Modulation is a key ingredient to synthesizer sounds. Modulation adds movement to the sounds, making them less static. Common modulation techniques include envelopes to shape the volume and partials over time, low frequency oscillators (LFO) to periodically alter the pitch of oscillators (vibrato) or the volume of the sound (tremolo), or velocity to add volume or brightness to notes played harder than others. Advanced synthesizers provide a modulation matrix which allows to route modulation sources (like the ones mentioned above) to various destinations.

As a rule of thumb, the more modulation capabilities exist, the more different sounds can be produced by a synthesizer and the more complicated it is to understand and use. As a consequence, some synthesizers are designed focussing on the quality of the basic building blocks (oscillators, filters) and provide little modulation capabilities (e.g. one LFO only synths like the Korg prologue and minilogue xd or the DSI/Sequential OB-6, for which Steve Hunt offers a “Low Frequency Expander for OB-6” breakout box).

When it comes to LFOs, it’s not only the amount that matters, but also the waveforms provided. The Korg prologue and minilogue xd’s LFO just provide three (saw, triangle, square). More advanced LFOs may also provide Random/S&H waveforms. A waveform seldom to find is Sample & Glide, which provides a less stepped random waveform. It can be found, for example, in the Korg Z1 (four LFOS) or emulated in the John Bown Solaris (four LFOS) by routing the S&H waveform through a lag processor (actually a low pass filter). This waveform allows for very subtle, unobtrusive modulations.

The abovementioned Korgs just provide one LFO with three wavefroms only. Additionally, the single LFO can only be routed to one destination at a time (pitch, shape, cutoff). This design is pretty straightforward, and the panel controls give the musician immediate access to the modulation. While I’d like to congratulate the designers for resisting the temptatoin to add more, I perceive the design as very limiting.

At the other end, there are synths (like the Access Virus or the Sequential Prophet 08) which provide both multiple LFOs and a modulation matrix. One can create a lot of very interesting sounds with them, but without reading (and understanding) the modulation matrix menu entries it is difficult to understand how a particular sound was designed. But anyway, the sounds of analog machines with modulation matrix are much sought after, as the still popular Oberheim Matrix-1000 proves.

The original Waldorf Microwave I, known for its extremely punchy envelopes, provides two special parameters for the LFOs. The first one is “Symmetry”, which has a special effect on the sine wave.

The second one is “Humanize”, which adds random variations to its rate. The Microwave also is known for its extremely flexible (and even loopable) third “Wave envelope”.

Admittedly, I’m a big fan of all kinds of weird modulation capabilities and can spend hours exploring what sounds can be achieved using them. On the other hand, machines limited in modulation are interesting as well, as I pay more attention on the details of the limited capabilities, which fosters creativity, as Kebu states.

As with the minilogue xd, the prologue updater tool asks to consult the user manual for details how to boot the synth into update mode. Unfortunately, neither the german nor the english manual contain the information required. It’s simple. Just hold the buttons six and eight while powering the synth on and wait until the display reads as “Version Up Mode”. Just upgraded mine from 2.0 to 2.1.

Both synths provide a favorite system. Unfortunately they work differently and are hard to remember in case you only use them every now and then. So here’s a quick reference.

minilogue xd

You can register up to 16 favorites using the panel buttons:

• Select the program you want to register.
• Hold the Shift button.
• Press the button which you’d like to serve as a shortcut to this program for about a second or so.

To recall:

• Hold the Shift button.
• Briefly press the button which represents the desired program.

prologue

To “like” or “unlike” a program:

• Select the program you want to “like”.
• Press button 4 for about a second or so.

To scroll through liked programs:

• Ensure button 4 is lit.
• Turn the Program/Value dial.

To scroll through programs by category:

• Press button 2 multiple times to select the desired category.
• Turn the Program/Value dial to scroll through the programs of the selected category.

To return to “normal” scrolling behaviour by program number:

• Press button 1.
• Turn the Program/Value dial to scroll through the programs one by one.
• Press button 1 multiple times to jump forward by 50 program numbers.

The prologue provides further sorting modes and a live set feature. See page 12 of its user manual for details.

Ages ago I was part of the Linux Audio community, but eventually I was bored by all the fiddling around and left Linux alone. Well, not exactly. For the kids of a relative, I configured a Raspberry Pi with a USB breakout box to use it as a pipe organ emulator. But some time later, they did the same I did – they bought a hardware pipe organ emulation. And I’m still extremely content with the instrument.

The advent of the Raspberry Pi 4, however, again makes the platform interesting for audio processing. And Zynthian, an open source project, upgraded to it. The v4 kit is available for 325 €. Before diving into it, I recommend an amazona.de article for v3 as well as the Zynthian wiki.

Should I buy one of those tempting gadgets? Well, probably :) .

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