For those confused, rather than amused, by the complexity of compressors, the Aphex Easyrider promises a reduction in gain without the pain. Bob Dormon rides his luck

Aphex made their mark on the audio industry with their Aural Exciters - devices that were claimed to restore missing harmonics in lacklustre recordings and re-introduce the presence and clarity of the original sound source. Some viewed these products with scepticism while others would swear by the improvements. Needless to say, the effect was sometimes subtle.

Since then, Aphex have expanded their range to include compressors of exemplary design. The Compellor was one such device that was out of reach for most and left many others out-of-pocket. But time brings forth progress and these designs have filtered down into the semi-pro marketplace in a simpler form.

But do we need yet another compressor? Well, one is never enough, two's company, and if you need three, then you might as well have four. The problem has always been one of cost and space. To have four compressors in a 1U rack is certainly appealing, if not exactly unique. And while Aphex don't claim to have produced the answer to all your compression needs (they'll happily sell you an Expressor or Compellor for that), they do have a tidy little low-cost box that'll take the pain out of too much gain.

The setting up of a compressor can be tiresome. It should be easy, but certain instruments (not to mention their players) can prove difficult. To have a unit that simply does the thinking for you is bound to find favour with the increasing tide of folk entering the domain of music recording and performance. Like the thousands who bought a DX7 synthesiser and never changed a single preset, there are many people who'll understand they need a compressor for certain applications but don't really care how it does what it does.

Aphex have their sights firmly set on this market with the Model 105 noise gate (reviewed last month) and the Model 106 Easyrider compressor under the microscope here. Both being four-channel devices, their cost can easily be justified to a studio, club PA, or conference facility.

Like the proverbial peas in the pod, the Model 106 Easyrider continues the styling of its sonic silencing sibling, the Model 105 noise gate. The John Major grey facia is highlighted by white legends and lighter grey graduation lines evenly spaced across the surface. Two bands of purple divide the four compressors into pairs, as these simple but effective processors can be stereo linked.

Controls

As I've already intimated, the designers of this compressor have clearly had simplicity in mind. Just two black rubberised knobs determine what goes in and what goes out. They control drive and output - highlighted with a light-grey plastic wedge to indicate their position. Drive simply alters the input level, while output makes up the level differences after the compressor's function of gain reduction.

"Do we need yet another compressor? One is never enough, two's company, and if you need three, then you might as well have four..."

Only quarter-inch jack sockets for input and output are provided, so there's no sidechain access. However, these sockets offer balanced lines when connected with an appropriately wired stereo jack plug.
Next along the front panel are two black pushbutton switches. The first one changes the response of the compressor. It's very basic - either fast or slow. The other switch is Bypass, always a welcome feature on any processor. Between this and the stereo link button is the 10-segment LED meter. The metering displays the gain reduction giving a range from 2dB to 20dB. The meter dims when input clipping occurs; said input can then be adjusted using the drive control or changing the rear-panel -10dBV/+4dBu operating level switch. The rear panel sports four of these switches, so each compressor can be matched to suit other equipment.
The lightweight yet informative manual is very keen to explain these benefits, along with alternative methods of connection. But before you start your hi-tech karaoke session, be warned: you can't connect a microphone directly to the Easyrider. The input signal(s) must be at line level.

The only remaining feature of the back panel is the 24V AC power socket. The Easyrider requires an external power supply of the kind that Americans describe as a wall wart (or a carpet carbuncle - Ed). This arrangement does help keep the weight down but I've never been that fond of external PSUs. They're easily lost, and a 24V AC supply is not going to be readily available from your friendly local electrical retailer.

Processing

The Easyrider has a fixed threshold - that is, the point at which the incoming signal will induce compression. Exactly how much compression will depend on the how hard you're driving the compressor, and that is controlled by, you've guessed it, the Drive control. The metering will relay the amount of gain reduction taking place so you can adjust the drive to suit.

What makes the apparent simplicity of the Easyrider deceptive is that behind the black knobs is a complex circuit that actually increases the compression ratio as the input gain/drive increases. The quoted range starts at 1.1:1 and runs up to 5:1 at 20dB of gain reduction. The engine behind this processing is, in Aphex-speak "...the 'legendary' Aphex VCA 1001". This voltage-controlled attenuator has appeared in older, professional Aphex products such as the Compellor and Expressor, so it should come as no surprise that they're willing to exploit this technology and introduce it into their budget models.

There's another feature too, described as the Wave Dependent Processor; this "monitors the peak to average ratio of the input signal" and then derives an appropriate compression ratio. This processor also deals with the attack and release times - two features that are absent from this particular compressor's front panel. Attack and release are adjusted automatically based on the 'texture' of the signal input, and the layered time constants are changed from the fast/slow switch on the front panel. Switching between the two does actually take a second or so before the effects kick in properly.

"Behind the black knobs is a complex circuit that increases the compression ratio as the input gain increases"

Performance

As the Easyrider will actually change its response according to whatever it receives, some of the more typical shortcomings of fixed devices are less apparent.
As for sidechain control, this is made possible by the stereo linking of channels 1&2 and/or 3&4. If you want to control one signal with another, you could use one side of a linked pair to work on another signal, provided the signal you want to act on doesn't get louder than your controlling signal on the other channel - otherwise it will take over the compressor's action.
On percussion sounds, the 'fast' setting brings out the bite while slow is more of a leveller. But loops come over quite flat in fast mode, while the slightly lazier slow setting allows more of the dynamics to creep through and works very nicely, thank you.

Bass guitar sounds exceptional in both modes. Slow is smooth while fast is precise and punchy. Guitars sound good, too, with the slow setting in particular doing a fine job of retaining the player's expression.

Of course, these elements change to a certain degree depending on how hard you're driving the compressor. This factor must be considered when using the Easyrider for vocals. Here, whether you choose to use fast or slow processing will depend on the musical style and tempo, as both have their own distinct qualities.

Stereo linking works fine and is a useful addition as the processing is well suited to this application. Be aware, though, that the output levels are independent so you'll have to create your own left-right balance.

Verdict

The Easyrider is bound to become one of those studio devices that'll fall into the 'funky little box' category. It delivers a useful sonic service with a minimum of fuss, and don't forget there are four independent modules to hand.

I'd have preferred the maximum 5:1 ratio to have been nearer 8:1, and a slightly faster 'fast' release. But, in general, the Easyrider has a definite 'feelgood' factor to it. At the end of the day, you get what you pay, er, four!

The essentials

Price inc VAT: £398

More from: Stirling Audio, (Contact Details)

The compression effects used in Bob Dormon's tutorial on this month's CD were all created using the Aphex Model 106 Easyrider...

- Compression Tutorial 1
- Compression Tutorial 2