Radio Music is a virtual radio Eurorack module. Like a radio, this module works on a series of banks and stations. Each of the 16 banks can contain many different stations. Each station is an audio file stored in banks of folders on the SD card. Choose a bank by pressing and holding the RESET switch. Choose a station by turning the STATION knob or plugging a voltage into TUNE.
You can put up to 75 files in each folder, but with that many files it might be hard to accurately tune to a station. If you’re between stations, you might get a rapid juddering sound as the module slips between stations. Just retune the knob. If you find it a big problem, put fewer files in each directory so the channels are more spaced out. Like real radio stations, the files continue to play in the background – they don’t re-trigger each time you select a new station.
The Start knob sets where the file will play from if you press the RESET button. It does nothing until you press the ‘Reset’ button! (This behaviour can be changed by editing settings.txt file on the sd card). The Start knob is quite a coarse control, with a resolution of 512 steps. So, if you have a 30 minute radio show, the smallest shift you can make will be around 3.5 seconds. If you’re playing a 4 second loop, the control will be finer. TAP the Reset button to restart the current track at the point determined by the Start knob or the Start CV input.
If you’re playing a large file (a 30 minute .raw file is 150mb) it will take a few milliseconds to skip to the end of the file, so the button feels less responsive than it does with smaller files, or the earlier parts of bigger files.
HOLD the Reset button for more than 200ms to change banks. Keep the button held down to skip through all 16 banks.
It’s possible to hot-swap SD cards. If the module detects the SD card has been removed, it will reboot. When the module boots up, it looks for an SD card for a while – the bank LEDs flash when no card is present. After a while it will give up, and you’ll need to turn the power on and off.
When an SD card is inserted into the module Bank position is saved on the module after power-down.
Bank and meter LEDs
The LEDs at the top of the module do two jobs. When audio is playing, they act as a simple VU meter. While choosing banks, they show the bank number in binary
– 0 ○○○○
– 1 ●○○○
– 2 ○●○○
– 3 ●●○○
– 4 ○○●○
– 5 ●○●○
– 6 ○●●○
– 7 ●●●○
– 8 ○○○●
– 9 ●○○●
– 10 ○●○●
– 11 ●●○●
– 12 ○○●●
– 13 ●○●●
– 14 ○●●●
– 15 ●●●●
INs / OUTs
Tune CV Input
This is the CV equivalent of the Station Pot. If the CV changes, the module will immediately re-tune to the relevant station.
The module ‘understands’ 0v to +5v signals, and is protected against higher or negative voltages.
The CV input is added to the knob position; if the knob is at 12 o’clock and 2.5v is applied to the CV, it’s the equivalent of the knob being fully clockwise. Unfortunately you can’t ‘pull the pot down’ by applying a negative voltage.
Start CV input
This is the CV equivalent of the Start pot. Like the start pot, it does nothing until a ‘Reset’ CV is received. This CV input behaves like the Tune CV – it’s zero to +5v, added to the pot position.
Reset Trigger input
A positive clock here triggers the reset button. It should not trigger the bank change.
The output level is set by the trimmer on the back of the module – the output is AC-coupled so cannot output control voltages
NOTE – you need to purchase a MicroSD card and a Micro-B USB Cable elsewhere to set up this module. The Micro-B cables are the smallest type shipped with Kindles and many Android phones. You also need a card reader to write files to the SD card, many laptops and desktops already have them built in now. – Read the setup and build documentation here.
The very cheap $2 MicroSD cards are not worth the trouble they will cause you, buy genuine SanDisk or Kingston branded MicroSD cards from Amazon or elsewhere. 32Gb maximum… that’s 108 hours of lossless audio in 16bit 44.1khz. Total file limit per card is 1200 files.
Read how to set up the SD card here: SD Card: Format & File Structure
Download the latest firmware here – http://polyfather.com/radio_music/
Full project details and documentation here – http://github.com/TomWhitwell/RadioMusic/
Radio Music on MusicThing.co.uk – https://www.musicthing.co.uk/pages/radio.html
Voltage Control Lab Playlist on Youtube – a fantastic five-part series on Radio Music