There aren’t a lot of 12-voice polyphonic synths on the market. Given you probably have 10 fingers, there are more than enough voices to go around. This synth features four digital oscillators plus one sub oscillator per voice. That makes 60 oscillators! Two filters (low-pass and high-pass), four envelopes and four LFOs shape the sound while feedback, stereo spread, delay, character, distortion really bring it to life.

Here are some highlights from the instrument…

There are 4 banks of 99 factory patches and another set of 4 banks of 99 user-customizable patches. With this many patches, the factory set runs the gamut of all types of sounds. Some are just silly, some are overdone, but many are quite usable and serve as a great reference to programming your own sounds.

Many of the factory presets employ the “Stack” feature allowing you to layer 2 sounds together. So, when deconstructing a factory patch, check to see if “Stack” is turned on. If so, turn it off and use the “Edit Layer B” button to toggle between the two layers until your hear the sound you’re interested in. Then proceed to analyze the patch settings. You may find it useful to press the “Show” button near the screen in order to view the patch settings without changing them.

The gang’s all here. Frequency Modulation (FM) and Amplitude Modulation (AM) both add enharmonic content in the form of sidebands. The Prophet 12 has both available at the same time, and FM has two different modes available: linear and exponential. Choose “linear” for the classic FM sound. Get crazy and choose “exponential” when you’re ready to venture out.

We’ve covered Oscillator Sync in an earlier episode. On the Prophet 12, you can sync an oscillator to its neighbor. This can create interesting textures when the synced oscillator is tuned higher than the one it is synced to. Automate tuning changes with an LFO or envelope to create vowel-like sounds.

Slop is unique to DSI. It basically takes the rock-solid digital oscillators and simulates tuning instability. This makes for less-pristine, natural sounds.

One of my favorite parts of the Prophet 12 is the shape mod. It boils down to being able to continuously alter the wave shape of the oscillators by morphing the shapes. Think of it like PWM (pulse width modulation) but for all the wave shapes including those non-traditional waves like “Tines” or “Mellow”. Spend some time morphing shapes to come up with unique textures.

On-board arpeggiator, touch sliders, polyphonic aftertouch, unison mode, almost 100 modulation destinations, and on and on make this one of the most feature-complete synths available.

This is a winner. One of those “if I only had one synth” candidates. Oh, and Taylor Swift plays one, so it must be great!

The Novation Bass Station is a monophonic analog synthesizer with some nice bells and whistles. Don’t let the name limit your opinion on this machine. It works well as a mono lead synth, and it also can operate as part of a polyphonic setup by chaining multiple Bass Stations together.

The Bass Station features 2 oscillators (saw or pulse), a resonant low-pass filter (12 or 24db/octave), 2 ADSR envelopes and an LFO (random, triangle, saw). It can even mix in an external audio source. It can be setup to emulate the famous Roland TB-303 by selecting a single oscillator and using the 12db/octave setting in the filter.

FM synthesis is the process of changing the frequency of one oscillator based on some other oscillator. Doing so creates “sidebands” which are extra frequencies above and below the original oscillator’s frequency.

At a relatively slow rate, this produces a vibrato effect when the modulation is performed by a sine or triangle wave. When the modulating oscillator is a square wave, the effect is a trill (rapid alternation between two notes).

Speeding up the modulation into the audible range is where we find extra frequency bands known as sidebands. Unless the two original oscillators are harmonically related, the sidebands seem to be random (although they are actually mathematically predictable.)

With so much harmonically-unrelated content, the resulting tone can sound metallic—similar to ringing a large bell. You’re left to shape the harmonics with filtering or by adding more oscillators to reduce the apparent presence of the harmonics.

MIDI (musical instrument digital interface) was developed to provide standardized communication between synthesizers. Today, it is much more than that and is found in computer, video games, effects processors and more. We’re primarily focusing on how to use it in music production—specifically with synths.

During the late 1970s and early 1980s as synthesizers became more powerful and polyphonic, controlling synths became more and more of a struggle. Traditional methods of using control voltage (CV) and gate signals was particularly problematic due to inconsistent CV requirements among the various manufacturers. Additionally, a single pair of CV/Gate connections could only send one control signal at a time. CV is inherently monophonic. Other control mechanisms had been developed, but these were strictly proprietary to each manufacturer.

MIDI solved these problems. In 1983, Dave Smith and Ikutaru Kakehashi demonstrated MIDI control between a Sequential Prophet 600 and a Roland JP6 promoting collaboration among synthesizer manufacturers.

MIDI’s original connectors are 5-pin DIN connectors. While other physical connections (USB, Firewire, etc.) are able to carry MIDI data, the original connectors are still widely used. Three different connections are possible: IN, OUT, THRU. Generally, a controller (like a keyboard or sequencer) is connected from its OUT jack to another device’s IN jack.

MIDI Thru duplicates the information arriving at a device’s IN jack and passes it back out to some other device. This way several devices can be controlled by a single controller.

MIDI sends its information on 16 channels. Using the connection method mentioned above, the devices connected to a controller can be configured to listen on one or more of these 16 channels and ignore information on others. Maybe a sequencer sends piano information on channel 1 and drum information on channel 10. The piano module and drum module in the chain are then configured accordingly.

MIDI organizes information into various message types. While not an exhaustive list, here are some of the most common message types:

MIDI also has provisions to keep everything sync’ed together. Sync messages are not sent on individual channels. All devices receive sync data unless configured to ignore it. Sync options include MIDI Timecode (MTC), MIDI Clock and Song Position Pointer (SPP). When syncing from a computer, it is best to configure your DAW to send either MTC or MIDI Clock and SPP. Transmitting both can cause double notes and hiccups.

Most audio interfaces offer a set of MIDI IN/OUT connections. This is okay when you only have a couple of devices in your MIDI setup. But, once your collection expands and you need more than 16 channels, look for a MIDI interface with multiple ins and outs. Mark of the Unicorn (MOTU) still has a few of these available.

The authority on MIDI is midi.org. Lots of documentation and helpful articles are now available on the official site. Additionally, consult the user guides for your synths. You’ll be surprised how much you can learn from the manuals.

In the podcast episode, Paul Soulsby describes his Atmegatron products. These are 8-bit digital synthesizers built on the Arduino platform. The Atmegatron hardware consists of a small, desktop module with a unique user interface and wood sides. The knob layout can be daunting at first, but you quickly get the hang of it.

The really amazing part of the Atmegatron is its hackability. Soulsby offers an accessory pack which allows you to load new software onto the Atmegatron which can completely change the behavior of the instrument. There are several different official software version available including a polyphonic string synth, a drum machine and an analog-sounding synth based on the ARP Odyssey. Each version can completely re-map the controls on the hardware. So, overlays are available to help you use each different instrument effectively.

During the podcast, Paul demonstrated how quick and easy it is to upload different versions. The process only takes 20-30 seconds. Each version has a dramatically different character.

And, if you’re the type who can jump in and edit code, you’ll have plenty of fun making your own synth. All of the source code is available on github. If not, there’s plenty of fun to be had with the standard offerings.

In our discussion, I briefly mentioned the mini-Atmegatron, but we didn’t go into details. This is a DIY-kit for building your own synth. It has a lot of the same features as the full-fledged version of the Atmegatron. The finished kit is an Arduino shield (little circuit board that plugs in to an Arduino). It is a quick build and incredibly affordable—especially if you already have a spare Arduino Uno.

Paul was a lot of fun to talk to, and I’m excited to see what he comes up with in the coming months and years. The ongoing development on the platform is a huge benefit to owners of the Atmegatron. I highly recommend picking one up from your favorite synth shop.

Soulsby Synthesizers Website

The Moog Mother-32 is a semi-modular monophonic analog synthesizer in a eurorack form factor. It can be used as a standalone synth or in conjunction with a larger eurorack modular setup.

The Mother-32 offers a single voltage controlled oscillator (VCO) which produces pulse and saw waves. One wave shape can be selected at a time, although both are available at the patch points which allows both to be used simultaneously if desired.

The sound of the VCO passes through a voltage controlled filter (VCF) which can operate in low-pass or high-pass mode. Familiar cutoff and resonance controls provide shaping controls. The VCF can be modulated by either the envelope generator or the LFO in either positive or negative direction.

The simple envelope generator (EG) offers attack time and decay time with switchable sustain (either on or off).

The onboard low-frequency oscillator (LFO) can take on either triangle or square shape. Its rate is controlled by a dedicated knob and also offers a patch point for control from some other source. Pre-wired destinations for LFO modulation include VCO frequency (vibrato-like), VCO pulse width (PWM), and VCF cutoff.

Glide offers a wide range of portamento from subtle to ridiculous.

The final step of the signal path passes through a voltage controlled amplifier (VCA). The VCA can be set to “on” which enables an always-on “drone” mode. Or, it can be set to be triggered with the envelope.

Either way, the 1-octave on-board keyboard can be set to control which musical note is generated. The range of the single octave is set with up/down buttons and results in a full 8-octave on-board control. You won’t use these push-buttons for complex soloing, but they’re handy for trying out sounds.

The keyboard is also used to enter notes into the on-board step sequencer. Each step can have its own duration, accent (on/off) and glide amount. The step sequencer has advanced features for swing and ratcheting as well.

Finally, notes can be triggered from an external MIDI controller connected to the MIDI input on the front of the Mother-32.

Moog includes 5 small patch cables to get you started connecting any of the 32 patch points. Ins and Outs are clearly labeled making it easy for a beginner like me to experiment. The user manual includes example patches and a complete explanation of each connection—again, making it easy for beginners.

Get one. Now.

The Roland RS-09 is a vintage organ/string synthesizer. Combining organ and string sounds together makes it really handy—although you can choose to play only organ or only strings. And the inclusion of analog chorus really helps fatten up the sound.

The vibrato section of the synth is really an LFO permanently set to control the pitch of the outputs from both the organ and string section of the synth. When only playing the organ section, the vibrato adds interest similar to a rotary speaker. (Although not nearly as exciting as the mighty Leslie speaker.) When playing the string section, vibrato re-creates the rapidly changing pitch a string player provides.

While you probably won’t buy the RS-09 for its organ sounds, the organ supports the string section by rounding out the overall sound when mixed together. If you’re used to the drawbars of a Hammond organ, the footage sliders will feel instantly comfortable. Organ I and Organ II buttons can be enabled individually or together. Organ II is a higher-octave, brighter sound from Organ I. The ensemble button within the organ controls enables chorus on just the organ.

This is where the RS-09 really shines. Two separate ranges of strings can be enabled together or separately. Unlike the organ section, the strings can be set to swell in gradually by using its dedicated attack control. When combined with the organ, a gradual attack on the strings creates a tone that evolves slowly and naturally. The strings also have a control to enable ensemble, and the combination of the strings with the ensemble (chorus) is really the sound you’re looking for from a string synth. Big, fat and synthy.

Next to the string section is a decay control which controls both the organ and strings. Setting this all the way up makes for a very long sustained sound.

The ensemble section has only one control: I or II. Ensemble one is more of an abstract, electronic chorus while ensemble two is a natural, smoother chorus. As mentioned, the organ and string sections have separate controls to enable the ensemble. As a bonus, the RS-09 includes an external input jack. A signal brought in here is routed through the chorus.

Of course you do ;)

If you’re looking for vintage synth strings, the RS-09 is a contender. If you’re scoring an orchestral soundtrack, don’t expect the RS-09 (or any vintage string synth) to sound like a real string section. It sounds like a synth—with occasional quirky, unpredictable nuances.

Amplitude modulation is the process of changing the volume of one wave according to the pattern of another wave (Volume is used here as a simple way to understand amplitude. The two are not exactly the same in practice.)

Changing the volume of a sound results in a tremolo effect when that change happens relatively slowly. When we speed up that change, we no longer perceive a simple change in volume. That periodic change itself becomes an audible pitch. In fact, when two simple sine waves are combined in this way, two audible pitches appear. These pitches are called “sidebands” and their frequencies turn out to be equal to the sum and difference of the two original waves.

For example, a sine wave ad 150 Hz modulating another sine wave at 100 Hz produces a sideband at 250 Hz (150 + 100) and another sideband at 50 Hz (150 -100).

That’s great, but what does it mean for synthesizing sounds? In the podcast we play a few samples so you can hear the effect. You’ll notice the sound has a very distinct character which may not be appropriate a lot of times. However, when you need something with a little extra abstract flavor, try some amplitude modulation.

Okay, so you’ve seen both terms: amplitude modulation (AM) and ring modulation. Amplitude modulation keeps one of the two original fundamental waves while ring modulation doesn’t. So, ring modulation may sound more hollow and strange. If your synth only has one or the other, you may be able trick it by manually mixing in (or mixing out) the original fundamental.

Many classic synths offered either amplitude modulation or ring modulation on board. The ARP 2600 and Yamaha CS-80 both offered them, and the Arturia V Collection includes these features. The Ensoniq ESQ-1 offers amplitude modulation, and the Korg microKorg and MS-20 offer ring modulation. These are just a few.

If you’re looking for ring modulation outside of the synth itself, take a look at the DOD Gonkulator Ring Modulator effect pedal.

But if you’re truly adventurous, try building one yourself. Refer to the Delptronics Ring Modulator as a guide.

Oscillator sync simply synchronizes the period of one waveform with that of another. What does that mean? Basically, the synchronized waveform restarts its wave each time some other waveform completes a cycle.

The naming may differ on some synthesizers, but typically there is a “master” oscillator (often OSC 1) which controls the cycles of the “slave” oscillator (often OSC 2). In order for oscillator sync to have any kind of audible effect, the slave oscillator must be tuned higher than the master. And, it must not be tuned to octave multiples of the master.

Listen to the podcast for examples of what it sounds like.

Fred Welsh’s book, Synthesizer Cookbook: Synthesizer Programming, Sound Analysis, and Universal Patch Book, is an excellent reference on using oscillator sync to produce sounds that couldn’t otherwise be achieved.

Looking for the ESQ-1 example patch we created near the end of the episode? Here it is: oscillator sync example for Ensoniq ESQ-1.