Friday 19 April 2013

Surround Sound – Making a Comeback?

BitPerfect user John Bacon-Shone correctly pointed out in response to my recent musings on DSD that the SACD format delivers a huge amount of music in surround sound format, which is a particular boon to classical music listeners.  And not many people are aware of that.

Surround sound as a consumer format goes back to the 1970’s although its roots precede that by several decades in cinematic applications, and even in concert performances such as Pink Floyd’s “Games for May” concert of 1967.  The appeal of surround sound is quite obvious – why constrain the sonic image to the traditional one of a stage set out in front of you?  Arguably, this idea was first reduced to practice by Hector Berlioz in his “Grand Messe des Morts” or Requiem, waaaaay back in 1837, which called for four brass bands to be located in the front, the back, and the two sides of the performance venue.

In the 1970’s several consumer formats appeared, each aimed at extending the two-speaker stereo layout with an additional pair of rear speakers.  The term “Quadrophonic” was coined to describe this arrangement, and there was much enthusiasm in the music industry to support 4-channel technology with recorded material.  As we now know, when new a consumer technology tries to emerge, the major stakeholders take turns to shoot themselves in the foot.  In this case, the hardware manufacturers brought forth a plethora of incompatible solutions to deliver a four-channel experience.  QS, SQ, CD-4 (all LP-based formats), 8-track tape, and surprisingly many others, all came and went.  It was another 20 years before the movie industry, and its DVD technology, finally lit a fire under the surround sound concept.

One of the problems with surround sound is that it is much harder to create a solid 3-dimensional sonic image which creates the same soundfield for multiple listeners distributed throughout the listening room.  This problem is exacerbated for home theater applications where there is a physical image (the screen), and a need for much of the sound – particularly the dialogue – to appear to come from it.  This resulted in the adoption of the front center speaker, through which dialogue can be readily piped.  Also, in movie soundtracks the role of deep bass is dramatically different from that of pure audio, and so a special channel which provides only deep bass (the “Low Frequency Effects” channel) was specified.  This complete configuration is well known today as “5.1”.  Additional main speakers tend to be added from time to time, and today’s home theater receivers often support up to “7.1” channels.

Now that surround-sound's structural formats have at last become established, the music industry can now focus on recording and delivering music in multi-channel formats.  The venerable CD is too old to be adapted to surround sound, and so SACD is now the only viable hardware format available for delivery of multi-channel audio content (its one-time competitor and supposed vanquisher, DVD-Audio, is all but extinct now).  Except that here in the West, as consumers, we omitted to climb on the SACD bandwagon.  If only Sony and Philips had marketed SACD as a surround-sound format rather than an audio quality format, things might have turned out differently.

Anyway, audiophiles being audiophiles, the surround sound debate is alive and well.  There is an emerging body of opinion that says the centre speaker is actually ruinous when it comes to creating a stable sonic image.  Additionally, sub-woofer advocates believe that a single LFE channel is inadequate, and that each full-range speaker needs its own sub-woofer.  There is also (thankfully) some agreement that, for classical music at least, the two rear speakers do not need the full 20Hz bass response.  What we used to refer to as “Quadrophonic” is now called 4.0 and one of its keenest advocates is Peter McGrath, a revered recording engineer whose day job is Sales Director for Wilson Audio Specialties.  Peter’s classical recordings are absolutely the finest I have ever heard, so his opinion counts for something!  But relatively few multichannel SACDs are presented in 4.0 format.