06-Feb-2021, 13:41
(06-Feb-2021, 13:13)struts Wrote:(05-Feb-2021, 16:54)streamy Wrote: From reading many posts here in the forum and all so over in the Roon forum there are a number of things happening, depending on the different versions of Phantoms. The Phantom Golds of the first years 2016 to maybe 2019 accept through the optical input 24/192k. Phantom Silver and White Phantoms also accepted 24/192k. The Phantom Premier Classic replaced then the White Phantoms and the Silver Phantoms were not offered anymore, except for refurbished ones. We heard from a number of people with newer Phantoms Premier and lately also from Phantom Gold users that the optical only accepts 24/96k, same as the optical input from the Dialog. This probably has to do with lowers spect components. Since optical in general is originally specified to 24/96k by Sony the higher resolution only can be achieved with a careful design and better optical components/connectors. That’s where there can be a bottleneck in the latest Phantoms on the hardware. The Phantom Reactors were from beginning specified to 24/96k. Now Phantom Premiers (Gold and Classic) are Phantom I and Phantom Reactors are Phantom II. That they only accept 24/48k has to do with downsampling and not with the optical input electronics. Therefore we could assume that the direct optical mode plays at least 24/96k or even 24/192k. The internal DAQ of the Phantoms is a TI chip that can handle 24/192k PCM, as almost all DAQs can. It wouldn’t make any sense for Devialet not to continue to build in the current TI chip but an inferior chip as they are dead cheap. And why should they invest into making a different design only to disappoint their customers? I’m very sure that the specs limitation has to do with quality of service of wireless networks and therefore is related to software.
I agree with some of your analysis @streamy, but there also seem to be a number of assumptions here, at least some of which I believe are incorrect.
1. The optical input. We know that earlier phantom models accepted S/PDIF input at 24/192 and then later this was reduced to 24/96 but afaik we don't know what Phantoms have ever done with that input, and specifically any spectral content above 24kHz. As far as I know no reviewer has ever measured the acoustic output above 24kHz to see if signal above that frequency is actually being reproduced. A lot of folks here are very upset that Devialet has "stolen" hi res capability from them but are we actually sure we were ever getting it?
2. "Direct optical" mode. We know it bypasses some of the circuitry and processing to reduce signal delay but afaik we don't know exactly which. Some folks talk about it as if it bypasses everything and the photons somehow directly bombard the drive units creating high resolution sound. Devialet has said that the DAC architecture in the new phantoms is 24/96-capable, but that under DOS 2 all inputs are limited to 24/48. What we don't know is where the bottleneck is and whether a "direct optical" mode implemented in DOS 2 might be able to avoid it.
3. One thing Devialet has said is that the hardware architecture in the new Phantoms (those sold as Phantom Is with the new matte finish, and by some accounts here maybe some late examples of the previous generation Phantom Classic/Gold with the gloss finish) has been substantially changed. Instead of an OTS DAC chip the DAC and most other processing and amplification functions have been combined on a proprietary SoC which is more performant and more efficient (particularly more thermodynamically efficient). So I disagree with your statement that "it wouldn't make any sense" to change. Devialet has changed and while there are obviously some advantages to the new architecture unfortunately there are also apparently some disadvantages too.
4. Why limit DOS 2 to 48kS/s? Here we are just speculating. The new DAC architecture can apparently handle twice the sampling rate, maybe the entire SoC architecture can? Is it a temporary restriction or a permanent one? Does it have to do with stereo sync issues, multi-room or the ability to support wireless transport protocols? We simply don't know.
5. Finally, as the owner of "legacy" Phantoms (as pretty much all of us here are by definition), I wonder whether Devialet will devote any engineering resources to enabling functionality, such as the ability to support hi resolution audio above 24/48, supported by the legacy "discrete" hardware architecture but not supported by the new SoC??
Happy to be corrected if I have missed any facts/proof/measurements which contradict any of the above.
A nice summary.
Ideally, it would be nice to see specifications similar to those provided by MiniDSP.
Eg.
Audio Input Connectivity
Unbalanced analog input, RCA terminated
Stereo Digital Inputs: TOSLINK (optical)
Stereo USB audio input: USB Audio
Supported ASCR (Asynchronous Sampling Rate Conversion): 20~216kHz
Internal Processing resolution & Sample rate: 32 bit / 96kHz
Why down sample? I think this overview might be informative.
