DSP in the PC

[bibo01]

Hi to all!

Premise: I do not use XXHighEnd nor Phasure NOS1 DAC, although - Peter knows it - I would have liked to lay my ends on the latest one.


I am attracted by the concept of having your DSP in a PC and send an upsampled digital signal to a filterless DAC like a NOS1. I would like to discuss its implication.

I can see that there is a future proof in dealing with software, rather than hardware through repeatedly changing a DAC. We keep one device - the DAC - unaltered (more or less) and "change" what it is ahead of it.
Fine!

However, what are the implications of having extensive calculation in the PC? I mean, in terms of noise, distortion...
I have a good experience with cMP2, a digital playback system perhaps some of you are familiar with. This project was started to have a PC Transport with the cleanest possible digital signal coming out. In order to achieve that various things are implemented at hardware and software level: separating CPU, MB and peripherals power supplies, stopping all Windows unused services, underclock and undervolt, various kernel mods...
In these terms, a cMP2 system becomes a very lean and mean music dedicated machine! :-)

So my question is: as PC changes quite dramatically with such HW and SW optimisations, and they influence also asynchronous DACs, what is needed for a 2ch 24-768?
For example, what's minimum CPU requirement?

In my experience one cannot take any PC, with a usual ATX PSU, and slap a 24/192 oversample on it and think that quality is going to be guaranteed, even less at 768!

[PeterSt]

Hey there !

(for the others, we exchanged quite some emails already about other subjects ...)

It all depends on the software. So, XXHighEnd in our case;

What you will see, even at 32/768 output, is that the CPU utilization is a virtual 0%. *What* you still see, comes from the driver (also to be taken into account, but I'm mentioning it because in there you can let the core servicing it go from relatively highly utilized to close to 0 again - depending on driver settings).

So, there it starts.
This can be done because of the preprocessing XXHighEnd does "to" whatever what's needed. So, e.g. FLACs are converted in advance, and the Arc Prediction Filtering is not done in real time.
Ah, cool.
Well, cool perhaps, but now think what it all takes to let this go unnoticed in the mean time (compare cMP maybe).

So, your presented DSP is no problem, but this is no problem more-often. I mean, pre-upsample offline, and it's also no problem.
But way inconvenient ...


No matter the virtual 0% cpu usage, it still will be so that something like a laptop won't do. It just contains too many energy saving elements to work well throughout. I can talk rather endlessly about it, but let me stick to a conveniency factor only : while my FLAC album plays within two seconds, your same album on the laptop may in 20 seconds. And next may not play gapless.
So, with this as the example, you can say "but then why not convert FLAC in real time ?". Well, you know the answer to that, right ?

In the end all is one big complex of matters, and XXHighEnd tries to arrange for that on behalf of you not needing to do it. This includes all the services stuff ... (today summarized in Minimize OS as a best option - with an explicit means for that due for laptops (but not in the next version yet)).


Was this something for an answer ?
Regards,
Peter

[bibo01]

Hi Peter,

thanks for your reply. Don't you worry I have many other questions for you! :-)

Are you saying that XXHighEnd has virtual 0% cpu consumption on, let's say, a 2100 at 24/768?!

Apart fron useless Win services, which can be deleted or frozen, I have seen that altering OS footprint (XP can be shrunk to less than 20MB) does change audio playback, even through USB or FW. Are you saying that with XXHighEnd this is not needed?!

You probably know that part of cMP2 project is to limit EMI/RFI by reducing the amount of elctricity going through the circuit. Do you feel that this kind of approach is not needed for XXHighEnd/NOS1 DAC? I must say that a cMP2 system, although is slightly reduced in "number crunching point of view", it is also much snappier than a similar untouched PC. (I am not promoting cMP2 - I am just checking if cMP approach can be useful)

In electrical terms, what kind of isolation from PC does NOS1 DAC USB receiver have?

Also, given that NOS1 DAC has ASIO support, will XXHighEnd get ASIO support as well?

[pedal]

My guess: The easiest way to make XXHE capable of DSP is to provide for "plug-ins"; A kind of digital loop where the user can load whatever (correction) file he wants.
-It can be EQ, room correction or even low-/high pass filters (for active XO). I think Foobar has it allready.

The filter itself has to be made outside of XXHE, with some other software available in the market.

-Can you do that, PeterSt? (Digital active XO is high on my wish list)

[PeterSt]

To start with the simple answers :

Also, given that NOS1 DAC has ASIO support, will XXHighEnd get ASIO support as well?

Not planned, although other "functional" reasons may come in order. Example : suppose that I find DSD multichannel to be more comfortable to deal with within ASIO than WDM, the support will be there for that reason. Otherwise I'd do it for "the connection" only, which in my view will only create the poorer sound (Q).

In the mean time I must be honest : when I judged this, all sounded so much more poor to begin with (including XXHighEnd) that maybe it is time to reconsider. It is a bit sad that it must be created first in order to check it. So, (ultra) low priority I guess.


Than the more difficult answers;

Although maybe hard to believe, I never wanted to go the route of cics. Btw notice that XXHighEnd was there first, cPlay etc. a small year later. This (really) is up to me not even looking into it, or following it. Really not.

Really not ? well, almost true;
The very first morning (which was on some Saturday) I maybe have been the very first to download it and try it. I also was the very first in that huge AA thread that commented - wow, of *that* is what's needed today, better be careful that your PC keeps on working (meaning : it looked mighty dangerous, and it took quite some effort to get my PC back up again, because it did not work at all).
Few people will have seen my comment, because the thread got deleted shortly after that, and was reposted. Without my comment of course, and maybe that was a good thing.
Next, I never tried again.

There's the more electrical part (cics) and the more sheer-from-software part (me). But along the way both *had* to grow to eachother. People obviously started to follow my advice on which registry entries to tweak (no, not Black Viper's - mine), what services to manually shut down, while from the other end, people quitre obviously started to notice that indeed a better (PC) PSU can help etc.;
No matter the source, things grow to eachother by nature, because we all want to have the best sound ...

I myself never dove into PC noise as such, because it is not my subject. Let it be cics'. Other can apply what they want, and in the combination they feel to. And yes, this includes Fidelizer which is a sort of weak derival from what has been done in here (not that he will admit that), but now for outside XXHighEnd. So again, combine what you like.

What I sure did though, was applying the noise subject to the Phasure NOS1 DAC. So, approach it from that angle, knowing that the DAC is key to it all (notice that all noise stuff hammers on "something" which happens inside of a DAC). So, there the NOS1 emerged, and more explicitly than I am able to tell afterwards (but posts in here tell about me starting to apply the actual weak software appliance, now in hardware).
This worked (out) very well, and had to be re-done for the Asynch USB version (USB being so noisy).

In summarize, the work has not been completed yet;
It won't be, until no software setting makes a difference. So, at one stage I started to tell that XXHighEnd had eliminated herself by first tweaking the OS, but next had to come to the conclusion that this still was not so. The "dials" in XX still matter, and so the PC still influences. This part, can or be solved my even nore OS tweaking (which is tough by now, but wait for 0.9z-7 which again etends on this), or -more easily- in hardware.

But what I call "more easily" is not so for most at all ...

Regards,
Peter

[PeterSt]

-Can you do that, PeterSt? (Digital active XO is high on my wish list)

I MUST. Otherwise any 8 channel (NOS1) DAC would be moot to begin with. So, all is about eliminating that pile of coils etc., which is my explicit objective too.
Well, you have seen that little pile ...

[bibo01]

-Can you do that, PeterSt? (Digital active XO is high on my wish list)

I MUST. Otherwise any 8 channel (NOS1) DAC would be moot to begin with. So, all is about eliminating that pile of coils etc., which is my explicit objective too.
Well, you have seen that little pile ...

Having a DSP Host in XXHihgEnd it is a good enough reason to have ASIO as well :-)

[bibo01]

...
What I sure did though, was applying the noise subject to the Phasure NOS1 DAC. So, approach it from that angle, knowing that the DAC is key to it all (notice that all noise stuff hammers on "something" which happens inside of a DAC). So, there the NOS1 emerged, and more explicitly than I am able to tell afterwards (but posts in here tell about me starting to apply the actual weak software appliance, now in hardware).
This worked (out) very well, and had to be re-done for the Asynch USB version (USB being so noisy).
...
Regards,
Peter

I am not sure I understand your explanation for the NOS1 DAC. Can you please say technically how you isolate USB receiver from PC?

Also, what is XXHighEnd's CPU consumption on a 2100 at 32/768? Sorry to ask again...

[PeterSt]

CPU ? still that virtual 0%. But what if you just tried ?

The noise subject on the NOS1 I like to keep for myself, but not any jitter-impeding isolation, if that's what you are after ...