z3 - scheme1 wrong behaviour?

[PeterSt]

Puh, watch me !                                                                                                                                                                                                                                      

[Marcin_gps]

Haha! Mani, dCS sounded wrong fed by Cantatis (coaxial or optical) and Cantatis was better as a DAC than as a tranport combined with dCS - strange, but true. The same was with Sony drive, but with RME - oh boy, Cantatis sounds like cr*p compared to dCS, so you see, nothing is plain, but I'm sure of one thing - a DAC should be fed by an outside source, totally isolated from the PC (Firewire?). I experimented one more time with undervolting and underclocking of CPU, but I accomplished that with an app, so I got to compare it right away to normal and overclocked settings. I underclocked my CPU to 400MHz (for each core) and lowered the voltage to 0.450V!!! (1.325 is default, and 1.5V overclocked). I also changed CPU coligation for all processes to CPU2 (third core), XXHE scheme 1 (processing on CPU0, 'sound' on CPU1), cpu affinities for all non-audio devices on CPU2, RME, PCI Bus and PCI I/0 Communications BUS on CPU3. That was the best sound I have ever heard from my system and so much better than default or overclocked setting. So I think our pc-audio playback is going to be better and better every year, because of increasing performance of new CPUs and their smaller TDPs and better architectures.

But nothing is perfect right? With 4x400MHz and quad upsampling (not QAP) I get a random click from time to time, because there is lack of horsepower on CPU0, where all the processing/loading is done. If the processing was spread around all of the cores (except CPU1, where is playback engine), then I guess it wouldn't be a problem. The app I used for underclocking/undervolting is called K10Stat and allows for much better adjustment than you have available in BIOS. Normally I couldn't go below 0.85V, even running a single core! But I guess that the app is for AMD CPUs only...

Let me know what you think
Best regards,
Marcin

[Flecko]

Haha! Mani, dCS sounded wrong fed by Cantatis (coaxial or optical) and Cantatis was better as a DAC than as a tranport combined with dCS - strange, but true. The same was with Sony drive, but with RME - oh boy, Cantatis sounds like cr*p compared to dCS, so you see, nothing is plain, but I'm sure of one thing - a DAC should be fed by an outside source, totally isolated from the PC (Firewire?)

I can affirm this. I used a RME HDSP9632 as spdif source some years ago. Sounded like cr*p. A decent CDP was faaaar better but now with highface and the new version of xxHE PC has become better. Don't know where this will go with the Legato but I expect a significant step up (still waiting for it to come).

[manisandher]

... but with RME - oh boy, Cantatis sounds like cr*p compared to dCS, so you see, nothing is plain, but I'm sure of one thing - a DAC should be fed by an outside source, totally isolated from the PC (Firewire?).

Marcin, I think Peter is rubbing off on you - you're starting to talk double-Dutch

So, you're convinced that the DAC should be fed by an outside source (e.g. firewire), and yet the source that you say sounds great (the RME) is internal (PCI). Hmmm... Care to explain???

FWIW, I can feed my ADC/DAC with an internal (RME AES-32 - PCI) or external (Weiss AFI1 - firewire) source. Both provide a dual-wire AES input to, and take a BNC wordclock from, the ADC/DAC. I'm not sure that I hear any obvious advantage of the external over the internal... What should I be listening out for?

Mani.

[Marcin_gps]

Mani,

RME and Cantatis are PCI-based, that's true and RME is much much better via dual AES, but it could be miles better if you undervolt your CPU by a large margin, like I did. The conclusion is very obvious here - the SQ depends on PC's EMI/RFI levels or whatever it is that is caused by high frequencies and high voltage of CPU (high TDP). I have tried it in the past and had the same results. I am 100% sure that you can't have the best quality using internal/PCI-based interface, unless you do some serious undervolting/underclocking of your CPU or provide external PSU to that interface and isolate it from motherboard's power, if that's possible. Mani, you should try a FW cable without a power leg in order to eliminate the power transmission from PC to DAC. It will cope with potential ground loop issues, but won't address noise issues, so it's not a perfect solution, but I guess it's the best at the moment. The bottom line is that PC audio is going to better and better every year, because CPUs and other components are getting faster and require less power (introduce less interference) at the same time, but I wouldn't build a high-end system based on internal interface - which is fed by a noisy computer power. That's why RME and dCS are going bye-bye.

Cheers,
Marcin

[manisandher]

... you should try a FW cable without a power leg in order to eliminate the power transmission from PC to DAC. It will cope with potential ground loop issues, but won't address noise issues, so it's not a perfect solution, but I guess it's the best at the moment.

Yep, that's what I'm doing with the Weiss - I use a 6pin-4pin adaptor. I agree that this doesn't address the noise issues, but that's exactly where AES3 comes in - it should provide common mode noise attenuation (30dB, if I understand the AES3 standards correctly).

That's why RME and dCS are going bye-bye.

Ah, OK. To be replaced by what?

Mani.

[Marcin_gps]

Weiss DAC202? I don't see any alternatives right now.

Yep, that's what I'm doing with the Weiss - I use a 6pin-4pin adaptor. I agree that this doesn't address the noise issues, but that's exactly where AES3 comes in - it should provide common mode noise attenuation (30dB, if I understand the AES3 standards correctly).

Still, PC affects SQ the most - try the undervolting/underclocking yourself and you will know what I'm talking about. The lowest Vcore - the best SQ.