Listening Examples

• Matthias Wolff: Procession Pt. 2, Online (2026)
• Matthias Wolff: Nightshift - Active Projects July 2026, Online (2026)

Audio and Signal Processing (Course 11388) for Digital Music Production

The fourth tune on the “Procession Pt. 2” album is an example of extensive audio signal processing. You hear twelve different voices of five vintage digital synthesizers: Casio VZ-1, Kawai K4r, Kurzweil K2000r, Roland D-100, and Yamaha TG55. They all produce an awful lot of noise at their analog outputs which completely messes up the sound spectrum making everything sound muddy.

To get rid of the noise, I used a static gate plugin at my analog-digital converter as a first stage. This mutes all instruments currently not playing (see Fig. 1). The yellow curve shows the gate threshold (-80 dB). Additionally, the gate features a 12 dB pre-amp which shifts the low levels of the synths into a better range for digitalization. For some synths I even needed to insert a 15 dB analog pre-amp before the analog-digital converter.

A static gate, however, cannot suppress noise while an instrument is playing, and the pre-amps of course also amplify the noise. Therefore, I inserted adaptive multi-band noise gates into the digital recording chain as a second stage (see Fig. 2). The blue curve shows a gate function. It mutes all frequencies in the sound spectrum which are currently not used. The green curve shows the current (very low) sound spectrum of the K2000r synth which is particularly noise riddled. The adaptive noise gates nicely clean up the sound making it silky and crisp (in this tune particularly the iconic “Gold String” pad of Roland’s D-110).

As the tune has an unusually wide dynamic range, I did not manage to suppress all the noise (bell intro). To remove the remaining noise, I could use the digital ADAT outputs of the (few) stone-age synths that feature them. 

Because of the wide dynamic range of the tune, I needed to insert a multi-band compressor into the mastering chain to achieve a reasonable loudness as a third stage. Otherwise, the tune would sound much lower than the other ones on this album. As a compressor changes the overall sound a little, I was forced into a tiring iteration of mixdown and mastering :(

As a last stage, I inserted a finishing equalizer, based on a filter bank, to the master bus (see Fig. 3). The equalizer preset is named “Master Bus De-Mudder” which is exactly what it does. A droning bass is not a good idea when mastering. Hence the bass band is lowered by (moderate) 6 dBs; I’d probably better go up to 9 dBs. Likewise, the treble is amplified a little, which compensates for the typical frequency characteristic of headphones and other play-back equipment. Additionally, I inserted filter no. 5 with a center frequency of about 2.5 kHz because D-110’s string pad pretty much clogs the sound spectrum in this band. Hence, I lowered it a little to improve the overall listening experience.

The final sound is not perfect, but its still pretty good; miles away from my old analog mixing and mastering equipment.