DRC Help

Thank you for your interest in DRC - Polyphonic Synthesizer.

DRC was designed to be a simple and powerful synthesizer, allowing beginners as well as experienced users to take control of the full potential of its sonic capabilities.

DRC is distributed as a free download. It is fully functional but it will invite you to unlock the synth engine to keep playing without interruptions, making it perfect for a test run and to get to know all of its incredible features.

Don't hesitate to contact us if you any questions, comments or other inquiries.

Contents

• Overview
• Settings
• Patches
• Oscillators
• Filter
• Mixer
• Modifiers
• Performance modes
• Troubleshooting

Overview

DRC features a minimalistic interface designed to operate in the various screen sizes, ranging from mobile to desktop. The interface is divided in four parameters panels and a perform section. Each panel is composed of several tabs that allow access to other parameters in a easy and intuitive way.

The following features are found on the left side of DRC's status bar:

• Midi Learn - toggle midi learn on and off
• Tempo - main session tempo
• Patch - indicates the currently selected patch. Tap it to open patch browser

Midi learn

The Mapping feature of DRC allows the mapping of its parameters for remote control by a MIDI controller.

Toggle the MIDI Learn function by tapping it and DRC's controls will get darker. When the desired mapping parameter is selected, it will get highlighted (if the parameter doesn't have any assignment it will be labeled as N/A).

Once a message from the MIDI Device is received, it will be mapped and displayed on DRC. Once you are done with the mappings, turn off MIDI Learn on the status bar and DRC is ready to operate with the given assignments.

Tempo

The tempo setting, controls the value of DRC's internal clock. If DRC is working in slave mode (as a plugin in a DAW or as a inter-app audio node), the tempo is defined by the host.

Patch

Tapping here opens the patch browser where it is possible to navigate between the different banks of patches and select any of the available DRC patches.

Status bar icons

On the right side of the status bar are 5 icons:

• Disk - This opens the save menu where you can name/save the current patch state as either a new patch, or overwrite an existing one, in either the local a custom bank.
• Revert - This resets the current patch back to its original saved state. (This button is only active/available if changes have been made to a saved patch - to indicate this, an asterisk will appear to the right of the patch name.)
• Random - When pressed this will assign a random value to each parameter.
• Up arrow - This selects the previous patch from the list of patches in the currently selected bank.
• Down arrow - This selects the next patch from the list of patches in the currently selected bank.

Settings

MIDI Clock and MIDI Channel

Send clock out option allows you to send midi clock messages throughout the available MIDI outputs. Use Sync to clock in to sync DRC to an external clock source.

You can filter the MIDI channels inputs individually by ticking the boxes numbered from 1 to 16. When a channel is off, the routed destination inputs will be ignored. Use the clear and select all options to activate/deactivate all the channels.

Voices

When playing the piano, 10 "voices" can usually be played simultaneously. Voices defines the total polyphony of DRC, this means the amount of notes that can be played simultaneously. A higher polyphony means a higher the CPU load. This is critical when running the synthesizer in older computers, or Android devices, which may lead to audio dropouts and glitches. If that is the case decrease the number of voices for optimal performance.

Knobs Sensitivity

This setting controls how much you have to slide the finger up or down to rotate a knob from minimum value to maximum value. This may be relevant depending on the screen size of the used device. For instance, you might want to lower the knob sensitivity on a phone and increase it on a tablet.

Color Schema

This feature lets you customize the look and feel of DRC, by changing the color used for details and highlights.

Brightness mode

Use this feature to invert the color polarity of the user interface. By default the brightness mode is dark. When using the synth under intense ambient light (eg: outside on a sunny day) you might want to toggle the brightness mode.

Background Audio

Use this option to determine if the synthesizer engine keeps running when the app is on background. When on, you are able to play the synthesizer with an external midi controller when using other apps. This option is disabled by default.

Ableton Link (iOS only)

Ableton Link is a technology that keeps devices synced in time over a local network, so you can forget the hassle of setting up and focus on playing music.

There are numerous iOS apps that have this technology integrated, thus making it possible to sync all app's tempo effortlessly. By default Ableton Link is disabled. Use this option to enable it.

Patches

The patch browser is divided in three columns: Banks, Patches and Filter. Three banks are available by default:

• Factory - the presets included by default in DRC.
• Favorites - your selected favorite presets.
• Local - The bank where your saved presets are stored.

Patches

This section allows you to navigate through the patches of a certain bank. Touch a patch to select it. If you want to select it to your favorites, tap the star icon on the right side of the the patches name.

Filter

Use this section to filter by tags the patches listed.

Factory presets

Factory presets are the presets included by default in DRC. You can select them by clicking, or by using the arrows on the top bar allowing you to browse through the database.

• Local - Click the plus button beneath the arrows on the top bar, to store presets in DRC locally. A dialogue box will open allowing you to name or rename the patch and create it's tag filters for simplified search.

Oscillators

The Oscillators are the foundation of any subtractive synth. They create harmonically rich waveforms (or simpler ones) which get “sculpted” as the sound passes from module to module.

You can decompose any periodic waveform as a bunch of sine waves or harmonics (this is called Fourier Series). A complex waveform (such as Sawtooth, Square or Triangle) can be described as a sum of harmonics or sine waves.

The first harmonic gets called the fundamental, all other harmonics will be multiples of the first. You can also group harmonics as being even or odd. The simplest waveform is the Sine Wave composed of only the fundamental frequency.

The Sawtooth waveform is the richest classic periodic waveform composed of all harmonics both even and odd. These harmonics get lower in amplitude as they grow higher in frequency, but nevertheless, mathematically speaking, they are of infinite number, getting infinitely smaller as you go.

The Square Waveform is composed of only odd harmonics as is the Triangle Waveform. But these two waveforms differ in the way in which the harmonics are attenuated as they grow, being a lot more attenuated in the Triangle.

A non periodic waveform such as White Noise, in particular, is composed of every possible frequency with every possible amplitude distributed over time.

You use the Filter to alter the frequency content of the waveforms, and the VCA to alter the amplitude. These changes can be made static or can be made dynamic by using modulation sources such as the EG’s (Envelope Generators) or LFO’s (Low Frequency Oscillators).

We provide 4 different and simultaneous sound sources: 2 oscillators, 1 sub-octave oscillator and 1 noise source. There is also an additional pseudo sound source which reaches the MIXER, the RING (Ring Modulation), and this waveform is not a source per se but a product of the multiplication between OSC 1 with OSC 2.

There are 5 TABs in this panel: OSC 1, OSC 2, SUB/NOISE, MOD and PERF.

Oscillator 1

OSC 1 is the default sound source in DRC and is the one that in a sense defines the pitch of the synthesizer. This Oscillator has some unique capabilities such as the ability to change the Pulse Width of the Square Wave and to do Pulse Width Modulation, but lacks for instance the ability to detune. In DRC you detune OSC 2 in relation to OSC 1 and the frequency of the Sub Oscillator is tied to the frequency of OSC 1.

Parameters

• WAVEFORM - select the waveform being produced in the oscillator. You can choose between SAW (sawtooth), SQR (square), TRI (triangular), SIN (sine)

• SAW - The Sawtooth waveform is the richest of all periodic waveforms being produced on DRC’s Oscillators. It is made of all harmonics, both odd and even. If you have more harmonic content to begin with you have more material to be able to sculpt with the filter down the line.

• SQR - The Square waveform is made of only odd harmonics. It is less harmonically rich than the sawtooth, but nonetheless a very useful and nice sounding waveform. A pure square waveform is very easy to produce electronically and so, very widespread use of it was made in cheap electronic sound devices.

• TRI - The Triangular waveform, like the Square wave, is only made of odd harmonics, but in a much lower quantity. This makes the triangular waveform much less rich harmonically. It is a subtle waveform that is works great with less aggressive filtering.

• SIN - The sine wave is the simplest, most pure waveform DRC can produce. It consists of only one harmonic, called the fundamental. It is a very “delicate” sounding waveform. In DRC we use a lot of saturation stages and so, a sine wave is almost always a little bit saturated, which gives it a richer tone and more harmonic content to filter out than usual.

• OCTAVE - The OCTAVE selector allows for you to choose the base octave of the oscillator. Here you can dial between -3 to +3 octaves.

• P. WIDTH (SQR only) - Pulse Width defines the duty cycle of the Square waveform, which changes its harmonic content. At the middle of the travel you have 50/50 duty cycle which represents a pure square wave. At the extremities you have a very small positive or negative going pulse.

• PWM LFO1 (SQR only) - PWM means Pulse Width Modulation. This slider allows you to modulate the pulse width or duty cycle of the waveform with the output of LFO1. This modulation is superimposed on the pulse width you define in the P. WIDTH slider. This modulation creates a very rich and evolving sound. To change the modulation frequency you have to change LFO1 Frequency in the MODIFIERS panel, LFO1 tab.

Oscillator 2

OSC 2 is similar to OSC 1 but with 3 additional parameters.

OSC 2 additional parameters

• SEMITONE - Here you can increment one semitone (one note) at a time the pitch of OSC2. You can make pseudo chords this way, and in conjunction with the FINE knob which spans +-1 semitone and the OCTAVE knob, you can seamlessly tune every possible frequency in the musical spectrum.

• FINE - The Fine knob allows you to fine tune the oscillator pitch in a very precise way. The entire range of the knob only spans one semitone, so in conjunction with the Pitch knob you can reach every possible detune amount (frequency) between OSC 1 and OSC 2 with a lot of precision. Detuning OSC 2 in relation to OSC 1 creates a beating effect which adds a lot of richness to the sound.

• SYNC - The Sync toggle button allows for you to sync OSC 2 with OSC 1. Syncing works by resetting the OSC 2 phase (going back to the beginning of OSC 2 waveform) whenever OSC 1 waveform repeats itself. Fine tune is very useful to take full advantage of this effect, try it.

Sub Oscillator and Noise Generator

In this TAB you control the Sub Octave Oscillator and the Noise generator section of the Oscillators. The Sub Octave Oscillator is an auxiliary oscillator used to fatten the sound. In analog synths it is derived from one main oscillator, usually OSC 1, by doubling consecutively its period, which is very easy to do with logic integrated circuits. Here things work a bit differently and we are able to provide different waveforms at the same processing cost, so, why not. The Noise Generator outputs White Noise, which is random static noise. Noise is used to give texture to sounds. In DRC the Noise can be Filtered in order to give more noise flavours with less high frequency content.

Parameters

• WAVEFORM - The WAVEFORM toggle button changes the waveform of the Sub Octave Oscillator allowing you to choose from Square, Sawtooth and Sine waveforms.

• OCTAVE - This knob changes the octave of the SUB Octave Oscillator. The SUB Oscillator frequency is always relative to OSC 1 frequency and goes from -1 octave to -3 octaves below OSC 1.

• NOISE BANDWIDTH - The NOISE BANDWIDTH knob allows for the noise output to be filtered with a 6dB / oct low pass filter. This can create a continuous flavour of noise from White Noise to Brown Noise.

• WAVEFORM - The WAVEFORM toggle button changes the waveform of the Sub Octave Oscillator allowing you to choose from Square, Sawtooth and Sine waveforms.

• OCTAVE - This knob changes the octave of the SUB Octave Oscillator. The SUB Oscillator frequency is always relative to OSC 1 frequency and goes from -1 octave to -3 octaves below OSC 1.

• NOISE BANDWIDTH - The NOISE BANDWIDTH knob allows for the noise output to be filtered with a 6dB / oct low pass filter. This can create a continuous flavour of noise from White Noise to Brown Noise.

Modulation

In DRC you can modulate the pitch (note) with LFO’s (Low Frequency Oscillators) and EG’s (Envelope Generators). In this TAB you can choose modulation sources and decide what gets affected by the modulation. You have two main modulation sources SRC1 and SRC2 and a common destination for both sources (OSC1, OSC2 or BOTH).

Parameters

• SRC 1 The SRC1 toggle Buttons turn on or off the LFO1 and EG1 Sources. You have an AMOUNT Knob associated to these sources. Basically you can choose which modulation source is active and in what dose it will affect the oscillators pitch.

• SRC 2 This works like SRC1 but now you can choose two different modulation sources: LFO2 and EG2.

• DESTINATION The destination toggles allow for you to choose if the modulation sources will affect OSC1, OS2 or BOTH Oscillators pitch.

Performance

The PERF tab contains parameters relating to the performance settings of DRC oscillators.

Parameters

• MODE - Choose one of the following voice modes:

• Polyphonic - One voice per note played, multiple notes can be played simultaneously, limited only by the global voice settings.

• Mono - One voice per note played, but only one note can be played at once. The last played note will have priority over any other note still pressed.

• Unison - all the voices will play the same note resulting in a richer sound.

• TRANSPOSE - This setting allows you to shift the global base note of DRC within a range of -24 to 24 semitones.

• PORTAMENTO - Toggles Portamento feature ON or OFF

• TIME - (If Portamento is ON) this defines the time it takes for a note to pitch slide to the next note played.

• LEGATO - Toggles Legato style note transitions ON or OFF

Filter

If you consider the oscillators the soul of a synth, the filter is definitely the body. It restricts the soul but at the same time it adds a whole different dimension unattainable by any other mean. A lot of attention and time was dedicated to the design of the DRC filters and a lot of the overall character comes from this piece of code. We analyzed lots of classic analog Ladder Filter Topologies, analog Multimode Filter implementations and tried to capture every little nuance of the most interesting examples.

In the FILTER PANEL you have access to every parameter regarding the Filter module and the VCA (Voltage Controlled Amplifier) module.

Pressing FILTER will bring you back to the default tab which is the MAIN TAB. In DRC the audio path is as follows: OSCILLATORS > MIXER > FILTER > VCA > FX

Main Controls

This tab is where you can access the main filter controls. The focus here is to be able to control the filter parameters in real time, with big knobs and an overall uncluttered interface. This is key to enhance expression and sound sculpting in real time. The MAIN TAB also the default tab for the FILTER PANEL, so you can press MAIN or FILTER to get here quickly.

Parameters

• CUTOFF - This knob controls the cutoff frequency of the filter. The cutoff frequency is the frequency where the filter begins doing its job cutting frequencies. The basis of Subtractive Synthesis is that you generate an harmonically rich waveform in the Oscillators and then filter out frequency content in the Filter.

• RESONANCE - The resonance occurs when the output from the filter is fed back to the input internally (with some caveats), creating a peak at the cutoff frequency. The RESONANCE knob controls the amount of resonance you create this way. IT is used to make the filter more aggressive. In the L4P Filter Type the Resonance is able to create such a peak that it creates self oscillation converting the filter in a sine wave oscillator. Remember you will only hear it if you press a key because you need to open the VCA in order to hear what comes out of the filter, and if you use KBD (keyboard follow) modulation you can play this filter.

• EG 2 - This slider controls the amount of the EG 2 (Envelope Generator 2) that affects the filter cutoff. This is the most important modulation to the Filter and thats the reason it is placed in the MAIN TAB, and all the other modulations are in the MOD TAB.

• LFO 2 - This slider controls the amount of modulation that is applied to the EG 2 parameter allowing more intricate filter results. You change all the characteristics of the LFO2 waveform in the MODIFIERS PANEL > LFO 2 TAB.

• MODE - The MODE toggle button allows you to switch between all the different Filter Modes DRC offers:

• L4P - 4 pole Lowpass Filter (24dB/oct attenuation) - A Lowpass Filter type allows low frequency content to pass through cutting high frequency content at a rate defined by the number of poles.This filter type is a digital implementation of the Moog Transistor Ladder Filter.

• L2P - 2 pole Lowpass Filter (12dB/oct - thus less frequency cutting effect than the L4P) - This filter is a digital implementation of an analog multimode filter topology in the Lowpass Mode. A Lowpass Filter type allows low frequency content to pass through cutting high frequency content at a rate defined by the number of poles.

• B2P - 2 pole Bandpass Filter (12dB/oct) - The 2pole bandpass filter allows only a restricted frequency band to pass throw cutting frequencies below and above at a 12dB per octave rate. In this filter the Resonance has a particular importance as it somewhat defines the bandwidth that can get through the filter.This filter represents the bandpass output of the analog multiband filter implementation.

• H2P - 2 pole Highpass Filter (12dB/oct) - A 2 pole Highpass Filter type allows high frequency content to pass through cutting low frequency content at a rate defined by the number of poles. This filter represents the highpass output of the analog multiband filter implementation.

• NOTCH - A notch filter is a filter that cuts a very narrow band of frequencies, you can think of it as a more aggressive form of bandpass, that instead of allowing a band to pass it cuts that band out. This filter is also a product of the multimode filter topology used in the other filters (except L4P). It gives the sound a sort of hollowness that can be interesting in some situations, if you use an LFO to modulate this filter you will get an effect that resembles a phaser. Try using with low resonance.

Modulation

The MOD TAB represents the Filter Modulation Section of DRC. You use the sliders to inject modulation in the Filter. All modulation goes to the Filter Frequency with the exception of VEL (Velocity - the velocity or force with which you press a keyboard key). VEL injects this force sensing control voltage in the EG 2 AMOUNT which in turn affects the Frequency, but in this way with an envelope instead of a constant voltage.

Controls

• LFO 1 - This slider controls the amount of LFO1 control voltage that affects the Filter Cutoff. You change all the characteristics of the LFO1 waveform in the MODIFIERS PANEL > LFO 1 TAB.

• LFO 2 - The same as LFO1 but this time the slider controls the amount of LFO2 control voltage that affects the Filter Cutoff. You change all the characteristics of the LFO2 waveform in the MODIFIERS PANEL > LFO 2 TAB.

• OSC 2 - This slider allows you to inject the output waveform of OS2 as a control voltage to the Filter Frequency. This type of modulation is a bit more uncommon and produces a very characteristic harsh texture to the sound. Try adjusting the OSC 2 COARSE and FINE parameters to get interesting interactions between the sound that enters the Filter and OSC 2 Modulation. A very sought-after synth that uses this technique is the ARP 2600 semi modular synth.

• KBD - The KBD slider allows you to track the Filter Frequency to the notes you are playing in the keyboard. You can think of it as a control voltage that is dependent of the note that you are playing and is injected in as a Filter Cutoff Modulation. This allows for you to dial a sound that being somewhat filtered, is still more or less consistent as you go up or down in the keyboard. This slider is bipolar meaning that you have no effect in the center, as you go up you give a positive effect and going below half way you are dialing a negative effect.

• VEL - The VEL slider allow you to control EG 2 AMT with a control voltage that is analogous of the velocity or force with which you press a key in a keyboard (a midi keyboard that has velocity sensing). This is a lot more expressive than to merely inject this control voltage in the Filter Cutoff. This slider is bipolar meaning that you have no effect in the center, as you go up you give a positive effect and going below half way you are dialing a negative effect.

Voltage Controlled Amplitude

Parameters

• LFO 1 - This slider controls the amount of LFO1 control voltage that affects the amplification factor of the VCA. You can use LFO’s here to make tremolo kind of effects. You can change all the characteristics of the LFO1 waveform in the MODIFIERS PANEL > LFO 1 TAB.

• LFO 2 - The same as LFO 1 but this time the slider controls the amount of LFO2 control voltage that affects the amplification factor of the VCA. You can change all the characteristics of the LFO2 waveform in the MODIFIERS PANEL > LFO 2 TAB.

• EG 1 - EG 1 is the default modifier of the VCA. The EG 1 slider controls the amount of EG 1 that modulates the amplitude of the sound. You can use it to make fast abrupt tones or slow and sustained ones. You use it mostly maxed out as per default, but you can dose it in conjunction with EG 2 amount to make more intricate envelope curves. You can change all parameters regarding EG 1 in the MODIFIERS PANEL > EG 1 TAB.

• EG 2 - This slider allow you to inject EG 2 (the EG that is hardwired to the Filter) as an amplitude modulation of your signal. You can change all parameters regarding EG 2 in the MODIFIERS PANEL > EG 2 TAB.

• KBD - The KBD slider allows you to track the VCA Amplitude to the notes you are playing in the keyboard. You can think of it as a control voltage that is dependent of the note that you are playing and is allowed to control the VCA Amplitude. This make sit possible to increase or decrease amplitude as you go up or down the keyboard which can be very useful in some circumstances, mostly when you are also using KBD modulation in other places. This slider is bipolar meaning that you have no effect in the center, as you go up you give a positive effect and going below half way you are dialing a negative effect.

• VEL - The VEL slider allow you to control the VCA Amplitude with a control voltage that is analogous of the velocity or force with which you press a key in a keyboard (a midi keyboard that has velocity sensing). This is analogous of what happens in most instruments which produce a louder sound as you play them harder. This slider is bipolar meaning that you have no effect in the center, as you go up you give a positive effect and going below half way you are dialing a negative effect.

Mixer

The MIXER is a central hub to where all sound sources go. Here the Oscillators get mixed before being sent to the Filter. It's in the mixer that you choose the balance between all the available sound sources. In DRC you are able to saturate the input of the FILTER and this has an effect not only in the overall tone but also in the perceived balance between different sources. After reaching a nice balance between sources you can take advantage of the PRE GAIN fader (pre-filter) to control how much signal goes to the FILTER input.

Its also in the MIXER panel that you find all the available DRC Effects. Effects are essential to add even another layer of sonic awesomeness to the DRC sound. We thought that it would be a waste of time and effort if we simply added some bread and butter DSP effects to the synth engine, it would serve no purpose to degrade what is already a really great sound. So, having access to a lot of amazing analog synths and effect boxes, we decided to study them, in order to bring out what's best in each one of them, always adding some interesting twists to the plot.

Amp

Parameters

• MASTER - The Master fader controls the final volume of DRC after the sound passed thru all modules.

• PRE-GAIN - With this slider you control the amount of gain given to the output of the MIXER. This affects the amount of saturation produced in the input of the FILTER and also affects the overall perceived balance of the sources.

• OSC 1, OSC 2 and SUB - These sliders controls the amount of the respective Oscillators being mixed and sent to the Filter.

• RING - OSC 1 waveform gets multiplied with OSC 2 waveform producing what is known as Ring Modulation Effect. This creates a very distinct product waveform that is very sensitive to micro differences in pitch between the two Oscillators. Try changing FINE settings of OSC 2 to explore this effect. This a somewhat aggressive waveform that will fatten the overall sound.

• NOISE - This slider controls the amount of NOISE being mixed and sent to the Filter.

Delay

The Delay effect of DRC is unique. The delay topology is inspired in classic BBD analog delay and Tape Delay topologies, but with a bunch of little tweaks that make it a very simple yet extremely powerful tool. The DRC DELAY uses modeled wow, flutter and noise typical of tape delay machines to give it a very pleasing characteristic with feedback pushed to the limits. The feedback repetitions are filtered and the cutoff frequency can be tailored from bright to very dark altering completely the behaviour of the DELAY. There are actually two separate delay lines working together and there is the possibility to SPREAD the time between left and right delay lines. There is a very unique trick employed here that makes the DELAY stereo image interact with the CUTOFF slider. On top of that this DELAY can be synced to the tempo and tuned to the notes being played, the later makes possible the use of the delay line as a "metalizer" effect.

Controls

• SYNC - The sync toggle button allows for the DELAY time to be synced to the main BPM. Press the button to change the slider to measures, ranging between 1/128 Beats and 2 Beats.

• KBD - The KBD toggle enables the tuned mode of the DELAY. In this mode the TIME is related to the note being played. If you play an octave above, the DELAY TIME is halved, if you play an octave below the DELAY TIME gets doubled. If you use long delays the effect is interesting but subtle, you notice a variation in the delay time, and it can be actually very interesting as it contributes to variation along the keyboard, but you cannot easily discern that it is actually musically related to the note being played because the human brain does not perceive such long delays (above 40ms) as being a musical frequency or note. If you use a very short DELAY TIME, then this effect grows a whole new interesting dimension to it, and becomes really tuned and playable. the brain starts to perceive the delay as a note and the sound becomes metallic and ringing. You can even shut down all oscillators and play only with the DELAY and FEEDBACK.

• LFO 1 - The DELAY TIME can be modulated by LFO 1. You use the LFO 1 slider to dose the amount of modulation. To change the characteristics of the modulation waveform you need to go to the respective LFO 1 PANEL. You can achieve a lot of different things with this modulation, from subtle Wow like detuning effects to crazy Shimmer effects. Fast transitioning waveforms such as square wave have a less pronounced effect here.

Note SHIMMER DELAY: If you decrease linearly a DELAY TIME you get an increasingly higher pitched output from it. You can use a Sawtooth waveform to achieve this, albeit there is an audible transition at the repetition of the waveform, but it is most of the time actually increasing the pitch steadily. This effect, even with some artifacts is the base of the Shimmer Effect. There is a way to get rid of this unpleasing transition artifact, but it is not applicable to the DRC DELAY. To achieve this effect try modulating a long FEEDBACK DELAY with a somewhat fast SAW waveform from LFO 1. This will Shimmer for sure.

• TIME - This slider controls the time of the DELAY. Like in a BBD or Tape Delay, here, screwing with TIME changes pitch of the delayed signal. TIME can be modulated using the LFO 1 slider.

• FEEDBACK - The process of feedback, as the name implies, consists of feeding back the output of the delay line, back to its input. You increase the number of repetitions this way, but you can also achieve uncontrolled repetition growth, even without any sound input, because of the inherent self noise modeled into the DELAY. This is exactly what happens in real life analog delays, and a very powerful and aggressive tool. Try adjust FEEDBACK until you achieve a sustained scream from the DELAY and then play with the TIME slider.

• CUTOFF - This slider allows for you to adjust a Lowpass Filter located at the output of the DELAY. Its after this Filter that the repetitions are fed back to the input so it has a major impact in the overall sound.

• SPREAD - The DRC DELAY uses two distinct DELAY Lines. One is for the Left Channel and the other for the Right Channel. Using the SPREAD slider you add a little bit of extra delay to one the the delay lines, creating a powerful Stereo Effect. There are some particularities with this, because we made the DELAY such that the Filter CUTOFF interacts with the SPREAD. Listen to the difference between High CUTOFF and Low CUTOFF in a very long FEEDBACK DELAY with SPREAD at maximum.

• AMOUNT - Here you can dose the AMOUNT of DELAY being mixed with the original, clean signal.

Reverb

Reverb is what defines the characteristic sound of a particular space, it's made of the build up of all the different reflections on surrounding surfaces. Your synth can sound great without it, dry as a bone, but one out of ten times, a little bit of reverb contributes to make a good patch sound even better/bigger, specially when not buried deep in a cluttered arrangement.

The REVERB in DRC is not trying to emulate any particular physical space, not even a Plate (a kind of electromechanical old school reverb, although it can resemble one in some aspects). It is very lush and great for giant outer space sci-fi landscapes, which might sound artificial, but what are synths for if not to create great unrealistic sounds that seem came from another planet? We made it so outrageously big that it can actually grow beyond decay. It has internal modulation contributing for added life and complexity to the sound, or to even more abused chorus like effects as you approach the limits of the controls. We also made possible for the AMOUNT to be modulated with LFO 2 after experimenting with a DIY analog modular setup that sounded great.

Controls

• LFO 2 - This slider controls the amount of LFO 2 that is used to automate the DECAY of the REVERB, try using it with a F S&H (Filtered Sample and Hold) in LFO 2 for added weirdness.

• DECAY - This slide control the time it takes for the REVERB to perish. If you go all the way to the extreme maximum region the REVERB will even grow pass decay and start to feed itself back. This can be bad to your speakers or ear drums if care is not taken, pay attention! There is some interaction between DECAY and DAMPING, as DAMPING affects internal feedback frequency response, and with that the all around gain of the REVERB structure.

• DAMPING - This is a term used to describe the sound damping effect of wall materials in real rooms. In DRC REVERB the DAMPING slider changes the frequency content of the reflections, like in a room, but in a simpler way, nonetheless the effect is alike and it also affects the REVERB DECAY time.

• MOD - This slider controls the amount of internal MODULATION applied to the reflections inside the REVERB. This modulation is independent of the LFO’s. If you use just a little modulation, the reverb gets richer, maintaining naturality, if you abuse it, the REVERB becomes a hybrid Chorus/Reverb kind of effect.

• AMOUNT - This slider controls the amount of reverb being applied and works like a dry/wet control. At minimum you have zero REVERB, at max you only have REVERB and zero dry sound.

Chorus

Chorus in the analog synth context is an effect which thickens the sound and also widens the stereo image. It accomplishes this by mixing the unprocessed signal with a small delay that is modulated. Many great synths and string machines have used it to capture the lushness and power of a whole ensemble. In DRC we implemented two types of chorus, both true stereo inspired in the best analog examples we were able to put our hands on.

Controls

• MODE - The MODE toggle button switches between the two available modes which are ANA and DIM. The two modes are identical but the DIM has some extra complexity cross feeding parts of the spectrum creating a more in your face sound while maintaining the overall desired effect.

• RATE - This slider controls the speed or rate at which the Chorus works, you can have very slow evolving effects or very unrealistic but still great super fast chorus going on.

• DEPTH - The DEPTH slider accounts for the depth at which the delay line is modulated. You can dial a subtle or an aggressive modulation with it. In a sense, DEPTH and RATE are somewhat related. As you increase RATE there is an apparent increase in DEPTH which you can compensate with this fader.

• DELAY - This slider adjusts the amount of initial delay that gets modulated. Increasing it gives a sense of a bigger chorus, but at some point you lose the illusion of unity and start discerning an actual delay. All this depends on the type of sound being processed. Long evolving, transient free sounds are more forgiving. Fast transient rich sounds require shorter initial delay.

• ENABLED - This toggle switch ON or OFF the effect.

Modifiers

In this panel you get to control all the available modulation sources (EG 1, EG 2, LFO 1, LFO 2) and also the Arpeggiator. This various modulations are then fed through the synth and give life and movement to the sounds. They are fed to the Oscillators, Filter and even to the Delay and Reverb Effects.

EG’s (Envelope Generators) are essential to make notes sound and behave like an instrument is supposed to sound, giving the notes a defined beginning, duration and eventually an end.

The Arpeggiator is a module which takes the notes you play and converts them to a rhythmic progression of notes, which are played automatically in sync with the master tempo of the DRC or of your project (if used in the context of DAW - Digital Audio Workstation).

Envelope Generators

EG stands for Envelope Generator. EG’s generate a control signal that resembles the envelope of real instruments (or not), generated when you hit it, or pluck a string, or whatever. You can control 4 major parameters, ATTACK, DECAY, SUSTAIN and RELEASE and with these construct any kind of sound behaviour.

We used a novel method which even gave the name to the whole synth (DRC - Digital Resistor Capacitor) to make our envelopes. This gives them a completely foolproof analog behaviour, because they are truly analogous of a real ADSR that charges a capacitor through a resistor.

In DRC you have two EG’s, one used by default in the VCA and the other hardcoded to the Filter Envelope.

Parameters

• ATTACK - The attack is the initial slope of the ADSR envelope. This slider defines the time it takes for the envelope to grow from 0 to its maximum amplitude. As the name implies it mimics the attack characteristic of instruments. You can dial fast, almost instantaneous attacks, or very slow ones. If you use the fastest possible attack you may hear a click in the beginning of each note, this is because you instantly switch on the VCA and it picks the sound waveform at a random point which may not be when it is crossing zero, this creates a click, typical of analog synths. If you want to avoid this click simply add a little bit of attack.

• DECAY - The Decay slider controls the amount of time the envelope takes to go from its maximum value, after climbing the attack slope, to the value dialed in the SUSTAIN slider.

• SUSTAIN - As long as you are pressing a key, the place where the envelope amplitude rests is the SUSTAIN level. The envelope does the Attack and Decay movements and rests at SUSTAIN value, so you can say this is the actual nominal level of a note pressed. If you use a low sustain you emphasise the ATTACK and DECAY part of the envelope giving rise to more percussive results.

• RELEASE - The RELEASE is the time it takes after you released a key, for the envelope to go from the SUSTAIN level to zero. It's the tale of the note if you like.

• A. VEL - This knob allows you to relate the velocity (force) with which you press a key to the ATTACK time. At mid position it does nothing. Turning it clockwise increases ATTACK time as velocity increases. Turning anti-clockwise decreases ATTACK time as velocity increases.

• R. VEL - This knob allows you to relate the velocity (force) with which you press a key to the RELEASE time. At mid position it does nothing. Turning it clockwise increases RELEASE time as velocity increases. Turning anti-clockwise decreases RELEASE time as velocity increases.

Low Frequency Oscillators

LFO stands for Low frequency Generator. As the name implies this is a special type of Oscillator which creates a slow moving waveform, below audible. This waveforms are used to control all sorts of parameters throughout the synth. This gives life to sounds, making them evolve in time. We use 2 LFO’s in DRC and both have many different waveforms for you to choose from. LFO’s can be delayed and Synced to master tempo.

Parameters

• WAVEFORM - This toggle button chooses between the different waveforms. You can choose between 6 different waveforms: SIN (Sine), SQR (Square), SAW (Sawtooth), TRI (Triangular), S&H (Sample and Hold) and F S&H (Filtered Sample and Hold). These are the usual waveforms, also present in the audio Oscillators, with the exception of Sample and Hold in its plain forma and Filtered form. Sample and Hold is made by sampling at a slow rate the amplitude of a random or noise waveform. The result is a stepped random waveform. Filtered Sample and Hold is a king of Sample and Hold, but instead of steps the value ramps from one random position to the other smoothly.

• DELAY - The DELAY in the LFO is the time it take from the moment you press a key for the LFO to start kick in. Also ramps up smoothly. This is very useful for instance to make string vibrato kind of sounds.

• PHASE - This slider ties the phase, or the beginning of the oscillation of the LFO to a key being pressed. If free, the LFO runs free unaware of any keys being pressed. If in KEY mode, it resets itself anytime you press a key, this can be crucial in some situations allowing you to have a more defined and predictable effect.

• RATE - This knob controls the frequency at which the LFO oscillates. It behaves differently depending if SYNC toggle is pressed or not. If SYNC is ON it allows only for the frequency to be changed in defined fractions of the master tempo and not continuous frequency values.

• SYNC - This toggle ties the frequency of the LFO to defined fractions of the master tempo (BPM. You need to manipulate the RATE slider to change the desired fraction. This feature is used to make synchronized movements with the sound. The values range from 2 Beats to 1/128 Beats.

• LFO 1 (LFO 2 Only) - This additional slider, only in LFO 2, allows for the modulation of LFO 2 with the waveform coming out of LFO 1. This way you can make LFO 2 behave in an even more dynamic way, changing it rate with time.

Arpeggiator

Parameters

• ENABLE - activates/deactivates the arpeggiator module.

• MODE - allows to choose in-between different melodic patterns for the triggered chords; currently, five modes are available:
• UP (plays the notes in ascending order)
• DOWN (plays the notes in descending order)
• UP/DOWN I - plays the notes in ascending followed by descending order
• UP/DOWN II - just like UP/DOWN I but repeats the previous before inverting direction
• RANDOM - the notes order are played in a stochastic sequence

• GATE - defines the time each note is on/off at each arpeggiator trigger period. Musically this results in more staccato or more legato articulation of the played notes.

• STEPS - allows to choose the number of steps in the generated arpeggio; if for instance you play a single note, this will determine the number of octaves arpeggiated on top and on bottom of that note (depending on the selected mode).

• RATE - controls the trigger time interval for the arpeggiator (i.e.: 1/4th note, 1/8th note, 1/8th note triplet, 1/16th note, 1/32nd note, etc.)

• SYNC - syncs the rate to synthesizer tempo.

• HOLD - chooses whether to hold the notes, allowing to sustain them until pressing the next key

Performance modes

As tools for performance, DRC features two modes: a Piano Keyboard and a Chorder.

These two modes can be toggled by pressing the button on the bottom left corner of the screen, the one marked with a red square on the next picture.

Piano Keyboard

The Piano Keyboard features an adjustable view-port, with pitch bending, modulation wheel and HOLD function which allows the sustain of notes, just like a sustain pedal.

The adjustable view-port located as a line right on top of the keyboard, allows the user to adjust the amount of keys available on the keyboard to play, thus making each one of these keys bigger or smaller. This is done by dragging any of the handlers marked on the picture above with blue squares to the left or to the right. It also allows the adjustment of the visible notes region by dragging the line left or right.

To open the Piano Keyboard configuration, a settings button is located right above the HOLD button (marked on the first picture with a green square). This section is a dedicated setup area for extra modulations and keyboard setup. This is where you control the PITCH BEND range and destination, and what is affected by the MOD.WHEEL and AFTER TOUCH. This section also features a keyboard SCALE setup panel from which you can configure the notes included in the Piano Keyboard. Lets cover them in detail.

Keyboard Scale Tab

Use this panel to configure the keyboard layout. You can select notes from a predefined scale or decide which notes make part of the Piano Keyboard. This configuration is saved along with the preset.

Mod Wheel & After Touch Tab

In order to add an additional layer of complexity or tweaking we provide the ability to enhance the already existing modulations through the use of the mod wheel. First you determine the ideal recipe of modulations for your preset, then you use this panel to increase or decrease the amount of modulation given by using the mod wheel or the after touch of an external MIDI controller. The controls are the same for each modulation type.

Controls

• CUTOFF - Increase or decrease the amount of FILTER CUTOFF. 1 at the top, -1 at the bottom, 0 at the center (no effect). Double tap to reset.

• RESONANCE - Increase or decrease the amount of FILTER RESONANCE. 1 at the top, -1 at the bottom, 0 at the center (no effect). Double tap to reset.

• LFO 2 RATE - Increase or decrease the amount of LFO 2 rate. 1 at the top, -1 at the bottom, 0 at the center (no effect). Double tap to reset.

• VBR LFO 1 - Add vibrato effect based on LFO 1 rate. 1 at the top, 0 at the bottom. Double tap to reset.

• OSCS MOD - Increase or decrease the amount of modulations on OSC1, OSC 2 and SUB oscillators. 1 at the top, -1 at the bottom, 0 at the center (no effect). Double tap to reset.

• FILTER MOD - Increase or decrease the amount of filter modulations. 1 at the top, -1 at the bottom, 0 at the center (no effect). Double tap to reset.

• TRANSPOSE - Transpose up or down the pitch. 1 at the top, -1 at the bottom, 0 at the center (no effect). Double tap to reset.

Pitch Bend Tab

• DESTINATION - Here you select the destination of the pitch bend modulation. It can affect OSC 1, OSC 2, FILTER or all of them at once.

• RANGE - This is the semitones range of the pitch bend control. You can choose between 0, 2, 3, 5, 7, 12 and 24 semitones.

Chorder

The Chorder mode has two main parts: the honeycomb keyboard which allows you to play three different chords (Minor, Major and Dom7) **and the strummers **that allow a strumming type of play like that of a guitar.

The honeycomb keyboard has two modes that can be toggled by pressing the key labeled PLAY on the bottom left side of the screen next to the strummer. This modes are PLAY and SELECT:

• Play Mode - each honeycomb selects and plays the specified chord at the same time.

• Select Mode - each honeycomb only selects the base key to form the chord which will be played on the strummer.

You can hold a chord, by pressing the HOLD button (same as using a midi sustain pedal) just below the PLAY button.

Right below the HOLD button, we have the melodic interval combo box which allows one to select the interval in which the notes on the Honeycomb** **keyboard progress.

On the bottom left corner, right under the interval select button we have the PAN function which allows us to pan the Honeycomb cells around, suiting each performance needs, particularly on the full screen mode in which the cells are much bigger and can be outside of the viewport.

To switch across different octaves on the Chorder keyboard, there are arrows buttons located on the bottom right corner of the screen.

Right above the arrow buttons to change the octave there is a performance adjust button (marked with a green square on the first picture of this page) allowing a full screen of the Chorder's play area.

Troubleshooting

DRC is telling me I need to purchase the software but i have already purchased (mobile only).

1. Try to restore purchase - Ensure that you have your device configured with the same account you have made the purchase with. Open DRC, open menu, choose Store, tap Restore Purchases.

2. Restore purchases doesn't do nothing - Sometimes, in some devices, Restore Purchases is not working. If this happens, choose to purchase the same item (you won't be charged again).

3. If any of the above don't work - A way to solve this problem might be to log out of the app store in settings, re-log, reboot DRC and try to restore purchase again.

Back to top

Updated on: 12/03/2026