How Audio Flows

Everything in Aura Mixer makes sense once you can picture the journey a sound takes through it. This page builds that picture. No knobs to turn yet — just the map.

The big picture

Sources → input channels → routing matrix → output buses → devices. The dashed box is the routing matrix: every input can feed any combination of buses.

Four stages, always in this order:

Sources — anything that produces audio: a mic, a single app, a whole playback device, a virtual cable.
Input channels — each source lands on a channel strip and passes through that channel's processing chain.
Routing — the matrix decides which buses each channel feeds. One channel can feed several buses at once.
Output buses — each bus sums everything routed to it, applies its own processing, and delivers the result to a real device (headphones, speakers) or a virtual one (OBS, Discord).

The key insight: a channel is processed once, but can be heard everywhere — and every bus is its own independent mix. Pulling the music fader down in your stream mix doesn't touch what you hear in your headphones.

Inside an input channel

Audio passes through the channel strip's processors in a fixed order — the same order a studio engineer would patch them:

One channel's DSP chain. Stages with the blue dot are always in the signal path; the rest are bypassable and use zero CPU when off.

Stage	What it does	Why this position
GAIN	Sets a healthy input level (−20…+20 dB), with optional PAD (−20 dB) and phase invert	Everything downstream works best with a sane level coming in
GATE	Cuts low-level noise (fan hum, keyboard) when you're not speaking	Gating before EQ/compression keeps noise from being amplified
EQ	Shapes tone — up to 12 parametric bands	Tone first, then dynamics react to the corrected sound
COMP	Evens out loud and quiet moments	Works on the EQ'd signal
FX inserts	Your custom rack: de-esser, reverb, pitch…	After the core chain, before the fader
FADER	The strip's main level — your mixing control	Mixing happens after processing, so the sound stays consistent at any fader position
SPATIAL / PAN	Stereo width, point-source HRTF positioning, left-right placement	Last, on the final stereo image — but only for stereo/mono sources (see the surround note below)

You can see this chain live on a channel's HOME tab — the signal-flow strip lights up each block that's active, and clicking a block jumps to its tab.

💡 Zero-cost bypass

Processors you switch off aren't just bypassed — they're removed from the processing graph entirely and cost zero CPU.

⚠️ Surround sources fold first

When a 5.1 / 7.1 source is set to Binaural HRTF, the surround→headphone fold does not happen at the SPATIAL stage — it runs at the very start of the chain, before Gain, Gate, EQ and Comp. Those processors are stereo-only, so the multichannel signal is first decoded to a binaural stereo image, and the rest of the chain then shapes that result (your channel EQ/Comp act on the already-folded binaural signal). The "SPATIAL last" rule above applies only to stereo/mono positioning — width, panning, and point-source HRTF. An imported Custom HRIR profile also gets a Treble Softening control to tame any residual high-frequency edge. See Spatial — Binaural 3D.

Inside an output bus

Buses have their own, shorter chain, applied to the sum of everything routed in:

Each output bus sums its incoming channels, then applies a shorter chain before delivering to a device.

EQ — correct the room or the headphones, not the individual sources.
LIMITER — a safety ceiling that stops the summed mix from clipping, with true-peak detection.
FADER — the bus's overall level.
DELAY — shifts the whole bus in time, e.g. to sync audio with video (lip-sync).

Metering checkpoints

Every stage has meters, and they answer different questions:

Channel HOME tab, INPUT meter — is the source arriving at all, and at a good level?
Channel strip VU — what is this channel contributing after its processing?
Bus strip VU — what is the final mix on this destination doing?

When something sounds wrong, walking these meters left to right tells you where the problem starts — which is exactly how the No sound? checklist works.

stuck? ask on Discord