Double The Power

What Parallel Processing Actually Does

In its simplest form, parallel processing involves taking an audio signal, sending it through a duplicate path (via a bus or track copy), applying some type of processing to the duplicate, and blending it back in with the original. The idea is to retain the integrity of the original while enhancing or reshaping the overall result using additional processing.

This could be compression, EQ, saturation, reverb, modulation, or any combination thereof. The technique isn’t limited to any one style of production — it’s routinely used in rock, pop, jazz, hip-hop, film scores, and electronic music. It's been part of modern studio practice since at least the late 1970s.

What makes it valuable is that it allows engineers to work on a secondary layer of the signal, adding aggression, tone-shaping, or ambience — without degrading what’s already working in the dry channel.

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Early Use in Analog Studios

Before digital DAWs, parallel chains were created via console sends, outboard gear, and separate return channels. Engineers working on large-format consoles used aux sends to feed signals into compressors or reverbs, returned the processed signal to an unused channel, and balanced it against the dry track.

One of the best-known examples of parallel compression is on Phil Collins’ “In the Air Tonight” (1981). The explosive drum fill, often attributed to the gated reverb technique, is also driven by heavy parallel compression applied via an SSL console’s bus structure. Similar workflows were used on Peter Gabriel’s third solo record and numerous Trevor Horn productions.

Another key example is the tight and dense snare drum sound on Michael Jackson’s “Billie Jean” (1982), mixed by Bruce Swedien. Swedien created dedicated ambient returns using Lexicon reverb units and compressed subgroups to give otherwise dry elements greater impact — all while maintaining clarity.

These setups required patch bays, console sends, and manual balancing. The intention was never hype — it was control.

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Typical Use Cases in Modern Sessions

Let’s look at where parallel processing fits into today’s mixing workflow, broken down by signal type and objective.

Drums: Compression and Density

Drums are the most common application. Sending the entire drum bus to a heavily compressed duplicate channel adds sustain and weight, especially on snares and room mics.

Example Setup:

• Dry: All drums routed to a main drum bus.
• Send: Auxiliary bus with VLA-FET from Black Rooster Audio, set to fast attack/release, high ratio (~10:1).
• Optional: Add Magnetite on the wet bus for tape-style saturation.
• Balance: Blend until the snare gains body without overwhelming the kick.

This gives the kit greater energy without masking transients. It’s the backbone of the so-called "New York Compression" method.

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Vocals: Presence Without Harshness

Vocals often need to cut through a mix while sounding full and natural. Applying aggressive EQ and compression directly can quickly introduce harshness or fatigue.

Parallel Workflow:

• Dry: Lead vocal with basic cleanup and level automation.
• Send: Duplicate track or bus with VEQ-5 adding top-end boost (10kHz+) and low-mid scoop.
• Dynamics: Add VLA-2A for smooth gain control.
• Space: Optional touch of RO-SPR for a short stereo spring reverb return.
• Balance: Blend subtly to enhance articulation and air.

This chain works especially well on vocals that need extra clarity without losing body — a common challenge in dense pop arrangements.

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Guitars: Reinforcing the Midrange

Electric guitars can often sound overly scooped or masked by cymbals and vocals.

Parallel processing can reintroduce bite or presence in a controlled way.

Practical Use:

• Dry: Amp sim or mic’d guitar track.
• Wet: Duplicate with midrange-focused EQ (~1–3kHz boost), possibly some mild saturation using OmniTec-67A.
• Compression: Optional gentle compression to stabilize dynamics.
• Blend: Mix just enough to support without sounding like a separate layer.

Especially effective when double-tracking isn’t an option.

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Bus Processing: Mix Glue and Lift

On mix buses (e.g. drums, instruments, vocals), parallel chains can glue things together or give movement without flattening dynamics.

Example:

• Create a stereo aux that receives parallel sends from key buses.
• Chain: VLA-3A for RMS compression, followed by Magnetite for harmonic thickness.
• Blend: Low mix level — ~10–15% of total mix volume.

This is similar to the way Tony Maserati or Serban Ghenea will build cohesion in a pop mix without resorting to master bus limiters.

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Implementing in Different DAWs

Every DAW handles routing slightly differently. Here are some brief implementation notes for major platforms.

Logic Pro X

• Use Bus Sends on the channel strip.
• Set sends to Post Fader for full-volume processing.
• Return via Aux Channel Strip in the mixer.

Ableton Live

• Use Return Tracks (A–D).
• Control blend using the Send knob per track.
• Chain processing on the return channel.

Pro Tools

• Use Aux Sends to route audio to an Aux Input.
• Consider inserting a Trim plugin on returns to help balance quickly.

Cubase

• Use FX Channels as return paths.
• Route with Send Level automation for fine control.

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Technical Considerations

Phase Alignment

Some plugins introduce latency. Always check phase alignment — particularly with EQs, modulation, or saturation. Use phase-flip (polarity) buttons, manual delay compensation, or phase-alignment tools to prevent comb filtering.

Gain Staging

Parallel paths are often pushed harder than dry signals. Keep levels in check to avoid unintentional clipping or build-up, especially when summing back into buses.

Frequency Isolation

In some cases, it makes sense to isolate frequencies. For example, adding low-end saturation only below 200Hz via an EQ on the wet chain. This technique is especially useful in kick/bass relationships.

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Classic Mix Examples That Used Parallel Workflows

• Peter Gabriel – "Intruder"
  The gated room sound was compressed, EQ’d, and returned in parallel to preserve impact while allowing extreme effects.

• Steely Dan – "Peg"
  Engineer Elliot Scheiner used parallel chains for reverb returns, particularly on snare and vocal doubles, to create width without cluttering the center image.

• Daft Punk – "Get Lucky"
  The bassline combines clean DI and parallel amp/saturation layers to achieve clarity and groove in a sparse arrangement.

• Radiohead – "Everything In Its Right Place"
  Synth and vocal textures use filtered, modulated parallel layers to build complexity without density.

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When Not to Use It

Parallel processing isn’t always the right move. Avoid it when:

• The source already has strong character
  Adding more may introduce phase or tonal conflicts.

• You’re fixing a flawed recording
  Parallel chains are not corrective tools. They’re best for enhancement.

• Mix context makes it redundant
  If a vocal sits well and has space, there's no need to “brighten” or “lift” unnecessarily.

Use it when it adds value — not by default.

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Final Thoughts

Parallel processing is a reliable, flexible tool — not a shortcut or a crutch. It lets you refine tone, shape dynamic response, and apply enhancements with granular control. Whether you’re working on a dense pop arrangement, a sparse jazz mix, or a high-energy EDM track, it’s a method worth integrating into your daily workflow.

More importantly, it keeps your decisions reversible and scalable — which matters as projects evolve from rough to final.

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Interested in trying parallel processing with dedicated analog-modeled tools?
Explore Black Rooster Audio plugins and build your own parallel chains with high-quality dynamics, EQs, saturation, and time-based effects.