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               CPLAY2 - AUDIO DSP & LISTENING SYNERGY GUIDE
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CPLAY includes a 7-module native 16-bit PCM audio processing chain built on
top of the BASS audio engine. Because DSP modules process audio sequentially,
understanding how each filter affects the stereo image and dynamic range helps
you achieve the optimal listening profile for your specific equipment.

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1. DSP MODULE OVERVIEW
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[1] Master 10-Band EQ
    - Function: Precision frequency adjustment across 10 fixed ISO bands
      (31 Hz to 16 kHz) with automatic safety precut headroom to prevent
      digital clipping.
    - Best For: Compensating for headphone sound signatures or acoustic
      room nodes.

[2] Volume Normalization (AGC w/ Exponential Smoothing)
    - Function: Evaluates block peak amplitude and applies dual-rate exponential
      moving averages (fast attack, slow release) to match target loudness
      across mixed tracks without "pumping" or volume jitter.
    - Best For: Multi-artist playlists, shuffle mode, and classical or live
      track compilations.

[3] Dynamic Compressor
    - Function: Narrower peak-to-average ratio reduction to keep soft nuances
      audible while taming sudden volume peaks.
    - Best For: High-dynamic-range classical or orchestral recordings in
      noisy listening environments.

[4] Acoustic Decay (Reverb)
    - Function: Simulates natural room/hall boundary reflections and tail decay.
    - Best For: Adding spatial depth to dry studio recordings or compensating
      for non-sealing flathead earbuds.

[5] Vacuum Tube Warmth
    - Function: Introduces gentle 2nd-order harmonic distortion and subtle
      high-frequency rounding.
    - Best For: Smoothing out harsh treble on sharp In-Ear Monitors (IEMs)
      or aggressive digital remasters.

[6] Stereo 3D Widener
    - Function: Extracts and amplifies the Mid/Side (L - R) difference signal
      to push the soundstage beyond the ear drivers.
    - Best For: Overcoming the narrow "inside-the-head" imaging characteristic
      of isolated IEMs and closed-back headphones.

[7] Headphone Crossfeed (Bauer Filter)
    - Function: Blends ~30% of attenuated, low-pass delayed audio (~220us) into
      the opposite channel to emulate speaker listening in room acoustics.
    - Best For: Reducing listener fatigue on hard-panned stereo recordings
      (e.g., 1960s stereo mixes) during extended headphone sessions.


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2. RECOMMENDED DSP COMBINATIONS
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PROFILE A: Deep Isolation In-Ear Monitors (IEMs)
Goal: Round off harsh upper-mids, expand narrow soundstage isolation, and keep
      dynamics smooth.
  - [ON]  Vacuum Tube Warmth
  - [ON]  Stereo 3D Widener
  - [ON]  Volume Normalization (AGC)
  - [OFF] Headphone Crossfeed
  - [OFF] Acoustic Decay

PROFILE B: Open / Flathead Earbuds (Classical & Live Tracks)
Goal: Add ambient hall body, compensate for open seal bass roll-off, and level
      classical dynamics.
  - [ON]  Acoustic Decay (Reverb)
  - [ON]  Master 10-Band EQ (Moderate bass shelf)
  - [ON]  Volume Normalization (AGC)
  - [OFF] Stereo 3D Widener
  - [OFF] Headphone Crossfeed

PROFILE C: Vintage / Hard-Panned Stereo Headphone Listening
Goal: Eliminate ear fatigue caused by extreme Left/Right panning on headphones.
  - [ON]  Headphone Crossfeed
  - [ON]  Master 10-Band EQ
  - [OFF] Stereo 3D Widener
  - [OFF] Acoustic Decay


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3. INCOMPATIBLE DSP COMBINATIONS (WHAT TO AVOID)
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[X] Stereo 3D Widener + Headphone Crossfeed
    - Why: They actively counteract each other. The Widener boosts the
      Mid/Side difference signal to pull channels apart, while Crossfeed
      feeds channel signal into the opposite ear to narrow spatial separation.
      Combining them causes phase cancellation, hollow mids, and unnatural
      soundstaging.

[X] Acoustic Decay + Headphone Crossfeed
    - Why: Delayed room reflections get cross-fed back into the opposite
      channel, resulting in a smeared, muddy mid-bass response.

[X] Volume Normalization (AGC) + Dynamic Compressor (at extreme settings)
    - Why: Both attempt to control dynamic range simultaneously. Running
      aggressive compression into AGC can flatten the natural transient
      dynamics of acoustic instruments.

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