Exploring the Dual State-Variable Filter: ALM Busy Circuits MCFx2 Eurorack Module

The ALM Busy Circuits MCFx2 Eurorack module is a versatile dual state-variable filter that offers a range of routing capabilities and CV controls for generating or processing sound in a modular system. The MCFx2 features two independent low pass filters with dedicated cutoff and resonance controls. The filter cutoff frequency can be controlled via CV inputs with attenuvertors and attenuators, providing the ability to shape timbres over time. Additionally, the unit offers 1V/Oct tracking inputs for each filter, making it easy to integrate with other modules in your system.

One of the standout features of the MCFx2 is its three simultaneous outputs for each filter, including a low pass, high pass, and a switchable band pass/notch filter. The band pass/notch filter can be set by a jumper on the back of the unit, providing even more flexibility for shaping your sound. Combining the various outputs allows you to gain different frequencies of the same signal, filter two different signals, or even perform cross-modulation and feedback.

The MCFx2 also offers a Link button for synchronizing control over both filters, allowing you to adjust the cutoff frequency of both filters simultaneously. In addition, the Feed button allows you to feed the output of filter one directly into filter two, creating complex and interesting soundscapes without the need for additional patching.

It's worth noting that the resonance goes into self-oscillation, providing the possibility of adding two additional synth voices to your modular system. The MCFx2 is a versatile and powerful module that can be used for a variety of applications, including filtering, modulation, and sound design.

In summary, the ALM Busy Circuits MCFx2 Eurorack module is a dual state-variable filter that offers a range of routing capabilities, CV controls, and three simultaneous outputs per filter. With a Link button for synchronized control over both filters, a Feed button for direct routing, and the ability to self-oscillate, the MCFx2 is a fantastic addition to any modular synth system.

Example Usage

As a novice, you can start by plugging in an oscillator module into the MCFx2 Eurorack module's input jack, then patching the low pass output of filter 1 to the low pass input of filter 2 using a patch cable. Adjust the cutoff frequency and resonance knobs to hear how the filters shape the sound. You can also use the Feed button to blend the two filter positions and create a more complex sound. Try experimenting with the CV inputs and attenuverters to modulate the filters in real time and create evolving timbres.

An intermediate-level patch idea for the ALM Busy Circuits MCFx2 dual state-variable filter would be to use it for creating a lush pad sound. Begin by sending an oscillator's audio output into the input of both filters. Adjust the cutoff and resonance knobs of each filter to create a sound that is pleasing to your ears. Next, patch a slow LFO into the CV input of one filter's cutoff frequency and adjust the amount to add movement to the pad. For the other filter, use a random CV source, such as a sample and hold or noise, to modulate the cutoff frequency for a more unpredictable sound. Use the band pass output from both filters and pan them left and right respectively for a stereo effect. Tweak the filters' resonance settings to allow for some self-oscillation and using the feed button to feed filter one into filter two. Finally, add some reverb and delay to create a spacious and ethereal pad. This patch demonstrates the versatility and creativity of the ALM Busy Circuits MCFx2 filter module.

Further Thoughts

One of the most interesting uses of the MCFx2 is through cross-modulation and feedback. By sending audio signals through both filters and using CV controls, you can create complex oscillating sounds that are both unique and unpredictable. For example, try patching a triangle wave from an oscillator into the 1V/Oct input of one filter, then send a square wave from another oscillator into the cutoff frequency of the second filter. Adjust the resonance and experiment with different CV inputs to explore the full sonic potential of the MCFx2. With its three simultaneous filter outputs and link button for synchronized control, the MCFx2 is a versatile and powerful processor that can be used in many different ways.