Recent content by LynnOlson

  1. L

    DSD comparison to PCM.

    Good analysis, Renee, much appreciated! My feeling is simple: why accept any slewing at all, even for a few nanoseconds? What is bad about passive filtering? It's standard practice in the RF world; well, this is a RF problem, why not solve it with RF techniques? Once we accept slewing, then we...
  2. L

    DSD comparison to PCM.

    Well, the source formats for most recordings made in the last twenty-five years is 44.1/20, 88.2/24, 96/24, 176.4/24, and 196/24 PCM. Is it unreasonable to ask to hear them in the original fidelity, as opposed to down-conversion to antique Red Book, or almost equally dated SACD/DSD-narrow? This...
  3. L

    DSD comparison to PCM.

    Hi PeterSt, this is a reply to your post #616. The latest PFO article, although serious in tone, is partly a joke aimed at the mid-fi PCM DACs out there. From my perspective, these DACs do a pretty bad job with both PCM and DSD. The high frequencies of PCM are rendered as harsh and gritty...
  4. L

    DSD comparison to PCM.

    What puzzles me are the very high bandwidths we're seeing here. Studio microphones have almost no output above 50 kHz; many are gone by 30 kHz. Above these frequencies, the output is both ragged and falling, with very uneven group delay since the diaphragms are no longer moving as a unit and are...
  5. L

    DSD comparison to PCM.

    What I heard at David's place with the Playback Designs was very, very good. We only listened to 64fs and 128fs DSD-downloads; no SACD's, Red Book CD's, or high-rez PCM, so I can't say anything how the PB does with those sources. The deficiencies you hear from consumer-grade one-box SACD players...
  6. L

    DSD comparison to PCM.

    I'm still learning this stuff myself, so don't be surprised if some errors have crept in. Thorsten brought my attention to Andreas Koch's FFT graph of DSD performance. He estimates it has 33 dB (!) of FFT Gain, presumably through very long averaging times. Although not shown in the graph, this...
  7. L

    DSD comparison to PCM.

    Thorsten discovered this blast from the past: http://web.archive.org/web/20071011014242/http://www.smr-home-theatre.org/surround2002/technology/page_07.shtml "Incapable of reproducing the same transient twice." Like the famous description of NTSC as "Never Twice the Same Colour", or Ford as...
  8. L

    DSD comparison to PCM.

    Well, it really does combine some of the worst features of PCM and DSD. All the noise of DSD, and the transient response of PCM. Probably very similar to what you get when studio-origination PCM is "upsampled" to SACD or DSD; all of the time-domain problems from the original PCM encoding remain...
  9. L

    DSD comparison to PCM.

    New article out at Positive Feedback: http://www.positive-feedback.com/Issue66/pcm_dsd.htm I'm pretty sure that the proposed dither-noise spectra would change the sound of mid-to-upper-mid delta-sigma DACs in some kind of way (maybe worse, maybe better). Class D amplifiers improved quite a bit...
  10. L

    DSD comparison to PCM.

    Good question. I have not auditioned a passive I/V driving a transistor long-tailed pair; the only ones I've heard used a RF-type vacuum tube (6DJ8) in a non-feedback circuit, which is linear right through television broadcast frequencies. The care and feeding of transistor circuits in the 1~50...
  11. L

    DSD comparison to PCM.

    There are three ways to deal with the fast edges that come out of a current-mode converter: 1) Passive current-to-voltage conversion with a resistor combined with a cap as a lowpass filter with a turnover around 70~100 kHz. Although it's only a 1st-order rolloff, it reduces the magnitude of 1...
  12. L

    DSD comparison to PCM.

    Based as it is on the TDA1541 architecture, I can't see how anything could be much different. You can quibble about the 7308 versus other tubes, but that's pretty much a subjective decision. I've had good luck with Pure Music converting 128fs DSD to 24/88.2 PCM ... what I heard sounded like...
  13. L

    DSD comparison to PCM.

    In the time domain, DSD looks like little clouds of noise, with an average cloud-size about 714 nanoseconds. Signal modulation is carried out by varying the size of these clouds; on any given group of samples, it's going to be very difficult to discern how this clump of noise is any different...
  14. L

    DSD comparison to PCM.

    Based on the in-thread comments posted by professionals who use DSD, at the highest level where almost unlimited amounts of money and processing power are available, signal processing involving delays, equalization, reverb synthesis, compression, etc. involves a conversion to DSD-wide (Sonoma)...
  15. L

    DSD comparison to PCM.

    Well, it's the yardstick that matters, doesn't it? If the criterion is movie soundtracks, that's a completely different thing. Since soundtracks are completely artificial confections, there's really no reference at all, unless you work at Skywalker Ranch in California, and have ready access to...
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