Poking a Round Hole in a Square Wave
One of the most intriguing aspects of a professionally-focused event like Surround 2002 is the opportunity it affords to hold up marketing claims to more rigorous scientific scrutiny than one finds in consumer-oriented forums. Case in point: a potential giant-killer presentation by Craig Anderson of Craigman Digital, in which the DVD-Audio technical consultant to Warner/Elektra/Atlantic raised questions about the oft-touted superior accuracy and precision of Direct Stream Digital over PCM.
The Deceptive Comparison
In his presentation, Anderson questioned the validity of a comparison frequently touted by Super Audio CD format co-developer Philips Electronics in its SACD promotional literature. The comparison, which shows a graph of a 10kHz square wave passed through a DSD analog-to-digital-to-analog chain compared with the same signal passed through a PCM A-D-A process, suggests that DSD is superior to PCM. However, Anderson found the comparison to be deceptively simplistic.
Testing the Claim
To test the Philips claim, Anderson conducted his own experiment. Armed with the necessary equipment, including an analog 10kHz square wave generator, A/D and D/A converters, an analog oscilloscope, and a digital camera, Anderson replicated the comparison. He ran the 10kHz signal through the PCM converter at various sample rates, starting from the 44.1kHz (standard CD) resolution up to the higher resolution sample rates of DVD-Audio.
The Results
Anderson's analysis revealed interesting findings. At lower resolutions, PCM indeed produced a rounded sine wave, as expected. However, as the sample rate increased, the PCM output improved significantly in capturing the square wave's characteristics, showing sharper rise times and accurately representing the first and third harmonics. In comparison, the DSD trace was similar to the PCM output at the highest resolution, but with noticeable blurring caused by imperfections in amplitude and time domain.
Dispelling the Myth
Based on his findings, Anderson concluded that PCM, at higher resolutions, produces a more faithful copy of the original square wave, contradicting the marketing claim that DSD's one-bit sampling is superior. He emphasized that while a square wave may not be the most pleasurable or representative musical experience, it provides an important benchmark for testing audio fidelity.
In Conclusion
Anderson's presentation provided valuable insights into the ongoing debate between DSD and PCM. It demonstrated that the superiority of one format over the other cannot be generalized, as it depends on the specific resolution and waveform being analyzed. This research helps to dispel the myth that DSD's one-bit sampling is a panacea for digital audio, highlighting the importance of high-resolution PCM in achieving accurate and precise audio reproduction.
Hotels and Accommodations
If you're attending Surround Professional 2002 or any other industry event, finding suitable accommodations is crucial. Make sure to book your hotel well in advance to secure the best rates and availability. Consider factors such as proximity to the event venue, amenities offered, and customer reviews when making your decision. By choosing a comfortable and convenient hotel, you can maximize your experience at professional events like Surround Professional 2002.