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192kHz-24-bit DACs and their use

 

PeterGalbraith
Unregistered guest
Hi all,

Now that I will soon have a h/k receiver with 192kHz-24-bit DACs, can anyone tell me when and how these are used?
Is this relevant to both CD and DVD?
Do you need special hardware on the CD/DVD player side to make fuill use of them (e.g. a 192kHz binary feed from the player), or does the 192kHz means oversampling and interpolation of the output to analog side of thing using normal input?

Thanks!
 

PeterGalbraith
Unregistered guest
Some more related questions since I just received my h/k avr-325 receiver this morning and have not hooked it up yet.

1- I could connect the DVD digital output to my receiver's DVD input (defaulting to 5.1) and the DVD analog stereo RCA output to my receiver CD input (plain stereo), but I guess I should not since I won't be using my fancy DACs if I do, right?

2- In lieu of a `real' digital coax cable (which I don't have) I'm told I can use a regular RCA cable. I assume that would be a video cable (coax, and not braided like audio), right? Good idea? or should I use an optical cable (which I do have)?
 

New member
Username: Petergalbraith

Post Number: 2
Registered: 02-2004
I found this link which addresses whether the CD playing should be connected in analog or digital:

https://www.ecoustics.com/electronics/forum/home-audio/4061.html
 

Silver Member
Username: John_a

Post Number: 254
Registered: 12-2003
Peter,

Yes, that is a good link. The rule is keep the number of D-to-A and A-to-D conversions to a minimum.

If the number of conversions is the same with two different ways of connecting, it is usually a good idea to choose the connection that utilises the better DACs: 912/24 is high resolution.

A Cd only carries 44/16 information, though; a DVD up to 96/24 (in DTS and multichannel DVD-A) and up 192/24 (in DVD-A two channel stereo).

But if you start with a two-channel source and convert it to 5.1 (or more) surround using prologic or a proprietary equivalant, the processing takes place on a digital signal, so it is best to skip any unnecessary A-to-D that is required to produce the DSP's digital input.

So, if you play a CD or, say, a digital satellite receiver with prologic (1/2/ whatever), "EARS" (NAD proprietrary equlivant to prologic 2), or any similar DSP device in the receiver, you will notice better sound if you give the signal to the receiver in digital form in the first place. If, however, you listen to that same material in stereo, you may get a better sound with analogue connection - provided, that is, it is the CD/DVD player (or other input) that has the superior DACs. If not, it will probably make little difference. Your receiver has excellent DACs.

Try it and see!

A regular RCA cable works fine for digital audio connection, but it could just act as a source of interference, so get a "real" digital co-ax eventually (I think they have 75 Ohm impedence, too). Personally I would choose the opical connection, anyway. There is no difference in sound between optical and electrical digital audio connections, though some will disagree, and have, before, on other threads.

Hope this helps.
 

New member
Username: Petergalbraith

Post Number: 3
Registered: 02-2004
Thanks John for a nearly complete answer! It is very much appreciated!

The only remaining point I have concerns the 192/24 DAC in the h/k receiver. Do you know if it up-converts (interpolates) a 44/16 CD or 96/24 DVD feed to 192/24 for processing before converting to analog at the end?
e.g. I bought them, but do I ever use them that that frequency?
 

Silver Member
Username: John_a

Post Number: 257
Registered: 12-2003
Peter,

Don't know. Sorry. Good question. I should think up-conversion (up-sampling) is best done in the CD-player. But I will be interested to read any answers to that.
 

New member
Username: Landroval

Post Number: 2
Registered: 02-2004
If it would upconvert 44/16 to 192/24, wich it doesn't, it would make no difference in the sound. For now I cant imagine any use for 192/24 DACs in a receiver except if you have i-link connection to a DVD-A/SACD-player
 

New member
Username: Laurencekarl

Post Number: 3
Registered: 02-2004
You cannot get 192khz into a receiver using digital transfer except with IEEE1394 aka firewire aka iLink because of copyright issues (seems retarded to me). A standard was devised/is being devised that allows you to do this. Some receivers e.g. Denon 5803 do this using a draft standard they call Denon Link.
 

New member
Username: Petergalbraith

Post Number: 5
Registered: 02-2004
So unless it uses it internally (analog -> digital 192/24 for DSP processing -> analog) it's all marketing...

Anyway, I couldn't really hear a difference on one recording (Holly Cole) between CD analog and digital when both listenned to in stereo (surround off).
 

New member
Username: Myrantz

Post Number: 10
Registered: 02-2004
With our Marantz Sr7300 I initially had the cd player hooked up via analogue. In stereo (not source direct) the peak signal would light up at reasonable listening levels and the attenuate button would reduce the signal to prevent this.

I now have the cd player connected via an optical cable and find the sound a little more 'out there'
 

New member
Username: Laurencekarl

Post Number: 4
Registered: 02-2004
The Optical and Coax inputs support 24/96khz. So for cd's and 5.1 DVD-audio it is a different story. Cds are 16/44khz and 5.1 DVD-Audio is 24/96khz so theoretically you would get some benefit from the DACs on the receiver if they were higher quality than the CD/DVD player's and/or there was less interference from the digital transfer vs. analog transfer between devices. For cd players and for 5.1 DVD audio players I would use digital if supported. The problem is that even though the frequency is theoretically supported through digital the DVD-Audio player may refuse to use it or send the lower quality DTS or Dolby signals through. Hence the 5-7 analog inputs specifically for DVD-Audio on most receivers. If you have a high quality DVD-Audio player the analog output isn't the end of the world. It should actually be better for stereo recordings at 24/192khz than the current optical and coax options because of the limitations imposed by copyright concerns. I have definitely heard some crappy cd and DVD players though so I think that they should have the D/A converters etc. in the receiver and just have the sources of input be raw data. That way you could upgrade the software in the receiver to support decoding various new formats rather than having to buy a new drive.
 

Silver Member
Username: John_a

Post Number: 262
Registered: 12-2003
Yes, Firewire is the way to go when this daft and misleading notion of analogue-only connection for DVD-A goes away.

I suppose this makes the h/k avr-325 receiver "future proof". Does it have firewire? If not, I cannot see the value in 192kHz-24-bit DACs, with present or foreseable connections. What does the manual say, Peter?

For the reasons Laurence mentions, I would prefer to have 196/24 capability in the player. I have my eye on an NAD T533 to replace my T532, and give me true DVD-A.

I have a small collection of DVD-As now. Mostly on Naxos (budget classical label). Even the DTS sound is stunning. The lowest recording spec (and it is on a new 2004 release I have just got) is 5.1, 44.1 kHz/ 24 bit. Even that is miles ahead of any CD I have ever heard.
 

New member
Username: Landroval

Post Number: 4
Registered: 02-2004
The only few receivers with firewire are top of the line Pioneers, Onkyos, Sonys and maybe some others. H/K, Maratz, NAD etc doesn't have that feature.

192kHz/24-bit DAC's could be used in the future with some hardware giving PCM-signal, like maybe Blue-Ray players or computer soundcards, like new Intel High Definition Audio 192kHz/32-bit.
 

Silver Member
Username: John_a

Post Number: 263
Registered: 12-2003
I also think there is no technical reason why 196/24 cannot be transmitted from player to receiver using existing digital routes.

An optical cable can transmit information at GHz frequencies.

On other threads such as What does"DVD-audio" mean here? I have read the suggestion that digital connections are incapable of the bandwidth required for high-definition audio, and therefore the interconnects have to be analogue. But a moment's thought shows this is nonsense: the info on the disc is in digital form and has to be tramsitted in that way to the DACs. Whether that connection is within the player or between the player and receiver should make no difference. Also, if it were true, the "analogue is best" camp were robbed of just victory by the CD-lobby in 1982.

A give-away is in the NAD brochure for the T733:

"Unlike all other digital formats, DVD-A can only be output as an analogue signal, due to Digital Rights Management agreements required by the format".

If we want to know why we cannot play DVD-A through 196/24 receivers, we shall have to know about "Digital Rights Management agreements".

Anyone know what they are, are who it is who agrees?
 

New member
Username: Petergalbraith

Post Number: 7
Registered: 02-2004
Well, perhaps the 192/24 DACs in h/k and Marantz receivers are simply an indication of quality DACs (not that lack of this feature would be an indication of lack of quality).

Anyway, I've made my purchase so there's no looking back and second guessing now. I probably would be equally happy had I bought a Marantz!

I'll keep trying out various combinations (digital vs analog) for a while. I haven't even tried to feed my speakers directly from my receiver yet (using a separate power amp for main L+R), so there's lots more to do. :-)
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