synctab fits snugly inside the ARPIE MIDI arpeggiator. It connects into the 6 pin "hack header" expansion port and adds two 3.5mm jack sockets to the side of the ARPIE.

The synctab fits inside an uncased ARPIE or inside the OLD style case (transparent plastic with overlapping top and bottom panels). It does not fit inside the NEW style case (black plastic with thick white plastic sides). To fit it in the old style case you will need to remove one of the side panels of the case

How It Works

The input socket receives incoming pulse clock signals and relays them to the output socket. ARPIE can use this pulse clock to synchronise its internal clock, acting as a synch slave.

When there is no cable plugged into the input socket, ARPIE sends its own internal clock signal to the output socket, so it can act as a sync master.

synctab relies on the pulse clock features of ARPIE firmware version 4. It is not compatible with earlier firmware versions (but you can upgrade). It also requires you to have a version of the ARPIE hardware which includes the "hack-header" expansion port. This is a 6 way female header which you'll find directly below the "N" of the TRAN label.

As well as simply providing the sockets for clock connection, synctab includes a Schmitt trigger chip to help keep the incoming clock signal clean and jitter free. The chip also buffers the clock output and drives a pair of LEDs which blink in response to internal and external clock pulses respectively.

Making and Using It

synctab is supplied as a kit and requires assembly by soldering.

To use synctab you need to

• Set the "hack header mode" to pulse clock mode and ARPIE Synch mode to internal clock (see the manual
• Make sure you reset ARPIE after plugging or removing cables to synch input. ARPIE only checks for the presence of external clock input at startup.

The pulse clock is expected to have the following characteristics

• 0V minimum level, 5V max level (although a couple of volts higher is probably OK on the input)
• Positive polarity pulses of 10-15ms
• Ratio of one pulse per quarter note

These match the clock signal of the Korg Volca range. Other clock polarity and rates can be supported but you'll need to change a couple of definitions in the code and recompile it.