Digital Sound and Recievers

johnnyamerika

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

HBombToo

This should not be happening... just to clarify, both dig coax and Toshlink do the same?

tough 1 here man!

HBomb

johnnyamerika

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

HBombToo

Does your owners manual mention anything? This does not seem correct to me... How old is your receiver?

Wierd it is...

HBomb

weavercr

I will check this out on my Onkyo 595 and post the results.

scottvamp

Ya interesting. That should not be happening. Let us know.

HBombToo

bump

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

HBomb

organ

Maybe the db levels were changed. Did you check to make sure every channel is at 0db for all modes?

Maurice

johnnyamerika

Yup, because it doesn't happen with the analog inputs for each channel, only on the digital assignments.

phuz

Could it be a difference in the DACs being used?

Are you switching between any DSP modes or 2/5ch stereo modes?

johnnyamerika

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.

phuz

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.

johnnyamerika

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.

phuz

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.

HBombToo

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

johnnyamerika

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?

HBombToo

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

johnnyamerika

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.

cruiser3

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........

weavercr

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.

HBombToo

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