Our analog powerhouse VCO, providing all basic waveforms and good tracking over eight octaves. Spice up its timbres using different FM options, PWM and Hard Sync. 555VCO provides a great start for any synth voice patch, it’s a no nonsense oscillator with that classic analog sound.

Summary (detailed info below):

• A stable, 1V/Oct, fully analog VCO, based on the legendary 555 timer chip.
• Triangle, saw, square and sine wave outputs
• PWM knob & PWM CV in (with attenuating knob)
• Linear & Exponential FM inputs (with dedicated attenuating knobs)
• Hard Sync input (for some more crunchy FM-ish sounds)
• Coarse & Fine tuning knob
• 2U wide
• Now with ABS frontpanels. Design was slightly updated from the design pictured above.

v2 updates:

• New frontplate design and beautiful pictures by Francesco Bernini ( https://www.instagram.com/the.salmone/ )
• Wider tuning range with the 'coarse' tuning knob
• PWM range does no longer go into non-hearable range
• Even more stable V/oct response

- Now fits the Quickswap case. However: only half of the 5x2 pin header slots into the quickswap case. This is no problem considering stability. Only downside is that you lose the bus CV signal. This will be solved in the next iteration!

We made it! With the help from French SMD & PCB wizard M4vrick, I designed a versatile, flexible, well-tracking analog oscillator based around the old-school 555 timer chip. Unlike my other kits, this is a finished, tested & calibrated module. It's an analog oscillator unlike any that exist yet in the AE ecosystem, as it really has it's own 'tone' AND it has a sinewave output for all your soothing ambient dreams! However, it has also the option to get really gnarly with FM inputs (both linear & exponential, each with their dedicated attenuator), Hard Sync input (drive another square/pulse oscillator in that input, and be amazed!), and PWM (both with a knob & CV input with dedicated attenuator).

Tracking is close to perfect for over five octaves (less than 6ct drift if calibrated at home). Only the high (ear-piercing) tones start to 'droop' a bit. But that is the nature of fully analog synths of course. Tuning drift with changing temperature is minimal, as there is a dedicated temperature-compensation circuit added to the oscillator. Again: it will not be perfect like digital synths, but it gets close!

Tracking calibration info:

For the true 'perfect tracking', it is best to calibrate the CV input frequency response at home, as this tracking can slightly vary due to temperature and humidity. In order to calibrate, you should remove the frontplate from the module if you have a first-generation (green) version. Later versions have the trimpots installed on the back, so taking it out of the rack is enough.

Find trimpots R11 and R13 clearly marked on the plate. Connect a tuner to your AE Modular (I use the Ableton Tuner) & feed your AE modular MIDI octaves. If you let it play octaves, your tuner should show you the same note for each MIDI note if the module is tracking well. If this is not the case, you can turn the trimpots using a small screwdriver. Be careful: because AE modular is only 5V, it only listens properly to +-4 MIDI octaves. Best is to input MIDI notes C0-C1-C2 for calibrating.

R11: V/oct adjustment - if the alround tracking is off, twist this trimpot & see if it gets better. R13: High frequency adjustment - if only the high frequencies are off, try twisting this trimpot. You will notice the super 'upper' registers (aka ear-piercing), might not be possible to track perfectly. You might also notice that after changing the R13 trimpot, it might be needed to also again tweak the R11 trimpot.

If you have any questions, or anything is off, don't hesitate to contact me!

Cheers

Keurslager Kurt / Zeno