The design and implementation of a DAB transmitter prototype is proposed. The system architecture, ensemble multiplexer, channel encoder, OFDM (orthogonal frequency division multiplexing) modulator and other digital baseband parts are described. The prototype is fully compatible with ETS 300 401 and other related standards. It supports different services with various data formats and provides a convenient PC-based user interface. All I/Os and core parts are based on a modular design with a universal internal interface, hence the prototype can be flexibly configured to adapt to different requirements. Compared with existing products, the proposed transmitter prototype offers higher flexibility and lower cost.