modular analog synthesizer for electronic music
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 Q105  Slew Limiter

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The Q105 Slew Limiter is used to limit the change in a signal. The amount of limitation is set by a front panel control. This function is sometimes referred to as 'Glide', 'Glissando', 'Lag Processing', or 'Portamento'. The operator has the ability to select the rising edge of a signal, the falling edge, or both with a front panel switch. A manual push button allows the operator to disable the module's function and a jack provides a way to enable/disable using an external signal or a foot switch (useful for portamento control). An LED indicator shows enabled/disabled status. Use the Slew Limiter as a portamento control by routing the keyboard's pitch control voltage through the Limiter then to an oscillator. Use the Slew Limiter as an 'AR' (Attack, Release) envelope generator by routing a square wave from the keyboard gate, oscillator, or sequencer to an amplifier or filter.

Controls and Connectors

    Amount Control
      Sets the amount of slew limiting.
      0=short time, 10=long time.
    Direction Switch
      Select limiting of signals going up, down, or both.
    Control Connector
      Allows on/off control from an external source or foot switch.
    Control LED
      Shows on/off status.
    Control Push Button
      Allows manual on/off control of slew limiting.
    Input Connector
      Input signal.
    Output Connector
      Slew limited output signal

Panel Size:  Single width 2.125"w x 8.75"h.
Slew/Glide Time: 10ms to 5 seconds per octave.
Input/Output Voltage Levels: 10V PP.
Power:  +15V@15ma, -15V@15ma.

$80.00 US.



Usage and Patch Tips

The most common use of the Slew Limiter is to create portamento for your keyboard. This is a gradual sliding from one note to the next. Do this by patching the pitch control voltage from your keyboard into the input on the slew limiter module then patch the output to your oscillators as normal. Start with a very low amount and adjust to get the effect you want. Usually the direction control will be in the 'both' position, but the 'up' and 'down' positions will provide portamento just for notes that go in that direction. A foot switch can be added to the control input if needed.

As an Envelope Generator
Another use for the Slew Limiter is to provide a simple envelope generator. Simply patch the gate output from the keyboard controller to the input of the slew limiter, and the output to an amplifier, filter, oscillator, etc. The amount control will set the Attack time and the Release time. The direction switch can be used to turn off the Attack or Release phase. An external signal can be used to turn it on and off.

As a Gate Delay
The Q105 slew limiter can also be used to delay and/or extend gate signals to create multi-stage envelopes, delayed modulation, and unusual keyboard responses. Simply connect a gate signal to the input jack. Setting the direction to Up will let the Amount control adjust the delay of the beginning of the output gate. Setting the direction to Down will let the Amount control adjust the extension of the output gate. Setting the direction to Both will let the Amount control adjust both the beginning delay and the extension resulting in a shifting of the entire gate signal.

As a Low Pass Filter
A slew limiter is basically a lowpass filter. By running a signal with harmonics through the slew limiter you can attenuate the high frequencies by adjusting the Amount control.

Creating Legato keyboard response
You can create Legato response from your keyboard by running the Gate signal through the Q105 slew limiter. The Q105 is used to slow down the gate signal and cover up the very fast ones between close keystrokes. See this article by Brad Frohock.

Q105 Slew Limiter Demo Sounds
Bass patch with fast slew then slow slew q105a.mp3 (153K), Patch
Osc w/PWM with slew direction UP q105b.mp3 (101K), Patch
Osc w/PWM with slew direction DOWN q105c.mp3 (103K), Patch
Dual Osc with pan and pitch with slew limiter q105d.mp3 (379K), Patch

End of Product Information