Frieve EffeTune
Documentation

Spatial Audio Plugins

A collection of plugins that enhance how your music sounds in your headphones or speakers by adjusting the stereo (left and right) balance. These effects can make your music sound more spacious and natural, especially when listening with headphones.

Plugin List

  • Crossfeed Filter - Headphone crossfeed filter for natural stereo imaging
  • Crosstalk Cancellation - Uses in-ear measurements to reduce crosstalk between stereo speakers
  • MS Matrix - Converts stereo to Mid/Side and back for advanced stereo adjustment chains
  • Multiband Balance - 5-band frequency-dependent stereo balance control
  • Phase Select EQ - Boosts or cuts frequency components selected by L/R phase difference and Balance
  • Stereo Blend - Controls stereo width from polarity-swapped stereo through mono to enhanced stereo

Crossfeed Filter

A headphone crossfeed filter that simulates the natural acoustic crosstalk that occurs when listening through speakers. This effect helps reduce the exaggerated stereo separation often experienced with headphones, creating a more natural and comfortable listening experience that mimics the way sound reaches our ears in a real acoustic environment.

Key Features

  • Simulates natural acoustic crosstalk for headphone listening
  • Adjustable crossfeed level and timing
  • Low-pass filtering to mimic frequency-dependent crosstalk
  • Stereo-only processing (automatically bypassed for mono or other non-stereo signals)

System Presets

Click Effect Presets in the effect header to choose a complete crossfeed amount for headphone listening.

  • Subtle Blend - A very light crossfeed that preserves most of the original width.
  • Vintage Receiver - A moderate crossfeed resembling a traditional headphone adapter.
  • Living Room Speakers - A strong speaker-like blend for recordings with very wide stereo separation.

Parameters

  • Level (-60 dB to 0 dB): Controls the amount of crossfeed signal
    • Lower values (-20 dB to -6 dB): Subtle, natural crossfeed
    • Higher values (-6 dB to 0 dB): More pronounced effect
  • Delay (0 ms to 1 ms): Simulates the time difference of acoustic crosstalk
    • Lower values (0.1-0.3 ms): Tighter, more focused image
    • Higher values (0.3-1.0 ms): More spacious, speaker-like presentation
  • LPF Freq (100 Hz to 20000 Hz): Controls the frequency response of crossfeed
    • Lower values (500-1000 Hz): More natural, frequency-dependent crosstalk
    • Higher values (1000-20000 Hz): Broader frequency response

Starting Points

Use the Subtle Blend, Vintage Receiver, or Living Room Speakers system preset as a complete starting point. Then adjust Level first: lower values preserve more stereo width, while higher values make the speaker-like blend more obvious.

Application Guide

  1. Headphone Optimization
    • Start with conservative settings (-15 dB level, 0.3 ms delay)
    • Adjust level for comfort and naturalness
    • Fine-tune delay for spatial perception
    • Use LPF to control frequency response
  2. Music Style Considerations
    • Classical/Jazz: Lower levels (-15 to -10 dB) for natural presentation
    • Rock/Pop: Moderate levels (-12 to -8 dB) can soften hard-panned guitars or vocals while keeping the music lively
    • Electronic or very wide mixes: Use lower to moderate levels (-18 to -10 dB) to keep width, or higher levels only when you want to tame excessive left-right separation
  3. Listening Environment
    • Quiet environments: Lower levels for subtle effect
    • Noisy environments: Higher levels for better focus
    • Long listening sessions: Conservative settings to reduce fatigue

Quick Start Guide

  1. Initial Setup
    • Set Level to -12 dB
    • Set Delay to 0.3 ms
    • Set LPF Freq to 700 Hz
  2. Fine-tuning
    • Adjust Level for desired crossfeed amount
    • Modify Delay for spatial perception
    • Tune LPF Freq for frequency response
  3. Optimization
    • Listen for natural, comfortable presentation
    • Avoid excessive settings that sound artificial
    • Test with various music styles

Remember: The Crossfeed Filter is designed to make headphone listening more natural and comfortable. Start with conservative settings and adjust gradually to find the optimal balance for your listening preferences and music material.

Crosstalk Cancellation

Crosstalk Cancellation uses measurements made at your ears to reduce the sound from each stereo speaker reaching the opposite ear. Use it with two stereo speakers when you listen from one measured position and want a more distinct, binaural-like stereo image. It is not for headphones or mono playback.

Unlike Crossfeed Filter, which adds a little speaker-like crosstalk for headphone listening, Crosstalk Cancellation reduces measured crosstalk for speaker listening.

Measure and Assign

  1. Place the microphone at your left ear position and make one measurement with both the left and right speaker outputs selected. Assign that measurement’s left channel to LL: L Speaker → Left Ear and right channel to RL: R Speaker → Left Ear.
  2. Move the microphone to your right ear position and repeat the same two-output measurement. Assign its left channel to LR: L Speaker → Right Ear and right channel to RR: R Speaker → Right Ear.
  3. Use single-point measurements made at the same speaker and listening setup. Assign a different measurement channel to every slot, then wait for the filters to become ready.

Start with the defaults: Taps 4096, Regularization 50%, Max Gain 12 dB, Freq Low 200 Hz, Freq High 6000 Hz, Direct Window 8 ms, Strength 70%, Output Gain 0 dB, and Latency 128 samples. Compare with bypass and make small changes while seated at the measured position.

Parameters

  • Taps (1024–16384): Sets the filter length. More taps can improve cancellation but require more processing and add a longer modeled delay. If the status warns that the filter tail may be truncated, increase Taps first.
  • Regularization (0–100%): Limits aggressive correction where the measurements are difficult to cancel. Increase it if the result sounds unstable or colored when you move slightly; decrease it only if the measured position needs more cancellation.
  • Max Gain (0–24 dB): Caps how much the correction filters can boost. A lower value is gentler and preserves headroom; a higher value can cancel more but may make the result less robust.
  • Freq Low (20–2000 Hz) and Freq High (1000–20000 Hz): Set the main correction band. Lower frequencies below the selected band and higher frequencies above it pass through. Begin with 200 Hz–6000 Hz; narrow the band if the effect is too sensitive to head movement.
  • Direct Window (2–50 ms): Sets how much of each measured direct sound is used. A shorter window reduces room reflections but can raise the effective low-frequency limit; a longer window includes more low-frequency information but may include more room sound.
  • Strength (0–100%): Blends from the delayed uncorrected signal at 0% to full correction at 100%. Start at 70%; reduce it if the sound becomes unnatural away from the measured position.
  • Output Gain (-24 to +24 dB): Adjusts the final level after correction. Keep it at 0 dB first, then reduce it if needed to leave headroom.
  • Latency (0, 128, 256, 512, or 1024 samples): Selects the processing block latency. Higher values can make filter processing easier; lower values are preferable when monitoring latency matters.

Status and Latency

The status begins with Assign all four measurements to begin. While the filters are being made it shows that design is in progress; when ready, it reports the maximum filter gain. A tail warning means increasing Taps or Regularization may help. A warning that Direct Window raised the effective low frequency means the selected window is too short to use the requested lowest frequencies.

If an assigned measurement cannot be found, reselect it. If the filters cannot be prepared, try fewer Taps or a higher Latency. Until four suitable measurements are assigned and the filters are ready, the plugin passes audio through unchanged and reports no added processing latency.

Once ready, the total added latency is the selected Latency plus the filter’s modeled delay; the app applies its normal pipeline delay compensation. Check Total Delay if real-time monitoring or audio/video synchronization matters. Crosstalk Cancellation has no graph or other visualization.

MS Matrix

MS Matrix converts normal stereo audio to Mid/Side format, or converts Mid/Side audio back to normal stereo. Use it when you want to adjust center and side information separately inside an effect chain, such as encoding to M/S, changing the Mid or Side level, then decoding back to stereo. For simple stereo width adjustment on normal music, Stereo Blend is the more direct tool.

Key Features

  • Separate Mid and Side gain (–18 dB to +18 dB)
  • Mode switch: Encode (Stereo→M/S) or Decode (M/S→Stereo)
  • Optional Left/Right swap before encoding or after decoding

Parameters

  • Mode (Encode/Decode): Encode turns left/right stereo into Mid on the left channel and Side on the right channel. Decode treats the left channel as Mid and the right channel as Side, then rebuilds normal stereo.
  • Mid Gain (–18 dB to +18 dB): Adjusts the Mid level during the selected conversion.
  • Side Gain (–18 dB to +18 dB): Adjusts the Side level during the selected conversion.
  • Swap L/R (Off/On): Swaps left and right channels before encoding or after decoding
  1. Subtle Widening for Normal Stereo
    • First MS Matrix: Mode: Encode, Mid Gain: 0 dB, Side Gain: +3 dB, Swap: Off
    • Second MS Matrix after it: Mode: Decode, Mid Gain: 0 dB, Side Gain: 0 dB, Swap: Off
    • Effect: Slightly strengthens the Side component, then returns the result to normal stereo
  2. Center Focus for Normal Stereo
    • First MS Matrix: Mode: Encode, Mid Gain: +3 dB, Side Gain: -3 dB, Swap: Off
    • Second MS Matrix after it: Mode: Decode, Mid Gain: 0 dB, Side Gain: 0 dB, Swap: Off
    • Effect: Brings vocals and centered sounds forward while reducing side ambience
  3. Decode Existing M/S Audio
    • Mode: Decode
    • Mid Gain: 0 dB
    • Side Gain: 0 dB
    • Swap: Off
    • Use only when the incoming signal is already Mid/Side format
  4. Creative Flip
    • Mode: Encode
    • Mid Gain: 0 dB
    • Side Gain: 0 dB
    • Swap: On

Quick Start Guide

  1. Decide whether you need a single conversion or a full Encode -> adjust -> Decode chain.
  2. For normal stereo listening, place one MS Matrix in Encode mode and a second one later in Decode mode.
  3. Adjust Mid Gain and Side Gain on the Encode stage.
  4. Enable Swap L/R only for channel correction or creative inversion.
  5. Bypass to compare and make sure the stereo image still feels natural.

Multiband Balance

A frequency-dependent balance processor that divides the audio into five bands and lets you shift each band slightly left or right. Use it when bass, vocals, cymbals, or other frequency ranges feel pulled to one side and you want to rebalance only that part of the sound without moving the whole track.

Key Features

  • 5-band frequency-dependent stereo balance control
  • High-quality Linkwitz-Riley crossover filters
  • Linear balance control for precise stereo adjustment
  • Independent processing of left and right channels
  • Automatic fade handling when crossover filters are reset

Parameters

Crossover Frequencies

  • Freq 1 (20-500 Hz): Separates low and low-mid bands
  • Freq 2 (100-2000 Hz): Separates low-mid and mid bands
  • Freq 3 (500-8000 Hz): Separates mid and high-mid bands
  • Freq 4 (1000-20000 Hz): Separates high-mid and high bands

Band Controls

Each band has independent balance control:

  • Band 1 Bal. (-100% to +100%): Controls stereo balance of low frequencies
  • Band 2 Bal. (-100% to +100%): Controls stereo balance of low-mid frequencies
  • Band 3 Bal. (-100% to +100%): Controls stereo balance of mid frequencies
  • Band 4 Bal. (-100% to +100%): Controls stereo balance of high-mid frequencies
  • Band 5 Bal. (-100% to +100%): Controls stereo balance of high frequencies
  1. Correct a Treble Pull to the Right
    • Low Band (20-100 Hz): 0% (centered)
    • Low-Mid (100-500 Hz): 0%
    • Mid (500-2000 Hz): 0%
    • High-Mid (2000-8000 Hz): -10% to -25%
    • High (8000+ Hz): -10% to -30%
    • Effect: Moves bright content slightly left while keeping bass and vocals stable
  2. Correct a Low-Mid Pull to the Left
    • Low Band: 0%
    • Low-Mid: +10% to +25%
    • Mid: +5% to +15%
    • High-Mid: 0%
    • High: 0%
    • Effect: Moves warm body and lower vocals slightly right without changing the whole stereo image
  3. Keep Bass Centered While Adjusting Air
    • Low Band: 0%
    • Low-Mid: 0%
    • Mid: 0%
    • High-Mid: +5% to +15%
    • High: +10% to +20%
    • Effect: Gently moves upper ambience to the right while the low end stays centered

Application Guide

  1. Listening Balance Correction
    • Keep low frequencies (below 100 Hz) centered for stable bass
    • Shift only the frequency range that feels off-center
    • Use small signed values first (about 5-20%)
    • Check mono playback for tonal or level changes
  2. Problem Solving
    • Rebalance frequency ranges that feel too far left or right
    • Tighten unfocused bass by centering low frequencies
    • Reduce harsh stereo artifacts in high frequencies
    • Improve recordings where different parts of the sound lean to different sides
  3. Creative Listening Effects
    • Create unusual frequency-dependent placement
    • Make high frequencies lean one way while low frequencies stay centered
    • Build a wider-feeling ambience by making small balance shifts in upper bands
  4. Stereo Field Adjustment
    • Fine-tune stereo balance per frequency band
    • Correct uneven stereo distribution
    • Avoid treating this as a stereo width control; use Stereo Blend when you want to widen or narrow the whole image
    • Maintain mono compatibility

Quick Start Guide

  1. Initial Setup
    • Start with all bands centered (0%)
    • Set crossover frequencies to standard points:
      • Freq 1: 100 Hz
      • Freq 2: 500 Hz
      • Freq 3: 2000 Hz
      • Freq 4: 8000 Hz
  2. Basic Enhancement
    • Keep Band 1 (low) centered
    • Make small adjustments to higher bands
    • Listen for changes in spatial image
    • Check mono compatibility
  3. Fine-tuning
    • Adjust crossover points to match your material
    • Make gradual changes to band positions
    • Listen for unwanted artifacts
    • Compare with bypass for perspective

Remember: The Multiband Balance is a powerful tool that requires careful adjustment. Start with subtle settings and increase complexity as needed. Always check your adjustments in both stereo and mono to ensure compatibility.

Phase Select EQ

Phase Select EQ boosts or cuts stereo frequency components selected by frequency, absolute left/right phase difference, and left/right level balance. All three ranges must match. It applies the same positive gain to both channel spectra, so it does not rotate, correct, or create a phase difference. Use it when an ordinary frequency-only EQ cannot separate a centered sound from another sound at the same frequency that is wider or panned to one side.

Five independent Bands are always available. Each Band has an inner Core, where its Gain is applied fully, and an outer Transition, where the multiplier fades smoothly toward 100%. Overlapping Bands multiply their gains; for example, overlapping 150% and 50% Cores produce 75%. Several boosts can therefore raise the signal above 0 dBFS, so leave enough headroom and compare with bypass.

Phase Select EQ reports processing latency equal to its FFT size plus its hop size. At 48 kHz, this is 4,096 + 1,024 = 5,120 samples, or about 106.7 ms (about 116.1 ms at 44.1 kHz). Check the complete chain in the app’s Total Delay display. This latency can affect real-time monitoring and audio/video synchronization.

Reading the Selection Map

  • The vertical axis is logarithmic frequency: low frequencies are at the bottom and high frequencies are at the top.
  • Use Phase or Balance above the map to choose its horizontal axis. Editing a Phase or Balance control switches to the corresponding view automatically.
  • In Phase view, 0° in the center means in phase, while -180° and +180° at the edges are the same opposite-phase point. Selection uses the absolute phase difference, so the frame is mirrored across 0° and processes +60° and -60° identically.
  • In Balance view, 50:50 is centered, the left edge is left-only, and the right edge is right-only. Balance is (right amplitude - left amplitude) / (left amplitude + right amplitude) × 100%; negative values favor the left channel and positive values favor the right. The frame is a single rectangle, not a mirrored pair.
  • Each dot represents a recently measured input component. Brighter or larger dots are stronger; older dots fade away.
  • White dots show the measured components. Only enabled Band frames are drawn; the Band being edited is bright green and the other enabled Bands are light green. The number in the upper-left corner of each Core identifies its Band.
  • The short badge beside every Core number shows that Band’s complete hidden-axis selection. For example, P 20°›40°–80°›100° means Phase outer low › Core low–high › outer high. A Balance badge uses left:right ratios in the same order, such as B 100:0›80:20–70:30›0:100. P full or B full means that Band does not limit the hidden axis.
  • The solid inner frame is the Core and the dashed outer frame is the Transition. In Phase view, a Band touching 0° joins at the center and a Band reaching 180° continues across both map edges.
  • The badge beside the Graph choices shows the hidden axis’s Core and, when needed, Transition range. Dots rejected by the selected Band on that hidden axis are dimmed, making the three-way AND selection visible without changing views.
  • A component present in only one channel has Balance -100% or +100%. Phase view places left-only components at -180° and right-only components at +180°, so hard-panned sounds can be selected from either view.

The Balance grid uses familiar channel ratios. Approximate level differences are shown here for reference:

Balance 0% ±17% ±33% ±60% ±82% ±100%
L/R level difference 0 dB ±3 dB ±6 dB ±12 dB ±20 dB one channel only

Listening Enhancement Guide

  1. Reduce wide high-frequency glare
    • Set a Band around 4-12 kHz and 90-180°.
    • Start with 70-90% Gain and broad transitions.
    • Effect: Softens strongly out-of-phase upper-frequency content while leaving more centered detail largely unchanged.
  2. Add presence to centered vocals
    • Set a Band around 1-4 kHz and 0-30°.
    • Start with 110-125% Gain.
    • Effect: Emphasizes near-in-phase midrange components without applying the same boost to widely spread ambience.
  3. Control diffuse low-mid ambience
    • Set a Band around 150-600 Hz and 60-150°.
    • Start with 80-90% Gain and widen the frequency transitions until the change is smooth.
    • Effect: Reduces broad stereo low-mid energy while retaining near-center fundamentals.
  4. Reduce a hard-panned instrument
    • Switch to Balance and select roughly -100% to -70% for a left-panned sound, or +70% to +100% for a right-panned sound. Narrow the frequency range around the instrument.
    • Set the Phase Core around 150-180° so it includes the one-sided points at -180° or +180°. If Balance alone should decide the selection, use the full 0-180° Phase Core instead.
    • Start with 70-90% Gain and a moderate Balance Transition.
    • Effect: Reduces the strongly one-sided component while leaving centered material at the same frequencies largely unchanged.
  5. Emphasize a centered source
    • Select a Balance Core around -17% to +17% and a Phase Core around 0-30°, then narrow the frequency range around the source.
    • Start with 105-120% Gain.
    • Effect: Favors near-equal, near-in-phase components over sounds panned away from the center.

These phase ranges describe typical tendencies, not fixed sound-source locations. Watch where the dots actually appear in the recording, make small changes, and confirm the result on both headphones and speakers.

Parameters

  • Band 1-5 / checkbox (Off/On): Selects a Band for editing and enables or disables it without changing its settings.
  • Gain (0% to 200%): Sets the level multiplier inside the Core. 100% leaves the level unchanged, 0% removes the selected component, and 200% doubles its amplitude.
  • Solo (Off/On): Lets you hear only what the soloed Bands select. While any enabled Band has Solo on, Gain is ignored and everything outside the soloed Bands is muted, with the same smooth Transition fade at the edges. Soloing several Bands at once passes the combination of their regions. Turning every Solo off restores normal processing.
  • Core Low Frequency / Core High Frequency (20 Hz to 40 kHz, limited by the current sample rate): Set the fully processed frequency range.
  • Core Low Phase / Core High Phase (0° to 180°): Set the fully processed absolute L/R phase-difference range.
  • Outer Low Balance / Core Low Balance / Core High Balance / Outer High Balance (-100% to +100%): Set the four Balance boundaries directly. The Core pair sets the fully processed left/right amplitude-balance range; the Outer pair sets where the Transition reaches no processing. Negative values select toward the left; positive values select toward the right.
  • Low Frequency Transition / High Frequency Transition: Set how far below and above the frequency Core the gain fades between 0% and 100%.
  • Low Phase Transition / High Phase Transition: Set how far toward 0° and 180° the gain fades between 0% and 100%. The map handles edit the same values as the sliders and numeric inputs: drag anywhere inside the selected Band’s outer frame to move the whole Band, drag Core edges or corners to resize it, and drag the outer edge handles to change one transition at a time. These gestures work with a mouse or touch. A low-phase handle stops at the center instead of crossing it: Core Low Phase stops at 0°, and Low Phase Transition stops at its maximum width. When Core Low Phase is exactly 0°, the center handle can initially move either left or right; after the pointer moves to one side, it stays locked to that side for the rest of the drag.

Stereo Blend

An effect that helps achieve a more natural sound field by adjusting the stereo width of your music. It’s particularly useful for headphone listening, where it can reduce the exaggerated stereo separation that often occurs with headphones, making the listening experience more natural and less fatiguing. It can also enhance the stereo image for speaker listening when needed.

Listening Enhancement Guide

  • Headphone Optimization:
    • Reduce stereo width (60-90%) for more natural, speaker-like presentation
    • Minimize listening fatigue from excessive stereo separation
    • Create a more realistic front-focused soundstage
  • Speaker Enhancement:
    • Maintain original stereo image (100%) for accurate reproduction
    • Subtle enhancement (110-130%) for wider soundstage when needed
    • Careful adjustment to maintain natural sound field
  • Sound Field Control:
    • Focus on natural, realistic presentation
    • Avoid excessive width that could sound artificial
    • Use negative width only for corrective or creative side-polarity inversion
    • Optimize for your specific listening environment

Parameters

  • Stereo - Controls the stereo width (-200% to 200%)
    • Negative values: Invert the polarity of the stereo side (L-R) component before reconstruction
    • -200%: Maximum width with inverted side polarity; use only for correction or special cases
    • -100%: Original stereo width with the left/right image swapped
    • 0%: Full mono (left and right channels summed)
    • 100%: Original stereo image
    • 200%: Maximum width enhancement; keeps the center component while strongly boosting the stereo side difference
  1. Headphone Listening (Natural)
    • Stereo: 60-90%
    • Effect: Reduced stereo separation
    • Perfect for: Long listening sessions, reducing fatigue
  2. Speaker Listening (Reference)
    • Stereo: 100%
    • Effect: Original stereo image
    • Perfect for: Accurate reproduction
  3. Speaker Enhancement
    • Stereo: 110-130%
    • Effect: Subtle width enhancement
    • Perfect for: Rooms with close speaker placement

Music Style Optimization Guide

  • Classical Music
    • Headphones: 70-80%
    • Speakers: 100%
    • Benefit: Natural concert hall perspective
  • Jazz & Acoustic
    • Headphones: 80-90%
    • Speakers: 100-110%
    • Benefit: Intimate, realistic ensemble sound
  • Rock & Pop
    • Headphones: 85-95%
    • Speakers: 100-120%
    • Benefit: Balanced impact without artificial width
  • Electronic Music
    • Headphones: 90-100%
    • Speakers: 100-130%
    • Benefit: Controlled spaciousness while maintaining focus

Quick Start Guide

  1. Choose Your Listening Setup
    • Identify whether you’re using headphones or speakers
    • This determines your starting point for adjustment
  2. Start with Conservative Settings
    • Headphones: Begin at 80%
    • Speakers: Begin at 100%
    • Listen for natural sound placement
  3. Fine-tune for Your Music
    • Make small adjustments (5-10% at a time)
    • Focus on achieving natural sound field
    • Pay attention to listening comfort

Remember: The goal is to achieve a natural, comfortable listening experience that reduces fatigue and maintains the intended musical presentation. Avoid extreme settings that might sound impressive at first but become fatiguing over time.