mopis

Parameter reference

A general note about parameters: some parameters vary in discrete steps. For others, it makes sense to vary them smoothly. In general, the first type of parameter is represented with switches or -/+ buttons, and the second type is represented with a slider or knob.

For example: Transpose is a discrete parameter. You transpose by an integer number of semitones, because if you want to transpose an octave down, you want the pitch to be transposed exactly an octave. On the other hand, finetune varies smoothly. If you are applying vibrato by moving the finetune control, you don't want to hear discrete steps for each cent.

Sample page

Mopis can hold two user waveforms at once, and each waveform can contain up to eight samples.

• Keysplit editor: The control that looks like a piano keyboard is the keysplit editor. The number on each key indicates the sample to be used when that note is played. Clicking on a key assigns the currently selected sample to that note.
• Transpose: Transpose the current sample up or down by a number of semitones. For example, if you set transpose to -12 and play A-5 on your keyboard, the sample will actually be played back at A-4.
• Finetune: Finely adjust the sample's playback pitch, from 0 to 100 cents. (A cent is 1/100th of a semitone.)

Timbre page

Oscillator section

There are two independent oscillators. Each oscillator can generate a tone based on one of the waveforms from the wavetable. Then the output of the oscillators is mixed together and passed through the filter, amplifier, and effects section before being played.

All these parameters except "Bend" and "Balance" are implemented independently for each oscillator.

• Wave: Select a waveform from the wavetable. UserA and UserB use a sample-based oscillator. Saw, Squ, Tri, or Sin use the built-in sawtooth, square, triangle, and sine wave oscillators.
• Xpose: Transpose the waveform by a fixed number of semitones.
• Loop: Loop mode. If a user wave is selected and loop mode is On, the oscillator will repeat a certain portion of the sample during play back. If loop mode is Off, the oscillator will play through the sample once and stop. This parameter has no effect if a built-in wave is selected.
• Bend: Pitch bend range in semitones.
• Fine: Finetune the pitch of the oscillator in cents.
• Sync: Synchronize the speed of sample playback to the host tempo. This feature has no effect on the built-in waveforms. This feature is only available in the full, registered version of Mopis.
• Pitch: If Pitch is On, Mopis will adjust the pitch of the sample to match the note played. If Pitch is Off, the sample will play at its original pitch, but you can still use the time stretching and looping controls. This is useful on unpitched samples such as drum loops.
• Off: Sample offset in percent of the entire wave. If it's negative, the oscillator fills in silence before the beginning of the sample, and the sample will effectively be delayed.
• LpBeg: Starting point of the portion of the sample to loop, if loop mode is on. The loop point is specified relative to the length of the sample. For example, if LpBeg is 25%, the beginning of the loop will be one quarter of the way from the start of the sample to the end. This paramter has no effect if loop is off.
• LpLen: Length of the loop, if loop mode is on.
• Speed: If Sync is Off, this controls playback speed relative to the speed of the original sample. At 200% the waveform will play in half the time of the original sample. At 0% the sample will never finish and instead just play a steady-state waveform from the current sample location. If Sync is On, this adjusts the length of the sample relative to the host tempo. For example, to stretch the sample to fit four beats, set Speed to 4 quarter notes.
• Bal: Oscillator balance, i.e., the relative volumes of the two oscillators when they are mixed together. At 0% only OSC1 is heard; at 100% only OSC2 is head; at 50:50 they will be equally loud. (Assuming, of course, that the samples are equally loud to begin with.)

Filter section

The filter section takes input from the oscillator section and attenuates certain frequency components, allowing you to sculpt the sound.

Lowpass filters attenuate frequencies above the cutoff frequency: the further above the cutoff, the greater the attenuation. Similarly, highpass filters attenuate frequncies below the cutoff frequency. Finally, bandpass filters attenuate frequencies symmetrically around both sides of the cutoff.

The resonance or Q control both tightens up the slope of the filter attenuation and boosts (or "resonates") the frequencies very close to the cutoff frequency.

• Type: Filter type.
  • None - bypass the filter section completely.
  • LP12 - 12 dB/octave lowpass filter.
  • LP24 - 24 dB/octave lowpass filter.
  • HPF - 12 dB/octave highpass filter.
  • BPF - 12 dB/octave bandpass filter.
  • AnaLP - 24 dB/octave lowpass, with analog-style nonlinearity.
• Cut - Filter cutoff frequency. The scale is logarithmic, ranging from 80 Hz to about 10 kHz.
• Res/Q - Filter resonance or Q.
• Env - Filter envelope modulation. This determines the extent to which the filter EG will modify the cutoff frequency. A positive env mod will cause the envelope to increase the cutoff, and a negative env mod will cause the envelope to decrease the cutoff.
• A - Filter EG attack. The time for the filter cutoff to rise to the env mod point.
• D - Filter EG decay. The time for the filter cutoff to fall to the sustain point.
• S - Filter EG sustain. The filter cutoff level to hold at, as a fraction of the env mod.
• R - Filter EG release. The time for the filter cutoff to fall from the sustain point to the original cutoff point.

Amplifier section

• OGain - Oscillator gain. This is gain applied to the output of the oscillator section before it passes through the filter section. You can increase or decrease the OGain to emphasize or de-emphasize the saturation in the analog-model filters. Alternately, just use it for extra gain on a quiet sample.
• Gain - How much gain to apply after the filter section.
• Pan - Panorama. Where to place the sound in the stereo field.
• A - Amplitude EG attack. The time for the gain to rise from 0 to the maximum gain level.
• D - Amplitude EG decay. The time for the gain to fall from the maximum gain to the sustain level.
• S - Amplitude EG sustain. The gain level to stay at while a note is held down, as a fraction of the maximum gain level.
• R - Amplitude EG release. The time for the gain to fall from the sustain level to zero after a note is released.

Voice section

• Legato - Legato mode determines the behavior when a new note is played while an existing note is still playing. When legato mode is off, an additional note is triggered. When legato mode is on, the existing note slides to the new one.
• Porta - Portamento speed. When legato mode is on, portamento determines the time that a note slide takes. Smaller values correspond to faster slides. This parameter has no effect when portamento is off.
• Unison - How many voices to allocate to each note. By using multiple voices for a single note, each with a slightly different pitch, the synth can produce a "fatter" sound. The tradeoff is that using unison voices reduces the number of effective voices.
• Detune - When unison mode is on, determines how far apart to spread the pitches of the unison voices. This parameter has no effect when unison is off.

Assign page

Assign table

The assign table allows you to modify almost any synth parameter according to other parameters in the style of a modular synth. Since these parameters can change over time, the assign table lets you create extremely complex evolving sounds.

There are eight slots in the assign table, and they are interchangeable. The assign source specifies the parameter that will control the destination parameter. The assign destination specifies the parameter that will be modified. The assign modulation amount controls the maximum amount to alter the destination parameter.

The valid assign sources are:

• Velocity - The MIDI velocity of the note.
• Mod wheel - The position of the MIDI mod wheel.
• Note - The original note that was triggered. C-4 corresponds to zero modulation. Higher notes cause positive modulation, and lower notes cause negative modulation.
• LFO1/LFO2/LFO3 - The current value of the appropriate LFO.
• Filter EG - The current value of the filter envelope. Regardless of the assign table settings, the filter EG will always control the filter cutoff, but the assign table lets you map it to another parameter simultaneously.
• Amp EG - The current value of the amplifier envelope. Regardless of the assign table settings, the amp EG will control the gain, but the assign table lets you map it to another parameter simultaneously.

Delay section

Mopis provides a built-in delay (or echo) effect. The delay is applied to the output of all the active voices together.

• Delay - Turn the delay effect on or off.
• Mode - Stereo or cross. When stereo delay is chosen, the effect is applied independently to the left and right channels. When cross delay is chosen, the right delay buffer is fed back into the left delay buffer and vice versa, creating the characteristic "bouncing" effect.
• Sync - Tempo sync. If it's on, the delay time may be specified relative to the length of a beat. Otherwise the delay time is specified in milliseconds.
• Filt - Filter. You can apply a 2-pole lowpass or highpass filter to the delay.
• Tempo - When tempo sync is on, this sets the tempo used to calculate delay times. When tempo sync is off, the tempo parameter has no effect.
• Len - Delay length. The amount of time to delay the dry signal before mixing it back in. When tempo sync is off, the delay length is specified in milliseconds. When tempo sync is on, the delay length is specified in beats as follows:
  • 1/4 - quarter note (1 beat)
  • 3/16 - dotted eighth note
  • 1/8 - eighth note
  • 3/32 - dotted sixteenth note
  • 1/12 - eighth note triplet
  • 1/16 - sixteenth note
  • 1/24 - sixteenth note triplet
  • 1/32 - 32nd note
• Wet - The level of the delayed signal output relative to the original signal.
• Feed - The level of feedback.
• Cut - The cutoff frequency for the delay filter. If the delay filter is off, this parameter has no effect.