Integrated Amplifiers

The core digital Class D amplifier at the heart of the TDAI-2210 is clearly related to that of the older TDAI-2200 [HFN Mar '07]. The newer model is less powerful but more load tolerant, the 200W/380W 8/4ohm output of the TDAI-2200 traded for 125W/244W here, respectively, but with a full 495W and 895W (30A) available under dynamic conditions into low 2 and 1ohm loads [Graph 1].

Overall gain is higher at +38.4dB (+20dB volume), +24.1dB at +6.0dB and +18.1dB at 0.0dB volume but the A-wtd S/N ratio is markedly improved at 101dB (re. 0dBW) – this directly linked to the lower noise of Lyngdorf's latest switching PSU [see boxout]. Digital jitter is also 'changed' as the correlated 110psec of the TDAI-2200 is traded here for an increase in decorrelated phase noise, estimated to be ~500psec. Measuring jitter through the preamp outs tells us nothing about the PWM amplifier but, at just 15psec, illustrates the quality of the ADC and DAC.

Unchanged is the impact of the amp's LC filter on its reactive output impedance (and response and distortion), the former increasing markedly from <0.1ohm from 20Hz-2kHz to 1.1ohm at 20kHz [dashed blue trace, Graph 2]. As a result, the amplifier's HF response varies according to the speaker load from +0.8dB to –0.5dB, –2.8dB and –6.1dB (all re. 20kHz into 8, 4, 2 and 1ohm loads, respectively). The maximum ~45kHz response, via analogue or digital inputs, is limited by the default 96kHz internal sample rate [Graph 2, below]. Similarly, distortion is lowest at 0.0005-0.006% at 1-10W through the midband, up to 0.02% at the rated 105W output, but increases with frequency to 0.05%/10kHz and 1.6%/20kHz (all re. 10W/8ohm). PM