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Trident Hi-Lo

500 Series Tracking Filters By Matt Houghton
Published March 2021

Trident Hi-Lo

PMI breathe new life into a classic dynamic EQ design.

The latest device to sport the Trident brand name actually has its origins in a product made back in the day by a company called CLM Dynamics. Alan Hyatt, who owns Trident’s parent company PMI, has long been a fan of CLM’s Expounder, which is a unique analogue four‑band stereo EQ that includes a pair of resonant high/low‑pass filters. It was the filter stages in particular that appealed to Hyatt — we have plenty of options for more conventional EQs now, but the Expounder’s filters are dynamic, adjusting their frequency according to the input signal level. So he decided to make them available in the form of a 500‑series module.

The result is called the Hi‑Lo and PMI decided to release it as part of their Trident range. The basic design is essentially the same as in the old CLM device, but some component choices and modern manufacturing methods have brought down the noise floor and distortion.

Dynamic Duo

The Hi‑Lo comprises two filters and the front panel is divided accordingly, with the high‑pass one in the upper section and the low‑pass beneath. With all the controls and labels, the panel may appear quite dense at first glance but it’s actually all very clearly presented and easy to read, and there’s plenty of space for your fingers to access all of the controls too.

Each filter has a pair of pots, one to set the Resonance and the other the filter Frequency. There’s also a trio of round backlit buttons that engage the Resonance control (red light) and amplitude tracking (green) and switch the...

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Published March 2021