When cutting to disc, you’ve got two planes of movement to think about. Lateral is the side to side movement of the stylus, representing your mid/sum signal, and vertical is the up and down movement, representing your side/diff signal. In this blog post we are going to talk purely about vertical modulation control.
Too much energy in your side/diff signal causes excessive vertical modulation. If it cuts too deep, particularly on plastic, it can cause stylus issues and distortion. If the signal pushes out of phase it does the opposite, pulling the vertical modulation upwards and resulting in thin, broken, or possibly hard to track, distorted grooves. Over the years of mastering we’ve developed a vertical modulation setup that helps control any nasty surprises, and it’s a regular part of our cutting workflow.
A good way of doing this yourself for very little money is to use a multiband dynamic processor set to only affect your side/diff signal. We use Tokyo Dawn Nova GE for this and have done for close to a decade, it’s extremely clean processing and massively affordable.
Here is a rough starting point...
- Open Nova GE and open the ‘6 Band Dyn’ preset. This is a 6 band dynamic EQ.
- Set the processing to ‘Diff’ in the top toolbar, this means the processing only affects the side/diff signal
- Set the ratio of each band to 4:1
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Set the threshold of each band to suit your audio. This processing should not be pulling back signal at all times, it is there to catch any stray peaks and bursts of energy, so check the loudest, and quietest parts of your audio. We often tend to set all bands to the same threshold, based on the loudest parts of the song with the most side/diff energy.
This is a starting point where you will need to dial it in from there, not all audio needs it, but when it does, it is crucially important to have the vertical modulation under control.
We will go more in depth into this in our online course we are working on, ‘Lathe Cut Lab: Online’, but for now, this is a good starting point for you to start learning with.