A telecommunication transmitter (TU) for a multi-carrier transmission system of the Digital Subscriber Line [DSL] type and which includes a coding circuit (MMC) able to generate “symbols” derived from carriers (Cl-Cn) modulated by incoming data, and a line driver circuit (LDC) to amplify these symbols. When idle data are received, the power dissipated in the transmitter is reduced because the symbols are then merely derived from a few or even a single carrier (the “pilot tone”) instead as from all the available carriers. The power dissipated is even more reduced because the line driver circuit is formed by a parallel connection of a high voltage but low efficiency (LL) and a lower voltage but higher performance (LH) line amplifier. The higher performance, and thus less power consuming, amplifier (LH) is used when idle data are received at the input (IN). In a variant, there is only one line amplifier of which the quiescent current is controlled as a function of the data traffic. In another variant, the number of carriers used by the coding circuit (MMC) is a function of the mean traffic of effective data received.