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Audio DSP & Mixing Castium Studio Docs

Pro DJ Mixer & 10-Band EQ

Deep dive into 3-band isolators, sound color sweep filters, and graphic EQ presets.

Professional DJ Stereo Mixer & Full EQ Guide

CASTIUM includes a native, hardware-class DJ Stereo Channel Mixer and Multi-Band Equalizer built directly into the real-time 44.1kHz audio DSP pipeline. It delivers studio-grade sound shaping, true stereo channel manipulation, and tactile frequency isolation inspired by club-standard DJ hardware and professional DJ software (such as Pioneer DJM, Traktor Pro, and Serato DJ).

1. Overview & Capabilities

Unlike conventional desktop players that only offer a basic global volume slider, CASTIUM provides discrete channel architecture, Mid-Side stereo spatial imaging, 3-Band Isolator / Kill filters, 10-Band ISO Graphic EQ, DJ Sound Color sweep filters, and analog soft-saturation limiting.

All processing runs natively in real time with sub-millisecond latency. Any EQ adjustments, channel trims, or spatial expansion are encoded directly by the MultiFormatTranscoder and broadcast in pristine stereo to all web listeners, Icecast mounts, and external media players.

2. Channel Architecture

🎵 Music Deck (Channel 1)

  • Trim / Gain Fader: -12.0 dB to +12.0 dB pre-fader gain adjustment for balancing track loudness.
  • Constant-Power Stereo Panning: Smooth Left-to-Right panning with constant acoustic power (-100% L to +100% R) and a quick center detent reset (C).
  • Stereo Width Expander (Mid-Side Matrix):
    • 0.0x (MONO): Sums Left and Right channels equally into True Mono. Essential for club sound system compatibility testing and mono radio checks.
    • 1.0x (STEREO): Completely transparent, natural stereo pass-through.
    • 1.0x - 2.0x (WIDE): Expands the stereo soundstage by selectively amplifying the Side channel relative to the Mid channel. Delivers an expansive, immersive spatial image in headphones and stereo speakers.
  • Mute & Solo: Instantly silences or isolates the music channel during talk segments or drops.

🎙️ Microphone Deck (Channel 2)

  • Mic Gain: -12.0 dB to +12.0 dB level adjustment.
  • Mic Pan: Positions the host/broadcaster voice in the stereo panorama.
  • 80Hz Rumble Cut (High-Pass Filter): High-pass filter tuned to 80Hz that removes desk vibrations, air conditioner hum, and vocal plosives without affecting speech warmth.
  • Live Talkover Status: Clear visual confirmation of microphone live / muted state.

🔊 Master Output Bus

  • Master Gain: Final output level adjustment from -12.0 dB to +6.0 dB.
  • Master Balance: Final master panorama balance.
  • Analog Soft-Clip Limiter: Uses transparent hyperbolic tangent (tanh) saturation. If a DJ pushes EQ bands or gain beyond 0dBFS, the limiter rounds peaks into warm analog saturation rather than harsh, jagged digital clipping.

3. Equalizer Modes

Mode A: 3-Band DJ Isolator with Kill Switches

Engineered specifically for DJ transitions, live track battles, and electronic music performance:

  1. HIGH Shelf: 2.5 kHz to 20 kHz (-26 dB to +6 dB).
  2. MID Peaking: 300 Hz to 2.5 kHz (-26 dB to +6 dB).
  3. LOW Shelf: 20 Hz to 300 Hz (-26 dB to +6 dB).
  4. Kill Switches:
    • [LOW KILL]: Drops low frequencies to -inf dB. Drops the bassline completely for seamless beatmatched transitions and drop build-ups.
    • [MID KILL]: Cuts vocals, leads, and snares, creating instant dub instrumental sections.
    • [HIGH KILL]: Isolates bass and drums by eliminating cymbals and high-frequency air.
  5. DJ Sound Color Sweep Filter (HPF / LPF):
    • Turned Left (-100% to 0%): Resonant Low-Pass Filter sweeping cutoff down to 160Hz with resonant analog edge.
    • Center (0%): Completely bypassed.
    • Turned Right (0% to +100%): Resonant High-Pass Filter sweeping cutoff up to 3.5kHz.

Mode B: 10-Band ISO Graphic Equalizer

For surgical broadcast audio tuning across the entire audible frequency spectrum:

  • 10 ISO Standard Bands: 31 Hz, 63 Hz, 125 Hz, 250 Hz, 500 Hz, 1 kHz, 2 kHz, 4 kHz, 8 kHz, 16 kHz.
  • Each band offers precision +/- 12 dB boost/cut with vertical faders and numeric readouts.

4. Real-Time Visual Feedback

  • Live SVG Response Curve: A real-time vector curve displaying the combined filter response curve across the entire frequency range (20Hz to 20kHz) with an illuminated gradient fill.
  • Dual Stereo Peak VU Meters: Real-time Left and Right level meters tracking peak amplitudes with yellow warning and redline overload indicators.

5. Pro DJ Presets

CASTIUM includes instant 1-click presets covering standard broadcast and club performance styles:

  • Flat / Bypass: Transparent, uncolored frequency response.
  • Club / EDM Bass: Heavy sub-bass boost with clean mid scoop and sparkling highs.
  • Radio DJ Voice: Broadcast vocal presence boost with high-end air and low-end clarity.
  • Rock & Live: Punchy mid-range presence for guitars, live drums, and punchy snares.
  • Warm Vinyl & Acoustic: Analog saturation warmth with gentle high-end attenuation.
  • Hip-Hop Thump: Deep, rumbling low-end response with crisp vocal cut.
  • Lofi Lounge: Warm, vintage, mellow response.
  • Treble Sparkle: Ultra-crisp top-end clarity.