The HA-609A is a modern take on the classic transformer coupled diode bridge compressor/limiter design, with several improvements added to accommodate the modern workflow. While some classic iterations of this design utilized IC chips and a Class A/B amplifier stage, the HA-609A features an entirely discrete, Class A design and a total of three Carnhill St Ives transformers per channel.

The addition of a fast attack mode for both the compressor and limiter section allows the HA-609A the flexibility to handle individual tracks as well as groups and 2-bus program material. Thanks to a proprietary system of diode bridge gain reduction cells, first introduced with the highly regarded SUCCESSOR, the HA-609A has better channel matching than any earlier incarnations; while the use of rotary switches and high quality, stepped pots allow for easy recall and maintain a perfect stereo image.