Mod Squad: 4MS Spectral Multiband Resonator

Six Bandpass Filters That Offer Deep Dynamic Frequency Control
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Even with so many new Eurorack modules being introduced each year, it’s difficult to find products that are both innovative and useful. But with the Spectral Multiband Resonator ($475), 4ms has hit both marks by adding a wealth of exciting features to the classic voltage-controlled spectral filter concept, but with a UI designed for real-time performance control.

Although the module resembles a 6-band graphic EQ, each slider represents an arbitrarily assignable frequency channel: There are six resonant bandpass filters, each with an independently tunable center frequency (and output level controlled via CV and fader). Overall, filter resonance is introduced by increasing the Q using a CV or knob.

A corresponding CV output for each channel provides an envelope (tracking fast or slow) or trigger based on the input’s frequency content and the channel setting. With the Pre/Post switch, you can determine whether the incoming signal is analyzed before or after the level sliders. CV slew can be used to smooth out transients.

With two inputs and outputs, the Spectral Multiband Resonator (SMR) can be used as a mono or stereo processor. In stereo, the Odds input and output correspond to the odd-numbered channels, while the Evens I/O is matched with the even-numbered channels. The built-in noise generator kicks in when nothing is patched into the Odds input, so you can use the SMR as a sound source on its own (or use the noise for the Odds while sending an external signal into the Evens input).

The Rotate function lets you move between 20 preset filter frequencies for each fader, manually or with a CV. As you increase the Morph amount (with the knob or via CV), the pitch changes become more gradual, softening the transitions. Additionally, you can create chordal sounds using Spread to put distance between the frequencies in each channel. You can then further alter the Odds and Evens pitches independently using the Nudge control and its CV, as well as lock the frequencies of any number of channels while the others change.

Eleven 20-note scales are available in each of the 16 scale banks. The scales range from common to exotic—diatonic and chromatic to 17-note equal temperament, just intonation, and Wendy Carlos’ Gamma scale. An entire bank is available for user-designed scales, which you program using the module’s sliders and buttons.

Moreover, each frequency channel can have its own scale. That means you can have up to six different scales available at once, or assign one scale to the odd-numbered channels and another to the even channels and pan them in stereo, and so forth. Also, a CV can be used to scan between each scale in a bank, while another CV scans through the pitches in that scale.

While all of this seems complex, the SMR is surprisingly easy to use; instant gratification is guaranteed. But if you want to get really tweaky, there are six Setting Slots, each of which can hold a complete setup of scales and parameters for easy recall.

But that’s not all: In addition to creating gorgeous, chordal sound-clouds with its resonant spectral processing, the SMR can be used for beat-synched harmonizing or vocoding (if you have a second unit), and it can be used as a resonant percussion module. It’s the kind of module that will continually surprise you as you dig deeper into it, and one that will end up in a lot of your patches. Highly recommended!