TUNA

Module introduction

Tuna is a four channels automatic tuner.

To make it short, you plug your VCO, press a button for a few seconds and boom, the VCO gets tuned automatically.
Tuna acts as an interface beween your v/oct signals and your VCOs.
Each channel (vertically) has a tuning button and four connectors.

Operating the module

Once connected to the VCO, press and hold the button on top of the channel to tune it.
You will hear the VCO's frequency increase until it reaches the target note (factory setting: C).

Let's say that the channel is set to C (i.e. 16.35 Hz, 32.7 Hz, 65.4 Hz, 130.8 Hz, ... , 8371.2 Hz).
When you press and hold the button, the Tuna will adjust its v/oct output to increase the VCO's frequency until it reaches a value from the list above (i.e. until it reaches a C note).

As soon as the VCO is tuned, the button starts blinking: you can release it.

Tuning one or multiple channels to an arbitrary note

C is the default tuning, but the Tuna can be tuned to any root note / frequency.

Do you like A 432 ? Let's tune the channels 2 and 3 to 432Hz :

• Press the learn button. By default, all the channels are set to "learning" (they are lit), and the blinking channel is where you have to put your reference frequency.
• Click the buttons 1 and 4 (to deselect them), because we just want to tune channels 2 and 3. The channel 2 flashes, as it expects the reference signal.
• Take a tuner or oscilloscope, adjust a VCO to 432Hz. Connect the VCO's output to "signal in" on channel 2.
• Long press the [learn] button. It flashes. Done.

Tuning all channels back to C

If you want to reset all the channels to a C, simply long press the [learn] button until it flashes, and you're done!

Module states

Here are the different possible states of Tuna:

Idle

This is the default mode, all the buttons are off.

Tuning

Hold a channel button pressed until it starts blinking. This will increase the offset sent to the VCO, until it becomes tuned to the desired note.

Once the button is released, the module goes back to idle mode.

Learning

Click the [learn] button. All the channels are lit, and channel one blinks. Uncheck the channels that you don't want to tune (if you unselect the 4 channels, the module goes back to idle mode).

Long press the learn button until it flashes. All goes off, you are back in idle mode. You can now actually tune your VCOs.

Using Tuna as a chord generator

Having 4 independent channels is pretty useful, as you can tune them to generate chords.
For example, if you tune the channel 1 to C, channel 2 to Eb and channel 3 to G, you will get a C minor chord!

Typical patches

With a VCO

As a chord generator

Rear view

Troubleshooting / limitations

Tuna measures the input frequency using the signal's positive side. It counts the rising edges. The waveform must be steady, i.e. no fancy FM, moving PWM...