There’s nothing quite like the sound of a classic Hammond B-3 organ--unless it’s the sound of an FPGA emulating the Hammond sound. A German company called KeyboardPartner has developed a Hammond B-3 organ hardware emulator and placed it inside of a Xilinx Spartan-3 XC3S400 FPGA (8064 logic cells). The product was originally called HOAX3 for “Hammond on A Xilinx” FPGA, but the €429 sound engine is anything but a hoax so the developers have shortened the name to HX3.
Here’s a short video of the HX3 in action:
The Spartan-3 FPGA simultaneously generates all 91 of the Hammond’s tonewheel signals using digital implementations of algorithms that physically model original Hammond hardware, so the board has “unlimited” polyphony. In theory, you could press every instrument key and get all of the sound a real Hammond could generate. The designers have made the emulation so close to real that you can hear the simulated key clicks at the onset of each note. Keyboard scanning is performed by a Xilinx PicoBlaze 8-bit microcontroller core in the FPGA. There’s also an optional emulation of a Leslie 122 rotating speaker built into the Spartan-3 FPGA emulation.