The PO-32 Tonic is a collaboration between Teenage Engineering and Magnus Lidström from Sonic Charge. "Tonic" is a reference to Microtonic, the drum synthesizer developed by Lidström and his brother Frederik (the other half of Sonic Charge). It's the basis of the PO-32's drum synthesis engine. Magnus made the CWO delay effect for the OP-1 but the PO-32 presented a different kind of challenge. Squeezing the complex drum synthesis engine of a modern plug-in into the limited microcontroller CPU used by the PO-series (where RAM is measured in kilobytes rather than gigabytes) required months of experimentation with DSP and CPU management.
The result of this work is a highly optimized version of the Microtonic plug-in, which uses 99.999% of the PO-32's processing capacity. One big benefit is the compatibility between Microtonic and the PO-32. This facilitates the loading of custom sounds and requires the latest version of Microtonic, which has been updated to send sounds "over the air" using the same style of data transmission that powered dial-up modems. The tones that us oldies remember from the start of our internet browsing sessions are received as data by the PO-32's built-in microphone and transformed into playable sound. If you're not keen on holding the PO-32 up to your speakers, you can transfer sounds with the line-in audio port.
Microtonic integration isn't limited to individual sounds. Full patterns can be transmitted to one of the 16 pattern slots on the PO-32, with some caveats. The PO-32 is monophonic and limited to four-note polyphony so patterns designed with Microtonic's stereo capabilities and eight voice architecture won't directly translate to the hardware. To ease this transition, Magnus developed some advanced utilities for Microtonic's PO-32 integration. When you open up the "sounds+pattern" transmit option, there is a button labeled "optimize for PO-32." This attempts to rearrange the sounds in such a way as to minimize voice stealing, with the end goal being pattern playback that's as close as possible to the original. This is the type of work that one might take for granted but it goes a long way to extending the usefulness of this little unit.
The PO-32 shares many of the same workflow designs of the other Pocket Operator units. The 16 patterns contain 16 sounds each, selectable using the dedicated pattern and sound button respectively. With the four note polyphony restriction, it's important to visualize your 16 sounds in four vertical sound lanes, where sounds triggered in each lane will steal the voice from other sounds in the same lane. This also means that holding down a button serves to mute all of the other sounds in that lane. In addition to little icons next to each button that indicate the type of sounds that ship with the factory patterns, there are vertical lines on the PCB that provide a reminder of this structure.
The effects on the PO-32 are a clever hack by Magnus that, rather than adding dedicated DSP code, uses the Microtonic synthesis engine to create pseudo delays, beat choppers and other useful tools. The PO-32 has the same two knobs as the other PO units, controlling pitch and a parameter morph value for the selected sound. Of these two, the latter is the more interesting. It uses the same morph engine found in the Microtonic, allowing you to set values for any of the synthesis parameters at two ends of a slider and then interpolate between them. In Microtonic, this morph is global for the entire plug-in but on the PO-32 you can blend between two variations of each sound individually. When you realize that both pitch and morph can be parameter locked within a sequence, a startling amount of synthesis power is revealed from this unassuming little unit.
The only issues I had are common to all of the Pocket Operators, especially the lack of a true mute function. The user guide instructs you to hold down a sound to mute its lane but the unit would be much more useful if you could mute individual sounds with a traditional toggle button. Also, every time you plug a cable into the audio output or input jacks, you have to reset the PO-32's volume level and sync settings, respectively. This gets a bit arduous when you're unplugging a sync cable every time you want to transfer a sound from Microtonic, a step that's required since the microphone is disabled any time a cable is plugged into the audio input. Outside of those minor complaints, the PO-32 is certainly worth the low price. I've never heard an affordable drum machine sound this good.
Ease of use: 4.0