, Lo: 220Ω). As a general rule, to ensure a properly bridged circuit, maximising signal and fidelity, and minimising noise floor, use a setting >10x the output source impedance of the microphone. On this basis, the Hi setting will be adopted by most as their default configuration, while the lower settings deliver creative variations for sculpting of tone, transient shaping and clarity. Perhaps a higher Hi setting (6kΩ+) would’ve delivered greater compatibility with some high impedance ribbon microphones, for example, but this is a speciality available on few preamps in the market. Quite reasonably the iD22 preamps operate at a fixed 3kΩ impedance.

BETWEEN THE LINES

In a design decision that speaks to the company’s console heritage and sets both of these devices apart from most of the competition, Audient has included insert points (separate send and return connections) for all input channels. While this obviously makes it easy to incorporate your favourite outboard processing in the pre-ADC signal chain, it also allows users to bypass the preamps, via the return inputs, when you’re after a direct and pristine converter input.

GIVE ME EIGHT

While the ASP880 can be connected to the iD22 via ADAT to form a potent studio front end, the eight channel preamplifier and AD converter should be very much in demand on its own terms. It features the same ADC as the iD22 while the preamps have been upgraded to run at the full console spec. This update of Audient’s previous ASP008 packs its preamps, dual ADAT/AES digital interface (eight channels of 24-bit/96k via either) and Word Clock sync into a single rack unit and subsequently should be installed with an empty space above it for heat management. Like the iD22 it includes balanced sends and returns on every channel (via two D-Sub connectors) and Channels 1 and 2 include dedicated instrument DIs. All channels feature phantom power, polarity invert, a variable HPF, variable impedance and the option to bypass the preamp entirely and run a line level signal direct to the ADC. Again Channels 1 and 2 are given the special treatment and add -10dB pads to the equation. Personally, I’d have been willing to trade in impedance switching or the variable HPF for pads on at least another couple of inputs. Give me an output trim pot and I’ll trade-in another couple.

At rough count, there are currently at least 40 interfaces from 13 different manufacturers who provide either ADAT or AES as a digital expansion option on their devices. Combine this with outstanding performance and you’ve really got something. Using Radial’s Jensen transformer-isolated microphone splitters, I recorded a broad range of sources through a combination of preamps and DI channels including: the UA 2108, Phoenix DRS1, Daking Mic Pre IV, Quad Eight MM312, and Radial JDV Mk3. The Audient’s were never out of place and in many cases, differentiating between them proved a challenge. In the end, I placed them tonally somewhere in between the 2108 and DRS-1 with a leaning towards the UA. When you consider the standard practice of pairing very neutral preamps with converters, the ASP880 offers something quite different. For under $250 a channel including conversion, they’re also a very viable alternative to those extra 500 series modules you’re lusting after. 

AUDIENT INSIDER

It’s hard to avoid the review clogging stream of specification features and statistics when compiling an overview of any new product. Audient’s Technical Director Tom Waterman takes AT beyond the numbers for a more detailed view of their design philosophy and implementation.

Tom: “The goal for the iD22 interface was simple: make it feel like a ‘mini Audient console experience’ in a small format. Make it affordable, easy to use and most importantly, make it sound great. Steve Flower, myself and David Dearden (the design legend) worked on the backbone for iD22.

“It builds around the Audient mic preamp; a design which has been optimised by David Dearden over the last 15 years, each iteration perfecting the PCB layout, grounding, noise performance and THD optimisation. The mic pre is fundamentally Class A (same as our console), with eight input transistors running as a discrete gain stage with low noise input pair. These are ‘linearised’ by wrapping the discrete stage up with an IC op-amp second stage in the feedback loop so they provide 60dB of clean and quiet gain.

“The mic pres and analogue stages of iD22 run on ±15VDC (similar to an API console for example) and provide plenty of headroom and professional output drive compared to a lot of 5V USB interfaces. To that end, the power supply design of iD22 is critical, with eight internal voltage rails provided regulated audio rails, AD/DA reference voltage sources and various low voltage rails for digital processing, etc — each section of iD22 is separated at the supply. Thus the audio rails are well isolated from dangerous switching digital power rail noise.

“We benchmarked against the usual mid/high-priced desktop interfaces (some German, some American if you can read between the lines) and decided upon a converter set after much testing and evaluation of various AD/DA chips to find the most natural sounding parts with excellent dynamic range specs. We settled on Burr Brown PCM4220 and PCM1798 (used in some very favourable hi-end mastering converters) and have optimised the ADC and DAC circuits to provide performance and sound quality we feel reflects the Audient sonic ethos (clean, open and sweet) and would stand up well against the competition.

“Clocking is performed locally by a high quality crystal oscillator and we use a two-stage Cirrus DPLL to regulate clocking and make sure the unit has stable stereo image. From there, we have a discrete headphone amp driver — very similar to the classic Neve BA640 op-amp idea; an op-amp with a current-boosting Class AB transistor output stage — and user-assignable functions for monitor control, directly on the hardware. 

“We use some very tried and tested analogue building blocks that hark back to David’s heritage in the ’70s and ’80s of the ‘Best of British audio’ era. But never seen in the public eye is our relentless optimisation stage which can last up to six months, where op-amps, capacitor types, resistor types are all auditioned and measured to find the optimum sound quality and (measured) performance for the target price. Ultimately the circuits are quite simple because they are distilled down and simple often sounds better. Design is all about implementation and not just parts choice.

“With the ASP880, we started with the same classic Audient mic pre, except it runs on ±18VDC just like the consoles; offering 2dB more headroom than the iD22. Eight channels of mic preamp in 1RU is definitely a squeeze, but we designed a completely new PSU which is actually lower noise than the old ASP008 supply, has virtually no mains hum component, and allowed us to remove the fan. Even running power from rear to front in a crammed 1RU case can be a bit dangerous from a noise point of view so there is no power switch. Truthfully, there’s no space on the rear or front panel even if we were inclined to compromise on this.

“The key is keeping the PSU noise as far out of the audio bandwidth as possible (in a switch mode type) and from there, critical layout, managing current loops and using appropriate inductive filtering to reduce any output noise is essential. The benefit to regulating current loops and keeping them as tight as possible, in David’s words, is to “separate the dirty current from the clean current” (grounds in particular) so that we can reduce any mains hum and other gremlins to almost nothing compared to a toroidal linear supply. The other benefit is that with no significant magnetic field in the enclosure, Channels 1-8 are pretty even noise-wise, whereas on the original ASP008, you might find that there is more induced hum in Channel 8 nearest the transformer. 

“Although specs matter to some degree, and so do all of these design decisions. When it comes to the crunch, whether a product is a killer unit or not, comes from the benefit it brings to either sound and/or workflow. If your ears say yes and the workflow is transparent so that creativity can happen, then that is most important and a great benchmark for a successful design.”

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