which DAC is being used?

[PaulE]

I have a Sony ES receiver and an audiosource amp3 driving the front stage, and a Sony DVP-C660 DVD/CD player. I feel that, for some reason, I'm not hearing an 'improved' signal when I choose 'Analog Direct' mode in the receiver, which uses the analog connection from the DVD player to the receiver, bypassing all digital signal processing...Even bass and treble controls become unavailable...Its about as pure and straight through as we can get. So, I'd expect this to be the purest and sweetest signal on my better DDD recordings....Yet, the DVD signal path via optical cable or digital coax seems just as pure and clean...

'Sweet' if you will.

The following factors might be involved: The analog cables are rat shack interconnects...I've already ordered some silver serpants from bettercables.com, which I'll use to pick that up. Or,perhaps, when I choose Analog Direct, its the DAC in the DVD/CD player which is converting the signal to digital, whereas when I choose any digital soundmode, its the DAC in the receiver which is doing it?

This is my question...How do we know which DAC is the one which is performing the conversion? I kind of thougtht that if we choose an Analog Direct mode, then the conversion would be done in the DVD/CD player...Otherwise, the signal would go to the receiver via digital cable in digital form, and be converted in the receiver once it does its DSP thing...

Is this correct? If so, what is the liklihood that the DAC in the ES receiver is of better quality than the one in the DVP-C660 player? Or, are they probably the same chip? At this level, is there likely to be a noticable difference between the two?

Or, maybe its due to the cheap analog cables ( being replaced shortly)? Or, maybe I'm so used to hearing the signal from the DSP that the native analog signal sounds less rich, and there's nothing 'wrong' at all?!

Whatever, the sound is indeed sweet coming from my RF-3s, and I'm not complaining...Just curious as to what's going on..

Thanks.

[jdm56]

PaulE,

I believe you are correct -- when using the digital output from your DVD player, the D/A conversion takes place in the receiver. Engaging "analog direct" mode generally bypasses everything but the volume control, but if that mode functions with digital inputs, it would have to be taking the signal after D/A conversion has taken place within the receiver.

To me, the difficulty you have hearing any improvement when in analog direct mode says more about the high quality of the Sonys' analog circuitry. I would expect the digital links to be a bit quieter than the analog, though.

Of course, you're really comparing more than one thing here. You are comparing analog to digital connection; and analog direct function on to adf off.

------------------

JDMcCall

[Ray Garrison]

Paul,

When you listen in "analog direct" mode, the digital to analog conversion is done inside the DVP-660. The analog signal is sent on to the receiver, which treats this signal the same way it would treat a tuner, tape deck, phone preamp, or any other analog source that you had hooked up to the analog direct input.

So, there are two questions here: first, which is better, the D/A section in the DVD player or the D/A section in the receiver? If the DVD player's D/A chipset is newer, of higher specification, or implemented "better" than that in the receiver, then it would seem that using the DVD player's internal D/A system and feeding the analog signal to your receiver would sound better. If the reverse were true, and the receiver's D/A section were newer or in some other way better, then feeding digital from DVD player to receiver might sound better, depending to some extent upon the quality (isolation from noise, accuracy of clocking signal, etc.) of the digital output driver on the DVD and receiver on the, er, receiver. There's also the question of how good the analog section on the DVD player is. Seems as though this could only have an impact if it were not good, as you're still using the receivers analog output regardless of where the signal comes from, so if the DVD player has a good analog output it won't make the receiver sound any better, but if the DVD player analog section is not up to snuff it could degrade the sound.

*** HOWEVER ***s>

I was poking around various websites looking for specs on what chipset the DVD and receiver use, and couldn't find anything, but did find this note on the Crutchfield site, talking about the DVP-660:

"...When a 96kHz/24bit 2-channel PCM disc is played, the sampling rate is down converted to 48kHz before the signal is output from the digital outputs. To enjoy the full benefits of a 96kHz/24bit disc, you must listen to the output from the analog 2-channel stereo line outputs (the built-in digital to analog converter processes the signal with full 96kHz/24bit resolution)..."

That means that the receiver is NOT decoding the SAME digital signal that the DVD players internal decoder is working with. The signal sent to the receiver is "dumbed down" from 96kHz sampling rate to 48kHz sampling rate.

This does not sound like it is a good thing.

That may explain why you found the receiver's analog direct input sounded at least as good as the digital input. In fact, now that you know that the receiver is getting a lower quality digital signal, you might be able to convince yourself that the analog direct input sounds BETTER than the digital input.

Ray

------------------

Music is art

Audio is engineering

[paulaelliott]

Thanks very much guys for the on target responses.

>>"...When a 96kHz/24bit 2-channel PCM disc is played, the sampling rate is down converted to 48kHz before the signal is output from the digital outputs. To enjoy the full benefits of a 96kHz/24bit disc, you must listen to the output from the analog 2-channel stereo line outputs (the built-in digital to analog converter processes the signal with full 96kHz/24bit resolution)..."<<

>>That may explain why you found the receiver's analog direct input sounded at least as good as the digital input. <<

Actually, Ray, I think I said that I found the receiver's Digital sound processing modes AS GOOD AS the receiver's Analog Direct mode! Which is kind of the opposite you quoted, and has a different point...We'd expect the Analog Direct signal to be sharper, cleaner, more accurate sounding, but I didnt find this...Now, with initial quote above, it makes it even less understandable...If the DVD/CD player is downconverting the digital sampling rate from 96 to 48 so that the REceiver receives the signal with half the digital information to convert to analog, then we would certainly expect the digital signal to sound not as clear as that which we hear when we listen to Analog Direct. So, if all this is consistant with a better sounding Analog Direct mode, then why on earth do the digital sound modes sound just as clear, or clearer?

I ventured forth in my original post another possible factor: The analog cables from the DVD/CD player to the receiver....I'm running a rat shack toslink cable to pass the digital signal when left in native digital form by the player. But I'm also running ratshack (non gold line, but heavier than the cheapest of the cheap) rca cables for the analog connection...I have some Ixos silver line cables on order, and maybe they will improve the sound of the Analog Direct mode. I should know in a few days.

From all this, it seems like the Digital signal, while already sounding at least as good as the analog signal, can sound even better, were it not downconverted in the player..Which brings me to another question....What about getting a better CD player? Would a good CD player not downconvert the signal? Would it contain a better DAC? Would it make sense to have both a DVD AND a CD player? Do most folks who have a DVD player, but care about music more than home theater, still use their DVD player for their CDs?

Thanks again for the input.

[paulaelliott]

Also Ray, from the Crutchfield site:

>>Direct Stream Digital (DSD) is the advanced recording technology that makes SACD possible. Standard CDs use 44.1kHz/16-bit PCM (44,100 samples-per-second Pulse Code Modulation, encoded at 16-bit resolution) to represent audio in digital form. <<

If the standard CD sampling rate is 44.1 khz, then what's the 'harm' in my DVD player downconverting from 96 khz to 48 khz...Isnt that still above the standard 44.1 khz sampling rate??

[avman]

WHEW!! just reading this thread makes my head want to swim i use the digital (optical) out of my pioneer dvd player to my strda777es receiver in order to:

1-allow the receiver's d/a converters to do the work-beleiving that my receiver's d/a's are better than my dvd player's d/a's

2-i use a.f.d.(auto format decode) sound field setting on my es recvr so when i play a dvd, it plays in dd or dts automatically,when i play a cd,it plays in stereo AND WHEN i get a sub, it outputs a line level signal to the sub.

3-if you use analog direct, you ARE using the dvd player's d/a converters, which i don't beleive are as good as the es rcvr's d/a's

4-if you use an analog connection to your sony receiver, and have the sound field in any mode other than analog direct(maybe 2-ch?)the receiver RE-CONVERTS the analog signal BACK to digital,'manipulates'it, then re-converts it back to analog.

5-just an aside...my pioneer dvd player has a menu selector to allow 96/24 digital data to pass to the d/a's in my receiver

avman.

------------------

1-pair klf 30's

c-7 center

sony strda-777ES receiver

NEW! sony playstation 2!

dishnetwork model 7200 dishplayer satellite receiver/digital bitstream recorder

pioneer dvd player

sharp 35"tv

panamax max dbs+5 surge protector/power conditioner

monster cable interconnects/12 gua.speaker wire

surrounds and a 'teens sub coming!

KLIPSCH-So Good It Hz!

This message has been edited by avman on 08-09-2001 at 02:53 PM

[Ray Garrison]

Paul,

Some of those questions are quite deep. To answer the simplest one first ....

"Would a good CD player not downconvert the signal...?"

I was a bit terse in my previous post, and possibly unintentionally misleading. First, in reagards to the 96/48 kHz digital bitstream output issue, if you are talking about CD playback, this is a non-issue, as there are no CD's that are encoded with anything other than 44.1kHz sampling frequency. The 96kHz sampling rate only applies to a very limited number of audiophile discs from companies like Chesky that released music on DVD-Video spec discs recorded at higher sampling rates. Almost all DVD players (due to licensing issues - Phillips? I think - and concerns about bootlegging) downsample a 96kHz bitstream to 48kHz before they make it available externally. A few companies - Pioneer, Theta - have players that will spit out the full 96kHz signal, licensing issues be damned, but there's basically nothing out there that takes advantage of this. DVD-Audio, which your DVP-660 will not play, are a nother whole issue.

As to the question about cables possibly being a limiting factor... I haven't found them to be a BIG factor in the sound of my system, but I have also never found that any two sound EXACTLY the same. They are ALL different. I expect you'll hear a difference when you replace the Radio Shack patch cords with the Ixos silverline interconnect cables but how much of a difference, and whether it improves the Analog Direct to the point where it's clearly superior to the digital, well... let us know?

Check out the Disctronics site at http://www.disctronics.co.uk/dvd/ for some interesting technical specs on DVD-Video (what we've got now) and DVD-Audio (just emerging)...

Ray

------------------

Music is art

Audio is engineering

[PaulE]

AVMan,

>>if you use analog direct, you ARE using the dvd player's d/a converters, which i don't beleive are as good as the es rcvr's d/a's<<

Well,thats easy for YOU to say...Your ES receiver has Burr/Brown Dac....mine doesnt

Still, ya gotta love the ES receivers...Mine sounds especially good driving my Audiosource Amp3...I read a review of the Amp3 in I think hometheaterhifi.com, and they said the Amp3 was far superior to any of the amps in any of the receivers they had received for review...I bet they didnt receive your DA777ES though...Thats a receiver a cut above all others... I trust youve seen the forum devoted to it?

http://pub7.ezboard.com/faussiedvdandhtforumsonytava777esstrda777esinformationforum

Sony should be shot for taking it off the market...I dont care if it DID 'steal' sales from their higher priced ES separates.

Youre right about AFD mode...The only reason I like Analog Direct is because its supposed to be the 'purest' and 'cleanest' signal, becauses its bypasses ALL digital circuitry in the receiver, just using the volume control...I dont even have access to bass and treble settings in this mode...So, for purists, wanting to best capture what is put down on CD, this is theoretically the best mode to use..However, the issue about the superior receiver DAC, if it truely exists, certainly might counter the purity issue. As I said, despite the theoretical purety to be gained in analog direct, I feel the sound has more dynamics and just sounds better when I too use the DAC in the receiver.

[PaulE]

Ray,

>>. First, in reagards to the 96/48 kHz digital bitstream output issue, if you are talking about CD playback, this is a non-issue, as there are no CD's that are encoded with anything other than 44.1kHz sampling frequency<<

So that the downconversion in digital signal before it goes to the receiver would make no difference for my cd listening, which is 90% of my use for the DVD/CD player.

>>The 96kHz sampling rate only applies to a very limited number of audiophile discs from companies like Chesky that released music on DVD-Video spec discs recorded at higher sampling rates. <<

Maybe one day I'll spring for an SACD player of DVD audio or someother fancy player...But even then, I thought our hearing goes from 20 hz to 20 khz...What's with the 96 khz? for our pets?

>>As to the question about cables possibly being a limiting factor... I haven't found them to be a BIG factor in the sound of my system<<

So what then could account for the digital signal sounding more 'dynamic' and even 'warmer' than the purely analog signal? Only thing I can think would be that the dac in the receiver is noticably better than the one in the DVD player...On avman's es receiver I can understand it...His has a burr/brown dac...Mine doesnt. Which doesnt mean its bad...But it doesnt necessarily mean its better than the one on the player...As a matter of fact, I kind of thought that most DVD dacs were pretty good, and certainly not noticeably better or worse than ones in receivers....But, who knows...Maybe its just that I'm 'used' to the digital sound, or the DSP is adding something to the sound making it 'sound' clearer and warmer...I guess I'll never get the answer to that one..Just play whichever one sounds better at the moment...Thanks alot ray for your answers...they cleared up alot of questions I had about when 96/24 is really used, and so on.

[T2K]

GENERALLY, the DAC's in receiver's will be superior to those in most CD players.If you look long and hard enough I'm sure you'll find an exception to my statement.Whilst you're looking,read why silver interconnects were probably a poor choice to use with a Sony receiver.Good luck.

Keith

[paulaelliott]

Keith,

>>read why silver interconnects were probably a poor choice to use with a Sony receiver.<<

Ok, I give....Why?

Here's what it says about the interconnects:

>>Our newest member in our Silver Serpent family of high-performance audio/video cables. This is an outstanding Silver-Copper hybrid analog interconnect that is sonically revealing without the harshness associated with most pure silver interconnects. Bare copper braid shield has 95% coverage and the center conductor is pure silver-coated copper. The early feedback from our customers has been WOW!<<

I've heard where silver can harshen the highs...First, its far from true that this is always the case...second, I'd wonder why the ES receivers are more prone to this as you suggest? Also, I'm planning on using them for the preout stage to the amp. I think I also ordered their digital coax cable...Do you also think this would be a problem? I've heard nothing but good things about the bettercables.com...

Lastly, I certainly know the older ES receiver had better DACS...They used to use burr/brown chips, which I dont think is true anymore..Still, this doesnt mean teh receiver's dac isnt better...it doesnt mean it is either...If it is better, then what should I do to get the best out of analog direct mode? Buy a better DVD/CD player? Get a separate CD player with advertised better DAC? Maybe find one with a burr/brown chipset? Any ideas?