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Connecting CD to AV receiver, really a difference between digi & analogue connection?

Discussion in 'AV Receivers & Amplifiers' started by Hallsy, Jan 5, 2005.

  1. Hallsy

    Hallsy
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    I have gathered, although I didn't know this was the case until recently, that whether you use digital or analogue connections into an AV receiver it is processed. i.e. a digital connection uses the internal DAC's of the AV reciever to give the DTS decoding, etc, and connecting an analogue source such as CDP goes in as analogue, but is then converted to digital at pre-amp level before returning to analogue again.
    Therefor does it make any difference which connection you make as surely the receiver is always adding it's own "sound" to it? This also makes me wonder whther much improvement can be made by altering source from budget DVD to budget CDP for 2-channel playback will make any difference on an AV receiver as everything is processed all the time, surely it's the same signal once it's been processed no matter what the source is so cutting out the better DAC's theory on a dedicated CDP?
    Or have I understood it all wrong!! I currently have a Yam RX-V640 and was considering buying a budget DCP (mara CD5400, or similar) to use as 2-channel source but then started to wonder if it would really sound any different to the budget Bush DVD player I have already?
    I realise having a separate 2-channel amp would be better, BUT as I use my lounge for both listening to music and watching movies I think it would be overkill to have one pair of speakers for my CD's, and another pair wired to the Yam for main L+R in my surround setup!! Well, the missus wouldn't like it anyway, she's not over the moon about the one pair of floorstanders already!!
     
  2. Ovation

    Ovation
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    If your receiver has an analogue bypass (often called "DIRECT AUDIO", "PURE AUDIO" or "SOURCE DIRECT" or something like that) then, if you engage this, your receiver will NOT process the analogue signal coming from your player. In this case, a good CD player can be worth it. However, if there is no analogue bypass of any kind, then, IMO, a digital connection from the player to the receiver makes the most sense, as it avoids an additional layer of A/D/A conversion--though today's gear is often fairly transparent in those conversions. I use my receiver's analogue bypass with my CD player because I consider it good enough to avoid reprocessing (and it can be configured as a 2.1 player internally, thus keeping my sub active without an additional layer of A/D/A). With my hi-res universal player, however, I use my receiver's digital bass management (which entails a layer of A/D/A) because it grants me more flexible bass management and speaker delay settings than the player can provide and the receiver's A/D/A is transparent enough not to degrade the hi-res signal in a way that's audible to my ears (and I've done blind tests with my gear to verify this). With my CD player's analogue section (actually a DVD player that I preferred in head to head tests with several CD players), I get a wider soundstage at the cost of a bit less bass definition versus my receiver's digital section--and I prefer the wider soundstage for most of my music collection.

    The upshot? A separate CD player can sound better/different if you have an analogue bypass. It can also, quite apart from its sound, be a useful device to split the workload (another major reason I have two players), thus permitting each device to have a longer life--and granting access to the bulk of your music should one player be in the shop. Without an analogue bypass, the sonic benefits of a separate CD player diminish greatly, but the workload splitting and the better programming abilities most CD players have over DVD players apply.
     
  3. Hallsy

    Hallsy
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    I was aware of pure direct modes, etc. I don't believe that my Yamaha has one, it has an audio group of analoue inputs,one of which is CD and can be selected to be in stereo mode, but I don't belive this is classed as pure direct.
    Also from reading old posts it has been said that "pure direct" is still put through ADA processing anyway, unless you get up to very expensive AV amps.
    I may suck it and see, just get or borrow a CD player and see if anything seems to be improved. At least the transport on something like a Mara CD5400 should be better than my el cheapo Bush DVD!!
     
  4. Zacabeb

    Zacabeb
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    I know for a fact that the RX-V1500 and 2500 bypass the A/D/A conversion in Pure Direct mode, and I assume this is the case with all their receivers that have a Pure Direct mode (I'm not sure of the latter though). Since the RX-V640 does not, it is probably not possible to bypass A/D/A conversion.

    Stereo mode mighty bypass the DSP though and go pretty much straight from the A/D to the D/A converter. That is an unnecessary detour indeed when no processing is applied anyway, which is probably why Yamaha introduced the Pure Direct mode in the more recent models.
     
  5. Ovation

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    I would think that something called "pure direct" (or its equivalent) would be fraudulent if A/D/A was still happening (there are very expensive pre-pros that do A/D/A on all inputs--I believe Meridian makes at least one) and, at least on this side of the pond, one doesn't need to spend too much to get such a mode.

    As to your idea about borrowing a player, that's the best way to test things before spending money.

    Good luck.
     
  6. Hallsy

    Hallsy
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    Yeah, have to see what I can borrow. the father in law has some old Technics separates, but would the age of them mean that I wasn't really giving a good comparison?
     
  7. Ovation

    Ovation
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    You might consider going to a store with a good return policy and "borrow" one that way. Your in-law's machine might be useful as well, at least in determining if there's a difference between the analogue and digital inputs (A/B the CD player via analogue with the DVD player via digital). Try to use two copies of the same thing for simultaneous comparison (either two burnt copies or two original discs).
     
  8. Hallsy

    Hallsy
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    Good idea, I'll see what I can sort out over the weekend. I've emailed Yamaha to ask them how the analogue inputs are processed on the 640, hopefully I'll get a decent reply.
     
  9. Mandel

    Mandel
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    Hallsy> Since I have a 640 (and a 340) too, and have been wondering the same thing, it'd be nice if you could post Yamahas response in this thread :smashin:
     
  10. Hallsy

    Hallsy
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    No prpblem, as soon as I get a reply I will post up.
     
  11. Hallsy

    Hallsy
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    Right, I think that yamaha are being a little vague here, hardly technical anyway. Maybe it was the fact that I was banging on implying that if every input signal is processed by the AV amp then it wouldn't matter WHAT type of input source you used, they'd all have a Yamaha sound, and hence wouldn't be worth spending silly money on sources?? Who knows.
    Here is what I sent initially:

    Hi,

    I am the owner of a Yamaha RX-V640RDS AV receiver.

    Could you tell me if when I use an analogue audio input, such as the CD
    input, and feed it with a signal from a CD player using RCA connection,
    whether the signal is processed, i.e converted from analogue, to digital
    then back to analogue again, or whether the signal is left as it was from
    the CD player, purely analogue?

    The reason I ask is because I wish to know whether I will detect any
    difference in sound reproduction from sending a 2-channel signal via a DVD
    player to sending a 2-channel signal from a dedicated CD player (both using
    same RCA connection).

    If the signal is processed through the RX-V640's internal DAC's whether fed
    with analogue or digital signal I don't think that different source will
    make nay difference as the Yamaha will always be giving the source it's own
    sound.

    Thanking you in advance,

    Andy Halls

    And a reply:

    From : Paul_Davey@gmx.yamaha.com
    To : hallsy@fsmail.net
    Copy to :
    Subject : Re: RX-V640RDS query
    The signal will be left in analogue format if you feed an analogue signal
    through the amplifier and vice versa for digital.

    Regards,
    Paul Davey

    Yamaha Electronics (UK) Ltd
    www.yamaha-uk.com

    So I replied with:

    Paul,

    thanks for your reply. I am aware that the output signal will be the same
    type as input, I was more interested in whether an analogue signal is
    converted from analogue to digital, then back to analogue again, or whether
    it stays analogue with no internal processing.

    Many thanks,



    Andy Halls

    And this is what I received back:

    From : Paul_Davey@gmx.yamaha.com
    To : hallsy@fsmail.net
    Copy to :
    Subject : Re: Re: RX-V640RDS query
    The signal will stay as analogue.

    Regards,
    Paul Davey

    Yamaha Electronics (UK) Ltd
    www.yamaha-uk.com

    I guess they are saying that an anlogue signal input is not processsed, i.e pure direct, but lets face it, he's hardly giving anything away!!
     
  12. cambridge540

    cambridge540
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    yeh i have a Yamaha AV amp too :) n i know that analogue stays analogue (just joined this thread a bit late i guess) the dedicated CD player will have massive sonic improvements over the alternative (your Bush DVD player). the Marantz's transport will be much more stable enabling a better pickup of information off the disc and therefore a better and more detailed sound. if you use the analogue outputs of the CD player into the amp it will also result in a much cleaner, more well defined sound as the D-A conversion of the music is being done in the CD player, away from the on board high power amplification that the amp has (in other words, less noise in the signal) another reason to use the CD players analogue outputs as opposed to a digital connection to the amp is that the DACs in the CD player as specifically designed to decode 2ch PCM stereo as opposed to the amps DACs able to decode 2ch PCM but designed more specifically for movie use ie decoding multichannel bitstreams such as Dolby Digital, DTS etc. in short, use the analogue outputs of a dedicated CD player, you will notice a massive difference to the Bush DVD player :)

    hope this helps :)
     

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