Altitude Limiter

Architecture Overview

Modular Research Platform

Altitude Limiter is a modular limiter designed for research and real‑world production. It supports a large matrix of configurations and can achieve deep gain reduction (down to roughly −2 to −3 dB RMS) while preserving clarity and musicality.

Core Architecture

Dual‑Sidechain Processing

Two independent sidechains analyze the signal in parallel:

• Sidechain 1 (Primary)
  Computes the main gain reduction based on the input signal.

• Sidechain 2 (Secondary)
  Analyzes how the signal would look after Pass 1 (the “limited” view) and computes a second gain reduction.

Both gain reductions are then combined and applied to the original signal in a single stage. You get the analytical benefits of cascaded limiting—without the cumulative artifacts and phase shifts of literally chaining two hard processors.

Sidechain Technologies

• ARIA PASS1
  Advanced envelope detection with configurable max filtering; transparent, musical response; strong stereo image retention.

• SIMPLE
  Clean, efficient, and CPU‑light; configurable knee; ideal for transparent peak control.

• STANDARD
  Feature‑rich with auto‑envelope detection, crest‑factor awareness, and smoothing; balanced between transparency and control.

• ENHANCED
  Maximum configurability; advanced max filtering with running averages, holds, and long windows; built for extreme scenarios.

Multiband Mode

Frequency‑dependent limiting with:

• Four bands and independent thresholds.
• Configurable crossover reconstruction methods.
• Tone balance controls.
• Multiple reconstruction strategies to suit program material.

Adaptive Gain Systems

• Adaptive Drive
  Intro-based drive learning that finds a practical starting point from the current limiter response.

• Output Adaptive Gain
  Post‑processing that stabilizes level without flattening dynamics.

Safety & Monitoring

• Safety Limiter
  Independent brick‑wall protection that prevents output from exceeding 0 dBFS.

• Real‑Time Monitoring
  Comprehensive meters and visualizations to validate behavior quickly.

Processing Flow

1. Input stage (conditioning)
2. Adaptive Drive analysis (optional)
3. Limiter Pass 1 (single or multiband)
4. Limiter Pass 2 (optional secondary wideband)
5. Soft Safety (configurable)
6. Output Adaptive Gain
7. Hard Safety (final brick‑wall at 0 dBFS)

Peak Detection Modes

• Instant
  Zero‑latency peak detection for the snappiest response.

• Windowed (Lookahead)
  Smoother, predictive behavior for more transparent control.

User Interface Layout

Plugin Overview

Altitude Limiter is organized around a left-side navigation stack, a main workspace, optional graphing views, and a bottom menu for utility pages and system tools.

Note: The screenshots below show the standalone Altitude Limiter product first, then the same limiter embedded in ARIA ONE's advanced view. The core limiter engine and controls are identical; ARIA ONE surrounds the limiter workspace with additional navigation cards, services, and routing, and moves some system pages into its own bottom menu.

Navigation System

Use the left‑side Navigation Panel to select the primary workspaces and utility views:

• ADAPTIVE DRIVE — Opens the adaptive drive workspace for intro-based drive learning; the nested power toggle enables or disables the adaptive layer
• LIMITER — Opens the primary control surface
• GRAPHS — Opens the graphing workspace and visual analyzers
• METERS — Shows or hides the integrated metering view
• HELP — Shows or hides the help strip; its nested power toggle controls hover tooltips
• SPLIT — Opens the optional second workspace column

The old MULTI and TEST tools still exist, but they are now launched from the LIMITER workspace's GLOBAL column instead of from standalone navigation buttons. Performance and utility pages such as Optimization Data, Account, Settings, Color, Audio Settings, and User Manual are accessed from the Bottom Bar menu.

Bottom Bar

The bottom bar provides quick access to the global menu and language selection:

• MENU — Opens the Bottom Menu, which contains Optimization Data, Account, Settings, Color, Audio Settings, and User Manual.
• Language — Select the UI language. Changes apply instantly and persist with the session.

Help & Tooltip System

Altitude Limiter provides two complementary ways to view control hints:

• Popup Tooltips — Small popups near the cursor appear after a short delay when the HELP tile's nested tooltip toggle is enabled.
• HELP Panel — A persistent help strip at the bottom of the interface that mirrors the hint for the control under your mouse.

Notes

• Popups are controlled by the HELP tile's tooltip toggle (parameter: tooltip_enabled).
• The HELP panel works independently of that toggle and can remain visible even when popups are disabled.
• Tips are localized. Changing the language in the Bottom Bar updates both popup tips and the HELP panel immediately.

Workflow suggestion

• Keep tooltip popups ON while learning. Disable them later and rely on the HELP panel for an uncluttered workflow.

Main Interface Panels

GRAPHS

Open the GRAPHS workspace from the left navigation stack when you want dedicated analysis views:

• Vectorscope
• Polar Sample
• Polar Level
• Five FFT windows
• Metering
• Waveform
• Loudness

LIMITER

Where you spend most of your time. Exposes the technical parameters that shape how the sidechain is built and responds.

• Dual‑pass configuration (Pass 1 & Pass 2)
• Algorithm selection (ARIA, SIMPLE, STANDARD, ENHANCED)
• Timing controls (attack, release, lookahead)
• Channel link and bypass
• Soft Safety and Hard Safety controls
• Multiband mode for Pass 1 (tone balance, reconstruction power, frequency‑dependent controls)

Note: Drive is part of the metering workflow rather than this panel.

MULTI

Curve editing for mapping threshold vs. drive when raw math doesn’t give the musical result you want. In current builds, MULTI is opened from the LIMITER workspace's GLOBAL column rather than from its own navigation button.

DATA

Real‑time performance metrics. Open this page from MENU in the Bottom Bar.

• CPU usage
• Buffer performance
• (Future) Optimization helpers

ADAPTIVE DRIVE

Adaptive Drive replaces the old INPUT workflow. It analyzes the opening section of a song, learns a drive setting from the current limiter response, and can either stay active for song-to-song consistency in ARIA ONE or be committed into the main DRIVE control for fixed use:

• Intro-based drive analysis
• Intelligent gain staging
• Learned drive suggestions based on limiter engagement and diminishing returns
• Commit-ready drive for standalone or fixed-playback workflows

TEST

Diagnostic tools to validate limiting and inspect envelopes. In current builds, TEST is launched from the LIMITER workspace's GLOBAL column rather than from a standalone navigation button:

• Limiting effectiveness
• Envelope behavior
• Signal verification
• Performance benchmarks

HELP

Context‑sensitive documentation strip.

• Shows a concise description of the control currently under your mouse.
• Lives at the bottom of the interface (above the status bar).
• Toggle with the HELP utility tile in the Navigation Panel.
• Localized: text changes with the Bottom Bar language selector.
• Works independently of the tooltip power toggle (the HELP panel can show hints even if pop‑up tooltips are disabled).

When you want fewer pop‑ups on screen, turn off the HELP tile's tooltip power toggle and leave HELP enabled for continuous guidance.

METER

Integrated metering column with input/output controls and drive/gr display.

• Three sections: INPUT, OUTPUT, and DRIVE (gain reduction).
• Each section includes responsive meters (peak and RMS) and a dedicated slider:
  • INPUT — Pre‑limiting trim.
  • OUTPUT — Post‑limiting level.
  • DRIVE — Controls overall compression intensity; GR meters fill top‑down for easy reading.
• Uses internal visualization for smooth ballistics and accurate readouts.
• Toggle with the METERS utility tile in the Navigation Panel.
• Layout toggle: Click the up/down arrow in the DRIVE section to switch between vertical column layout and horizontal row layout.

Interface Workflow

• Quick Operation — Start in the LIMITER workspace.
• Deeper Control — Open MULTI from the LIMITER GLOBAL column when you need frequency‑dependent mapping.
• Monitor — Use GRAPHS and METERS for signal inspection; open Optimization Data from MENU when you need performance diagnostics.
• Optimize — Use the ADAPTIVE DRIVE workspace for intro-based drive learning, song-to-song consistency, or commit-ready drive staging.
• Verify — Open TEST from the LIMITER GLOBAL column before print.

Licenses & Staying Connected

Altitude Limiter is licensed through your Altitude Audio account. Sign in once and your license is saved to your machine.

License Tiers

Tier	What you get	How long it lasts	Notes
Demo	Full feature set	30 days, one time per account	When it ends, the plugin stops processing (audio passes through unprocessed) until you purchase — there is no reduced "free" tier
Paid	Full feature set	Permanent	Tied to your account; activate on up to 5 machines

A new account starts on the Demo tier with full features for 30 days.

Staying Connected

Your license is saved to your machine, so the Limiter does not need a constant internet connection.

• Offline use: A paid license keeps working offline indefinitely — there is no offline time limit and no periodic re-verification requirement for your license. A Demo runs until its 30-day expiry.
• Launch check: The plugin performs a quick license check when it launches. If you happen to be offline, it keeps running on the license already saved to your machine.
• Signing in again: The only thing that expires is your login session, not your license. After roughly 90 days without signing in, you may be asked to sign in once to refresh the session. Your license and settings are unaffected.

In short: Sign in once. Your license lives on your machine. You will only be asked to sign in again if you stay signed out for about 90 days or when you authorize a new machine.

Presets

Use the Preset Panel to load factory and user presets for the limiter. Factory presets are installed with the product; user presets are the settings you save while working.

Factory Preset Drive

Factory limiter presets can include a tuned drive value. Altitude Limiter lets you choose how that built-in drive is applied when factory presets load, using Preset Settings > Factory Preset Drive from the gear button in the Preset Panel title bar.

• Neutral — Default. Factory presets load with Drive at 0 dB so you can set the amount yourself.
• Baseline — Loads the factory preset's authored drive value.
• Personalized — Reserved for hearing-profile-based scaling. Until that profile scaling is active in the client, it loads the same way as Baseline.

This setting only changes factory preset loading. User-saved presets and AI-personalized presets always load their own saved Drive value, and the Drive lock always takes priority: if Drive is locked, loading any preset keeps your current Drive.

Panel Controls and Parameters

Navigation Panel

The Navigation Panel lets you build a clean workspace by selecting the primary workspace you want to see, then adding utility views as needed.

Buttons

• ADAPTIVE DRIVE — Open the adaptive drive workspace for intro-based drive learning; the nested power toggle enables or disables adaptive processing
• LIMITER — Open the primary limiter control surface
• GRAPHS — Open the graphing workspace and visual analyzers
• METERS — Toggle the integrated meters and I/O/DRIVE sliders
• HELP — Toggle the help strip at the bottom of the window; the nested power toggle controls hover tooltips
• SPLIT — Open the optional second workspace column
• Inside LIMITER — The GLOBAL column provides access to MULTI and TEST
• Bottom Bar MENU — Opens Optimization Data, Account, Settings, Color, Audio Settings, and User Manual

Tips

• Start simple — Work in LIMITER first.
• Add as needed — Open MULTI and TEST from the LIMITER GLOBAL column when you need them.
• Inspect intentionally — Use GRAPHS and METERS for analysis, and use MENU for Optimization Data and system pages.

LIMITER Panel — Modular Signal Processing Architecture

The LIMITER panel is a modular surface that scales from simple to advanced. Enable only what you need, and the panel lays itself out intelligently—columns appear, scroll, and resize so you always have a clear view of your chain.

Layout and navigation

• Dynamic columns
  Columns arrange themselves as you enable modules. The panel scrolls horizontally when needed and adapts from compact to full width.
• Navigation controls
  Six toggle buttons control column visibility. Each limiter slot has its own Algorithm dropdown.
• State persistence
  Your column states and configurations are saved with presets.

Workflow patterns

• Minimal (2 columns)
  Limiter Slot 1 + Output/Tone.
  Ideal for quick limiting, low CPU, clean workflows.
• Standard (3 columns)
  Global + Limiter Slot 1 + Output/Tone.
  Ideal for mastering and enhanced peak behavior.
• Advanced (4–5 columns)
  Global + Limiter Slot 1 + Output/Tone + Limiter Slot 2 + Safety.
  Ideal for complex material, broadcast, demanding masters.
• Maximum (6 columns)
  Everything enabled with Auto Output for intelligent chains.
  Ideal for automated, template‑driven sessions.

Like assembling a studio rack, you can build exactly the chain your material needs—from transparent single‑pass limiting to sophisticated dual‑stage dynamics with intelligent protection.

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Column Parameters Reference

GLOBAL Column (Column 0)

The GLOBAL column sets system‑wide behavior—threshold reference, channel linking, and peak detection strategy. These choices shape how every downstream stage behaves.

• Threshold
  Master reference level for the entire system.
• Ch Link (Channel Link)
  How much left/right influence each other during gain reduction.
• Peak Detect
  Choose the detection style:
  • INSTANT — Fast, low‑latency, great default.
  • WINDOW — Windowed analysis for smoother, more predictive response.
    Enables extra controls when selected:
  • Buffer Length — Size of the detection window (larger = smoother, higher latency).
  • Hold Samples — Hold time to stabilize detection and avoid flutter.
• Buffer Defense
  Additional buffer‑safety logic for stability on stressed systems.
• Animation
  UI animation processing; disable to save a little CPU during heavy sessions.

Global settings apply to both limiter slots and establish the system’s overall character.

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LIMITER SLOT 1 Column (Column 1)

The first limiting stage. Choose the algorithm that fits the material; the column adapts to show only the relevant controls.

• Algorithm (Dropdown)
  ARIA PASS1, SIMPLE, STANDARD, or ENHANCED.

ARIA PASS1

Original ARIA behavior with refined peak analysis and envelope filtering.

• Attack / Release — Response timing.
• Lookahead — Predictive smoothing.
• LOW PASS (toggle) — Enables envelope low‑pass filtering with:
  • Cutoff — Filter cutoff frequency.
  • Slope — Roll‑off steepness (e.g., 6–48 dB/oct).

SIMPLE

Straightforward, efficient limiting with musical knee.

• Attack / Release — Response timing.
• Knee — Softer/harder onset around threshold.
• Lookahead — Transparent peak anticipation.

STANDARD

Feature‑rich with content‑adaptive timing.

• Lookahead / Attack / Release — Core timing.
• Smooth — Overall GR smoothing.
• Auto Atk / Auto Rel (toggles) — Content‑aware timing.
• Auto Trans — Transition time for auto logic.
• Auto Env Mode — Where the auto analysis happens:
  • AUTO PRE — Before limiting.
  • AUTO POST — After limiting.

ENHANCED

Maximum control with running averages and deep analysis windows.

• Lookahead / Attack / Release — Core timing.
• Avg Size — Running average window (larger = steadier).
• Avg Weight — Emphasize recent vs historical samples.
• Max Length — Depth of max‑filter analysis.
• Max Hold — Hold time for detected maxima (reduces flutter).

Slot 1 shapes the program’s character first; your choice here colors every stage that follows.

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L1 MULTIBAND Column (Column 2)

Frequency‑dependent control for Slot 1’s output—tone shaping, band behavior, and reconstruction.

• Tone Balance — Overall tonal tilt/weighting.
• Freq Response — Contour of the resulting spectrum.
• K Power — Reconstruction power factor.
• Intensity — Global processing intensity.
• Freq Attack / Freq Release — Timing scales across bands.
• METHOD — Reconstruction strategy:
  Minimum, Weighted, RMS, Peak‑Aware, Energy Conservation.
  Weighted is a solid default; Energy Conservation for added punch.
• TONE (toggle) — Enable multiband/tone processing.
• SOFT OUT (toggle) — Gentler output behavior.
• Safety (toggle) — Extra protection against overs and artifacts.

Usage notes:

• Use for complex material that needs frequency‑aware behavior.
• Correct tonal shifts introduced by limiting.
• Prepare the signal cleanly if you plan to enable Slot 2.

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LIMITER SLOT 2 Column (Column 3)

A second limiting stage for the most demanding material. It operates after L1 MULTIBAND and uses the same algorithm family as Slot 1.

• Algorithm (Dropdown)
  ARIA PASS1, SIMPLE, STANDARD, or ENHANCED.
• PASS 2 (toggle)
  Master enable for the second stage.

ARIA PASS1 (Slot 2)

• Attack / Release / Lookahead — Secondary timing.
• LOW PASS (toggle) with Cutoff and Slope — Same envelope filtering approach as Slot 1.
• PASS 2 (toggle) — Stage on/off.

SIMPLE (Slot 2)

• Attack / Release / Knee / Lookahead — As in Slot 1.
• Threshold — Independent threshold just for Slot 2.
• PASS 2 (toggle) — Stage on/off.

STANDARD (Slot 2)

• Lookahead / Attack / Release / Smooth / Auto Trans — As in Slot 1.
• Auto Atk / Auto Rel (toggles) — Content‑aware timing.
• Auto Env Mode — AUTO PRE vs AUTO POST for the second stage.
• PASS 2 (toggle) — Stage on/off.

ENHANCED (Slot 2)

• Lookahead / Attack / Release — Core timing.
• Avg Size / Avg Weight / Max Length / Max Hold — Same advanced analysis controls, tuned for the second stage.
• PASS 2 (toggle) — Stage on/off.

Column Type System

Altitude Limiter’s LIMITER panel is built from fixed and optional columns. Keep the essentials visible, and add optional stages as your material demands.

Fixed Columns

• Column 1 — LIMITER SLOT 1
  Always present. Core limiting stage with selectable algorithm type.
• Column 2 — L1 MULTIBAND
  Always visible. Essential tone and frequency‑dependent controls for Slot 1’s output.

Optional Columns

• Column 0 — GLOBAL
  System setup and peak detection strategy. Enable for enhanced control and stability.
• Column 3 — LIMITER SLOT 2
  Secondary limiting stage. Enable for complex or demanding program material.
• Column 4 — AUTO OUTPUT
  Intelligent output management and level matching. Enable for automated workflows.
• Column 5 — SAFETY
  Final brick‑wall protection. Enable for critical prints and absolute peak control.

Algorithm Selection Matrix

Each limiter slot supports four algorithms, tuned for different use cases.

ARIA PASS1 — Transparent Peak Control

• Characteristics: Ultra‑transparent, minimal coloration, strong stereo image retention.
• Core controls: Attack, Release, Lookahead, Low‑pass (Cutoff, Slope).
• Best for: Mastering, clean program material, invisible control.

SIMPLE — Musical Dynamics Control

• Characteristics: Soft‑knee, efficient, musical response.
• Core controls: Attack, Release, Knee, Lookahead (Slot 1); Threshold (added in Slot 2).
• Best for: Mix bus work, gentle shaping, vintage‑style limiting.

STANDARD — Advanced Envelope Control

• Characteristics: Program‑adaptive behavior with auto envelope detection.
• Core controls: Attack, Release, Lookahead, Smooth, Auto Atk/Rel, Auto Trans, Auto Env Mode (PRE/POST).
• Best for: Complex material, broadcast applications, adaptive processing.

ENHANCED — Maximum Flexibility

• Characteristics: Running‑average analysis with extended max filtering.
• Core controls: Attack, Release, Lookahead, Avg Size, Avg Weight, Max Length, Max Hold.
• Best for: Demanding masters, surgical control, creative effects.

Interface Modularity

Dynamic Column Management

• Automatic Layout: Columns arrange dynamically based on enabled modules
• Intelligent Scrolling: Interface scrolls horizontally to reveal newly enabled columns
• Adaptive Width: Panel width adjusts from 280px (minimal) to 630px (full configuration)

Navigation Controls

• Column Toggles: Six navigation buttons control column visibility
• Algorithm Dropdowns: Independent algorithm selection for each limiter slot
• State Persistence: All column states and configurations save with presets

Workflow Optimization

• Quick Access: Common configurations require minimal column management
• Progressive Complexity: Advanced features appear only when needed
• Visual Feedback: Color-coded columns and clear signal flow indicators

Practical Applications

**Minimal Setup** (2 Columns)

• Limiter Slot 1 + Output/Tone
• Perfect for: Simple limiting tasks, CPU efficiency, clean workflows

**Standard Setup** (3 Columns)

• Global + Limiter Slot 1 + Output/Tone
• Perfect for: Professional mastering, enhanced peak detection

**Advanced Setup** (4-5 Columns)

• Global + Limiter Slot 1 + Output/Tone + Limiter Slot 2 + Safety
• Perfect for: Complex program material, broadcast compliance, demanding mastering

**Maximum Setup** (6 Columns)

• All columns enabled with Auto Output for intelligent workflows
• Perfect for: Automated mastering chains, template-based processing

The LIMITER panel's modular architecture provides unprecedented flexibility while maintaining intuitive operation. Like connecting hardware modules in a professional studio rack, you can craft the exact processing chain your material demands, from simple transparent limiting to complex multi-stage dynamics control with intelligent automation.

Column Parameters Reference

GLOBAL Column (Column 0)

The GLOBAL column sets the tone for the entire system: it defines your threshold reference, how channels interact, and how peaks are detected. Set it once to match your session style, and every downstream stage follows suit.

• Threshold
  Master reference level for limiting across the system.

• Ch Link (Channel Link)
  How much left and right channels influence each other during gain reduction.

• Peak Detect
  Choose the core detection style:

  • INSTANT — Fast, low‑latency, a solid default for most material.
  • WINDOW — Windowed analysis for smoother, predictive behavior.
    When WINDOW is selected, two supporting controls appear:
  • Buffer Length — Size of the analysis window (larger = smoother, higher latency).
  • Hold Samples — Short hold to stabilize detection and avoid flutter.

• Buffer Defense
  Additional buffer‑safety logic for extra stability on stressed systems.

• Animation
  UI animation processing. Turn it off to reclaim a bit of CPU during heavy sessions.

Tip:

• Use INSTANT when tracking or for percussive, low‑latency work. Switch to WINDOW when you want smoother behavior and can afford a little more lookahead/latency.

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LIMITER SLOT 1 Column (Column 1)

The first limiting stage. Select the algorithm that fits the material, and the column adapts to show only the relevant controls.

• Algorithm (Dropdown)
  ARIA PASS1, SIMPLE, STANDARD, or ENHANCED.

ARIA PASS1

Original ARIA behavior with refined peak analysis and optional envelope filtering.

• Attack / Release — Response timing.
• Lookahead — Predictive smoothing for cleaner peak handling.
• LOW PASS (toggle) — Adds envelope low‑pass filtering with:
  • Cutoff — Filter frequency.
  • Slope — Roll‑off steepness (e.g., 6–48 dB/oct).

Best for:

• Clean, transparent control with minimal coloration.

SIMPLE

Straightforward, efficient, and musical—great when you want results fast.

• Attack / Release — Core timing.
• Knee — Softer/harder onset around threshold for musical shaping.
• Lookahead — Transparent peak anticipation.

Best for:

• Mix bus work, gentle shaping, and low‑CPU sessions.

STANDARD

Feature‑rich with content‑adaptive timing.

• Lookahead / Attack / Release — Core timing.
• Smooth — Global GR smoothing (higher for less chatter).
• Auto Atk / Auto Rel (toggles) — Content‑aware timing.
• Auto Trans — Transition time for auto logic.
• Auto Env Mode — Where the auto analysis happens:
  • AUTO PRE — Before limiting (default).
  • AUTO POST — After limiting.

Best for:

• Complex program material and broadcast‑style consistency.

ENHANCED

Maximum control and stability via running averages and deeper analysis windows.

• Lookahead / Attack / Release — Core timing.
• Avg Size — Running average window (larger = steadier).
• Avg Weight — Emphasize recent vs historical samples.
• Max Length — Depth of the max‑filter analysis.
• Max Hold — Hold time for detected maxima (reduces flutter).

Best for:

• Demanding masters and surgical, highly controlled results.

Note:

• Slot 1 sets the character for everything that follows—choose the algorithm here with intention.

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L1 MULTIBAND Column (Column 2)

Frequency‑dependent control for Slot 1’s output—tone shaping, band behavior, and reconstruction. Use it to correct tonal shifts, shape the spectrum, and prepare a clean signal for dual‑stage workflows.

• Tone Balance
  Overall tonal tilt/weighting across the spectrum.

• Freq Response
  Fine contouring of spectral balance.

• K Power
  Power factor for reconstruction (energy distribution).

• Intensity
  Global processing intensity.

• Freq Attack / Freq Release
  Attack/release scaling across frequencies—how quickly bands respond and recover.

• METHOD
  Reconstruction strategy tuned to program material:
  Minimum, Weighted, RMS, Peak‑Aware, Energy Conservation.
  Weighted is a strong default; Energy Conservation tends to feel punchier.

• TONE (toggle)
  Enables multiband/tone processing.

• SOFT OUT (toggle)
  Gentler output behavior and smoother transitions.

• Safety (toggle)
  Extra protection against overs or reconstruction artifacts.

Usage notes:

• Reach for L1 MULTIBAND when the program calls for frequency‑aware control—e.g., taming sibilance while preserving low‑end power.
• If you plan to add Slot 2, use this stage to hand off a balanced, well‑behaved signal.
• Start with METHOD = Weighted, then explore Peak‑Aware or Energy Conservation if you want different energy profiles.

LIMITER SLOT 2 Column (Column 3)

A second limiting stage for demanding material. Slot 2 runs after L1 MULTIBAND, analyzing the already‑shaped signal and applying additional control where needed. Use it when a single pass doesn’t fully tame transients or when you want a distinct second character.

• Algorithm (Dropdown)
  ARIA PASS1, SIMPLE, STANDARD, or ENHANCED (same family as Slot 1).

• PASS 2 (toggle)
  Master enable for the entire second stage.

Notes:

• Keep PASS 2 off until you’ve balanced tone and dynamics with Slot 1 + L1 MULTIBAND.
• Enable PASS 2 when you need extra headroom control, stricter compliance, or a contrasting envelope character.

ARIA PASS1 (Slot 2)

Clean, refined control with optional envelope filtering—mirrors Slot 1’s ARIA approach, but voiced for post‑multiband material.

• Attack / Release — Secondary response timing.
• Lookahead — Predictive smoothing for cleaner peak handling.
• LOW PASS (toggle) — Adds envelope low‑pass filtering with:
  • Cutoff — Filter frequency.
  • Slope — Roll‑off steepness (e.g., 6–48 dB/oct).
• PASS 2 (toggle) — Stage on/off.

Best for:

• Polishing “nearly there” results without adding weight or grit.

SIMPLE (Slot 2)

Efficient, musical behavior with an additional threshold for independent level control in the second stage.

• Attack / Release — Core timing for the secondary pass.
• Knee — Softer/harder onset around threshold.
• Lookahead — Transparent peak anticipation.
• Threshold — Independent threshold for Slot 2 (decoupled from global/Slot 1).
• PASS 2 (toggle) — Stage on/off.

Best for:

• Fine‑tuning overall loudness handling after tone is set; glue without fuss.

STANDARD (Slot 2)

Feature‑rich, program‑adaptive timing—ideal when the post‑multiband signal is complex and you need controlled consistency.

• Lookahead / Attack / Release — Core timing.
• Smooth — Global GR smoothing (higher for less chatter).
• Auto Atk / Auto Rel (toggles) — Content‑aware timing.
• Auto Trans — Transition time for auto logic.
• Auto Env Mode — Where the auto analysis happens:
  • AUTO PRE — Before second‑stage limiting (default).
  • AUTO POST — After second‑stage limiting.
• PASS 2 (toggle) — Stage on/off.

Best for:

• Broadcast‑style reliability and material with mixed transient/sustained content.

ENHANCED (Slot 2)

Maximum stability and control via running averages and deep analysis windows—tuned for the second stage’s role.

• Lookahead / Attack / Release — Core timing.
• Avg Size — Running average window (larger = steadier).
• Avg Weight — Emphasize recent vs historical samples.
• Max Length — Depth of max‑filter analysis.
• Max Hold — Hold time for detected maxima (reduces flutter).
• PASS 2 (toggle) — Stage on/off.

Best for:

• Surgical refinement and maintaining a tight envelope under stress.

Parameter interactions

• PASS 2 dependencies

  • PASS 2 = OFF: Slot 2 is fully bypassed; signal passes through.
  • PASS 2 = ON: The selected algorithm’s controls become active.

• Algorithm consistency

  • Each variant shows only its relevant controls (plus PASS 2).
  • Switching the dropdown swaps parameter sets, but the stage position stays fixed.

Workflow tips

• Shape first, control second
  Use Slot 1 + L1 MULTIBAND to get the spectral and macro‑dynamics right; use Slot 2 for stricter headroom and envelope polish.

• Pick complementary characters
  Pair a transparent Slot 1 with an adaptive Slot 2 (e.g., ARIA → STANDARD) for musical yet consistent results.

• Threshold strategy
  If you need level separation between stages, use SIMPLE in Slot 2 for its independent threshold.

• Latency and feel
  Favor INSTANT‑style behavior (via algorithm/timing choices) when immediacy matters; use lookahead, smoothing, and ENHANCED‑style windows for more graceful behavior when latency is acceptable.

AUTO OUTPUT Column (Column 4)

An intelligent post‑processing stage that keeps output levels consistent while adding a gentle safety net. It analyzes the already‑limited signal and applies adaptive gain to keep things steady without flattening the mix. Labeled “SOFT SAFETY” in the UI.

• SOFT OUT (toggle) Master enable for the entire stage.

• Block Size Analysis window size for automatic gain.
  Larger = steadier decisions; smaller = faster reaction.

• Overlap Window overlap for smoother transitions.
  Higher = smoother, slightly more CPU.

• Peak Smoother Smoothing for peak tracking.
  Higher = cleaner, less twitchy gain changes.

• RMS Smoother Smoothing for RMS tracking.
  Higher = more consistent loudness behavior.

• Limiter Release Recovery time for the built‑in soft safety limiter.
  Fast = transparent; slower = silkier return.

• Max Gain / Min Gain Bounds for automatic adjustment.
  Max Gain caps upward boosts; Min Gain caps downward attenuation.

• Crest Comp (Crest Compensation) Balances peak vs RMS influence.
  Higher = more transient‑aware; lower = more sustained‑level focus.

Interactions:

• SOFT OUT must be ON for any processing here to apply.
• Block Size and Overlap work together to define the “feel” of the analysis window.
• Peak vs RMS Smoothers let you tune response to transient vs sustained energy.
• Limiter Release only affects the soft safety behavior at this stage.
• Max/Min Gain define the playground—auto gain never goes beyond these limits.

When to use:

• You want level consistency without a hard ceiling.
• You’re printing stems or references and need reliable loudness across tracks.
• You want a soft “auto trim” after creative limiting is set.

Tips:

• Start with moderate Block Size (e.g., mid‑range) and low‑to‑medium overlap.
• Increase Peak/RMS smoothing when material feels too “nervous.”
• Use a conservative Max/Min range for critical prints; widen it for creative bounce‑downs.

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SAFETY Column (Column 5)

Final, transparent brick‑wall protection at the output. This is your “HARD SAFETY” stage—an absolute ceiling so nothing escapes above 0 dBFS.

• SAFETY (toggle) Master enable for the stage.

• Attack How quickly the hard safety reacts to overs.
  Faster = stricter peak control.

• Release How quickly gain returns after an event.
  Faster = more transparent; slower = smoother but more audible.

• Knee Shapes the transition around the fixed safety threshold.
  Softer knee for less abrupt behavior.

Design notes:

• Threshold is fixed at 0.0 dBFS for true brick‑wall behavior.
• This stage sits at the very end of the chain and should normally be inaudible.

When to use:

• Final prints, broadcast compliance, and any deliverable where clipping is not an option.
• Projects with variable upstream gain where occasional spikes might slip through.

Tips:

• Keep Attack fast and Release moderate for “set and forget” transparency.
• If you hear the safety working often, reduce upstream output or revisit Slot 1/Slot 2.

MULTI Panel — Threshold vs Drive Curve Editor

Shape how threshold behaves as you turn up Drive in multiband mode. In current builds, the MULTI editor is opened from the LIMITER panel's GLOBAL column. It lets you draw an adjustment curve so the limiter responds exactly how you want across the 0–20 dB Drive range. Use it when the default math is close but not quite musical for your material.

Panel structure

• Mode tabs ARIA PASS1, SIMPLE, STANDARD, ENHANCED.
  Each tab has its own independent curve and settings.

• USING UI / MATH ON toggle

  • USING UI: Edit the curve directly by dragging points.
  • MATH ON: Use built‑in math instead of the UI curve (editor is dimmed and disabled). When MATH ON is active, the graph overlays “USING MATH FUNCTIONS” as a reminder.

Graph layout

• X‑axis (Drive)
  0 to 20 dB
  Grid every 2 dB, labels every 4 dB (0, 4, 8, 12, 16, 20)

• Y‑axis (Adjustment)
  −1.0 to +1.0
  Grid every 0.2; zero line highlighted for reference
  Above zero = threshold boost (less limiting)
  Below zero = threshold reduction (more limiting)

Control points

The curve is defined by 6 points:

• Point 0 (Blue) — fixed at 0 dB Drive
  Vertically draggable (−1.0 to +1.0)

• Points 1–4 (Purple → Orange) — fully draggable
  Horizontal and vertical movement with left‑to‑right order preserved

• Point 5 (Blue) — fixed at 20 dB Drive
  Vertically draggable (−1.0 to +1.0)

Visuals:

• Endpoints = Blue (with vertical guide lines)
• Middle points = Purple → Dark Orchid → Orchid → Orange
• Clear outlines and hover feedback for precise edits

Workflow

1. Select the tab for the sidechain algorithm you’re using.
2. Set the toggle to USING UI to enable editing.
3. Drag points to shape the curve; audio updates in real time as you move them.
4. Switch tabs to tune curves for other algorithms as needed.
5. Save as part of your preset when you like the response.

Shaping guidelines

• Threshold boost (points above zero)
  Less limiting at that Drive region; useful for keeping openness at low/moderate Drive.

• Threshold reduction (points below zero)
  More limiting at that Drive region; useful for reining in high Drive without harshness.

• Keep curves smooth
  Avoid abrupt zig‑zags; smooth transitions produce more predictable musical results.

• Align with multiband goals
  Use the curve to complement L1 MULTIBAND METHOD and tone choices—e.g., let low Drive remain neutral, and only push harder as Drive approaches 12–20 dB.

Advanced techniques

• Drive‑dependent compensation
  If multiband reconstruction adds perceived loudness at certain Drive ranges, pull points slightly below zero there to keep loudness natural.

• Mode‑specific tuning

  • ARIA PASS1: Subtle curves work best—preserve transparency.
  • SIMPLE: Use a gentle S‑shape for musical glue.
  • STANDARD: Pair with Auto modes; keep the curve moderate to avoid fighting auto timing.
  • ENHANCED: Longer windows benefit from thoughtful shaping—avoid extremes, emphasize consistency.

• Handoff to Slot 2
  If you plan to use LIMITER SLOT 2, leave headroom—don’t push the curve too far negative at high Drive, so Slot 2 has space to work gracefully.

Visual feedback

• Color‑coded points for quick identification
• Live numeric values for each point while dragging
• Cursor change on hover to confirm what’s draggable

This panel gives you fine control over how Drive translates into limiting behavior in multiband. When the default math is close but not perfect for your program material, a few well‑placed points here can make the limiter feel effortless.

DATA Panel — Performance Monitoring

A real‑time health dashboard for Altitude Limiter. Open it from the Bottom Bar MENU when you want to spot bottlenecks, confirm stability, and diagnose issues quickly. The panel title appears as rotated text on the left: “OPTIMIZATION.”

Panel layout

Two clear columns:

• CPU Metrics (left)
• Audio Status (right)

CPU Metrics (left)

• CPU Load
  Current real‑time CPU usage.
  Color coding: Green (<50%), Orange (50–80%), Red (>80%).
  Updates ~10×/sec for responsiveness.

• Peak CPU
  Highest CPU usage since last reset.
  Use the reset button to baseline before tests.

• Avg CPU
  Running average for trend insight.
  Smooths out momentary spikes.

• Block Time
  Processing time per audio buffer (ms, 2‑decimal precision).
  Watch this relative to your DAW’s buffer duration.

• Buffer Usage
  Percentage of available audio buffer consumed.
  Helps identify when you’re approaching real‑time limits.

• Reset CPU Metrics
  Clears CPU statistics (Peak/Avg/etc.) to start fresh measurements.

Audio Status (right)

• Audio Status
  Overall indicator:

  • OK (Green): No issues detected
  • ISSUES DETECTED (Orange): Minor dropouts/spikes present
  • GLITCH DETECTED (Red): Serious overruns affecting audio

• Dropouts
  Count of brief interruptions in audio processing.
  White (0), Red (>0).

• Spikes
  Count of momentary CPU usage peaks.
  White (0), Red (>0).

• Overruns
  Count of critical processing overruns impacting audio.
  White (0), Red (>0).

• Reset Glitch Counters
  Clears dropout/spike/overrun counts to re‑baseline while troubleshooting.

ADAPTIVE DRIVE Panel

Adaptive Drive listens to the intro of a song and learns a drive setting from the way that material reacts to the current limiter setup.

It works by gradually increasing drive, waiting for real limiter engagement, and measuring when added drive starts producing diminishing returns. That bend point becomes the reference for the learned result, and Target % controls how much of that result is applied.

In ARIA ONE, Adaptive Drive can often be turned on and left running to help smooth level differences between songs. If you want one learned level to stay fixed across multiple songs, let it analyze a representative track and press COMMIT to write that result into the main DRIVE control.

In the standalone limiter, Adaptive Drive is best used as a fast starting point: play from the beginning, let it learn, listen, then refine or commit if needed.

Panel structure

• Adaptive Drive Enabled (power toggle) Turns the adaptive analysis layer on or off from the ADAPTIVE DRIVE card. When OFF, the shadow analysis and adaptive-drive system stop updating.

• Live readout Shows the currently learned adaptive drive amount and status while analysis runs.

• COMMIT Writes the learned adaptive result into the main DRIVE parameter, clears the adaptive drive amount, and turns the adaptive layer off. Use this when you want to keep the learned result as part of the preset instead of continuing to run adaptive analysis.

• RESET Clears the current adaptive result and restarts analysis from the beginning.

• ADVANCED Shows or hides the deeper adaptive controls: baseline timing, shadow mode, GR threshold, peak threshold, ramp rate, evaluation interval, velocity-floor tuning, and slow-mode pass weights.

• Main controls The primary day-to-day controls are Target %, BEND, GR Count, and Max dB.

• Advanced controls Additional timing, threshold, mode, and weighting controls are available when you need deeper tuning.

Suggested workflow

1. Reset Adaptive Drive if needed.
2. Start playback from the beginning of the song or intro.
3. Let Adaptive Drive analyze the opening section and assign a drive amount.
4. Listen and adjust if needed.
5. Press COMMIT to bake the learned result into the main DRIVE control.

Main controls

• Target %
  Adjusts how much of the learned result is used. Lower values back the system away from the learned bend point; higher values push closer to the full learned result.

• BEND
  Changes how quickly the system settles on its learned point. Lower settings tend to let the system settle earlier; higher settings tend to make it wait for a stronger bend in the response.

• GR Count
  Changes how much limiter engagement is required before the analysis locks in. Lower values react earlier; higher values ask for a more confirmed limiter response before committing to a result.

• Max dB
  Limits the maximum drive Adaptive Drive can assign.

Advanced controls

• GR Threshold
  Sets the minimum gain reduction that counts as real limiter engagement during analysis. Lower it if the material is gentle and the system seems slow to engage; raise it if tiny GR movements are causing the analysis to react too early.

• BASELINE
  Sets how long the intro-baseline capture runs before ramping begins. Shorter settings start analysis sooner; longer settings are useful when the opening is sparse, quiet, or slow to establish itself.

• Peak Gate Mode
  Controls how hot peaks are handled during analysis. With peak gate mode ON, hot peaks can clamp drive while analysis continues. With it OFF, the system follows pure bend tracking. ON is the safer choice for peaky material; OFF is the more exploratory choice.

• SHADOW MODE
  Selects the background analysis strategy. Fast uses a single analysis lane and is the quickest everyday option. Slow uses multiple background passes and is better for long intros, slower-building tracks, or material that needs a more patient read.

• PEAK THR
  Sets the hot-peak threshold used by the peak gate. Lower values make the system react sooner to hot intros; higher values let the ramp travel farther before peak protection steps in.

• RAMP
  Sets how quickly Adaptive Drive increases drive during analysis. Faster settings learn more quickly and more aggressively; slower settings are more conservative and easier to judge by ear.

• EVAL
  Sets the time between analysis evaluations. Shorter intervals feel more responsive; longer intervals smooth the read and can feel less twitchy.

• VEL FLR
  An advanced velocity-floor control for edge-case tuning. In normal use, leave this at its default and focus on Target %, BEND, GR Count, and Max dB first.

• A1 MOM
  Weights Lane A's momentary result in slow mode.

• B RMS
  Weights Lane B's RMS result in slow mode.

• B MOM
  Weights Lane B's momentary result in slow mode.

• C RMS
  Weights Lane C's RMS result in slow mode.

• C MOM
  Weights Lane C's momentary result in slow mode.

Weight controls:

• Raise a lane weight to give that pass more influence in the final slow-mode decision.
• Lower a lane weight to reduce its influence.
• In most sessions, leave the slow-mode weights at their defaults unless you are deliberately comparing how the different passes behave on difficult material.

Notes

• The default behavior is intentionally fairly aggressive.
• For long-intro or slow-building material, especially classical music, try GR Count = 1 and BEND below 1.0 as a rough starting point.
• If Adaptive Drive is over-shooting, lower Target %, lower Max dB, or try lower BEND and lower GR Count so the system settles earlier.
• If Adaptive Drive is under-shooting, raise Target %, raise Max dB, or try higher BEND and higher GR Count so the system waits for a stronger result before settling.
• If sparse or slow-building intros are being misread, lengthen BASELINE or switch to Slow shadow mode for a more patient read.
• During active analysis, Adaptive Drive can use roughly 4x DSP/CPU instances because it runs the live limiter path alongside multiple background analysis passes.
• Adaptive Drive is designed to provide a strong starting point, but final decisions should still be made by listening.

TEST Panel — Limiting Verification and Analysis

Verify your limiting and inspect envelope behavior with a purpose‑built test harness. In current builds, TEST is opened from the LIMITER panel's GLOBAL column. It generates a controlled signal, runs it through your current chain, and visualizes the results with peak markers and an RMS envelope.

Panel structure

• Test controls (top)

  • TEST button
    Starts the verification run. Shows “TESTING” and disables while running; re‑enables on completion.
  • Channel Mode
    STEREO (both channels), LEFT (expanded left), RIGHT (expanded right).

• Waveform display (center) Dual, high‑resolution views with grid overlays:

  • Left channel: Purple/magenta waveform + white RMS envelope.
  • Right channel: Pink/magenta waveform + white RMS envelope.
  • Grids: Time (horizontal, ms) and amplitude (vertical, −1.0 to +1.0).

• Navigation (bottom)

  • Zoom
    1%–100% time‑axis zoom for macro ↔ micro inspection.
  • Pan
    Enabled when zoomed; scrolls the time window.

• Configuration and results (right or bottom, depending on layout)

  • Carrier Freq
    Test tone center frequency (20 Hz–20 kHz; default 4 kHz).
  • Peak Level Indicators (L/R)
    Post‑test peak readouts (dBFS, 0.1 dB precision).

Visual guides

• Peak markers (green)
  Absolute peak positions in the processed output.
• Pulse markers (orange)
  Start positions of injected test pulses.
• Envelope (white)
  RMS envelope overlay to visualize attack/release behavior.

Running a test

1. Set the desired Carrier Freq (default 4 kHz is a good general check).
2. Choose Channel Mode (STEREO for overview, LEFT/RIGHT for detail).
3. Click TEST. The button shows “TESTING” during capture and processing.
4. Review the waveforms, markers, and the L/R peak readouts when complete.
5. Adjust your chain (e.g., Slot 1, L1 MULTIBAND, Slot 2), and retest as needed.

Interpreting results

• Success criteria:

  • Peaks at or below 0 dBFS.
  • Envelope shows controlled, stable gain reduction.
  • Pulse (orange) and limiting response align logically in time.

• Potential issues:

  • Peaks > 0 dBFS
    Reduce Drive/output, increase lookahead, or adjust thresholds/knee.
  • Irregular/chattery envelope
    Increase smoothing, adjust attack/release, or consider STANDARD/ENHANCED behavior.
  • Misaligned markers vs response
    Revisit lookahead/latency settings; check for heavy upstream processing that shifts timing.

Navigation and inspection

• Macro overview (100% zoom)
  Quick confirmation of general behavior, overall peak safety.
• Micro inspection (<10% zoom)
  Sample‑level view of transient handling; study attack and recovery shape.
• Channel focus
  Use LEFT/RIGHT modes to isolate and compare channel behavior, particularly when Channel Link is low.

Practical tips

• Use a few representative Carrier Freq values (e.g., 1 kHz, 4 kHz, 8 kHz) to see how timing behaves across the spectrum.
• If the safety limiter (Column 5) frequently triggers in the test, reduce upstream output or refine Slot 2 timing/smoothing.
• For broadcast‑style consistency, try STANDARD in Slot 2 with modest Smooth and Auto Trans; confirm with micro inspection.
• When transparency is the goal, prioritize lookahead and gentle knees; verify that envelope transitions are smooth and peak markers sit at or below 0 dBFS.

This panel is your “trust but verify” step: it confirms that Altitude Limiter’s limiting behaves exactly as intended before you print or ship.

Graphs & Views Reference

WAVEFORM GRAPHING VIEW

The waveform view gives you a live, zoomable picture of the limiter at work. Toggle which traces to show, zoom time and level to taste, pause to inspect a moment, and use the built‑in peak readouts to confirm headroom and limiting activity at a glance.

What you see

• Input: The raw signal arriving at the processor.
• Output: The post‑processing signal leaving the limiter chain.
• Gain Reduction: How much the limiter is pulling the signal down (around a 0 dB baseline).
• dB Grid: Fixed 2 dB lines and labels for quick level reading.

Core controls

• GRAPH: Master on/off for the display.
• INPUT / OUTPUT / GAIN REDUCTION: Show or hide each trace independently.
• RESET: Clear history and snap back to a sensible time window.
• Y‑AXIS (Range): Choose the vertical scale (tight detail down to broader views, ~−8 to −60 dB).
• Time Window: Horizontal zoom (0.5–60 s). Short for transients; long for envelopes/trends.
• PAUSE: Freeze the graph to inspect a moment without losing context.
• Position (Rewind): When paused, scrub back through recent history in seconds behind live.

Peak detection and readouts

• On‑trace callouts: Small dB labels appear near the right side for prominent peaks, pinned to the exact moment; they move with the scroll and fade as they exit.
• Peak summary table: A compact overlay beneath the graph showing:
  • Top 3 peaks in the current viewport (what you’re looking at now).
  • Top 3 peaks seen over the last second at the live edge (short‑term headroom).

How to work with it

• Understand the limiter: Enable OUTPUT + GAIN REDUCTION to see action vs result.
• Gain staging: Add INPUT to compare pre/post levels directly.
• Detail vs overview: Tighten Y‑AXIS and shorten Time Window for micro‑events; widen both for long‑form behavior.
• Investigate moments: PAUSE, scrub with Position, read the on‑trace peak labels and the 1‑second/viewport peak table to confirm exactly what happened.