ClassD amps and their performance

Thats something I need to investigate is Class t in comparison to class d. The Lygndorf amps do get good reviews and are relatively cheap particularly second hand.I am not even sure if I have read any articles about class t but somewhere in the old grey cells I seem to remember seeing an article,hifi news perhaps.I have a Trends t something but dont know if its class t or if the names a coincedence.

 

Class D refers to the state of the output devices, and in this class they are always either fully on or fully off. In a class D amp the width of these on/off pulses is varied in accordance with the programme signal (Pulse Width Modulation - PWM). This programme signal could be either an analogue or a digital one. In the case of the Lyngdorf it is digital. They convert the digital output from the CD player as a digitally coded signal directly to PWM. In other words everything stays digital until the switching carrier is filtered out when the signal goes to the speakers. This is why Lyngdorf label their amps TDA, which stands for True Digital Amplifier.

As you indicate, there are Class D amps on the market which can be driven by an analogue signal. Lyngdorf have one - its called the SDA, Semi Digital Amplifier. Here the signal will have its D to A conversion done in the CD player, or via a separate DAC, and the analogue signal then drives the Class D stage.

I have not heard of Class T amplification, so cannot comment how that might be different.

 

Class T amplification is done by using Tripath chips (Naim N-vi for example).