draft: false
Name: Tape Bias
short-description: 1960s-inspired reel-to-reel record/replay simulator with virtual bias calibration.
summary: >
  Tape Bias is a first-pass mono record/replay processor inspired by 1960s
  reel-to-reel machines. It models record drive, virtual AC-bias calibration,
  tape formulation, transport speed, replay head loss, magnetic memory, and hiss
  without generating an ultrasonic bias carrier at the 48 kHz audio rate.
Language: C++ (Pico SDK + ComputerCard)
Creator: Adrian Vos
Version: "0.1.1"
Status: Beta
License: MIT
date-created: 2026-07-30
date-updated: 2026-07-31
demo-link: https://www.youtube.com/watch?v=F0PJVCJKk94
uf2:
  - path: uf2/TapeBias.uf2
    name: Tape Bias 0.1.1 (current stable)
tags:
  - effect
  - tape
  - reel-to-reel
  - saturation
  - experimental
panel:
  inputs:
    - id: AudioIn1
      name: Audio In
      type: audio
      description: Mono source recorded into the virtual tape path
    - id: CVIn1
      name: Bias CV
      type: cv
      description: Strong bipolar modulation of bias calibration around the X control
    - id: CVIn2
      name: Tape CV
      type: cv
      description: Modulates tape formulation around the Y control
    - id: PulseIn1
      name: Erase
      type: pulse
      description: Clears tape state and creates a brief replay dropout on a rising edge
  outputs:
    - id: AudioOut1
      name: Replay Out
      type: audio
      description: Virtual tape replay output
    - id: AudioOut2
      name: Replay Out
      type: audio
      description: Duplicate virtual tape replay output
    - id: CVOut1
      name: Bias Offset
      type: cv
      description: Full-scale effective bias calibration relative to nominal bias
    - id: CVOut2
      name: Tape Flux
      type: cv
      description: Slow magnetic-memory state of the virtual tape
controls:
  switch:
    up:
      name: 3.75 ips
      description: Slow transport with reduced replay bandwidth and stronger head loss
    middle:
      name: 7.5 ips
      description: Standard transport setting
    down:
      name: 15 ips
      description: Fast transport with wider replay bandwidth and reduced head loss
  knobs:
    - main:
        name: Record Level
        description: Sets record drive into the magnetic transfer curve
      x:
        name: Bias
        description: Moves from under-biased through nominal to over-biased response
      y:
        name: Tape Type
        description: Moves from lower-output ferric toward higher-output tape response
  leds:
    - display: list
      items:
        - id: LED0
          name: Record Level
          description: Follows the Main record-level control.
        - id: LED1
          name: Effective Bias
          description: Follows the X Bias control after Bias CV modulation.
        - id: LED2
          name: Magnetic Flux
          description: Shows the magnitude of magnetic memory and flashes fully during an erase pulse.
        - id: LED3
          name: Over-Bias Treble
          description: Full brightness at under-bias or nominal bias; dims as over-bias reduces replay treble.
        - id: LED4
          name: Effective Tape Type
          description: Follows the Y Tape Type control after Tape CV modulation.
        - id: LED5
          name: Transport Speed
          description: "Indicates switch position: brightest at 3.75 ips, medium at 7.5 ips, and dimmest at 15 ips."
contact:
  social:
    github: https://github.com/soveda