Frap Tools Falistri

MUSICAL FEATURES

The Frap Tools Falistri is a fully analog, versatile movement manager designed for voltage generation and editing. The Falistri is divided into four main sections: the top section of the panel consists of two function generators , while the bottom section comprises cascaded dual frequency dividers and slew limiters , as well as a four-quadrant multiplier (ring modulator) .

HOW TO USE

The Falistri front panel is color coded by functional section.In addition, by labeling the signal input / output related to each parameter and the dotted line or solid line indicating the normalized signal path, the desired operation can be performed smoothly. 

Interface

Function generators

The two generators are designed for quick and intuitive access to necessary functions and feature numerous inputs and outputs. The slope shape control has the following features: ( See reference video link )

• Shape-independent duration --When shaping the envelope, you can freely morph the slope shape from logarithmic to linear or exponential while maintaining the time values ​​of Rise and Fall.
• The shape can be adjusted for each stage --Can be set to logarithmic Rise and logarithmic Fall, linear Rise and logarithmic Fall, or any other mode combination.This allows deep sound engraving, both as a control voltage and as an audio source.

Times

The duration of each stage is set using the Rise and Fall knobs. The Rise knob sets the time it takes for the function to reach its maximum level, while the Fall knob sets the time it takes for the function to decrease and "rest" after the Rise stage (in Transient mode) or after the Hold stage (in Hold mode). These parameters can be individually modulated with any CV using the corresponding jacks, and can also be modulated simultaneously via the V/Oct input. This input works in reverse to the individual CV inputs. To achieve perfect operation across various octaves, you can use it like a V/Oct converter by setting both the Rise and Fall stages to equivalent values. See the reference video links 1, 2, 3.

The Time Scale switch scales the Rise and Fall of each generator, the time coefficients of both stages.

Trigs and Modes

Two manual buttons and external trigger / gate input are available in three modes:

• loop --Trigger the start of Rise at the end of the Fall stage.It does not require a trigger input, but if it does, it will trigger the Rise stage again. Suitable for use as an LFO or oscillator.
• Transient --At the start of the Rise stage, the trigger / gate signalOnly transition from low to highIs used and the Fall stage is automatically triggered at the end of Rise.One-shot Rise-Fall function, orADIt can be used as an envelope.
• . --The low-to-high transition of the gate signal is used to start the Rise stage, and the Fall stage is the gate signal.Transition from high to lowTriggered by.Hold the Hold stage when the gate signal is "high (1.5V or higher)" longer than the Rise stageAHRIt will be an envelope.The Fall stage is triggered when the gate is low.

Any retrigger signal while the function is active will call back the function's Rise stage. Specifically, it works as follows:

• If the function is already in the Rise stage, it will not be retriggered
• If the function is a Hold stage, it will not be retriggered
• If the function is the Fall stage, start Rise from the level at the time the trigger was received.
• If the function is the Rest stage, launch a new function

Falistri is a triangle core generator with a wave shaper stage applied after the core, causing retriggers during the Fall stage and some interesting discontinuities when using non-linear waveforms. Will occur.

Green Alternative Retrig (On Rest)

Green, the second generator provides a unique feature that can be enabled with a switch on the back of the module.

• To rise(Upper position) -Same operation as the yellow generator 
• On Rest(Lower position) -Retrig is accepted only when the generator is in the Rest stage.

The On Rest function allows you to use the generator like a formant oscillator . This function roughly maintains the spectral components of the designed function over several tones, and if this "slave" period is longer than the "master" period, the frequency division (/2, /3, /4, /n...) of the external frequency used for triggering is performed. When the green generator is set to On Rest and the Play mode is set to Transient, the Trig/Gate LED will not light up. To check whether the generator is set to To Rise or On Rest, set the generator to Transient mode and press the Trig/Gate button. If the LED lights up, it is set to To Rise; if it does not light up, it is set to On Rest. Note that when operating in Quadrature mode, it will be in To Rise mode regardless of the switch position. Reference video link

outputs

Each generator has 2 gate outputs and 3 CV outputs, for a total of 5 types of outputs.

• Bipolar CV output: ± 5V range. Suitable for use as an oscillator for LFOs and audio rates.
• Unipolar CV output: 0 / + 10V.Suitable for general envelopes, etc.
• CV output with Athenu barter: Adjustable to any polarity and amplitude from 0 to + 10V or 0 to -10V.Reference video link1, 2
• EOR (End of Rise) Gate Output: Output the gate at the end of the Rise stage
• EOF (End of Fall) Gate Output: Output the gate at the end of the Fall stage

quadrature

Quadrature mode is enabled by setting the switch labeled "Q" to the right position. Quadrature is a special feature that generates more complex functions by linking the stages of two generators , and can be thought of as a pair of envelopes in which the stages depend on each other. For example:

• Cycle start → Yellow generator starts Rise
• Yellow Rise ends → Green starts Rise / Yellow is Hold
• Green Rise ends → Yellow starts Fall / Green is Hold
• Yellow Fall ends → Green starts Fall / Yellow goes to Rest
• Green Fall end → Cycle end

To run Quadrature, set the Q-switch to the right position and set the green generator to Hold mode.This will give you three different results based on the operating mode of the yellow generator.

Yellow in Loop : A loop-type Quadrature that automatically restarts from the yellow Rise stage when the green Fall stage ends.

Yellow in Transient : Single Quadrature Cycle

Yellow in Hold : In a single Quadrature cycle, the yellow Hold stage depends on both the green Rise time and the length of the impulse/gate to trigger the yellow generator. As explained in the On Rest section, Quadrature mode disables the green On Rest function.

ADSR

When Quadrature is enabled, you can create envelopes such as ADSR and AHDSR by setting relative levels with the Max output and the attenuator. Attack can be controlled with the yellow Rise, and if a Hold is needed, it is defined with the green Rise and yellow Hold (yellow = Hold mode). When the yellow Fall begins, the green generator enters Hold mode until the yellow envelope reaches its endpoint. The green Hold level is set with the attenuator. As long as the yellow Fall level is higher than the green Hold level, the envelope is in the Decay stage. When the level of the green Hold stage becomes higher than the yellow Fall, the envelope enters the Sustain stage, and the duration is set by the yellow Fall time. When the yellow Fall ends, the envelope enters the Release stage , which is set by the green Fall time . See reference video links 1, 2, 3, 4

Function Processors

Dual Cascaded Frequency Divider

Each of these processors, also known as a flip-flop or sub-octave processor, changes its logic state whenever it detects a transition from low to high. The two DCFD circuits, one above the other, are semi-normalized to obtain 1/2 and 1/4 outputs from a single input signal. Setting the output range switch to the upper position generates a unipolar signal (0V/+10V), while the lower position generates a bipolar signal (±5V). When an audio signal is used as input, it functions like a sub-octave generator (a square wave or pulse wave would be good as the carrier). When a clock signal is input, it functions like a clock divider . When a trigger signal is input, the output is always a gate. This is because the flip-flop circuit holds its state high or low until it detects a new rising edge input. Also, when using a random clock from SAPEL, etc., it is possible to create interesting variable-width gate sequences. In the example below, a clock is used as input to obtain 1/2 and 1/4 clock frequencies.

The following example takes a random clock as input.

The last example takes a rectangular wavy waveform as the audio rate input and outputs -1 and -2 octaves.

Reference video links 1, 2

Four-quadrant multiplier

The Four-Quadrant Multiplier (4QM) is a circuit that adds two signals together, one by one. Similar to a VCA, the main difference is that both inputs are bipolar signals, allowing for free combination of positive and negative polarity. This can be thought of as a ring modulator , balanced modulator , or through-zero VCA . It boasts extremely high linearity and a bandwidth of over 20kHz from DC, and the calculation results are highly dependent on the source used. Of the 4QM's two input jacks, the upper input 1 is semi-normalized to the unipolar output of the yellow generator, and the lower input 2 is semi-normalized to the unipolar output of the green generator. This allows for the use of yellow as an envelope and green as an audio source without the need for patch cables. The Level knob affects the overall output by setting the amount of the two signals. Additionally, a four-LED matrix indicates which quadrant is currently being used. Input 1 moves the LED vertically (down is negative, up is positive), while input 2 moves the LED horizontally (left is negative, right is positive).

Amplitude Modulation & Ring Modulation (2 vs 4 quadrant)

When one of the signals used is bipolar and the other is unipolar, the 4QM effectively functions like a linear VCA. This is the default behavior, meaning that if the green generator is operating as an oscillator, the yellow generator controls the amplitude. In this setting, Falistri can be used as a simple yet practical synth voice. ( See reference video link)

When the yellow generator is also set to audio rate, Falistri begins amplitude modulation ( AM ). AM is also called unbalanced modulation. This is because one of the two signals is only positive, and only two of the four quadrants of the virtual Cartesian plane are used. Amplitude modulation results in a signal with frequencies called "sidebands" added while maintaining the carrier frequency. If both signals are pure sine waves, there will be two of these sidebands: the sum and difference of the carrier and modulator frequencies, whose amplitude depends on the amount of modulation but will never exceed half the amplitude of the carrier. If the modulator frequency is higher than the carrier frequency and the difference is a negative frequency, the phase will be inverted.

When both signals are bipolar, Falistri performs a "balanced modulation" called ring modulation (RM), which uses all four quadrants (combinations of positive and negative polarity). The result of RM is very similar to AM, but the main difference is that in RM, the carrier frequency is suppressed, and the sidebands become the only audible output. In this case, their amplitude is the same as the carrier amplitude. [Reference video link]

The 4QM section of the front panel has a small trimmer.This is useful for setting a unipolar envelope that drops to zero and a zero level for use, reducing the DC offset that causes low-order attenuation.

Linear Slew Limiter

A Linear Slew Limiter, also known as portamento or glide when using quantized CV , smooths all kinds of voltage transitions by independently controlling the rising and falling edges of the incoming signal. The left knob sets the slewing of the rising voltage patched to the input, and the right knob sets the slewing of the falling voltage, with the results sent to the output. Two LEDs help to indicate the processor's operating status.