Class TD Output Stage

Delivering the high Efficiency of a Class D design with the sonic purity of a Class B design amplifier.


The foundation of  Lab.gruppen’s prowess in power amplification, Class TD is a breakthrough design that occupied Lab.gruppen’s co-founder Kenneth Andersson for nearly two years. Class TD combines the high efficiency of a digital Class D with the sonic purity of classic Class B designs.

The power supply rails precisely track the audio signal at all times, providing the required voltage plus additional headroom. This process is highly efficient, with only a tiny portion of the supplied voltage emitted as heat in the output stage. The audio path itself remains entirely in the analog domain. And because the audio path remains outside the switching portion of the circuit, the signal is free from any filtering ripple effects.

Class TD is bridgeable, highly reliable, and maintains a flat response with complex loads as low as 2 ohms nominal. Also, it does not interfere with RF equipment such as wireless (radio) microphones. Though treated separately here, R.SMPS and Class TD were conceived and engineered as an integral design within the amplifier platform. Working together, this new generation of proprietary circuits produces more power from a smaller package while at the same time maintaining Lab.gruppen’s peerless reputation for sonic excellence. The highs stay crisp and transparent. The mids are defined, warm and natural. And the tight low end delivers breathtaking visceral impact.