The HOC500 is labeled as a "parallel opto compressor," and is a cousin to Hamptone's HOC1 half-rack version [Tape Op #100]. Adapted for a 500 Series chassis, there's a lot less room for controls, so a unique feature set has been adapted here. A pair of house-made opto cells are run through Hamptone's testing, and their characteristics are logged for precise matching so that the desired linearity of compression can be programmed specifically for each unit. How many companies build units at this level of detail? The Hard Wire I/O switch is a must. I'm so annoyed by the number of compressors that do not allow for complete bypass of the electronics – how am I supposed to set my mic levels if I can't turn off the compressor first? The six-segment LED metering is superb, and meters are something I always count on to help me set compression (before using my ears, duh). The dB reduction is clearly labelled, and it’s easy to understand what this unit is doing from across the room. Alternate metering level setups are adjustable via internal jumpers.
The HOC500’s three knobs, VOL, MIX, CMP LVL, handle the main functions. I found myself turning the MIX knob all the way right (fully wet) to hear only the compressed signal, getting either a softly compressed setting or a full squish with the CMP LVL knob below, and then dialing MIX back until the DRY signal added a bit of openness or clarity as needed for the part. Then I'd adjust VOL to set the appropriate makeup gain level for feeding the console or Pro Tools track while popping the Hard Wire I/O switch in and out to make sure I wasn’t feeding a ridiculously hot or quiet signal. One smart little feature is the recessed Link switch on the unit’s front panel; take a tiny screwdriver (or similar tool) and pop it on or off. Linking is set up via a standard 2.1 mm cable that can be plugged in between adjacent units when racking. One might think the HOC500 offers few options for attack and release times beyond the Rate switch's Slow or Fast settings. However, pulling the unit out of the rack, studying the printing on the side, and noting the instructions for configuring the four trim potentiometers will offer an unlimited number of variations for both Slow and Fast settings. (Don't hot swap 500 Series devices!)