96/24 DVD from Pioneer DV-414 to Assemblage DAC-3

Picked up a Pioneer DV-414 DVD player for the express purpose of playing 96 kHz x 24-bit audio. This Pioneer is one of the DVD players that actually outputs full 96 x 24 on it's digital outputs. Be aware that many DVD players do not.

The Pioneer had an original retail price of $500+ and a real street price of $399 at the end of 1998. These were being closed out at Circuit City in early 1999 for $299, and I paid $249 for an out of box demo model. (One nice thing about a demo model is that you can prove it works immediately at the store. They even had it connected using the digital outputs.)

The Pioneer also has 96 x 24 internal DACs, but the post-DAC analog output implementation is so poor that the sound is extremely grainy, compressed, and essentially unlistenable. Even with the poor analog stages, when playing 96 x 24 source material such as the Chesky DVDs, the sound is amazing. There is way more detail, reverberation information, and correctness of instrumental timbre than I've ever heard from recorded music. I can only imagine what it will sound like with a good output like the DAC-3 should provide.

(Note that Classic Records also markets 96 x 24 DVDs. Most are originally older analog recordings but they include classic albums such as Muddy Waters Folk Singer, other well known jazz and blues, and some of the most famous Vox classical albums. Note also that these 96 x 24 DVDs are using the 96 x 24 audio designed into the DVD-Video standard. They don't have live video on them though, just super high quality audio. The future DVD-Audio standard will likely supersede this format, but these discs will remain playable on any backward-compatible DVD-V player.)

The Assemblage DAC-3 should take 96 x 24 or conventional CD on clock-doubled Toslink or S/PDIF from the DV-414 without any problems. In order to try for a lower-jitter interface between them, I had gotten a I2Se cable and I2Se transmitter board from Sonic Frontiers (the board was actually made by Ultra Analog). But upon investigating the signals available in the DV-414 it looks like it may not be possible to use the I2Se board in the Pioneer without extensive modifications.

The Pioneer appears to use the Burr-Brown/Sony standard for inter-chip digital audio serial communications, whereas I2Se wants to follow the Philips I2S standard (naturally). Specifically, Sony/Burr-Brown clocks left channel data on the falling word clock whereas Philips clocks left on the rising word clock. I proposed to fix this by swapping the inverting and non-inverting outputs from the Motorola PEC driver used for the I2Se transmitter between the chip and output connector. Peter Schut, the designer of the DAC-3 confirmed this should work.

Much more difficult to fix, however, audio data for Sony/Burr-Brown is right justified whereas Philips is left justified, with a 1 bit delay from the word clock edge. This could be fixed with a receiver chip like the Crystal CS 8414, or with a bunch of glue logic. The problem is much more difficult to fix with your own glue logic when you consider that multiple sampling frequencies and word lengths would need to be supported. A better approach than adding this complexity to the transmitter side would be to improve the receiver side with a second, precision PLL. It's also quite likely that the clock in a dedicated high-end DAC would be cleaner than the one in a low-end consumer DVD player.

So it looks like I'm going to connect the Pioneer to the DAC-3 using S/PDIF. The PLL in the DAC-3 is essentially the reference implementation from the Crystal datasheets.

I may try to make some improvements in the Pioneer's electronics, specifically the power supplies. Many modifiers have found they can lower jitter and increase performance of digital gear by improving or adding power supplies. For example, adding more voltage regulator sections can help decouple noise induced by digital circuitry on the power supply lines from affecting other sections of the system. The goal is mainly to reduce jitter-induced timing errors due to power supply interaction. (Remember that digital circuits pull large but brief current spikes from their power supplies due to their steep signal edges. This modulates the voltage seen at a common power supply, which in turn modulates the timing of the digital signals, causing jitter, which in turn modulates the analog output produced by the DAC.) Dan Wright has some Pioneer DV-525 modifications that should apply equally well to the DV-414 and other related players.