Axiom Home Page Forums General Discussion Technical Questions Analogue input Vs Digital

Please explain DAC's (digital anologue converter?) and wether using HDMI for sound is better than anologue cables.
I would assume digital is better.

Don't know what sort of DAC explanation you're looking for. If the sending unit has converted digital program content to analog with its DAC, a coaxial cable can carry the analog signals to a receiver or other unit. If the digital material hasn't been converted to analog, it can be carried by HDMI, optical cable, or coaxial cable to be converted by a DAC in the receiving unit. Neither process is necessarily better.

I'll need to do a bit more homework.

Everything (except speakers) I have connected to my reciever is by HDMI. Am I missing anything (SQ)by wiring this way?

Hey BR.

Think of digital signal as in the signal is still in computer format. All of the frequency information has been converted to binary data, ones and zeros. This is the way music is now stored on modern media like CDs and in media files like MP3s.

Digital is a very accurate way to get musical data from point A to point B. Essentially, the musical information should never never change from the player to the receiver as long as it stays digital.

At some point, the information has to be converted to analog. Speakers are simple electronic devices and required an analog signal. An oversimplified way to explain analog signal is that the sound frequencies (waves) are represented by the equivalent waves/frequencies in an electrical signal. Think of a wave pattern and the top of the pulse will drive the speaker driver out a corresponding amount and and the bottom of the pulse will suck it back in the corresponding amount.

The DAC, Digital to Analog Converter does just that. It does the math one the binary information and sends out the corresponding electrical frequency waves.

There are two schools of thought as to where you want that to happen.

1. Keep it digital until as close to the end as possible. Saves on the number of cables used and the binary data stays the same longer.

2. Some DACs do a better job of converting the binary data into frequencies than other. Use the device in the line that has the best DAC or even add a third party DAC into the mix.

Proponents of number 1 will say that the differences in modern DACs is negligible and not audible. They will say that if it's not doing the math the same, it's broken not better or worse. I'm not going to argue one way or the other here. I'm trying only to explain who it works.

As above, to send a digital signal you require a HDMI, co-ax, or optical cable. All of the channels for surround sound can be sent in the same single cable. Also with HDMI, it can send the video data as well. Some copy-write schemes are requiring certain levels of HDMI in their protections schemes.

Analog cables can only carry a single channel of data. So wherever you use the DAC to convert from digital to analog, from that piece of equipment on, you will be required to use a set of analog cables per channel. It's typically run on speaker wires or co-ax/RCA wires if you are going in between components.

You expect to do this at the end where you need to run a pair of speaker wires from the receiver to every speaker but lets say you decided to use the DAC in your CD player for whatever reason. You will need to run a set of RCA cables from the player to your receiver for every channel. Stereo would just need two pairs. 5.1 would require 5 sets plus another for the subwoofer channel.

If you choose to stay digital between your player and receiver, you can make do with just one HDMI.

What devices support what sound formats is another factor, but I've already typed to much. I hope this helps though.

Murph, an excellent explanation and in today's mature digital technology, in my mind, whatever differences between analog and digital exist, those differences are highly overrated.

Just to give you an example, although I didn't buy it specifically for that reason, but when the Oppo BDP95 was introduced last year, of course, the internal allegedly "state of the art" Sabre DACs were touted as being the ultimate for a Blu-Ray player operating in the analog domain. After making both multi-channel analog and HDMI connections through the inputs of three different AVRs during this time and trying, of course, to use my ears to make comparisons between the two, when all was said and done, I sat back and wondered what all the fuss was about?

Some would argue that what you are using as an external input source can vary in sound(I have my doubts), in the end, I went back to the straight HDMI connection which not only allowed me much greater versatility in bass management and other features, the HDMI connection was comparably louder than the analog and, of course, I had a lot less cables to hook up.

Perhaps others have had different experiences and this is not to doubt the Oppo's outstanding analog capabilities but, once again, you are talking products, such as the Oppo, that just seem to bring out their best operating in the digital format and why someone would spend that kind of money without getting the best out of it, to me anyway, seems kind of silly.

Whoa whoa whoa Murph.
You lost me at 'hello'.

So then what about the term "bit" used in the specs on a bluray players.
Is it in relation to video quality or analogue sound quality or digital sound quality?

depends on if your talking about a bit (basic capacity of information in computing/telecommunications values of 1 or 0, or bit as in bitrate which is basically the ammount of bits that are processed in a unit of time.

what is that saying, just enjoy the music.

The bluray player I was looking at earlier this year stated "192kHz / 32 bit DAC".
If I understand you correctly, had I purchased it, I would not have benifited because I'm only using HDMI cables. Correct?

Correct, your avr is doing all the decoding.