After this chapter you'll understand what Omnissiah is for, the parts of your system it controls, and the simple loop you'll follow to get great sound: measure → correct → apply.
What Omnissiah is
Omnissiah is the desktop app for your Really Mean Sub. Your Really Mean Sub is an active subwoofer with a built-in signal processor (DSP) and three outputs:
- one low-passed output that drives the subwoofer, and
- two high-passed outputs that feed your left and right main speakers.
Omnissiah connects to the Really Mean Sub over USB-C and lets you:
- set levels, delay, polarity, a crossover and a parametric EQ for each output;
- measure how your speakers actually sound in your room with a microphone;
- automatically calculate room correction filters that fix what the room is doing to the sound, and load them onto the device;
- back up and restore all of it.
The correction lives on the device, so once you've applied it, your system sounds corrected whether or not the app is running or your computer is connected.
The key idea: your room changes the sound
A speaker that measures perfectly flat in a lab will not sound flat in your room. Walls, floor, furniture and the speaker's position create peaks (boomy notes), dips (missing notes) and timing errors. Your ears hear the room + speaker together, not the speaker alone.
Omnissiah's job is to measure that combined result and calculate the opposite (gentle EQ cuts and boosts, small delays, and level matching) so that what reaches your listening position is closer to how the music was meant to sound.
How your system is laid out
Three concepts, from biggest to smallest:
- 1Device is your Really Mean Sub. Omnissiah discovers it automatically when you plug it in.
- 2Outputs are the three channels on the device (the subwoofer output and the two speaker outputs). You select an output to work on it.
- 3DSP blocks are the processing on each output, in signal order: Gain · Polarity · Mute · Delay · Crossover · Parametric EQ. Chapter 7 — Shaping sound covers each one.
| Output | Processing chain |
|---|---|
| Sub output | Gain · Delay · Crossover (low-pass) · EQ |
| Left output | Gain · Delay · Crossover (high-pass) · EQ |
| Right output | Gain · Delay · Crossover (high-pass) · EQ |
The measure → correct → apply loop
Almost everything in Omnissiah follows the same loop:
- 1Measure: play test noise through your speakers and capture the room's response with a microphone. (Chapters 8–9.)
- 2Correct: the app calculates correction filters aimed at a target curve (the tonal balance you want). (Chapter 9.)
- 3Review & apply: compare before/after, then load the correction onto the device. (Chapter 10.)
You can also skip measurement entirely and adjust the DSP blocks by hand (Chapter 7 — Shaping sound), which is useful for quick tweaks once you're set up.
If you want sound as fast as possible, go straight to Chapter 3 — Quick start. Come back here when you want to understand what you did.
