This portable sample player packs quite a punch. [Lee] wanted a nice portable way to take his samples with him, but refused to water-down the features just because it is portable. He set of goal of playing between 3-8 simultaneous notes from a large assortment of stored samples.
Sample space was the first design consideration, and it’s hard to beat the price per megabyte of an SD card. After some calculations he concluded that it is possible to pull these samples off the card quickly enough to achieve his simultaneous note goal at CD quality frequencies, but only if there is little or no latency when reading from the card. This means [Lee] needed a fast processor so he chose the LPC1769 which is an ARM Cortex-M3 processor which can run at 120 MHz.
The project box includes room for a volume knob to control the output from the in-build headphone amplifier. There’s also a rotary encoder for selecting sample sets. But we’re a bit confused on this part as the device is MIDI controlled. [Lee] is the creator of the electronic Moolodeon, which itself has MIDI out and will be used as a controller for this project.