Issue 91
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30 March 2006

API Lunchbox

An old favourite has hit our shores once again offering the best in all-American audio… lunch has never tasted so good.

Text: Greg Walker

Automated Processes Inc., better known to you and I as API, has been around since the late ’60s. Its pioneering modular designs were initially aimed at the remote recording and broadcasting sector but it wasn’t long before record producers and engineers discovered their potential as high quality studio tools. API’s 500 series modules are all discrete solid-state designs renowned for their openness, headroom and power as well as their exceptional reliability (a five-year warranty comes standard) and exquisite build quality. Based around Saul Walker’s well regarded 2520 op amp, most of the modules covered here are bona-fide studio legends which have been re-issued to meet the ever increasing demand for classic ’60s and ’70s studio kit (see Neve, Universal Audio, Chandler et al). So, in a sense, this article is both a review and a revisiting of some truly heavyweight audio tools, which have only grown in stature over the past 40-odd years. The 500 series modules are an extremely compact (135mm high, 40mm wide and 150mm deep), and in the Lunchbox configuration patching between modules is done via rear-mounted XLRs. Given the 500 series’ diminutive footprint the Lunchbox has become a particularly elegant and flexible portable audio solution, albeit a heavy one – the box I’m having for lunch here is a model 6B, housing a power supply, two preamps, a compressor and three separate EQs in something less than a 3U footprint – Yum!


The 512c is a mic/line preamp closely based on the original 512 (the very first modular mic pre, according to API). It features additional front XLR mic inputs as well as instrument/line jack inputs. Also on the front panel are switches for mic/line selection, –20dB pad, phantom power and polarity reversal, as well as a diminutive gain pot and a seven-section LED meter. The 512c provides 65dB of quiet, crystal clear mic pre-amplification with bucketloads of API’s signature headroom-derived grunt.

The 525 Compressor is an exact copy of the original early ’70s model, working on the ‘feedback’ principle a la the Urei 1176 and Fairchild 660. The controls for this module are somewhat unusual – two small input (threshold) and output pots are linked to the ‘ceiling’ control, allowing the amount of compression to be adjusted without changing the output level. A small but easily readable horizontal strip VU meter provides visual feedback, and separate switches engage an auto de-essing circuit and a silent hard-wired bypass. The compression ratios are 2:1 (compression) and 20:1 (limiting). Attack time is fixed and four release times can be selected using a two-switch matrix.


The three-band 550A parametric equaliser graced all of API’s ’70s consoles and has an outstanding recording pedigree. 12dB of stepped boost and cut is available at five set frequencies on each of the overlapping bands, with the top and bottom bands switchable between peak and shelving EQ curves. A band-pass filter can be independently inserted via a separate toggle switch and a full bypass switch is also provided. This is a no-nonsense yet very versatile EQ which can be set up very quickly via the dual concentric switches and recalled with ease. The 550b is a somewhat modernised version of the 550a with four bands of EQ featuring seven overlapping frequency settings per band, high and low band shelving/peak switches and bypass. The extreme frequency settings are opened up to a dog catching 20kHz and a brown note inducing 30Hz. Last but not least is the 560 graphic EQ – again, a very close sibling to the original ’60s model with a few sonic upgrades. Ten bands of equalisation run from 16kHz to 31Hz with 12dB of boost/cut available. The singularly red 1kHz band’s control helps with speedy visual navigation and a bypass switch is also provided. The 560 epitomises what all these modules have in common – powerful functionality combined with simplicity of use. All three EQ modules utilise API’s ‘proportional Q’ circuitry, which narrows the focus of the equalisation as more gain is applied, yielding a more musical result at high boost settings.


The 500 series mic pres are famously good for loud, aggressive guitar and drum sounds, and they delivered fantastic results on these sources during a solid month of sessions. I also found the 512c to be a great preamp for full-bodied, in-your-face vocals and used them extensively for this purpose on several different singers to great effect. The API sound isn’t my first choice for bass guitars or more subtle, softer sounds and textures, however the 512cs proved to be good all-round performers on a wide variety of acoustic and percussion instruments, bringing noise-free character and attitude to dynamic and ribbon mics as well as the more standard condenser setups. Generally speaking they are a superlative preamp as many a studio owner can attest.

The 525 compressor is capable of a great many uses ranging from subtle vocal control through dynamic enhancement of electric guitars, kicks and snares to the brutal mashing of drum overheads and room mics. It is almost incapable of misbehaving and packs a lot of features and control into such a small unit. My only minor criticism of the 525 is the auto de-esser – undoubtedly it does a job but I found the lack of control somewhat frustrating. However, there are a great many other things to like about this compressor. With the silent bypass and the gain-levelling of the ceiling control circuitry, it is possible to switch this compressor into the recording chain on-the-fly and ride the compression ratio like a horse with the listener being none the wiser. Also, when searching for that elusive magical compression setting, experimenting with the release settings and the ceiling control allows for some very swift and radical compression character changes without having to constantly adjust output gain – altogether a great sounding and very nicely thought out compression solution.

The two 550 varieties of parametric EQ are also extremely versatile and eminently musical, the generous overlap of frequency settings allowing both corrective and creative equalisation to be applied simultaneously. Being top quality analogue EQ, you can really crank things up and get some spectacular results due to the generous amounts of headroom available. I found the 560 graphic EQ useful for remedial sonic surgery and adding colour and gentle curves to various sources but I’d have to say that the parametric models with their selectable peak and shelving modes are more useful for day-to-day studio chores. Chaining the various modules together, I was really impressed with the lunchbox’s ability to add new life and colour to pre-recorded signals, be they vocals, drums, electric guitars, piano or strings. The potential is there to dramatically change a sounds’ personality through the many possible combinations of pre-amplification, compression and EQ, and even seriously mangled sounds come through with negligible amounts of noise or unwanted distortion. Overall the API 500 series Lunchbox gets a resounding thumbs-up as a wonderful all-round production tool, pairing sonic excellence with ease of use and precise control. I can already foresee the ugly scenes as the AT courier attempts to prize this box of joy from my gollum-like grasp, with me wheedling and blubbering about how I can’t work properly without my lunch.


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