Programming the Overcycler
About a year ago, I wrote a review of the Pro-800, which was inspired by the Sequential Prophet-600 with a GliGli-Mod. I also created 100 sounds for that affordable 8-voice analog synthesizer and you probably already know that I really like the GliGli mods in general. Fast forward 8 months and I received word of Fabrice’s latest project: the Overcycler.
On paper, this is a 6-voice hybrid DIY synthesizer with some very impressive specifications. In this review, I’ll walk you through those features and share my experience with it – let’s see if this is a synth worth adding to your shortlist.
The Overcycler
The Overcycler is available as a DIY and pre-assembled kit. The DIY kit consists of parts and a pre-assembled circuit board, you only have to do some soldering for the panel, but it’s only through-hole (ie. all the surface mounted parts are soldered already), which isn’t that difficult even if you aren’t a solder-head.
At the moment of writing the price is around €264 for the DIY kit and €314 for the pre-assembled version (ex. shipping). Fabrice and I got in contact and after some discussion, I quickly decided to go for the pre-assembled version so I could help Fabrice with tasks like writing the manual and adding some new factory patches.
A couple of days later, the unit arrived at my doorstep. It was packaged really well in a sturdy box with bubble wrap and other protective materials. In the box, you’ll find the unit itself and a USB A-to-B cable for power and other functions, but more on that later. Here’s the unit with the protective plastic still on the display:
Dimensions and hardware features
This synthesizer weighs about 1 kg and measures approximately 28x8x22 cm (WxHxD). It features 10 sturdy knobs (arranged in 2 rows of 5), a 4×4 numeric pad, a 4-row, 40-character back-lit LCD screen and a stereo output (TS). If you plug in headphones (TRS) to either the left or right output, it will act as a stereo output.
One minor detail is that it’s unclear which side is left and which is right. However, since the synth only has fixed panning per voice and no modulation options for panning, it’s not a big deal. If you want to use it in mono, you can adjust the width control in your Digital Audio Workstation of choice or use the pan knobs on your mixer to control and narrow the stereo field.
Additionally, it includes a MIDI DIN input, a volume knob, a pedal input and the power button. Power will be supplied via the USB socket, meaning it can also be powered by a power bank – perfect for taking the synth on the go as part of a compact setup for performances.
But what makes this synth so special and why did Fabrice wanted to create this synthesizer? Well, the manual gives a bit of history, as apparently this project has been a long time in the making:
Quote from the manual:
This project started about 10 years ago, when I wanted to make use of spare SSM2044 voltage controlled low pass filters I had laying around.
The goal was to make a synthesizer that had a very strong character, while staying focused on polyphonic sounds, and the SSM2044 was perfect for that because even when strongly over-driven, it never sounds aggressive. It went through 3 major revisions until it became the full-fledged retail synthesizer it is now.
As new SSM2044 are becoming rare, the synthesizer uses SSI2144, which are modern surface-mounted clones, and also embarks LM13700-based voltage controlled amplifiers.
So, the filters are one thing, but what do they actually filter? And what about the rest of the synthesizer? Let’s start with the oscillators and waveforms. But first, let’s power it on!
Digital oscillators (page 1)
This synthesizer features two digital single-cycle syncable oscillators, which run on an NXP DMA controller (ARM Cortex-M3) and are quite special – hence the name Overcycler. These oscillators have the ability to run one-cycle waveforms that you can modulate in different and interesting ways. Additionally, they operate at 64 kHz, resulting in really clean sounds – if that’s what you’re after.
The single cycle waves are stored in the internal flash memory which can be accessed via the USB connection. You can select a bank and then a specific wave. Next to the factory fitted GliGli single cycle waves you will find the public domain AKWF and Prophet VS waves. You can also create and transfer your own waves to the synthesizer via a file transfer over USB.
This is another feature that makes this synthesizer both versatile and powerful, offering great sound with ‘cycle-over-the-top’-capabilities.
You can detune the oscillators with a dedicated knob and both oscillators have their own mix knob. Combined with an analog noise generator – again, with its own mix knob – you have plenty of tools to start crafting new sounds. And that’s just the first page!
Speaking of the USB port and its influence on the audio path, I noticed that the Overcycler has a very low noise floor. This is by design, as the USB port – used here to power the Overcycler – incorporates a USB isolator chip (ADUM3160). In some designs, a lack of such an isolator can result in a higher noise floor as an unwanted consequence.
WaveMod (page 2)
Another benefit of the hybrid design is that Fabrice included a couple of clever manipulation features for the oscillators, which he calls WaveMod. This feature allows you to manipulate these waveforms in really wild ways. There are currently 7 modes, although I started writing this review with 5 available modes:
- Normal (‘None’)
- Grit
- Width
- Frequency
- Crossover
- WaveFolder
- BitCrusher
The Normal mode plays the cycle waveforms exactly as they are. Initially, you might think the same about the other modes, but the magic happens when you engage the WaveMod feature.
The Grit mode can produce ring-mod and bit-crushed sounds, which is fantastic. Imagine a sound evolving from almost zero sample rate to full sample rate. Fabrice told me that it is time domain decimation, which means the single cycle has less and less sample rate, while keeping the same pitch. It can drop down to a few Hz, where it appears as if a square wave is being amplitude modulated by the single cycle.
Width mode can create pulse-width effects, but it isn’t limited to the pulse wave – it works with any single-cycle waveform, which is a brilliant touch. For example, you can achieve an oscillator sound similar to the Roland Alpha Juno-2 by adding pulse width modulation to a saw wave, or to a blend of a saw and square wave within a single cycle.
Add Frequency modulation on top of that to create cool sync sounds, soaring leads (Prophet-5 anyone?), plucks, or even percussion sounds.
The Crossover mode lets you blend between waveforms within an oscillator. You can swap the crossover at page 1 with A and B. Standard it morphs between a saw and a sine wave, but you can select any of the available waves for this, even your own custom ones.
The WaveFolding vertically folds waveforms (through amplitude). When they go past the maximum, they fold (or “bounce”) back. The WaveMod amount is the pre-amplification (from 1 to 16).
And lastly a BitCrusher WaveMod, that works by lowering the amplitude resolution of the single cycle (contrary to the “Grit” one, which lowers the frequency resolution).
This second page also provides direct access to the WaveMod envelope, with base amount and per-oscillator envelope controls and initial setting (more on envelopes later).
Note from Fabrice: The last WaveMod will probably be FM feedback, but that will be for a future release.
Filters (page 3)
The third page of the Overcycler focuses on filtering your sound. The SSI2144 filters used here are clones of Dave Rossum’s legendary SSM2044 filters, known for their beautiful sound. These filters use an OTA 4-pole (24dB/octave) design. If you need more information, you can visit the Sound Semi Conductor (SSM) page here.
It’s worth noting that these may be the same filters used in modern and well-regarded synthesizers like the Dreadbox Nymphes, UDO Super 6 and Waldorf M. When pushed hard these filters produce a musical overdriven sound that’s highly pleasing to the ear. For instance, the Korg MonoPoly used this resonant filter to create powerful bass sounds found in many classic electro tracks.
Other great synthesizers that featured the SSM2044 include the Crumar Bit One (first 300 models), Kawai K3, SX-210 & SX-240 and the Korg PolySix & Trident, as well as iconic models like the PPG Wave 2.2 & 2.3 and the Siel Opera 6. These filters were also found in some legendary samplers such as the Fairlight Series II/X and the E-mu SP-12 and SP-1200. Given the impressive track record of these instruments, it’s easy to understand my excitement upon hearing that the Overcycler uses these new clones as its filters.
The Overcycler’s filter lives up to this reputation, sounding exceptionally musical. It can self-oscillate and responds well to key tracking. In fact, the first time I used the filter with just an init (empty) patch, it brought a big smile to my face.
When the combined values of the noise and the two oscillators stay below 1000, the filters produce a clean sound. However, if you push the combination above that threshold (whether with noise or just the two oscillators), you’ll hear the satisfying drive kick in. In other words, it starts to sound really juicy! This is especially rewarding when you add some envelope modulation to bring the sound to life.
Another trick is to crank up the oscillator levels, keep the filter open and add lots of resonance. You will probably hear the nice and pleasing saturation instantly, as the filter and amplifier will be driven hard. Let’s continue talking about the amplifier, shall we?
Amplifier (page 4)
The output of the filters is then sent to the amplifier section, which is available via the 4th page. You can modify the amplifier envelope, its shape and how it responds to velocity. Additionally, you can adjust the voice count, unison and its detune, master tune and note priority (last, low, high).
As mentioned, the Overcycler also has a unison mode where you can detune the voices and select the amount. However, it’s a bit cumbersome that you can’t use 3 voices with a 2-note unison configuration (yet?). Combined with the hard panning, I can imagine this might make things difficult. Nonetheless, you can still use it as a chord mode, which is a nice bonus. To activate this, just hold a chord and press 4A or A if you’re already on the Amplifier page.
The detuning function ‘Mdet’ also acts as a tuner for each voice, so in poly mode, you get a different pitch for each voice. It ranges from scientifically clean to way out of tune, like an old, unserviced poly synth. How cool would it be if you could do this for the filters and envelopes per voice as well. Perhaps something for an improved firmware somewhere in the future. Speaking of pages, there are 10 in total.
Envelopes (page 2, 3 and 4)
The Overcycler has the three envelopes per voice and are not the typical ADSR’s and can be used for the oscillator WaveMod feature as Fabrice calls it, the usual suspects: the filter and the amplifier. Well in fact they are typical ADSR’s, but they have two nifty extra features: looping and custom curves – the latter as found on the GliGli mod of the Prophet-600, so linear and exponential types with both slow and fast options.
Both the linear and exponential curves sound musical, depending on what you’re looking for, so you have a lot of options to shape your sound. From blazing fast to extremely slow. The slow modes are 4 times slower than the fast ones.
For looping, the attack and decay are used with what’s left of the sustain level. When sustain is at maximum level, there is no looping.
At the time of writing there is one feature that you may or may not like, but the envelope for the amp can introduce clicks in the audio due to a hardware limitation on the amplifier. For me this isn’t really a problem as many synths have these clicks and you can use them for character or work around them by setting the release to a value of around 300 or higher.
LFOs (page 5 and 6)
This synthesizer features two LFOs on pages 4 and 5. At the moment of writing, they are free-running LFOs and cannot operate as one-cycle LFOs. Unfortunately, they also do not trigger per note, which would be great for creating percussion sounds or adding an extra bit of snap to a filter envelope for example.
Update: Time sure flies when you’re having fun and writing this review! This has already been addressed with a firmware update. You now have additional trig modes: Free, Trig, Hper (unipolar once), and 1, 2, 4, and 8 bipolar periods (1Per…8Per).
The rate can range from 0 to 999 BPM and can be set to audio rate using multipliers of x2, x4 and x8. These very high – even audio – rates can result in metallic tones for example. The modulation waveforms for both LFOs include square, triangle, random, sine, noise, saw and reverse saw. The destinations for both LFOs are Pitch (*Pit), Wave Modulation (*Wmo), Cutoff (*Fil), Resonance (*Res) and the VCA (*Amp).
Besides that you can delay the modulation by roughly 10 seconds max from where the modulation depth fades in. Unfortunately it isn’t possible to have seperate delays for LFO1 and LFO2 yet.
Lastly, it would be nice to have a way to modulate the LFO rates, either through the opposite LFO or via one of the envelopes for example.
Other modulation sources (page 9)
Besides the three envelopes and two LFOs you can use velocity, aftertouch, mod wheel and of course pitch bend on page 9. Velocity can be used for the amount of depth of the aforementioned envelopes. Aftertouch (monophonic) for Pitch, Cutoff, Volume, WaveMod and both the LFO amounts.
The pitch bend can be assigned to control pitch, cutoff, volume, or WaveMod. Additionally, the mod wheel can adjust the amounts of LFO1 or LFO2, or be assigned to one or more destinations of LFO1 and LFO2 when their speeds are set to 0. I specifically requested this feature, so you can always use the pitch bend for pitch while still controlling parameters like cutoff with the mod wheel when playing the synth via a MIDI keyboard with pitch and mod controls.
On the 9th page you are also able to load a basic saw preset, have a panic mode, a mode to return to the main page and tune the filters.
Arpeggiator and sequencer (page 7 and 8)
Just like the Pro-800, it features an arpeggiator. You find it on page 7 and has three modes: ‘up/down’, ‘random’, and ‘assign’, which plays the notes in the order you play them. I’ve suggested adding more modes, such as ‘up/down2’, which may be included in future updates.
Additionally, there is a sequencer on page 8 with two lanes that can operate independently or together. Recording sequences is very straightforward, so I won’t elaborate on that here. The Overcycler can store 20 A/B sequences, essentially allowing for 40 sequences in total. You can also transpose the sequence while it’s playing using your keyboard, which is very useful for performances.
The last page, is page ‘0’ or 10. This is where you can load, save and switch between patches. When saving a patch, you can assign a Type and Style. Initially, it was a bit disappointing that you couldn’t name your patches, but Fabrice has since added that feature. You can now rename patches by simply editing the text files directly on the synth (or on your harddrive when you decide to backup your sounds). With the ability to save up to 1,000 patches, there’s more than enough space for most users.
All ten pages have their own display layout and the knobs and buttons can be easily used to adjust the parameters. If you prefer to input a value instead of using the knob, simply twist the knob slightly to change the value, press * and then enter the number from 000 to 999. For example, press 500 for 500, 050 for 50 and 005 for 5. It’s as simple as that.
Additionally, the knobs operate in pick-up mode, preventing any sudden jumps in parameters. There’s also an arrow indicator that shows where the current value is set when the Overcycler detects that the knob’s position doesn’t match the saved value.
This synthesizer is slightly angled towards you, making patch editing really comfortable. Sometimes, using the numpad feels like you’re patching people through on an old telephone! In the beginning, you might refer to the manual a lot, but over time, you’ll become familiar with it and navigate through the pages easily.
When you adjust a a parameter, the display will tell you by showing PM (patch modified) and when you play, you will not only see how it cycles through the voices, but also how loud it it is and how the VCA behaves over time per voice.
The synthesizer includes a detailed manual and can be controlled through MIDI CC and NRPNs. As it’s open source, regular updates are to be expected. GliGli is dedicated to achieving perfection and values user feedback, ensuring you’re well-supported.
Is the Overcycler a real page turner?
Well, let’s talk about one crucial aspect: the sound of the Overcycler. It’s almost unbelievable how good it sounds, especially considering the price! Fabrice mentioned he had a wavetable kind of synthesizer in mind like the PPG Wave, Sequential Circuits Prophet VS and Korg DW-8000 while designing his Overcycler.
While it’s not technically a wavetable synth, its WaveMod options like XOvr and Fold bring that kind of feel, but a bit more anlog sounding or thicker so to say. If you want even more thickness, say for a bass sound that already feels full, just hit ‘4’ & ‘A’ – you’ll get instant unison fatness! Not enough? Detune the voices a bit more on page 4 via ‘Mdet’ et voila!
The Overcycler feels solid and well built (in the case of my pre-assembled module) and offers a lot of versatility and a retro-inspired design that I personally really like. It reminds me a bit of the cool MFB drum machines and synths from a while back. Furthermore, this synth has a lot of character and is intuitive. So in my opinion, this is definitely worth putting on your shortlist if you are looking for an affordable and characterful hybrid poly synth!
Pros
- Custom oscillator waveforms, check!
- The modulation options are great.
- The sound of the filters is delicious.
- It is available in two options DIY and pre-assembled.
- It is open source.
- It is very affordable.
Cons
- None at this price.
Sound Examples
Here are a few factory sounds I created while writing this review. I recorded the sounds dry initially and toward the end, you’ll hear some of my favorite effects – TAL-G-VERB, TAL-Chorus-LX, Bitwig Delay+, Kilohearts DualDelay, Relab Sonsig Ace and Relab Sonsig Rev-A – applied:
And some more sounds that I will release soon for the Overcycler:
Tips and tricks
Save to another slot then the current one
Press B to save once, then quickly press * and type in the slot you want to save to. So for patch 50, you type ‘*050’. Then again press B once for an empty patch or twice if you want to overwrite the just loaded patch.
Using the Crossover
Select an init patch or load one on page 9 by pressing ‘9’ and ‘A’.
Go to page 2 and press ‘A’ four times until you’ve selected ‘XOvr’.
You can now setup your envelope and change the envelope amount via ‘AWEA’ (‘Oscillator A, WaveMod Envelope Amount’) on that same page.
You could also modulate the effect via an LFO on page 6 by pressing ‘6’ and change the 2Amt and 2Wmo values.
Or you could decide to modulate it via page ‘9’ via Mod Wheel – ‘MRng’, Pitch Bend – ‘BRng’, or via Aftertouch/Pressure ‘Prng’.
Pulsewidth modulation – for Nick Batt only 😛
Select an SQR wave (#003) on page ‘1’ for ‘Awav’
On page ‘2’ Press ‘A’ two times to activate the “Width” mode.
Press numpad ‘6’ to go LFO2 (since ‘5’ LFO1 is by default patched to pitch modulation for the mod wheel) and change the amounts of ‘2Amt’ and ‘2Wmo’ to about 500 – or more – and slow down 2Spd from 300 to 50.
Now go to page by pressing numpad ‘3’ and change the cutoff with the first knob on the left and resonance to taste with the second knob of the first row.
Use note-stealing creatively
Create a pad sound and play 5 notes with your right hand and keep them sustained. The play a bass note quickly, you sometimes will hear that it steals a note but gives it back so to say, which sounds nice if you ask me. Here is an example:
Help!
If all else fails – i.e. you don’t know ‘where you are’ – just press ‘9’ and ‘C’ on the numeric keypad. And you’re back at the intro screen where you started when you turned on the Overcycler, so no need for a manual. Very clever!
Panic!
To reset the voices, press ‘9’ and ‘B’. For example, if you want to start with the bass note, Voice 1 or Voice 2 work well since they are panned to the center. Voices 3 through 6 are panned more toward the left and right.
More Information
For more information about the GliGli’s Overcycler project, point your browser to Fabrice his blog: https://gliglisynth.blogspot.com/
Disclaimer: We normally use affiliate links. When purchasing gear via the following links you support my website, YouTube channel and make reviews like this possible (at no extra costs to you).
Check out my recommended gear affiliate page here: https://www.thomann.de/nl/thlpg_1qcjdhepq0.html
Buy GliGli’s Overcycler here: https://gligli.store/en/
Consider purchasing my sounds for GliGli’s Overcycler here: https://www.solidtrax.nl/product/cyclic-chaos
