Stereo with 3 speakers – is that heresy or maybe a really good idea?
Purists would have you believe that stereo means a recording with 2 channels and played back with 2 speakers. It turns out that early research done on “stereo” in the 1930s included experiments with both 2 and 3 channel recordings (left, center, right) and with 3 speakers. Later on, Paul Klipsch (of Klipsch Loudspeaker fame) did experiments and demonstrations with 2 versus 3 speaker playback of a 2 channel stereo recording, and concluded the 3 speaker setup was superior. Some famous classical recordings were recorded with both a center (mono) and stereo set of microphones, although not released to the public as 3 channel.
In the 1990s, Michael Gerzon wrote and presented a series of papers describing a method for playing the sound from M channels with N loudspeakers, where N>M, and in the simplest case we have 2 channels, 3 speakers. A commercial implementation of his ideas was the Ambisonics Trifield processor which was implemented by Meridian Audio.
I’ve never heard a Trifield setup, but I’ve read some rave reviews. More recently, it seems Magnepan is doing experiments and marketing a 3 speaker stereo solution. Reading about 3 speaker stereo got me thinking and wanting to do some experiments at home.
What might be the advantage of three speakers over two? With two speakers, sounds that come from the center of the soundstage are present in both the left and the right channels, and our brains create a “phantom” center – if you stand or sit right in the middle between the two speakers, sound mixed equally in both channels will appear to come from the center.
But what if you are not positioned in that perfect sweet spot? And even if you are, there are those who believe there is less listening fatigue with a physical (not phantom) center speaker, as well as a reduction in “intra-aural crosstalk” – the left ear hears sounds from the right speaker, and the right ear hears sounds from the left speaker. So I thought maybe there’s something to the idea of 3 speakers.
Now the argument for a center channel speaker is well established for movies and surround sound systems for a home theater have become the norm. Nonetheless, I have resisted the surround sound argument and watch movies with just 2 speakers mainly because of simplicity, effectiveness, and cost. For example, I reasoned, I would rather have 2 good speakers and a good 2 channel amplifier than (for the same money) 5 speakers and inferior electronics. In my house, in the setups for movies, I do get to sit in the sweet spot, and for equal quality 2 channel/2 speakers costs less than 3 or 5 or whatever. But I do my best listening for music in a different room, I don’t get to stay in a sweet spot, and that’s a story for other blog posts.
http://www.stereophile.com/reference/407upward/index.html (Keith Howard article)
http://www.audiosignal.co.uk/Gerzon%20archive.html (articles by Michael Gerzon)
http://www.audiosignal.co.uk/Resources/Three_channels_A4.pdf. (3 channel stereo, Michael Gerzon)