Below are links to the current firmware versions for the D4 series products. These are zip files, after downloading extract them into a temporary folder. Use the Quadra/D4 Firmware Update Utility program update firmware.
NOTE: D4 firmware version 3.00 and higher is compatible and interoperable with the Lectrosonics Quadra IEM system (reduced latency). It is NOT compatible with older D4 units running version 1.xx and 2.xx firmware. Please upgrade any older D4 units to version 3.00 or higher to make them compatible.