4ms QPLFO (DIY)

4ms QPLFO

• Quad "pingable" LFO's -- frequency is set by time between pulses ("ping")
• Each of the 4 channels is an independent LFO
• Can produce a variety of waveshapes: "Pluck," to ramp-down, to triangle, to ramp-up, and all shapes in between
• Channels can easily modulate, trigger, and reset each other for complex and slowly morphing outputs
• Slowest period is about 71 minutes (0.0002 Hz), fastest speed is about 500Hz (marginal tracking up to 1kHz)
• Tap tempo button is free-running (LFO runs indefinitely), but external clock/Ping is auto-stopping (LFO stops when external clock stops)

Controls and jacks

• Tap tempo button ("Ping") for manually setting the tempo
• Ping jack sets tempo with an external clock (any complex signal can be used as a clock)
• On/mute button enables or mutes the output (latching button)
• Skew knob and CV jack control the waveshape by altering the ratio between rise and fall times
  • At 0% Skew (0V of CV), the shape is a "plucky" near-expo curve
  • At 1% Skew (just over 0V of CV), the shape is ramp-down
  • At 50% Skew (about 5V of CV), the shape is a triangle
  • At 100% Skew (about 10V of CV), the shape is ramp-up
  • Skew knob provides offset to the incoming CV signal, so any range of CV is acceptable
• Reset jack restarts the LFO without changing the tempo (rising edge triggered)
• OUT jack outputs either a 0 to 10V waveshape, or a -5V to +5V waveshape (jumper selectable)
• LED flashes and dims to the signal on the OUT jack
• Tap tempo button flashes to the internal tap-tempo clock or to incoming pulses on the Ping jack
• On/Mute button lights up when channel is On

Advanced

• Ping and Reset inputs use comparators, so any waveshape can be used for triggering (audio waves, complex LFOs, even the QPLFO itself!)
  • Trim-pot on PCB allows for adjustment of comparator threshold value


• "Fire-on-unmute" jumper per channel:
  • When this optional jumper is installed, pressing the On button to turn the channel on will reset the LFO.
  • If the jumper is not installed (factory default), pressing On will unmute the LFO without resetting (LFO runs in the background when muted)


• Bipolar/Unipolar jumper:
  • Setting jumper to Bipolar makes the outputs -5V to +5V
  • Setting jumper to Unipolar makes the outputs 0V to +10V
  • One jumper controls all four channels


• One-shot mode: Reset jack can be used to trigger a one-shot envelope if the external ping clock is stopped. See manual for detailed discussion
• Floating Reset mode: Holding a high gate on Reset jack allows the waveshape to run freely without automatically re-syncing to the ping clock. A bare cable plugged into the jack causes a high gate


• Connects to other modules using ribbon cables:
  • Outputs can connect to the 4ms VCA Matrix, or the 4ms SISM, the Circuit Abbey Intermix or the Toppobrillo Mixiplexer
  • Normalization of ping jacks can connect to the 4ms Quad Clock Distributor