Axiom Home Page Forums General Discussion Technical Questions Audio CD signal via Coax or RCA?

When I listen to CD's through my DVD player, is there and advantage to using the coax input instead of the RCA left and right cables like I traditionally would? I would think the receiver would see the signal coming in and try to decode it as DD, DTS or Dolby Pro-Logic as opposed to two channel stereo.

I am curious which connection others use for listening to two channel stereo.

Greg

Coax or Optical will be a digital signal from the DVD/CD to the Receiver which will sound better as it does not need to be converted. RCA is analog.

What about the the receiver trying to "decode" the coax signal into more than just two channels? Maybe that can't happen, I don't know.

Greg

To expand on this a little further. If you use the digital output from your DVD palyer (either optical or coax) your receiver will be performing the digital to analog conversion, vs. sending the signal using the RCA connectors. In this case your DVD player will be doing the conversion. All DAQ's are not created equal, so one may sound better than the other by virtue of the difference in the DAQ's, not the difference in the cable type, although the latter will have some effect as well.

Greg, fortunately the receiver's processing "knows" what format is being input and the mix-up you suggested can't happen. When you use the digital input for CDs too, the DAC in the receiver, rather than the one in the player, does the conversion, but this should no longer be a determining factor. As Alan and others have pointed out, DACs are now a mature technology and while small measurable differences still exist, they aren't audible to our ears.

Any processing(except simply volume and tone)would have to be done in the digital realm(and therefore re-converted from analog)so in general the digital output should be used. Also keep in mind that digital processing such as for bass management and ambiance retrieval(using DPLII,etc.)can increase the enjoyment of two channel source materials. If we've bought HT receivers and speakers there's no good reason not to use them to liberate the ambience contained in two channel sources and send it to the surrounds where it belongs.

In reply to:

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so one may sound better than the other by virtue of the difference in the DAQ's

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This implies that the cheaper player mated to a newer (better) receiver/prepro should be a good option. Am I correct?

Okay one last item.

I have the coax cable from the DVD player plugged into the coax input on my receiver. To get this source during playback, I have to select the "DVD" input on my receiver. If I do this, I get sound out the center speaker and minimal sound out of the front left and right. Also, my receiver, 7 year old HK AVR65, says it is decoding Pro-Logic????

So how do I get my receiver to playback two channel stereo and not try to create some sort of Dolby Pro Logic Matrix sound?

Greg

I'm not familiar with your receiver, but you should have a digital input for the CD source, or be able to "reassign" the coax input to the CD function. Or, as a last resort, you can change the sound mode from Pro-Logic to Stereo.

Al

Hi GregM and all,

I'm almost certain your HK AVR65, being 7 years old, is not a Dolby Digital/dts unit, and is likely equipped with the "old" Dolby Pro Logic, which was fairly crummy for music playback. With CD playback, it tended to move too much into the center channel, narrowed the stereo soundstage, and channel separation was only so-so. Besides, the surround channels were mono, extracted by a matrix.

By contrast, DPLII was a huge improvement, especially for simulated 5.1-channel music playback, ambience extraction and much improved logic steering and separation.

Check your receiver or the manual and see if it has a "Dolby Digital" and "dts" logo, and also if it has Dolby Pro Logic II (I doubt it).

You should also be able to defeat any surround processing with a remote or front panel button "Surround off" or "DPL Off".

Another clarification: "RCA" is a common type of connector. It does not denote analog or digital per se. Coaxial cables are shielded with a center conductor and may carry analog or digital audio signals. Your DVD player and/or H/K may have "optical digital" or "coaxial digital" outputs and inputs. If one or the other uses a coaxial digital output, it will be labeled thus and will use a coaxial cable with male RCA jacks on each end. An "optical digital" connector uses a special little plastic Sony/Philips plug, quite unlike RCA jacks and plugs.

Early Dolby Pro Logic appeared first in an analog version, then in a Digital version. The latter was a slight improvement over the analog but not by much.

The big improvement was discrete Dolby Digital 5.1 (or dts's version), as was the "II" version of Dolby Pro Logic (DPLII), which, as JohnK pointed out, can bring a lot of enjoyment with any stereo source.

Regards,

Thanks for clearing the RCA thing up. I should have been more carefull.

I currently have the digital coaxial cable running from the DVD player to the receiver's DVD coaxial input. I also have the red and white "RCA" cables running from the left and right output's on my dvd player to the receiver as well. These are connected to the CD input.

The receiver is Dolby Digital and DTS which is one reason I bought it. While playing back an audio CD with "DVD" selected on the front of the receiver, the Pro Logic lights are illuminated (It may say Pro-Logic II, I am not sure). As someone else mentioned, maybe I can hit the DVD button to get the source I want, and then over ride any surround sound processing to get the two channel stereo I am after.

I'll fool around a little bit more tonight. Maybe I should get that AVR435 after all.

Greg