The first was the Invicta, which is a pretty decent ESS 9018-based DAC (and designed in close collaboration with the ESS team) with direct DSD playback. What underlined this was a direct comparison, of several DSD tracks, recorded at a very high quality level, played with two very different converters: What's behind this half-baked hypothesis? Well, what I hear from DACs with current-output ladder converters and non-slewing analog electronics is a sound a lot like professional-grade DSD. In effect, all it does is raise the noise floor, instead of create a myriad of sum-and-difference tones. But it impairs Nyquist reconstruction of the waveform, and the departure from ideal reconstruction is greatest at high frequencies.ĭSD, by contrast, has a spread spectrum in the 1~10MHz region, which results in very different IM products down in the audio band. The slewing interval is very short, which means that it hardly shows at all in a long-duration FFT measurement. Nearly all opamps, and many transistor circuits (like the Marantz/Philips HDAM circuits), are too slow for PCM - by a factor of 100 or more. I suspect most, or maybe all, of the edgy, flat, and tonally impaired "PCM" sound is the result of the wrong choice of electronics for the I/V converter and active lowpass filter. I'd like to make a few subjective comments about the sound of DSD vs PCM. With the indulgence of the readers of this forum. The functions, particularly the track level changing performed in the E-Chip contained in Sonoma were performed in multiple FGPA's, contained on each mixer channel. It's also been used on several SACD pure DSD releases, and sounds stunning. Genex also made a 48 channel DSD mixer, which it sold a number of copies to Clear Channel, for their Hard Rock Cafe "instant" concert performance productions. It's the decimation (low-pass filtering to avoid the Nyquist conflict at the lower new PCM sampling rate, that does the sonic harm., as opposed to the conversion from a derivative like series of samples (DSD) to separate stand-alone discrete level words (PCM). These functions were performed in DSD-Wide, which are 8-bit stand alone words, like PCM, but is derived without decimation. It contained multiple E-Chips, just like the fewer E-Chips contained on a Sonoma card. Sonoma was originally available with a multi-channel mixer module, and software, that performed many of the more common post production processing functions, including level changing, EQ, etc. Again, he can provide the explanation details. They're both single sampling rate 128fs D/A converter back ends.Īccording to Andreas, the algorithms for any signal processing are the same, whether DSD or PCM. Both the EMM Labs and PD DAC's upsample to 128fs DSD for D/A conversion, regardless of the format and sample rate presented. Lynn, your questions would be best addressed to Andreas Koch, who I'm sure will reply. Is this a correct picture? You have one of the few studios that specialize in DSD, so you must know more about the origins of SACD and DSD-download recordings than most of us. If the 24-track analog master still exists, the recording could always be re-mixed in a purist Sonoma environment, but if the multitrack master is PCM (on disk or tape), there has to be a transcoding step into the world of DSD-wide, then a reduction to DSD-narrow. I'm guessing these recordings from this era might be partially analog, but have passed through at least one stage of PCM of varying quality. What about recordings from the mid-Eighties to the early 2000's, before Pyramix and Sonoma? The 24-track tape machines and EMT reverbs were gradually replaced by all-digital systems, at fairly low PCM resolutions (20/44.1?) at first, then 24/88.2 and 24/96 by the mid-Nineties. What we're hearing are either all-analog sources, dating from the Eighties or earlier, or more modern recordings which are sourced and mixed in studio-grade PCM, DXD/PCM, or DSD-wide.īruce, you're the professional, and know the answers here. If that's so, then "pure" DSD recordings hardly exist at all, in the narrow audiophile sense of 2 microphones -> preamp -> ADC -> DSD -> DAC -> consumer playback. (D) are sourced from two-track analog mastertapes (C) are converted from PCM sources varying from 20/88.2 to 24/192 If I understand correctly, in the real world where multitrack recordings are the norm, nearly all SACD and DSD-download releases have passed through:
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