The latest ESI drivers (for julia, and some other cards) are quite good and support Vista. The ones for the older cards are a no-go for me for this same reason.
About linux world, the Envy24ht is well supported, so that's also a go.
Last but not least, there is the word clock issue. IIRC i2s contains a clock signal. I wonder if an external clock would be needed, like it is for spdif, or that can be skipped without compromising SQ too much.
It seems that the Envy 24ht might be a significant consideration. (How long until 24 bits are insufficient? ) The same chip is incorporated into ESI interfaces of any age. Even for the discontinued equipment the most recent driver supports Vista 32 and 64 and was updated only a few months ago.
Regarding the ESI card, there are no crystals on the rack-mount board so the only clock seems to be on the PCI card. I'm not an engineer, but I think an external clock may be generally desirable because even with the transceiver chips I observed that the length of the cable to the DACs affects sound quality. The stock cable is 3 meters. I replaced that with one that is ~80cm and improved SQ noticably (from the stock AKM DACs).
One wonders what is the limit of interface jitter that the new ES9018 can ignore? It seems like a very different beast.
This concerns me a bit. Are you talking about a rca cable using the AKM dacs in their cards or something else?
Back to the "from the ground up" proposition for this thread, methinks that the controller chip of choice plus the software to run it are central issues in this chain of information. What would produce the highest quality source? Isn't the VIA Envy 24ht getting old and isn't there anything significantly better? Farther along, can't you engineers just 'use a bigger hammer' as it were to improve transmission and 'fidelity' of the original I2S signal ???
I am afraid Envy24HT was the peak in high-fidelity sound card technology. It does its job - moving data from memory to I2S via DMA, clocked by separate crystal-based clocks for 44.1kHz and 48kHz families, plus simple mixer and integrated SPDIF transmitter. Complete documentation freely available, without signing an NDA. Reasonable range of supported latencies. No DSP, effects, synthesis, PLL'd clocks to spare the second crystal.
All new generation soundchips are made to save money on BOM, not to provide top sound quality. The only PCIe card with double crystals I have been able to find so far is the aforementioned http://www.esi-audio.com/products/esp1010e/ which I suspect somehow runs on the Envy24 chip too (perhaps some custom-made variant with PCIe support) - check out the board picture.
More importantly, there is a pin for wordclock input?
About software, how is the sample rate selected? I know that RME drivers are transparent, in the way that they do not change arbitrarily the sample rate of the track playing.
francolargo said:For the older board, the drivers are straightforward. A small screen containing I/O and level controls has a sample rate section. One can choose 'auto', in which case it detects the rate of the source and passes it on. In manual mode you can output anything from 8kHz up to 192kHz in predictable increments of 44.1 or 48. In either mode the output frequency is displayed. Again, the manual is available for download from the ESI site.
francolargo said:Question to wise readers regarding 'jitter' and re-sampling: Without resampling *after* Envy 24ht output, would you expect better DAC performance from I2S at 'native' frequency (e.g. 44.1 kHz recordings) or would you expect better performance by upsampling in software prior to the Envy 24ht input?
About your CoreWorks I²S core : you plan to use a FPGA ? Implementing I²S is quite straightforward, a few hours of work, so I'd not consider buying a core for this...
Question to wise readers regarding 'jitter' and re-sampling: Without resampling *after* Envy 24ht output, would you expect better DAC performance from I2S at 'native' frequency (e.g. 44.1 kHz recordings) or would you expect better performance by upsampling in software prior to the Envy 24ht input?
peufeu said:What do you mean by a transceiver ? that could be lots of different things...
You going to use FPGA, CPLD, uC ? Can you tell more about the setup ?
francolargo said:However, the reverse is true for MPEG-4 files. Sound quality of MPEG-4 sources is clearly superior at 44.1kHz compared to 176.4kHz. When MPEG-4 files are oversampled the sound is unacceptably "hollow".
[Why MPEG-4? I have a large collection of digitized 78's.]
Does it mean, that 44.1 kHz MPEG-4, converted to wav (a.wav), upsampled x4 to 176.4kHz, sounds worse than the 44.1kHz a.wav, while regular 44.1kHz b.wav upsampled by the same algorhithm to 176.4kHz sounds better than the original 44.1kHz b.wav?