Build Moog DFAM in VCV Rack: Step-by-Step Guide

Introduction

The Moog DFAM, known as the Drummer From Another Mother, is a distinctive semi-modular analog percussion synthesizer. Its unique sound and versatile capabilities have made it a staple in many music production setups. For those who are fans of Eurorack synthesizer modules, replicating the DFAM using VCV Rack can be an engaging and rewarding project. VCV Rack is a free, open-source software that simulates modular synthesizers, providing an excellent platform for both learning and sound design.

This guide will walk you through the process of recreating the Moog DFAM in VCV Rack step-by-step. By following along, you'll learn not only how to build and configure each component of the DFAM but also gain a deeper understanding of modular synthesis. Even if you are new to both the Moog DFAM and VCV Rack, this guide aims to be beginner-friendly while also offering insights that experienced users will appreciate. The guide starts with the basics, like setting up oscillators, and moves towards more advanced features like implementing the hard sync and setting up frequency modulation.

In recreating the Moog DFAM, we'll utilize various modules available in VCV Rack to mimic the hardware features of the original synth. We'll ensure that oscillators, noise sources, filters, and envelopes are accurately represented. Moreover, we will delve into the specifics of sequencer setup, pitch modulation, and fine-tuning that are essential for achieving the classic DFAM sound. This process not only replicates the DFAM's capabilities but also allows for creative customization, letting you tailor the synth to your unique needs. By the end of this guide, you will have a fully functional digital version of the Moog DFAM ready to be used in your musical projects.

Setting Up Oscillators

Begin your journey by setting up the primary oscillators to emulate the foundational sound of the Moog DFAM. The DFAM originally comes with two primary oscillators, so in VCV Rack, we will also employ two Voltage-Controlled Oscillators (VCOs) to achieve this. Start by selecting two VCO modules from the available library in VCV Rack. One popular choice is the VCO module from Bog Audio due to its robust features and quality sound output.

After selecting the modules, properly label them for easy reference within your patch. You can use the text module from Submarine to label the first VCO as "VCO1" and the second one as "VCO2." This step ensures your patch remains organized and easier to troubleshoot if required.

Each oscillator should produce two types of waveforms to closely mimic the DFAM: a square wave and a triangle wave. These waveforms are key to creating the rich and dynamic sounds the DFAM is known for. Connect the square wave output of VCO1 to one input of a switch module and the triangle wave output to another input. Repeat this for VCO2 using a second switch module. This setup allows for easy toggling between waveforms, similar to the original DFAM’s functionality.

Using color coding for your patch cables can also make the process more intuitive. For instance, use a red cable for audio signals, helping you quickly identify critical signal paths at a glance.

By carefully configuring and integrating the oscillators with appropriate labels and switching mechanisms, you now have the basic oscillators ready and set up in your VCV Rack patch. This foundational step primes you for the more advanced configurations that will follow, ensuring a clear and organized approach to building your DFAM emulation.

Adding Noise Source

To introduce a noise element into your Moog DFAM emulation, it's essential to select an appropriate noise module. For this tutorial, we will use the white noise source from the Bog Audio module library. Locate the noise module and place it within your rack setup. This module will serve as the foundation for adding texture and character to your synthesized sounds.

After adding the noise module, label it clearly as "Noise" to maintain an organized workflow. The purpose of using noise in your DFAM patch is to incorporate a range of sound frequencies that add a subtle yet impactful layer to your oscillators' output. The Moog DFAM traditionally utilizes white noise, which features an equal intensity across the audible spectrum, resulting in a consistent hiss that can enrich your drum patterns and overall sound design.

To integrate the noise source effectively, it will need to be routed through a VCA (Voltage Controlled Amplifier) before being sent to the mixer. The inclusion of a VCA ensures that you can dynamically control the amplitude of the noise, either manually or via control voltage modulation. Connect the output of the noise module to the input of a VCA, followed by routing the VCA's output to a channel in the mixer.

Routing the noise through a VCA not only gives you control over its volume but also mimics the Moog DFAM's patch bay feature, which allows the amplitude of the noise source to be modulated using another control source. With this setup, you can easily mix and balance the noise source with the other elements of your patch, such as the oscillators and any subsequent audio processing modules like filters.

Now, with the noise source in your audio chain, you will be able to add a raw and textural layer to your synthesized sounds, enhancing the overall complexity and richness of your Moog DFAM emulation in VCV Rack.

Creating Waveform Switches

Each oscillator in the Moog DFAM can output either a square wave or a triangular wave, and it's essential to replicate this functionality within VCV Rack. To achieve this, we need to add waveform switches. Start by locating the switch module; the one from Bog Audio works perfectly. For our setup, we will require two of these switches, one for each oscillator.

Connect the square wave output of the first oscillator to the "high" input of the first switch. It is helpful to use color coding for ease of identification, with a specific color like red denoting the audio signal. Next, route the triangular wave output of the same oscillator to the "low" input of the switch. Now, you will have the ability to toggle between the square and triangular waveforms easily by clicking the switch.

Repeat this process for the second oscillator. Connect the square wave output to the "high" input and the triangular wave output to the "low" input of the second switch. Again, utilize consistent color coding for clarity.

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The next step is to enable the latch mode on both switches. This will allow the waveform to change with each click, much like the behavior of the Moog DFAM. When you click once, the waveform switches from triangle to square, and another click toggles it back. This gives you a dynamic control similar to the hardware version.

After setting up the waveform switches, you can observe the waveform changes using a scope module to confirm the proper functioning of your switches. This visualization ensures that you are accurately replicating the waveform switches found on the original Moog DFAM. By having these switches in place, you can seamlessly alternate between square and triangular waves for both oscillators, maintaining the authentic DFAM experience as you proceed to the next stages of your setup.

Mixing Oscillators and Noise

After setting up your oscillators and noise source, the next step is to mix these different audio signals. Start by selecting a mixer module, such as the one from Lindenberg Research. Connect the output of each oscillator to separate inputs on the mixer, using a color-coding system for ease of identification; for instance, red for audio signals. The white noise signal should first pass through a VCA (Voltage Controlled Amplifier) before being routed to the mixer. This is crucial because the Moog DFAM includes a control for the noise amplitude via the patch bay, allowing external sources to modulate its level.

Send the output from both oscillators to the mixer inputs. For the first input, connect VCO 1's output from the switch, and the second input will receive VCO 2's output. Take the white noise from the noise module, pass it through the VCA, and finally connect it to the third input of the mixer. By adjusting the levels on the mixer, you can balance the contributions from each oscillator and the noise source, creating a nuanced and dynamic audio signal that mirrors the functionality of the Moog DFAM.

Carefully set the volume levels for each input to avoid clipping and ensure your mixed signal is balanced. This process allows for intricate sound design opportunities, providing a robust foundation for further modulation and filtering. This balanced mixed signal is now ready to be processed through the next stage, which involves adding a filter (VCF), to shape your sound further.

Implementing Hard Sync Feature

Once you've mixed your oscillators and noise sources, it's time to implement the hard sync feature to synchronize the frequency of your second VCO to the first VCO. This feature can add rich harmonic content and dynamic textures to your sound. Start by identifying the hard sync input on the second VCO module. To enable hard sync, you'll need to route the square wave output from the first VCO into the hard sync input of the second VCO.

In VCV Rack, you can achieve this by using a switch module to control the on and off state of the hard sync. Connect the square wave output from the first VCO to the high input of the switch. Then, take the output of the switch and connect it to the sync input on the second VCO. This setup will allow you to toggle the hard sync function on and off by changing the state of the switch.

To ensure your signals are properly managed, label your connections and use consistent color-coding to maintain clarity in your patch. Typically, audio signals might be labeled in red and sync signals in blue, but you can adjust this based on your own system of organization.

With the hard sync in place, you can activate the feature by switching the module on. When active, the frequency of the second VCO will be synchronized to the first VCO, creating those unique, complex sounds characteristic of hard sync synthesis.

This technique can be particularly useful in genres and styles that emphasize aggressive or harmonically rich tones, such as electronic dance music or atmospheric soundscapes. Experiment with the position of your oscillators and the sync to discover a wide array of sonic possibilities.

Setting Up Frequency Modulation (FM)

For frequency modulation, the triangle waveform from VCO 1 will be employed to modulate the frequency of VCO 2. Start by routing the triangle wave output from VCO 1 into a VCA, which allows controlling the modulation amount. The purpose of using a VCA here is to enable dynamic control over the FM amount through a dedicated patch point.

Next, send the output from the VCA to the FM input on VCO 2. Make sure the attenuator for the FM input is opened fully, and you can now manipulate the VCA CV to modulate the FM depth dynamically. In VCV Rack, ensure the FM mode is set to linear as per the Moog DFAM’s specification, providing a more precise and scalable frequency modulation effect.

Once connected, you can experiment with different VCA levels and modulate the frequency of VCO 2 with various external sources, adding layers of complexity to your synthesizer patch and exploring rich, evolving soundscapes inherent to frequency modulation synthesis.

Adding Filter (VCF)

With the oscillators and frequency modulation set up, it is time to integrate a filter, essential for shaping the timbre and character of the synthesizer sound. For this patch, we will use a voltage-controlled filter, or VCF, that replicates the behavior of Moog DFAM’s distinctive ladder filter. The VCF controls the frequencies that pass through, fundamentally sculpting the output sound into warm, smooth, or bright and aggressive tones.

In VCV Rack, we’ll employ the ‘Stairway’ filter by Squinky Labs, known for its Moog-style characteristics and flexibility. Connect the output from the mixer, where the oscillators and noise source are combined, to the input of the Stairway filter. This filter allows for high-pass and low-pass filtering, although it does not offer the same degree of control over the high-pass mode as the original DFAM filter does; it proves to be sufficiently close in operation for accurately emulating the DFAM’s filter behavior.

Next, to enable dynamic modulation of the filter cutoff, we utilize an Attack/Decay (AD) envelope generator. This will make the filter responsive to changes over time, adding movement and expressiveness to the sound. Insert an AD envelope module and route an output from the module into the ‘CV 1’ input of the filter, ensuring modulation cables are correctly color-coded for ease of organization. The amount of envelope modulation is adjustable through dedicated attenuators, which inversely or directly affect the filter's cutoff point, giving a range of effects from mellow swells to sharp, staccato pulses.

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For further control, patch the noise source directly into a second modulation input of the filter. Experiment with different noise types, such as white noise, to introduce texture and complexity into the filtering process. The noise level and influence over the filter’s cutoff can be adjusted to create varied sonic landscapes.

With the filter setup, the next step involves routing the output of the filter to a Voltage-Controlled Amplifier (VCA), transforming the processed audio into a final output signal ready for mixer integration or further processing. This ensures all elements of the synthesized sound – from raw oscillator waves to modulated noise textures – blend harmoniously, paving the way for detailed sound design and rhythm creation akin to the DFAM’s unique capabilities.

Configuring Envelopes

In the realm of modular synthesis, configuring envelopes is a crucial step to shape the sound and dynamics of your signal. Envelopes in VCV Rack, just like in any traditional hardware synthesizer, allow you to control the evolution of a sound over time. For the Moog DFAM (Drummer from Another Mother) emulation in VCV Rack, you will use envelopes to control various aspects of the sound synthesis, particularly the amplitude and filter cutoff.

First, you will need to add an ADSR (Attack, Decay, Sustain, Release) envelope generator module. In VCV Rack, there are several options, but for this guide, let’s use the BogAudio ADSR module which is versatile and visually clear. Start by routing the gate signal into the gate input of the ADSR module. This gate signal typically comes from your sequencer or manually triggered via a button.

Next, route the envelope output to the control inputs of the VCAs (Voltage-Controlled Amplifiers) controlling the amplitude of the oscillators and noise source. The Engage button can be used to manually trigger the envelope to test its response.

To shape the sound, tweak the ADSR stages:
– **Attack**: Sets the time it takes for the envelope to reach its peak level from zero after a note is triggered. For percussive sounds, a short attack is usually desirable.
– **Decay**: Determines how long it takes for the envelope to drop from the peak level to the sustain level. Adjust this to taste based on how you want the transient to behave.
– **Sustain**: Sets the level that the envelope will hold after the initial decay until the note is released. This level remains until the gate is turned off.
– **Release**: Controls the time it takes for the envelope to fall from the sustain level back to zero after the gate is turned off. Longer release times can create more ambient and lingering sounds.

Additionally, to emulate the DFAM exactly, pay special attention to the interaction between the envelope and the VCF (Voltage-Controlled Filter). The envelope can also modulate the filter cutoff, creating dynamic timbral changes. Route the envelope output to the filter’s CV input, typically labeled something like “FM” or “CV In”. This will allow the envelope’s shape to dynamically alter the filter’s cutoff frequency as the sound evolves.

Fine-tuning the interplay between the oscillator’s amplitude envelope and the filter envelope will allow you to mimic the organic and punchy characteristics of the DFAM’s sound. Experiment with different attack and decay times to find the sweet spot that adds rhythmic movement and complexity to your patches.

Lastly, consider using more than one envelope generator, especially if you want separate control over amplitude and filter modulation, as it allows for greater flexibility and more intricate sound design.

By mastering the configuration of envelopes, you can harness the true potential of the Moog DFAM's sound shaping capabilities within VCV Rack, creating anything from sharp, percussive hits to long, evolving soundscapes.

Sequencer Setup

To set up the sequencer in VCV Rack, begin by replicating the tempo control feature found in the Moog DFAM, which essentially serves as a clock. Use a clock module like the one from JW Modules and label it accordingly for easy reference. You'll then need to set up two sequencers: one for pitch and one for velocity, which you can achieve with the ADDR sequencers from Bog Audio. They are compact and versatile, allowing you to set different voltage ranges suitable for your needs. Configure the velocity sequencer to range from 0 to +10 volts and the pitch sequencer from -3 to +3 volts, matching the range to create pitch adjustments over six octaves.

Connect the clock to both sequencers to synchronize their operation, then link the sequencers to trigger the envelope generators, ensuring they all work in tandem. Set the pitch sequencer so it modulates the pitch of both oscillators, and the velocity sequencer to adjust the amplitude and thus the velocity of the sounds produced. Incorporate manual triggers that allow you to step through the sequence, making changes as required, similarly replicating the manual advance and trigger buttons found on the Moog DFAM.

Make sure to label each component to maintain clarity and ease of use. You may also mix clock signals with manual triggers using a unity mixer like the UMix from Bog Audio, ensuring that both are passed to the envelopes. Finally, adding smaller utilities like flow modules can aid in routing the correct pitch information to each oscillator, allowing for more advanced sequencing options, such as sending pitch data to only one oscillator or none at all, giving you greater flexibility in sound design.

Adding Trigger and Advance Buttons

To include trigger and advance buttons, you'll need to first set up a trigger input for manual step progression. This can be achieved using a manual gate module, such as the one from Bog Audio. Position the manual gate module within your patch and name it appropriately for easy identification. Next, you'll need to blend this manual trigger with the clock signal that drives your sequencer. Utilize a unity mixer to achieve this, ensuring that it is set to control voltage mode. Connect the clock signal to one input of the mixer and the manual gate to another. From the mixer, route the combined output to the trigger input of your sequencer. This setup allows you to manually step through the sequence by pressing the manual gate button, overriding the clock whenever necessary. Remember to clearly label all components to keep your patch organized and functional. This added control over your sequence progression can help you fine-tune each step, ensuring precise and desired outcomes in your sound design.

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Sequencing Pitch Information

To sequence the pitch information for both oscillators, you need to configure a pitch sequencer. This step is crucial for defining the melodic structure of your patch. Start by adding a sequencer module to your setup. A common choice is the ADDR sequencer in VCV Rack due to its flexibility and ease of use. Once added, configure it to output pitch voltages that match the musical scale you want to use.

First, connect the output of the sequencer to the VCOs' volt per octave inputs. By doing this, the sequencer will control the pitch of each VCO according to the steps you set. You can start by setting simple intervals or mimic the melodic progression you have in mind.

Next, set the range of the sequencer to match the typical pitch range you desire, usually within a few volts to cover multiple octaves. Some sequencers allow you to set specific voltage ranges for more precision. Adjust the settings so that when you turn a knob to its maximum, it outputs the highest note you need.

After configuring the pitch, sync the sequencer with the rest of your patch by connecting a clock signal to it. This will ensure your sequences move forward in time with your other modulation sources. You can use a clock divider to create interesting rhythmic patterns, making your sequence more dynamic and intricate.

To add variety, consider using switches to alternate the pitch sequence between oscillators or to reroute pitch information differently. This allows you to change which oscillators receive pitch data from the sequencer and creates more complex interactions between the VCOs. For example, you might want one VCO to always follow the sequencer while the other sometimes stays constant or follows a different pattern.

Finally, fine-tune your sequence by adjusting the step values and sequence length to suit your composition. Use the manual trigger or advance buttons to move through steps individually as you tweak each note and ensure it fits the overall sound you are designing. By carefully programming your sequencer and integrating it with the rest of your patch, you can create engaging and evolving pitch patterns that form the backbone of your Moog DFAM emulation in VCV Rack.

Adding Pitch Envelopes

For incorporating pitch envelopes in the Moog DFAM emulation, it is important to understand how these envelopes function to modulate the pitch over a specified time. Start by adding an AD (Attack/Decay) envelope generator to your patch. You will need to connect the trigger input of the AD envelope to the same clock signal that steps your sequencer, ensuring synchronization.

Next, route the output of the AD envelope through a dual attenuator, which will act as a modulation source to control the amount and direction of the pitch modulation. The dual attenuator allows you to scale and potentially invert the modulation signal, hence offering greater control over the effect on pitch.

Connect the output of the dual attenuator to mix with the primary pitch signal from your sequencer. This setup utilizes a Unity mixer module where the pitch CV from the sequencer is combined with the modulation signal from the envelope. Then, connect this mixed signal directly to the 1V/Oct input on the oscillators.

By doing this, you can effectively control the pitch variation for each step of the sequence, giving you the characteristic glide and pitch dynamics that are typical of the DFAM. Experiment with different attack and decay times on your envelope generator to find the right feel for your modulation and use the attenuator to fine-tune the subtleties of the pitch shifts.

This approach will add expressiveness and complexity to your sound, mimicking the responsive and dynamic nature of the Moog DFAM.

Final Adjustments and Testing

With all sections set up appropriately, the final stage involves fine-tuning your Moog DFAM emulation and initiating thorough testing to ensure its functionality and accuracy. Begin by verifying that each oscillator, noise source, filter, and envelope operates as intended by switching between different waveform options, adjusting volume levels, and experimenting with various modulation settings. Ensure that the sequencer runs smoothly, advancing accurately through steps and triggering envelopes correctly.

Test the pitch sequences by altering the range and observing changes in both oscillators to confirm that they are responding in sync. Introduce minor adjustments to the filter cutoffs and resonance levels, and tweak the envelope attack and decay times to achieve the desired timbral character. Cycle through the hard sync and frequency modulation settings, monitoring their impact on the sound, ensuring the unit mimics the distinctive characteristics of the Moog DFAM.

Additionally, inspect the advance and trigger buttons, confirming that they navigate through sequences as expected and trigger sounds without delays or glitches. Modify the pitch envelopes to see how they affect the oscillators over time, exploring the full extent of possible dynamics and expressions. Finally, maximize the playability by ensuring that all controls are labeled clearly in your VCV Rack, allowing for intuitive operation.

By conducting comprehensive testing and making necessary refinements, you ensure that your virtual DFAM offers the same versatility and responsiveness as the original hardware. Through these adjustments, you not only replicate but also fine-tune the specifics, enhancing the potential for creative exploration within VCV Rack.

Useful Links

VCV Rack Official Site

Moog Music – DFAM

Omri Cohen’s VCV Rack Modules & Patches

VCV Rack Library


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