The 522 is a stereo / dual-channel VCA compressor / Limiter / Expander / Gate / Ducker in a neat 1U package. Each channel has a dedicated Control Loop with Send & Return jacks, allowing external control of dynamics. The Return jack can be used as a key input for ducking, pumping & etc, or the loop can be used to eq the sidechain

Attack, Release, Range and Threshold all have front-panel controls. Range is also labelled as Ratio, and the control does different things in different modes of operation. In Compress / Limit mode it sets compression ratio. In Expansion mode it sets expander ratio and in Gate mode it sets gate attenuation

The rest of the front-panel controls are duplicated for the two channels: Mode switch, In / Out (bypass) switch and an Internal / External switch to set the sidechain source. Gain Reduction is shown via an LED meter and Mode selection is shown via another LED display. The Mode switch toggles between four basic settings: Comp/Limit, Expand, Gate & Duck. Channel 2 has an additional Slave position for stereo linking

On test the Symetrix 522 sounds great. There’s lots of scope in all the controls. Attack & release times are variable over a wide range and varying the compression ratio has an easily-audible effect – not always the case with cheap VCA compressors. The controls are all well-judged, which makes setting-up easy & accurate. It’s possible to make the Symetrix very subtle in operation or make it pump. In that respect I liked it a lot

These models use the Valley People TA-101 VCA chips designed by Paul Buff, a man responsible for some of the juiciest compressors ever built. The TA-101 is responsible for part of the sound of the 522, but the rest is down to the design team at Symetrix. It’s the sidechain that really determines the sound of a compressor and Symetrix have nailed it with the 522

The 522 is built in a substantial steel chassis and the controls have a quality feel. It accepts both balanced and unbalanced connections via the rear-panel jack sockets so will be equally at home in a studio rack or home setup. In my opinion Symetrix has nailed the balance between super-clean and effect compression – the unit sounds very clean but is capable of pretty vicious pumping when required