LA Audio 4x4

Always ready for some off‑road action, Paul White scrambles for his XLR adaptors and test drives LA Audio's latest incarnation of the 4x4.

With so many compressors and gates on the market, companies need an angle to make their products stand out from the crowd. Some go straight for the jugular and set rock bottom prices, while others go to the other extreme, offering fancy colours, high prices, and the promise of vintage performance.

LA Audio seem to prefer the 'added value' route; their original 4x4 processor comprised two compressors and two gates, plus filters which could be assigned to either the gate (for frequency‑conscious gating) or to the compressor (for de‑essing/de‑popping). I remember being impressed by the sound quality of these compressors, as well as the overall flexibility of the system, but LA Audio clearly thought they could go further. In the 4x4 2, they've delivered added value with a vengeance.

Rethink Remodel

Rather than being an upgrade, this is a complete redesign based on the circuitry used in the LA 4C and 4G dedicated compressor and gate units. The cosmetics are new, the internal design is new, and the features on offer have been extended to include separate filters for the gate and compressor, plus electronically balanced inputs and outputs on XLR connectors. Further jack connections are provided, so that the gate filter can be used as a separate equaliser if required. There gate also offers a Key Input, for external triggering. And for good measure, there's a basic but useful single‑ended noise reduction mode thrown in.

The compressor has the benefit of an external side‑chain In/Out connector, allowing additional EQ or other processing to be inserted in the compressor side‑chain. Taken as individual compressors and gates, these features would be welcome but unremarkable — after all, we've seen most of them before in LA Audio's own 4C and 4G models. It's only when you consider that you get two compressors and two gates, complete with all the above facilities, in a sensibly‑priced 1U package, that the 4x4 2 begins to look rather special.

Both the gate and compressor retain LA Audio's proprietary FET technology, which is designed to emulate the warm overload characteristics of tube designs. The compressor also has a soft‑knee characteristic coupled with a ratio control — a combination I've always found to work well.

The gates and compressors may be used independently or in combination with the gate before the compressor in the signal path. Linking is achieved via the Ext/Gate button in the compressor section, and when linked, the gate output and compressor input become unavailable — a good system if you want to leave the unit wired to a patchbay.

Great Gate?

Looking at the gate section first, this has almost as many features as you'd find on a stand‑alone dual gate, the main difference being that the envelope attack is switchable between Fast and Auto rather than being fully variable. Fast mode has a very fast attack time, suitable for use with percussive sounds, while Auto continuously adapts the gate attack time to the transient characteristics of the input signal. Release, Range and Threshold are all fully variable, with Range setting the amount of attenuation when the gate is closed, and may be varied continually between 0dB to 60dB.

Triggering is switchable from Internal (where the gate triggers from its own input signal) to External, and a green status LED indicates when the gate is open. Bypass switches with red status LEDs are provided separately for the compressors and gates, while a Key Listen switch allows the gate keying signal (post‑filtering, where applicable) to be monitored.

Filtering follows the familiar, variable frequency high‑pass and low‑pass formula originally introduced by Drawmer, but an Int/Ext button enables the 4x4 2's filter to be disengaged from the gate, so that it can be accessed via the rear panel sockets. The filter section comprises two independent, variable‑frequency shelving filters, each with a 12dB per octave response. The Lo filter has a high‑pass response, while the Hi filter has a low‑pass response. Steep shelving filters of this kind can usefully extend the flexibility of more conventional equalisers, as well as being ideally suited to their more usual role of helping reduce false gate triggering. The idea of making them accessible for external use is thus very welcome.

A further filter option is the SNR mode, which uses the filter to implement a simple, single‑ended noise reduction process. This works rather differently to most stand‑alone SNR units, in that the filters are used to determine how much of the signal will be allowed to pass when the signal falls below the gate threshold setting. For example, you might set the Lo filter to 150Hz and the Hi filter to 3kHz, so that when the signal level falls below the threshold, the audio bandwidth closes down to reduce hum below 150Hz and hiss above 3kHz. Though this arrangement isn't quite as sophisticated as a sliding filter SNR, it is surprisingly effective, and reasonably transparent — provided you're careful with the settings.

Expressive Compression

Like the gate, the 4x4 2's compressor compromises by having a switchable attack time, though this time the choice is between Fast and Slow rather than Fast and Auto. Personally, I feel Auto would have been a better choice, as the Auto setting on my own Drawmer 441 adapts beautifully to anything you throw at it. The main compressor controls comprise the usual Threshold, Ratio, Release and Gain (output make‑up gain) with switching that allows the compressor to be used independently or after the gate. An 8‑section LED gain reduction meter monitors how much level is being trimmed off by the compressor at all times, while a Stereo button in the centre of the front panel (accompanied by an amber LED) allows the two channels to operate as a ganged stereo pair.

The designers really have gone flat out to provide you with just about every possible combination of options based on gates, compressors and filters...

The 4x4 2 sees the compressor with its own filter; in this case a switchable high‑ or low‑pass filter continuously variable from 100Hz to 10kHz. This is normally employed in the side‑chain, where it can be used to make the compressor react in a selective way to pull down the gain of high frequency sibilant sounds (in high‑pass mode), or reduce low frequency artefacts such as popping (in low‑pass mode).

Another use for the filter becomes evident when you select Half mode, which configures the compressor as a half‑band compressor. This is a very creative mode — it lets you split the frequency spectrum using the filter, then (depending on whether you've selected high‑ or low‑pass filtering), you can compress just the upper or lower end of the spectrum, leaving other frequencies unchanged. The Gain control adjusts the level of the compressed portion of the spectrum against the uncompressed portion, so you can do lots of neat things like compressing the top end, then bringing it up in level to create an enhancer‑type effect. Similarly, you can compress just the bass end of a sound — or even a full mix — then crank it up to deliver a very punchy sound, without affecting the brighter elements in the mix. The split point is set by the Frequency control, allowing you to be very precise about where the effect comes into play.

Off‑Road Action

Checked individually, the 4x4 2's gates and compressors behave very much like those fitted to the 4G and 4C — hardly surprising, given that these are the very circuit designs upon which the new 4x4 2 is based. The compressor has a deliberately warm character. When you really pile on the compression, the gain pumping becomes clearly audible but in a constructive, 'vintage' sounding manner rather than being unpleasant. Of course, you can provoke the pumping to excess if you choose a fast compressor attack, a fast release and lots of gain reduction — but used sensibly, the compressor is smooth and flattering.

In split compression mode, I had great fun trying to create very beefy mixes by compressing just the bottom end. At the opposite extreme, you can create a very exciter‑like effect simply by compressing everything above 4kHz or so — then bringing up its level while using the Bypass button to check that you haven't overcooked things. Similarly, the filter is useful for gentle de‑essing, but lacks the focus of a dedicated de‑esser unit. Such devices usually include a band‑pass filter option, allowing you to tune into the sibilance more precisely.

The gate works well, and the Auto setting means that you don't miss a separate Attack control — except when you wish to use a gate to impose a deliberately slow attack on a sound. The side‑chain filters are suitably sharp, and the overall balance of features is impressive. I also rather like the 'quick and dirty' SNR option, which can really help quieten noisy synths and guitars. It works just like a gate, except when the gate closes: instead of nothing, you're left with a filtered version of the original, and how filtered this is depends entirely on your filter settings.

Performance

At almost £465, the LA Audio 4x4 2 doesn't quite fall into the lower end of the budget equipment category, but when you take into account that you're getting two comprehensive gates and two very flexible compressors for your money, there's no disputing its value. The designers really have gone flat out to provide you with just about every possible combination of options gates, compressors and filters, and for this reason the 4x4 2 is a very powerful creative tool as well as a useful all‑rounder.

Criticisms are few, and perhaps the only shortcoming worthy of mention is the lack of an Auto compressor attack setting. The two switchable options perform well enough for most applications, but Auto would have been even better. My favourite creative mode is the split‑band compressor, but it's also good to be able to use the gate filter externally, without having to lose the use of the entire gate. Full marks (almost) for lateral thinking — a well thought‑out British design with impeccable styling.