IK Multimedia UNO Drum Mods

Although this little drum machine by IK Mulktimedia offers so much in terms of sound and functionality, it somehow manages to fly under the radar. The latter might be realted to some aspects (potential) users on fora were complaining about, mostly the lack of individual intrument outputs. After I found a reasonably priced unit second hand (and after the licence transfer…), I was positively surprised of what can be done with this little box.

With a couple of folks asking on GS, I put together a more detailed guide on how to implement individual instrument outputs for the five analogue instruments and the PCM sound channel and plan on posting more information on what can be had by tinkering with that formidable monster of a bassdrum as well as the clap and hi hats.

Since the UNO Drum can well be used without the touch plate section exclusively using midi notes and CCs, my long term plan is to give it a single height rack case with proper 6.3mm jack sockets and knobby knobs for mod controls – will need to up my usb socket soldering skills first, however.

Here is a quick and dirty recording of the UNO drum recorded in realtime via the multi outs and using different FX per instrument:

Uno Drum Multi-Out shenanigans

In the meantime it emerged that a company rep active on gearslutz has shown this mod to the UNO drum product manager. Even though this does not mean there are any plans, it’s a nice gesture. 🙂

Instrument mods

Analogue Instruments in the UNO DRUM

The UNO drum features five analogue instruments and one audio channel for multiple PCM-based instruments.

I think all instrument envelopes are created digitally. Many digitally changeable parameters, such as BD1 FM amount, for instance, go via the two NJU72343 8-channel volume controller ICs on the left of the PCB, which also carry the individual instruments (and might also regulate FX amount). Further PWM/control signals are provided directly by the ARM microprocessor on the very right of the PCB.

As regards instrument level control, some/all instrument levels are already regulated at the final instrument stage rather than a final mixing unit. For instance, the final OPAMP stage of BD1 responds to volume control, while BD1 also goes through one of the two 8-cahnel level control ICs at final summing.

BD1 Mods

BD1 is oriented towards a Roland TR909 kick, yet offers quite a bit more. Apart from a click/noise component in the attack portion, you have one main VCO that undergoes a pulse shaper (like on the 909) and diverse forms of envelope modulations. A very neat feature is a second VCO that can frequency modulate VCO1. The pitch information for both VCOs is provided from PWM signals from the CPU, and, if I’m not entirely mistaken, the pitch and VCA envelopes are also provided digitally. Hence, you can dynamically change and motion-record various sound aspects. The BD “click” transient is provided by an entirely separate audio channel and mixed together with the main BD sound at the instrument summing stage.

As for mods, I personally implemented Pitch CV input, a pot for changing the pulse shaper, and some variable output boost/compression.

BD1 with pulse shape and out level/compression mods
BD1 with pulse shape mod and external FM input
Mods points in BD1 circuit
Rough equivalents on a well-known bass drum schematic


Here you go, some samples of the modded BD1, recorded with an AKAI MPC ONE.