PCM1794A left/right channel distortion difference

Basically in all of my PCM1794A measurements I have seen something strange going on in the distortion figures between left and right channels. Right channel is constantly weaker but the results are very consistent between measurements, parts, and even different opamp models, while left channel shows better performance but the results are very inconsistent. I will show few examples from different measurements. To be honest, I still do not know what … Continue reading

PCM1794A output stage opamp measurements: LM4562, NE5532, and OPA2134

LM4562 and NE5532 show almost identical performance in I/V stage, while OPA2134 is 2 dB weaker. LM4562 is the best performer in differential amplifier. The best solution is to use NE5532 in I/V-stage and LM4562 in differential amplifier as it gives almost identical performance to all-LM4562 implementation Differences in distortion are mostly due to odd left/right channel differences of PCM1794A. Introduction PCM1794A has differential current outputs and therefore requires some analog … Continue reading

Understanding DAC filters and their impact in time and frequency domains

Many DAC chips and devices using those chip have user selectable options for digital filter response to fine-tune tonal characteristics. I will take PCM1794A used on H-DAC as an example and see what effects these filter types have on impulse and frequency responses. This is just scratching the surface of the topic by briefly introducing some technical effects that can be measured. Tonal characteristics are not discussed here; those are highly subjective … Continue reading