Mixer Assist
Explained
A plain-language walkthrough of how the Input and Output Mixers work in Arc Audio DSP software — what every preset does and exactly when to use it.
The Arc Audio DSP has two separate mixers, and they do very different jobs. Understanding where each one sits makes all the difference when setting up a system.
Input Mixer
- Sits at the very front — before any DSP processing occurs
- Takes up to 10 sources: Inputs 1–8 plus L Digital and R Digital (optical S/PDIF)
- Routes those sources to the 8 internal DSP processing channels
- Can combine (sum) multiple inputs into a single DSP channel
- Think of it as: deciding what the DSP will work on
Output Mixer
- Sits at the very end — after all DSP processing is complete
- Takes the 8 processed DSP channels and distributes them to up to 12 physical outputs
- Lets you send the same processed signal to multiple amplifier inputs
- Critical for systems with more amp channels than DSP processing channels
- Think of it as: deciding where the processed audio goes
The Key Difference in One Sentence
The Input Mixer controls what goes in to the DSP engine. The Output Mixer controls where it goes out to your amplifiers. Every lit dot in the matrix represents an active connection between a row (source) and a column (destination).
The Input Mixer is a routing matrix. Each row is an available input signal. Each column is one of the 8 DSP processing channels. A lit dot means that input is connected to that DSP channel. Select a preset to see how it works.
All Off
No connections are active. All input sources are disconnected from all DSP processing channels. The DSP receives no signal.
This is a reset or starting-point state — not a working configuration. Use it to clear the matrix before manually building a custom routing from scratch.
Starting fresh. Clearing the matrix before setting up a custom install-specific routing that doesn't match any preset.
2-in 8-out
Two source signals — typically a stereo Left/Right pair from a head unit — are spread across all 8 DSP processing channels. Input 1 (Left) feeds DSP channels 1, 3, 5, and 7. Input 2 (Right) feeds channels 2, 4, 6, and 8.
This is the most common starting point for a typical car audio install. One stereo source drives the full active system — tweeters, mids, midbass, and subwoofer — all from one stereo pair.
Standard stereo install with a single aftermarket head unit. Full 2-channel source driving a complete active system.
4-in 8-out
Four input signals are each mapped to two DSP processing channels. Input 1 drives channels 1 and 5. Input 2 drives channels 2 and 6. Input 3 drives channels 3 and 7. Input 4 drives channels 4 and 8.
Ideal when your source has dedicated outputs — front left, front right, rear left, rear right — and you want the DSP to handle each independently while still having two output channels per input.
4-channel LOC, head unit with discrete front and rear outputs, or OEM speaker-level signals from four separate locations.
6-in 8-out
Six input channels are distributed across 8 DSP channels. The first two inputs each cover two DSP channels, while inputs 3 through 6 each connect to one. Factory premium audio systems (Bose, Harman, Bang & Olufsen) often have separate outputs for multiple speaker zones — this preset maps all of them cleanly into the DSP.
OEM premium audio integration where the factory amp has 6 speaker-level outputs. Retaining the factory signal topology while applying correction processing.
8-in 8-out
A true 1-to-1 mapping. Each of the 8 physical inputs feeds exactly one corresponding DSP processing channel — no sharing, no combining. Input 1 goes to Channel 1, Input 2 to Channel 2, and so on down the line.
This is your maximum-fidelity, maximum-control configuration. Every EQ curve, crossover point, time delay, and gain setting operates on one unique input signal.
High-end OEM integration with 8 factory speaker outputs, or a full active system where every driver group has its own dedicated input. The audiophile configuration.
2-Way Summed
Multiple input channels are summed (mixed together) before reaching the DSP channels. Instead of each input being isolated, several are blended. This collapses multiple inputs down to 2 mixed channels driving all 8 DSP outputs.
Summing is used when you need to combine signals — for example, mixing front and rear together for a subwoofer feed, or combining left and right into a mono sum for a center channel reference.
Creating a summed mono or blended stereo feed for a subwoofer channel. Also useful for OEM integration where you want to blend all available speaker outputs into a cleaner two-channel reference.
Toggle S/PDIF
Activates the L Digital and R Digital inputs — the optical S/PDIF (TOSLINK) digital input — and routes them to all 8 DSP channels using the same 2-in 8-out pattern. This replaces the analog inputs with the digital input stream.
S/PDIF carries a lossless digital signal directly from the source, eliminating the noise that can come from analog RCA connections — alternator whine, ground loops, and interference from the vehicle's electronics.
Any source with a TOSLINK optical output. Many factory head units in newer vehicles output digital audio. Ideal for the cleanest possible signal path into the DSP.
After the DSP processes your audio — applying EQ, crossovers, time alignment, and gain — the Output Mixer sends those processed signals to the physical output terminals. Each row is a processed DSP channel. Each column is one of the 12 output jacks. A lit red dot means that DSP channel feeds that output.
2-in 12-out
Two processed DSP channels are distributed across all 12 physical outputs. Channel 1 (Left) drives outputs 1, 3, 5, 7, 9, and 11. Channel 2 (Right) drives outputs 2, 4, 6, 8, 10, and 12.
Simple stereo duplication — the same two processed signals are replicated so every connected amplifier receives the same stereo pair.
Simple passive systems where all amplifiers share the same processed stereo signal, or whole-car audio distribution across multiple zones playing the same content.
4-in 12-out
Four processed DSP channels are each mapped to three physical outputs. Channel 1 drives outputs 1, 5, and 9. Channel 2 drives 2, 6, and 10. Channel 3 drives 3, 7, and 11. Channel 4 drives 4, 8, and 12.
A 4-channel processed system gets replicated evenly — useful when each processed signal needs to drive multiple amplifier channels.
A 4-channel active system (front L, front R, rear L, rear R or 4-way front stage) where each zone runs multiple amps, or a 4-channel system with additional sub outputs bridged from the same signal.
6-in 12-out
Six processed DSP channels each map to two physical outputs. Each processed signal — tweeter L, tweeter R, mid L, mid R, sub L, sub R — gets its own pair of output terminals.
The sweet spot for a full active front stage with a stereo subwoofer. Six channels covers a 3-way stereo system, and each driver has two output terminals for amp wiring flexibility.
Full active 3-way system (tweeter + mid + sub per side) — each channel gets a second output for a bi-amp configuration or a dual-amp sub setup. The most common high-end build preset.
8-in 12-out
All 8 processed DSP channels are routed to 12 outputs. The first four channels each get two outputs, while channels 5 through 8 get one each. This is the most complex preset — a fully loaded 8-channel active system with multiple amp channels per critical driver group.
Competition builds and high-end installs running 8 active channels. A full 4-way front stage per side (tweeter, midrange, midbass, sub) where the highest-priority channels drive more than one amp input.
Here's how the two mixers work together in actual installs. You always configure the Input Mixer first — deciding what enters the DSP — then set the Output Mixer to match your amplifier layout.
Standard install with an aftermarket source unit providing two stereo RCA outputs, driving a full active 2-way front stage plus subwoofer.
Keeping the factory head unit but upgrading the sound. The OEM amp has 6 speaker-level outputs feeding the DSP via a LOC or direct connection.
Factory head unit has an optical digital output. Using S/PDIF input eliminates analog noise and delivers a lossless signal to the DSP.
About the Upmixer
The Arc Audio DSP includes a built-in Upmixer visible in Mixer Assist. When enabled, it uses SuperBass and spatial processing to generate a multi-channel signal from a stereo source — useful for factory integration where the source doesn't have discrete channel outputs. The Upmixer sits between the Input Mixer and the Output Mixer in the signal chain, outputting channels labeled Left, Center, Right, LS, and RS that the Output Mixer then distributes to your amp outputs.
All 11 presets at a glance. A fast reference for dealers and installers in the bay.
| Preset | Mixer | What It Does | Best Used For |
|---|---|---|---|
| All Off | Input | Clears all connections — no routing active | Starting point for fully custom manual routing |
| 2-in 8-out | Input | Stereo L/R fans to all 8 DSP channels (L → odd, R → even) | Aftermarket head unit, single stereo source, full active system |
| 4-in 8-out | Input | 4 inputs each paired to 2 DSP channels | 4-channel LOC, factory front/rear outputs, 4-way active system |
| 6-in 8-out | Input | 6 inputs mapped to 8 DSP channels (first 2 get doubles) | Factory premium audio with 6-channel OEM amp output |
| 8-in 8-out | Input | True 1:1 — each input gets its own dedicated DSP channel | 8-channel OEM integration, max channel independence, audiophile builds |
| 2-Way Summed | Input | Multiple inputs blended into 2 channels across 8 DSP outputs | Summed mono sub feed, blended reference from multi-zone OEM signal |
| Toggle S/PDIF | Input | Activates optical digital (L/R Digital) in 2-in 8-out pattern | Factory or aftermarket head units with TOSLINK optical output |
| 2-in 12-out | Output | 2 processed channels replicated across all 12 outputs | Simple passive systems, whole-car stereo distribution |
| 4-in 12-out | Output | 4 processed channels each mapped to 3 outputs | 4-channel active system with multiple amps per zone |
| 6-in 12-out | Output | 6 processed channels each mapped to 2 outputs | 3-way active front stage per side (tweeter + mid + sub) — most common high-end preset |
| 8-in 12-out | Output | 8 processed channels to 12 outputs (first 4 get doubles) | Full 8-channel active systems, competition builds, max channel count |