Digital Sound and Recievers

johnnyamerika
johnnyamerika Posts: 382
edited December 2002 in Electronics
Hi all,

I have an Onkyo 595, and I've noticed on this and many other recievers an issue with the digital sound inputs.

I have 2 optical and 2 coaxial digital inputs that are all assignable. I have 4 modes that accept the inputs, DVD, Video 1, 2 and 3. I noticed that certain inputs, i.e. OPT 1, COA 1... sound better on different modes. For example, OPT 1 sounds best when placed on Video 2; on any other mode it starts losing volume (some more than others).

Has anyone experienced this, and do they know why it occurs?

Thanks,
John
Post edited by johnnyamerika on
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  • HBombToo
    HBombToo Posts: 5,256
    edited December 2002
    This should not be happening... just to clarify, both dig coax and Toshlink do the same?

    tough 1 here man!

    HBomb
    ***WAREMTAE***
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  • johnnyamerika
    johnnyamerika Posts: 382
    edited December 2002
    Yup, here's the full list:

    DVD - coax 1 works best
    Vid 1 - coax 2 works best
    vid 2 - opt 1 works best
    vid 3 - opt 2 works best

    Wierd.

    John
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  • HBombToo
    HBombToo Posts: 5,256
    edited December 2002
    Does your owners manual mention anything? This does not seem correct to me... How old is your receiver?

    Wierd it is...

    HBomb
    ***WAREMTAE***
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  • weavercr
    weavercr Posts: 289
    edited December 2002
    I will check this out on my Onkyo 595 and post the results.
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  • scottvamp
    scottvamp Posts: 3,277
    edited December 2002
    Ya interesting. That should not be happening. Let us know.
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  • HBombToo
    HBombToo Posts: 5,256
    edited December 2002
    bump

    find anything out???????????

    HBomb
    ***WAREMTAE***
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  • organ
    organ Posts: 4,969
    edited December 2002
    Maybe the db levels were changed. Did you check to make sure every channel is at 0db for all modes?

    Maurice
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  • johnnyamerika
    johnnyamerika Posts: 382
    edited December 2002
    Yup, because it doesn't happen with the analog inputs for each channel, only on the digital assignments.
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  • phuz
    phuz Posts: 2,372
    edited December 2002
    Could it be a difference in the DACs being used?

    Are you switching between any DSP modes or 2/5ch stereo modes?
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  • johnnyamerika
    johnnyamerika Posts: 382
    edited December 2002
    Nope, same modes, but I didn't think about DACs, that may be the difference. I have on very good OPT cable and one very not so good OPT cable... I will investigate.
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  • phuz
    phuz Posts: 2,372
    edited December 2002
    The real question is do your source component(s) and reciever have the same DACs? If not that might be the issue.

    I think there is a DB difference in analog and digital signals when being sent out from source components as well. It's not a problem as far as I know.
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  • johnnyamerika
    johnnyamerika Posts: 382
    edited December 2002
    I'm unsure how the DACs would effect it? Dont' Digital Audio signals from Toslink and Coax come from the source unconverted? And I'm talking about using the same source on multiple modes, like V1, V2 etc., so the disparity is not between different sources.
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  • phuz
    phuz Posts: 2,372
    edited December 2002
    You are right, I missed something on one or two of your posts. I was thinking regular coax/rca (analog) vs. digital.

    I'm stumped.
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  • HBombToo
    HBombToo Posts: 5,256
    edited December 2002
    Originally posted by johnnyamerika
    Dont' Digital Audio signals from Toslink and Coax come from the source unconverted?

    YES!

    Are you comparing 2 channel with 2 channel and dd with dd?

    If we stay with 2 channel,(CD Redbook is I believe 16 bit and HDCD is 20 bit), the TTL out is a PCM scheme out @ 44.1 Khz into the dac. Looking at any of the inputs into your avr there should be no delta in losses and the output level should be the same.

    If we input the the analog out, from a cd player, then apply prologic or logic 7, within the avr for simulated multi channel then you will hear losses.

    I have been experimenting with external dacs and have found that my h/k 520 does not do the same high quality conversion of Redbook or DTV PCM input. With that said I have also noted that the analog out from the external dac then into the h/k sounds worlds better when applying the prologic or logic 7 processor in the h/k.

    This most definetly is an interesting hobby!

    HBomb
    ***WAREMTAE***
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  • johnnyamerika
    johnnyamerika Posts: 382
    edited December 2002
    Heh heh, well, I did a reset to factory defaults and it seems the problem has cleared?!? I don't know what was set wrong, but it's working correctly now. Regardless, we've spawned an interesting DAC discussion.

    So is there more to rating a DAC besides the bit conversion rate? Do quality of parts come into play?
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  • HBombToo
    HBombToo Posts: 5,256
    edited December 2002
    Originally posted by johnnyamerika

    So is there more to rating a DAC besides the bit conversion rate? Do quality of parts come into play?

    OH Yes, and I have been struggling to figure it all out.

    Higher bit rate means more accurate replication of the original signal. example over a simple SIN wave is if it were 2 bit then there would be 2^^2 or 4 voltages for replication. 3 bit would be 2^^3 and so on up to 20bit.

    Clocking circuits have to be extremely accurate and if not the output stage to analog can kill us. In higher end DAC's the power supplies, chip sets, clocking and analog stages are always isolated. There is so much to talk about here it could drive ya nuts.

    HBomb
    ***WAREMTAE***
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  • johnnyamerika
    johnnyamerika Posts: 382
    edited December 2002
    heh heh, sounds complex...I'm asking for some good books for x-mas so I can read on the more complex parts of sound reproduction. Should be fun. :)
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  • cruiser3
    cruiser3 Posts: 47
    edited December 2002
    and here I thought it was my hearing....*L*......I encountered the same thing with my Oink 696. HBomb has it right. Its too complicated for my feable brain to explain, but HBomb pretty much nails the problem........
    Onkyo 696 receiver, Panasonic DVD RV31U,Polk RM6600 w/ 350 sub (rti28's 2nd zone), JVC Dual tape deck, MMF-2.1 Turntable, JVC 5010 CD R. ((its simple, its cheap, it works))
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  • weavercr
    weavercr Posts: 289
    edited December 2002
    I glad you got your RCVR corrected, Mine on the optical were the same on all selections. I didnt relpy because I didnt get to thet the coaxial inputs yet.
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  • HBombToo
    HBombToo Posts: 5,256
    edited December 2002
    There is a lot of cool info on the web. Do a search on AES in yahoo and all the standards are available.

    When your eyes are bleeding from that stuff then go deeper. :)
    I'd hold off buying source material untill you feel you have exausted the Web.

    Much talk about seperates has transpired on the forum lately and I believe that having the DACs isolated from the rest of the components is really the way to go. The problem is that this a very expensive way to go and frankly speaking I don't think there are huge benefits from a HT standpoint.

    For the 2 channel world I feel this is the only way to go. For example playing cd's the benifits of seperate transport, dac, preamp and amp will provide the best power isolation possible and yield a beautifull stereo image. When I finish that part of my system I think I'll look into the LSI series but till then I'll just keep adding.

    These are just my thoughts and I hope I'm not beat about the head, neck, and chest too bad. ;)

    HBomb
    ***WAREMTAE***
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