This blog post is about signal flow, specifically because we've had a few messages recently about HF limiting when using a feedforward, entry level system like we work with. In a feedforward system, you map your cutterhead's frequency response and mechanical resonances and account for them digitally in your DAW via EQ. The aim is to reproduce a flat frequency response where the cutterhead responds accurately and cuts to the best of its ability.
What we've found is that some people are using a dedicated HF limiter after the cutterhead EQ, trying to stop distortion when cutting. This isn't the correct approach. The cutterhead EQ is the final step in your signal chain, think of it as part of the cutterhead itself, not part of your mastering chain. HF limiting is part of mastering, and this is the key point.
If your cutterhead is mapped correctly and cutting cleanly but you're still experiencing distortion on certain audio, this is either a mastering issue or a volume issue, not something to fix post-cutterhead EQ. Where the confusion lies is in the difference between HF limiting and peak limiting. Sometimes a safety peak limiter may be used after the cutterhead EQ, but this should only catch the occasional stray peak. In our studio we never use a peak limiter post-cutterhead EQ, but that's because we run a mastering studio. We understand many people don't and are purely cutting, in which case a safety peak limiter can be beneficial as long as it's barely working.
The point we want to make is understanding what is mastering and what isn't. HF limiting is a crucial tool when cutting to disc, but it's used to treat the audio, not to compensate for the cutterhead. The cutterhead EQ is purely a tool to correct the head's frequency response and resonances. Anything you add after the cutterhead EQ will also affect the head's response, in severe cases, completely uncalibrating the system.
For anyone starting out, make sure you have your signal flow correct. With feedforward systems, mastering is done first - things like mastering EQ, compression, HF limiting, de-essing, and so on. Then you should be able to run the mastered audio through your cutterhead compensation EQ and cut to the best of the system's ability. If you're experiencing problems like distortion, this is something to fix in mastering or it's potentially just cutting too loud.