Tuesday, February 28, 2012

Digital vs. Analog Sound

Last weekend I attended an audio club meeting in the greater Tampa area, It was held at the home of someone who had the ability to play various sources and formats of material (vinyl, CD, SACD, FLAC, etc.) through the same system. The meeting was touted as a shootout between the characteristic sound of these sources intended primarily to see if there were discernible differences between the 24/96 and 24/192 sampling formats. Let's see what happened and what we learned.

After the preliminary demonstrations of the system's capabilities, the meeting snagged several pairs of signal sources playing instantaneously switchable cuts from these two sources. Although not a true double-blind test in the scientific sense of the words, the host did not tell the audience which source they were listening too. I was standing at the very back of the room centered on the two speakers as best I could and forward about ten feet from the rear wall. The rest of the serious listeners were huddled at the sweet spot.

We were listening to Dire Straights: Brothers in Arms, a personal favorite, and the psycho-acoustic position of Mark Knopfler's guitar shifted wildly as the signal sources flipped here and there. All others were focused on tonality and nuances but on this particular system such distinctions were extremely difficult to hear and equally inconsistent in identification. After trying to hear such imperceptible changes, I observed something others had ignored.

To me, there was no challenge in being able to consistently hear the differences as demonstrated by the dramatically changing size of the sound stage. And once I pointed out this shift, others joined in on finding similar consistently changing clues all hinged on this fact.

Ignoring any colorations or limitations imposed by an link in the playback chain, what was confirmed was that the vinyl source produced the widest sound stage with the guitar extending at least six feet beyond the outside of the right speaker. The 24/192 source collapsed the stage to about 2 feet outside of the speakers and the 24/96 source collapsed it again to about a foot inside of the speakers, something no one was ready for.

Several rounds of changes were also evaluated and all sounded roughly the same with certain distinctions here and there, none of which anyone could really agree upon with any consistency. Why was this?

The playback system did have a characteristic limitation, one that I presume also limited us in being unable to note other differences: sound stage depth.  Front-to-back depth is a signature of a high quality playback system where the extreme rear corners are where details on the finest systems hide. This particular system struggled in this area and more than likely concealed other distinctions.

The moral of the story is this: when there are very few noticeable differences in signal sources played through your system, there is something else wrong in the playback chain. There is a built-in issue that prevents one from hearing such differences because such differences in signal sources are obviously there. If one cannot hear them, there is an undiscovered factor masking the sound.

So in pursuit of perfect sound, digital or otherwise, you need to get your "ducks in a row" so to speak. Identifying which particular piece of equipment is the weak link can be a challenge. Typically when one thing changes, it introduces an audible alteration; however, that's really starting at the middle and trying to solve a problem before verifying other assumptions you have made about your system are indeed correct.

While some view this as a tedious and unnecessary process, I prefer always to start at the beginning. I start at the place where electrical power enters the home and work my way forward from there. Once I am certain this issue is correct, I move on to the next and so on. In this way, I methodically analyze the problem and assume nothing is correct from the start.

When you are ready to troubleshoot your system, you may be tempted to jump into the middle. While this often is successful in changing the sound, there may be other issues hiding behind your assumptions that are truly the weakest link in the chain.

My advice is this: Be methodical and be consistent. Every piece of gear in your system may be operating perfectly and need not be replaced. Finding the source of issues that allow the music to come through is part of the fun of this fascinating hobby.

Yours for higher fidelity,
Philip Rastocny

I do not use ads in this blog to help support my efforts. If you like what you are reading, please remember to reciprocate, My newest title is called Where, oh Where did the Star of Bethlehem Go? It’s an astronomer’s look at what this celestial object may have been, who the "Wise Men" were, and where they came from. Written in an investigative journalism style, it targets one star that has never been considered before and builds a solid case for its candidacy.


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