Review: API A2D
One of the most highly-respected and widely-used professional mic preamps now comes with digital converters.
1 February 2007
Review: Brad Watts
API has been one of the staple options in professional recording circles for many years. These iconic American EQs, compressors and mic preamps – all derived from the company’s broadcast console designs – have been widely regarded for several decades as some of the best in the business. With a history dating back to the late ’60s, the company has enjoyed an esteemed reputation alongside the usual prestige European and American suspects. In fact, API is responsible for a number of universally accepted innovations, including the first computerised console automation system for control of fader levels, and the first voltage controlled amplifiers (VCAs).
More recently (1999) the company was absorbed by ATI (Audio Toys Inc), which manufactures the Paragon live and broadcast mixing console – a legendary broadcast console in itself. This amalgamation has allowed the API team to focus on newer designs, not least of which is the focus of this review, the A2D mic preamp and converter.
OLD & NEW COMBINE
The A2D is a single rackmounting unit that houses two of API’s famous 312 preamps. This legendary ‘rock’ pre utilises the tried and true API 2520 op-amp and RE-115K mic input transformer design commonly used in all of API’s products, including its consoles and the wildly popular 3124+ and 3124MB+. The A2D also represents API’s very first foray into A/D conversion and perhaps the company’s first ever attempt to directly entice the home studio market.
The 312 preamp makes no bones about having its own sound. It’s fast and dynamic and punchy as hell, and I’d wager it’s this reputation combined with the all-new integrated digital output stage, that API is hoping will give it a foot in the door of the home-based recordist – those folk wishing to bypass their budget A/D stages in favour of some top-shelf signal path.
BUILT LIKE A BASTA2D
As we’ve come to expect from API equipment, the build quality of the A2D is exceptional. The front panel is crafted from thick-milled aluminium, hex-head screws reassuringly feature throughout the construction and blue anodised aluminium side-panels act as glamorous heat-sinks for the unit – which tragically can’t be seen when it’s bolted into a rack. The overall look and feel of the A2D is API all the way: solid, tough, military grade and seemingly indestructible.
FUNCTIONLITY
Although it looks like a fairly simple device, the control set of the A2D is quite comprehensive. The rear panel offers balanced XLR inputs and outputs, for discrete analogue access to and from the mic preamps (i.e., you don’t have to use the digital output); the A2D will function as a standard pair of analogue pre’s without a problem. There is also a balanced 1/4-inch TRS connector for each channel, which provides an insert point between the preamps and A/D converters, to enable external analogue processors (EQs, compressors and the like) to be directly inserted into the signal path prior to the A/D outputs. This is a critically important facility that allows other devices into the recording path between the analogue front end and the digital back end of the device.
Digital output is also available in the form of AES/EBU XLR and coaxial S/PDIF. A BNC input allows sync via external wordclock if required, that accepts what API refers to as ‘superclock’ – not to be confused with other manufacturers’ 256x ‘Superclock’. ATI go to great pains to point this out in the manual, explaining that its use of the words ‘super’ and ‘clock’ refer to a clock source that operates between 20 and 26MHz. No wordclock output exists as ATI provide a proprietary clocking output system on 9-pin D-sub connectors for syncing multiple A2D units to a single clock source. Above these ports on the rear panel is an expansion port for future expansion of the digital output options. Adat and SMUX optical would be the most pertinent candidate, but I could be wrong. Finally, power comes via an IEC connector switchable between 115 and 230V.
EASY AS A2D
Controls on the front panel are a simple affair. There are two high-impedance instrument inputs (one per channel) for direct insertion of your instrument. Each channel also sports a 20-segment LED input peak-reading meter graduated from –30dB to +27dB, below which is a gain pot and five pushbuttons. The first of these (on the left) is a polarity inversion control, followed by 48V power for the microphone path, a 20dB pad affecting both instrument and mic paths and a mic button for choosing which path is in service. All buttons feature a cool light blue luminescence when set to their ‘on’ positions.
The fifth and final button is labelled 2:1; a feature that’s unique to the A2D – within API’s product range, at least. This button attenuates the mic preamp’s output transformer by 10dB by selecting another tap of the transformer and allowing you to drive the 2520 op-amp section into higher gain ranges. The reason for this? To enjoy the sound of a driven preamp of course – all without increasing the output levels to a voltage that’s too hot for the equipment that follows in your recording chain.
A third meter, this time a dual set of 20-segment LEDs, shows the actual DAC output levels – the highest inevitably being 0dBFS. Below this meter section are two attenuation pots, one for each channel, which is an unusual and very cool feature. A few people have inspected the A2D while it’s been with me and were slightly bamboozled as to why you’d need these controls when the output is digital. Well, what these pots do is allow you to attenuate (lower) the signal before the signal hits the digital converters. Again, this feature will allow you to send the two preamp circuits into utterly glorious API overdrive and distortion, without tripping the 0dBFS threshold of the ADC, and consequently the digital input of your recording system. Seriously… stick a Telecaster through one of the pre’s and wind the input gain up toward full for some very pleasing harmonically-laden crunch.
Lastly, to the right of the output meters is a single, larger knob for choosing the internal sample-rate – from 44.1 through to 192k, including 88.2k and 176.4k. A push power button with associated blue LED finalises the straightforward layout of the unit.
CLOCKED ON THE HEAD
In use the A2D could hardly be simpler. The only hassle people may run into is when attempting to sync the unit via wordclock from a device without a high-resolution (20MHz-plus) clock. Wordclock outputs from units whose highest sample-rate is 48k typically won’t provide a quick enough clock signal to sync the A2D correctly, resulting in the A2D failing to produce audio from the digital output. My lowly Digidesign 96 I/O wasn’t worthy of the task, so, as suggested, if you’re without a classy wordclock generator such as the units I mentioned earlier, you’ll have to use the A2D as the master clock source for your system, via either S/PDIF or AES/EBU (although, according to API, an adapter that will allow the unit to sync to – and spit out – wordclock frequencies is currently under development). Be that as it may, the current design is not a bad scenario in itself as the A2D is a top-shelf, low-jitter system.
As I’ve alluded to already, the 312 preamp sound is a renowned studio favourite for guitars (both acoustic and electric), bass, and it’s no slouch when used to capture drums either – snare and overheads especially. In the grander picture it may not be your first-choice preamp for vocals, but I’d aim that comment mainly toward those with plenty of other preamp options. Personally, I’d be more than happy recording vocals via the A2D. The sound is punchy and purposeful, with a lovely degree of top-end sparkle. Plus, there are some fantastic tones available when pushing the unit ‘into the red’.
If you’re after a stereo front-end to replace the surgically clean preamps in your system then the A2D is well worthy of consideration. If you’re after that API sound at a lower price point, on that score the A2D is also a winner.
RESPONSES