SIMON TILLBROOK reckons that you could do a whole lot worse than adding a pair of 527’s to your daily Lunchbox. II have recently returned from a trip to Nashville where I once again enjoyed working on an API console with other peripheral API processors. It always puts a smile on my face when I get the opportunity to properly reacquaint myself with API and the wonderful musical way its range of products works in such a wide variety of scenarios. API has adopted the 500 series modules in a big way, producing both a selection of modules and hosts. The Thrust switch, when engaged, places a HPF with 3dB per octave slope at 1kHz immediately before the RMS detection. The idea here is to maintain the low frequency integrity by reducing the sensitivity of the signal <strong>com</strong>ing into the sidechain to low frequency signals that are often of high amplitude. So the mids and highs still receive the dynamic control that is intended, but reduces excessive reduction to the low end maintaining more natural depth and punch. API 527 Compressor/Limiter THE REVIEWER SIMON TILLBROOK is the Principal Music Tutor at Islington Music Workshop in London. The rest of his time is spent as a freelance engineer, mainly in the USA. Taking A Look For me to look at, this time, is the API 527 Compressor/ Limiter. This is a single 500 series slot VCA based <strong>com</strong>pressor that shares design aspects primarily from the <strong>com</strong>pany’s 225 and 2500 <strong>com</strong>pressors. Connections are simply XLR sockets for both input and output, with no external sidechain connections available. If you have a pair of API 527 units you can solder a link on the host unit’s main circuit board, and activate a link switch on the front face of the API 527 for such operation. The API 527 Compressor/Limiter uses the 2510 and 2520 op amps along with a large output transformer. Looking at the unit, before slotting into the host, you can see the usual API quality with all surface mounted <strong>com</strong>ponents on the boards. Looking at the front face of the API 527, you are greeted with the familiar colour <strong>com</strong>binations and control shapes that tell you instantly that you are in front of a unit from API. From the top, we have a ten segment LED meter that can be switched to show either gain reduction or act as a VU. This small toggle switch is immediately below the meter and, when in GR mode, the scale to the left of the LED meter runs from -1.5dB to -23dB and, when set to VU, the right scale starts at -20 and goes through to +3VU. The maximum input and output levels that the API 527 can accept are +26dBu, and there is an overload LED that illuminates at +27dBu. To the right of the LED metering we have a series of rotary controls dealing with the various parameters of the API 527. An output level control with a very wide continuous range from infinity to +10dB sits above the threshold with a fully variable selection from +10dBu to -20dBu. Attack and release parameters are adjusted with a dual concentric rotary control that allows variation of the attack time from 1 millisecond to 25 milliseconds, and release from 0.3 seconds to 3 seconds. The final rotary control under the dual concentric pot is your ratio. This can be set from 1:1 to infinity. As well as the meter and link switches, the API 527 has three further toggle switches and an illuminated in/out hard relay bypass switch. The first of the toggle switches is a hard/soft <strong>com</strong>pression curve knee selector typical of many such dynamic devices available. The next function of the API 527 is something that has been taken from the <strong>com</strong>pany’s 2500 bus <strong>com</strong>pressor. This toggles between new and old referring to the method of detection. ‘New’ configures the sidechain circuit to accept the input signal to an RMS detector. This is generally referred to as feed-forward and is most <strong>com</strong>mon in modern VCA <strong>com</strong>pressor designs. When set to ‘Old’, the sidechain is configured for feed-back detection. In this state, the API 527 takes the sidechain signal from the unit’s output that is the design approach we see on older <strong>com</strong>pressors. Use If you are not too familiar with API consoles or processors then a quick look over the front panel of the API 527 is a must. Some people do find that the layout initially appears a little tight and cluttered, but this feeling soon evaporates when you start to use it. The controls feel intuitive when you are into your stride, and are solidly put together. Again if you are aquainted with the 225 <strong>com</strong>pressor from API consoles or other units, then the API 527 will be familiar. The sound of the API 527 when used conjures up words like ‘clean’, ‘clear’, ‘transparent’, ‘punchy’, and so on. Setting up the API 527 on your signal is fast, finding the desired results through the parameter controls easily. The resulting sound is always robust. You do not feel the API 527 losing grip of the signal. When you start to use more extreme processing then the addition of the Old/New and Thrust facilities makes more and more sense. Utilising the API 527 with various drum and bus <strong>com</strong>pression examples, you appreciate how much the Thrust function maintains the low punch to your sound even with extreme settings. I think it is fair to say that when dialing in more aggressive setups with the API 527 you need to exercise a little more finesse with your parameter control, but results <strong>com</strong>e just as well. With bus <strong>com</strong>pression, especially, I found having both Old and New options (along with hard/soft knee curves) gave me a wide sonic range. I only had two API 527 units to really try this out, but you can’t have everything! Conclusion As a fan of API consoles, I found the API 527 a joy to use across the applications I tested it with, from simple light duties through to more aggressive tasks. The facilities borrowed from other API units have been well chosen and offer greater sonic possibilities, which is what I would want from a peripheral processor. If you have the means then a pair of API 527 Compressor/Limiters in your Lunchbox would be a real productive addition. ∫ ................................... INFORMATION £ GB£750.00 (exc.VAT) A Automated Processes, Inc. 8301 Patuxent Range Road Jessup, MD 20794 USA T +1 301 776 7879 W www.apiaudio.<strong>com</strong> A UK Distributor: KMR Audio, 1375 High Road, Whetstone, London, N20 9LN T +44 (0) 208 445 2446 W www.kmraudio.<strong>com</strong> 20 AUDIO MEDIA JUNE 2011
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