API The Channel Strip
Review: Is API’s Channel Strip the perfect link between your sound source and your DAW or recorder? John Pickford puts it to the test.
Price: £2,400.00
Manufacturer: API
Website: http://www.apiaudio.com
The Channel Strip
Manufacturer API
Price £2,400
Contact KMR Audio 020 8445 2446
Web www.apiaudio.com
The idea of a standalone channel strip is a relatively new one in the field of sound recording. But with so many of us now recording and building our tracks at home – often quite literally track by track – it makes sense to have a single, high-quality recording channel that will preserve the integrity of your audio signal while providing control over dynamics and tone. The Channel Strip – or All Discrete Complete Input Model, as API describes it – comprises a preamplifier, compressor, equalizer and line-driver (output section) that delivers the sound of classic API consoles.
In control
The input section is the 512C microphone/instrument/line preamplifier that makes use of the 2510 and 2520 op-amps that give API products much of their character. Both the XLR microphone input and the 1/4-inch jack line input are situated on the rear panel, with the instrument input sensibly accessible from the front. Also on the front panel is a stepped rotary pot for gain, giving 68dB of gain on the microphone preamp and 50dB on the instrument preamp. The line input operates at unity gain.
Four push buttons are situated alongside the gain pot, all of which illuminate when engaged. The first (marked POL) is a phase-reverse switch that inverts the polarity of the signal; the second switch engages 48V phantom power. It’s recommended that the Channel Strip output be muted (via the CUT switch) when engaging phantom power to avoid potential damage to delicate equipment such as ribbon mics.
Next up is the PAD switch, allowing -20dB pad for microphones and -6dB for line-level sources. The final switch is the input selector, which changes colour to indicate which source input is active. This switch also acts as a peak indicator, changing colour again when the output of the preamp exceeds +27dB.
Feeding time
API’s 527 compressor – a fully featured VCA design – follows the preamp section and offers two distinct types of gain reduction, selectable by making use of the TYPE switch on the front panel. In ‘feed-back’ mode the compressor emulates the smooth, transparent sound of older units such as the legendary UREI 1176 and API’s own classic 525, while in ‘feed-forward’ mode a more modern, hard and aggressive compression character can be achieved. The KNEE button selects the response curve at the onset of compression. Soft knee (the default setting) gives a rounded response curve, while hard knee employs a much sharper curve (useful when using the device as a limiter).
Other front-panel pushbuttons include LINK, which enables the unit to be used alongside a second Channel Strip for stereo applications; POST EQ, which places the compressor after the equalizer in the signal path; and COMP BYPASS, which completely removes the compressor from the audio path.
The final switch, marked THRUST, is an API-patented design, which the company describes as the ‘little more punch’ switch; it makes use of a high-pass filter to create a punchy low end. Indented rotary pots control Threshold and Ratio and a dual-concentric pot controls Attack and Release times. Attack is continuously variable between 1 and 25ms; the Release time, also continuously variable, is between .3 and 3 seconds. The ratio (again, continuously variable) can be set between 1:1 and infinity; an LED meter indicates the amount of gain reduction taking place. A Compressor Side Chain In jack is situated on the rear panel but is effective only when the compression type is set to NEW.
The next section of The Channel Strip is the discrete 550A equalizer, designed by the highly regarded Saul Walker in the late 1960s. This is a three-band EQ with each band offering seven API-selected frequency centres.
These equalization points overlap, providing a total of 15 selectable frequencies ranging all the way from 30Hz right up to 20kHz. The low and high frequency bands can be used as either a peaking or shelving EQ, selectable via two switches on the front panel; another switch introduces a band-pass filter that rolls off frequency extremes by -3dB at 50Hz and 15kHz. The IN switch silently activates the equalizer and the EQ BYPASS switch removes the equalizer from the signal path completely. Three dual-concentric rotary pots select frequency ranges and boost/cut, with the centre knob allowing for the selection of frequencies and the outer ring providing up to +/-12dB gain or attenuation as required.
The output section features the 325 Line Driver circuit, taken directly from API’s legendary consoles. A LED VU meter may be switched (via the VU PRE button) to show either the main output of The Channel Strip or the output direct from the 512C preamp. A final pot controls the output of the unit and a switch marked CUT mutes the main output and illuminates red when active.
The last switch activates the insert return accessible on the rear panel, which also features jack inputs and outputs to enable the insertion of auxiliary effects across both the compressor and equalizer. The DC LINK socket allows for other API 527 compressors to be connected together, and when the LINK switches are engaged, the DC control voltages from all units are summed together.
Bypass operation
Our listening began by connecting an AKG 414 condenser mic to The Channel Strip and bypassing both the compressor and equalizer in order to assess the quality of the 512C mic preamp. The first thing we noticed was how quiet the unit is in operation, even at fairly high gain settings. On acoustic guitar the sound was crisp and detailed, and when compared to the mic inputs of our DDA console it was clear that the API gave more air and space to the sound. The midrange displayed a lovely open quality that allowed us to hear every subtle nuance of gentle fingerpicking without being too clinical.
We then swapped the AKG mic for our trusty Neumann U67 valve condenser to record some speech – always a reliable way of sussing out the inherent nature of a piece of kit. Again, we were impressed with the clarity of the 512C but felt that the sound lacked a little body in the low mids by comparison to our regular mic preamps. This is not a phat-sounding device.
Using a previously recorded untreated vocal, we experimented with the 527 compressor. We started off by selecting the old ‘feed-back’ style of compression, based on classic units from the 60s and 70s; the result was a very transparent and natural sound. The vocal was nicely smoothed out in an unobtrusive manner. Switching to the new ‘feed-forward’ method, the sound changed dramatically. Now the vocal sounded much more processed and (to use modern parlance) ‘in-yer-face’ – a sound instantly recognisable in many modern pop recordings. A bass guitar was plugged into the instrument input and heavily compressed to the point at which pumping effects were audible. Engaging API’s trademark THRUST control transformed the sound, still keeping dynamics under control but giving a gorgeously rounded bottom end with no unpleasant side effects.
A mono mix of drums was treated in a similar fashion, with results that sounded so wonderfully punchy and coherent it left us wondering why we even bother with stereo. Very impressive indeed!
All things equal
The 550A equalizer is a much-loved device. Its use in API mixing consoles is a large factor in the company’s excellent reputation and will surely be a major selling point for The Channel Strip. Having said that, though, we felt that the layout and feel of the dual-concentric pots took some getting used to, being somewhat clunky and a bit fiddly in operation. But this is a minor criticism as the 550A is a fully featured EQ that is pleasingly musical but also has the capability to be a forensic tool when corrective equalisation is necessary.
On our acoustic guitar a 4dB shelving boost centred on 2.5kHz sounded incredibly sweet, with great presence and a glistening top end. Cutting some low mids from the compressed bass guitar enhanced the punchy feel created using the 527 compressor and finished off the sound nicely. The band-pass filter is quite subtle in what it does, offering -3dB gain reduction at 50Hz and 15kHz, but could be useful in helping sounds such as electric guitar sit well in the mix.
API’s Channel Strip is an extremely versatile piece of kit, packed with useful features not found elsewhere. As a front end in tracking situations there would probably be very few instances when additional hardware was required, and with its flexible compressor and world-class equalizer it needn’t sit idle during mixdown. However you record your music – be it at home or in a professional studio – if you’re looking for a comprehensive, high-quality recording channel, API’s The Channel Strip should be at the top of your audition list. MTM
WHY BUY
Fully featured tracking device
Versatile compressor section
Great-sounding, flexible EQ
WALK ON BY
Mic preamp lacks a little body
EQ pots a bit fiddly
VERDICT
The Channel Strip is a comprehensive recording channel that offers fine control over dynamics and tone. Build quality is every bit as good as sound quality and the patented THRUST control found in the compressor section is definitely worth the price of admission alone. A fabulous way to lay down your tracks.
★★★★★★★★★ (9/10)
Score: 9
This review first appeared in Music Tech Magazine issue 98
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