Saturday, 3 February 2018

Missing fundamental!

The pipe organ uses a version of ‘Trendline synthesis’, in this case more accurate would be ‘trendline voicing’ as the actual synthesis is wavetable trajectory. I have slightly extended the 4-parameter trendline method described by Pykett to add one extra feature - an individual harmonic that can be boosted or cut. And I found a great use for this feature - implementing ‘missing fundamental’ in the pedals. The lowest C on the pedals at 16’ is about 32.7Hz, very much below what my little studio monitors can reproduce with their 5” ‘woofers’. So I can’t hear it. Worse, it is there, and is using up the dynamic range of the playback system. But by totally eliminating the fundamental - harmonic 1, cut down to zero - the pedal tones come through much clearer, with an implied but absent fundamental, and the whole system has more headroom as the sub-50 Hz stuff isn’t swinging the instantaneous DC value around. Nice to know the extended feature has a use. The intended use is for boosting outliers that would otherwise have been pulled down by the trendlines, but this is a great way to repurpose it. And cheaper than buying a subwoofer.

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