Audio Effects Pipeline
From a dry microphone signal to a polished, produced sound — every stage in the chain is a different DSP algorithm applied in sequence.
The Complete Chain
Each stage solves one acoustic problem. The conventional order reflects acoustic logic — not arbitrary tradition.
Parametric EQ
Each band is a biquad IIR filter — just five coefficients and nine MAC operations per sample. Stack four biquads; get a four-band EQ.
Four Filter Shapes
The same biquad structure, different coefficients — each optimized for a specific acoustic task.
- Low shelf: boost or cut all bass below a corner frequency
- Peaking bell: boost or cut around a center frequency with adjustable Q
- Notch: deep cut at one frequency — removes hum or resonance
- High shelf: boost or cut all treble above a corner frequency
Room in a Box
Compression & Limiting
- Threshold: level above which gain reduction begins
- Ratio: 4:1 means 4 dB in → 1 dB out above threshold
- Attack/Release: how fast gain reduction is applied and removed
- Makeup gain: restore level after compression
- Limiter: ratio ≥ 10:1 with look-ahead — prevents clipping
Delay & Chorus
Delay: a circular buffer read at an offset. Chorus: modulate the delay time with a slow LFO to create the ensemble effect.
Wet / Dry Mix
Each effect blends its output with the original via a mix control. Reverb and delay are almost always parallel — preserving the dry transient attack.
Delay Accumulates
- Biquad EQ & compressor: sample-by-sample → ~0 ms latency
- Convolution reverb (overlap-add, 1024-pt block): ~21 ms at 48 kHz
- Look-ahead limiter: 5–10 ms fixed delay
- Target <20 ms total for live monitoring without noticeable lag
- DAW host compensates plugin latency in recording contexts
DSP in Communications
OFDM receivers, channel equalization, timing synchronization — the DSP engine inside every Wi-Fi and 5G modem.