Groovesizer RED

Review of the Groovesizer RED- Synthesizer and Sequencer

And now for something completely different.

One of my hobbies is building DIY electronics, particularly synthesizers and noise makers. I find soldering, generally speaking, very relaxing, save for the few times I’ve spent hours testing joints with the multimeter, building up to near ‘toys-out-of-the-pram’ levels of frustration, only to find that the problem was a flat battery all along.

The Groovesizer RED is a little synth/sequencer kit designed and sold by MoShang and shipped out, as far as I can tell, from his one-man operation based in Taiwan. The instrument itself is an Arduino (ATMEGA32) based lo-fi granular synth and 16 step sequencer. In layman terms, that means it can produce a 16 step repeating melody with a gritty synth sound. It’s also capable of sending and receiving MIDI messages. Splendid.

The Kit
I consider myself to be a somewhat confident builder these days. I’ve built many things from kits and designed some circuit layouts myself on perfboard. Most of them worked! The Groovesizer was a relaxing build due to the low parts count and no need for offboard wiring. I wouldn’t say it’s the ideal build for a completely novice hobbyist on the other hand, as the 16 LEDs are extremely fiddly to solder. They’re very close to some other components and it makes it difficult to get the iron in there. I find that soldering one pad on each then reheating it while pushing the LED into place is the most effective method. Even using this technique some of my diodes remain ever so slightly wonky.
Moshang provides a very informative step by step guide to building the kit on the Groovesizer site, including some handy practical tips and notes on which part of the circuitry each component is involved with.
The cost was around £55GBP, including delivery although you’ll likely need to pay an additional customs fee for your country to import it. That was around another £13 for me. I’d say that’s a reasonable price for what the unit offers in terms of the pleasure you’d get out of building it as well as the usability it offers.

Look and Feel
Wow, this thing is stylish. A lot of thought has gone in to making the circuit board part of the aesthetic, with the components visible through clear acrylic plates. The knobs, which boast neat red markers and the bright red switch covers, both included with the kit, add to the visual appeal.

Groovisizer shoes - 1.jpg
Tenuously related picture of my shoes. What? They’re red!

The design is only really let down by the feel of board mounted pots and switches, which aren’t nearly as solid as I would like. They’re far from being flimsy, but something slightly weightier would just finish it off for me.

Groovisizer - 1 (1)
The one downside of transparent perspex: it produces more shadows than Cliff Richard.

The Synthesizer
Ok, the payoff of that last joke was pretty weak, but fortunately that can’t be said for the Groovesizer RED’s synth section. It has five main sound parameter controls. Grain Pitch 1 and 2 act a lot like the cutoff control on a filter while grain decay 1 and 2 behave like the resonance. Combining these results in a smorgasbord of different sounds from subtle to extreme including wild tweeting or throaty sounds with the grain decays set to max. The final control sets the decay of each note. Subtly changing this also has a noticeable effect on the way the filters react. There is also the option to automate grain pitch 1 over the course of a sequence to imitate the sweep of a voltage controlled filter.

After playing around with the Groovesizer for the best part of a week, I’ve discovered that perseverance is the key to getting the most out of it. Having so many options in an instrument that doesn’t have an LCD comes at the expense of ease of use. Inputting sequences is not particularly intuitive and getting to grips with adding slides and accents is even more confusing, as you have remember to add them before releasing the note input button. With that said, learning the controls thoroughly is extremely rewarding and with a little practice, it can become second nature.

There certainly is a deceptively large amount of options hidden in the instrument. Pattern mode is one of my favourites. There are a number of preset scales saved in the memory. Selecting one automatically brings up an ascending pattern based on that scale. Load up a minor arpeggio in UP and DOWN mode, knock it down an octave and you have an instant Muse-circa-2003 bassline.
Other functions that are crammed into the synth include transposing a pattern via MIDI, storing and recalling patterns and tap tempo. If you’re curious, visit the Groovesizer website where you can read about all of the RED’s many functions.

Naturally, the more creative you are, the better the results you’ll get when programming sequences. A quick look at any of MoShang’s Youtube videos on the Groovesizer show the breadth of what can be achieved and I’ve mostly only tried to imitate famous patterns so far.

Fun. Lots of fun! The RED has fiddle value. Even with a basic sequence programmed in, it’ll keep you occupied for hours noodling around with the tempo, swing and sound. Would I use it as a legitimate instrument in the studio? I’m not sure. The sound is certainly convincing enough to base a tune on; perhaps not varied enough to use all the time. What I would certainly do is keep it on display in the studio so I could say to people ‘I made that!’ at which point they’d exclaim ‘You made it? Wow, it looks great’. Because it does. It looks really cool.

Visit to read more about the Groovesizer RED and MoShang’s other DIY projects which all look equally good.



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