We are at the end of our first small production run of the HOC1. I started designing the compressor in 2003, and began prototyping in 2006. Over the course of 7 years, I built 12 prototypes, each one was loaned out, and used in the Portland area. Both from personal ideas, and user feedback, each rev added new features, and refined those already in place. I’ll be posting an operator’s manual soon, so I won’t go into too much detail here.
The last phase which I am working on now is the opto cell matching (2 cells are used, one for audio, the other in a feedback loop for temp stability, linearity, …). Cell matching / calibration is complicated, and involved designing automated test hardware/software to aid in the process. After spending a couple weeks refining the test procedures, the idea of adding a calibration routine to existing firmware came up. This would make field calibration (with a sine wave generator and an RMS voltmeter) possible without the need for the racks of test equipment and software that we use here. Using internal pcb jumpers read only at power up, the detector will become a function generator, with various waveforms required for calibration. I don’t expect this will be needed to be done regularly if ever (and we will always re-calibrate them if needed for free), but I’m trying to future proof these in every way I can.