Bit-perfect ASIO drivers to solve issues with Windows audio quality

By default, Windows audio quality can be technically not superb. ASIO drivers or similar can improve audio output significantly by bypassing Windows resampling and other audio processing stages. This post is a consequence of testing the USB-input of H-DAC. Its PCM2707C-circuit is capable of “only” 48 kHz / 16-bit audio so I was not expecting superb measurement results but was still amazed how bad they actually are. This is purely technical … Continue reading

LME49724 vs. OPA1632 in Addon BalOut

Following performance figures have been measured in Addon BalOut module: Both opamps are so good that it is difficult to measure differences directly. LME49724: Noise level: -117 dBV (A-weighted), THD+N ratio: at least -109 dB (1 kHz, 2 Vrms), around measurement instrument limits. OPA1632: Noise level: -118 dBV (A-weighted), THD+N level: at least -109 dB (1 kHz, 2 Vrms), around measurement instrument limits. Measurements Originally the balanced addon board Addon BalOut for H-DAC have LME49724 fully … Continue reading

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

Understanding audio measurements: THD+N vs. amplitude and frequency

Presents the unwanted part of the signal – something that was not put there and should not be there. THD+N vs. amplitude graph is important as it reveals SNR, dynamic range, and THD+N ratio; all are expressed as ratio compared to a specified signal level. Signal level, signal frequency, and measurement bandwidth must be known (or guessed) when analysing results. THD+N, Total Harmonic Distortion plus Noise, is one of the best audio … Continue reading