Surround Sound for Stereo Music…Sacrilege??

Surround sound processing for stereo music has been around since the early ‘70s and it even survived the quadraphonic era. With surround sound decoding technologies like DTS:X and Dolby Atmos today's 3D sound technologies are, putting it mildly, spectacular! If you have recently upgraded your system, this might be a good time for you to try some of your stereo recordings in surround sound…

Recently I was reading a white paper on surround sound, because, let’s face it, I have no life. While marveling at the author’s considerable expertise on the subject, I started to notice a few areas where he and I disagreed. For one, the article dealt almost entirely with motion picture surround technologies, and it barely mentioned surround sound for music. Next I noticed that the piece only seemed to authenticate surround sound that is encoded and then decoded. The author derisively referred to multi-channel surround sound gleaned from a 2-channel stereo source as “fake stereo.” Actually, “fake stereo” was a real thing, and it had nothing to do with surround sound. “Duophonic” was a process used in the ‘60s and ‘70s where a monaural recording was split in half, and one channel was delayed, bass was reduced in one channel, and treble was reduced in the other. The result was always hideous, but at least, technically, there were now two different channels. True surround sound processed from a stereo source, however can be quite nice. I fully realize that many of you who consider yourselves purists would never listen to stereo music in surround. I totally get that.  I don’t listen in surround the majority of the time, but there are times when it really works well.

A little surround sound history…music preceded movies in the home surround market…

I was fortunate enough to have worked with some heavyweights in the area of analog surround from the 1980’s and on.  The surround sound units themselves were called “processors” because they took a stereo signal and generated (processed) a three, four, or five channel surround field from those two channels. In those early days of what would become surround sound, the source material we played was stereo music from records or (later) CDs. Cassettes often had phase issues that messed up the surround matrix. It was only after the advent of the stereo VCR that movies at home could be enjoyed in surround sound, as primitive as it was. The caveat was you needed two channels to create surround. Around 1984, VCRs were not only stereo, but also hi-fi, and a very satisfying surround field could be generated from a stereo VCR tape. This was essentially the beginning of home theater. In 1982, Dolby Surround was introduced. It was a primitive matrix that had three front channels and a single surround channel, often split into two rear surround speakers. Separation between front and rear channels was about 3 dB; not very much. Previous to this same period, I was selling and installing systems that used active matrix processors with actual steering logic, and full-range, stereo rear channels. The imaging was dramatic, but not seamless and not without annoying audible artifacts. It worked fairly well on music and stereo movie soundtracks. While Dolby Surround was simply “better than nothing,” having an active matrix and full-range, stereo surround channels was far superior for listening to music in surround sound.

In 1986, Dolby Pro Logic was launched. It derived a center channel to go with the left and right channels, and it still had a bandwidth-limited single rear channel. The attack and release times of the steering logic were slowed down to make it smooth during movie pans. The image was center-heavy, and while it worked okay on movies, nailing the dialog to the center of the screen, it was not especially suitable for music. The original Pro Logic was very conservative in its implementation, and not very exciting. Despite their artifacts when playing movies, I found Jim Fosgate’s Tate 101A and Charlie Wood’s Audionics Space & Image Composer far superior to Pro Logic on stereo music sources, as well as on most movies. These two processors were introduced way back in 1978, and they were both based upon the Tate chipset. You may have noticed this was eight years before Dolby Pro Logic was launched.

There was (and still is) a faction of music lovers and audiophiles who prefer to listen to at least some music in surround sound. Although some listeners will recoil, a good argument can be made for listening in surround, as long as it’s done properly. There are also recordings that are encoded in various forms of surround sound that are then decoded. They’re actually encoded in surround sound, with five or more discrete channels. This article is not about that encoded program material; it is about stereo recordings, only. And most of us own hundreds of records and CDs in stereo. Many of them can benefit from being played back in surround.

Dolby Pro Logic II…one giant leap for mankind…

The folks at Dolby realized that Dolby Pro Logic was long in the tooth, and years later, Jim Fosgate’s most advanced analog surround technology was adopted by Dolby and named Dolby Pro Logic II. The bonus was, it worked equally well on both movies and music. The attack and release times of PLII steering logic are 10-100 times as fast as the original Pro Logic, and the rear channels are full range stereo. Subsequent versions of this surround technology include Pro Logic IIx and Pro Logic IIz. There are also excellent surround technologies from DTS as well as the superb Logic 7 Music mode from Lexicon. And they all process a stereo source into surround sound. In fact, under dynamic conditions, you would be hard pressed to discriminate between a Dolby Digital soundtrack and one being processed with one of these surround technologies. (I’ve done double-blind tests, and the similarities are remarkable.)

Digital reverb is not surround sound!

One clarification to make is that the “digital soundfield processors” that were introduced in the early ‘80s are not surround sound. They simply add digital reverb to the recording to (allegedly) recreate the sound of particular rooms. True surround sound manipulates the material in the recording, but doesn’t add anything new. These “DSP” units superimposed the sound of another additional room on top of the original recording. This is particularly useful if you want to hear The Who’s “Live at Leeds” as it would sound in a parking garage, gymnasium, or an empty Home Depot. I do not disguise my disdain well.

A live classical performance in a good concert hall will present the instruments across the front, with the natural ambience of the room all around you. A stereo playback of this same event would present the instruments across the front, with all the ambience also coming from the front. The advantage of listening in one of several surround modes for classical music is you are surrounded by ambience, as you would be in a live setting. Ambience (out of phase information) is extracted and steered to the sides and rear. No additional information is added to the playback; information is simply moved around to emulate what you might hear in a live performance. Without artificial additions to the sound, surround can add to the realism of classical music playback, especially with large orchestral pieces. You feel more like you’re actually in the live acoustical space.

There can be dramatic advantages to playing pop studio recordings in surround sound too. When using a hard center channel, imaging of vocals isn’t limited to one seat. A good 2-channel stereo system will float a solid “phantom” center image, but only for a single listener, while a derived “hard” center channel will work well for multiple listeners. Vocals mixed dead center are nulled out of left and right front channels and steered to the single center channel speaker. (No, don’t ever use two center channel speakers. Just don’t. Hey…idea for another article!)

Certain music recordings work far better than others…

Probably the most interesting music listening in surround sound comes from recordings where at least some sounds are mixed hard to the left and right. In a surround music mode, sounds recorded to the far right or left front will be pulled more to the sides and rear creating a holographic soundstage in the shape of a horseshoe. When I first heard Pink Floyd’s “Dark Side of the Moon” in surround on a big system in 1979, I was stunned. The processor appeared to turn the recording into quad, with four discrete channels. Another recording of the era that was quite dramatic played in surround sound was Supertramp’s “Crime of the Century.” Sounds were panned left and right, front and back, and the effect was quite alarming. Most Alan Parsons recordings open up when played back through the most current analog surround modes. Quite a few rap titles are unnerving in surround sound, and I’m not just talking about the lyrics. Sounds seem to pop from all over the room.

“Amused to Death” is the motherlode…

If I were to play one entire album for someone to show what a stereo recording can sound like in surround sound, it would be Roger Waters’ “Amused to Death”. Enough phase manipulation went on in the mix of this intricate, powerful, and quirky recording that in PLIIx, you hear discrete sounds coming from wide to the sides and even behind you. My personal favorite surround mode for this album is PLIIx “music” mode, although DTS-Neo6 and Lexicon’s Logic 7 are also very exciting. Try “Amused to Death” in surround. If you feel dirty after listening in surround, just take a shower…

The newer analog surround technologies are seamless in how they operate on two-channel sources, and they’re free of the noise, pumping, and breathing of those processors from the late 1970s and 1980s. While many recordings lose their purity and don’t work well in surround, other recordings; especially processed studio recordings, have added depth, imaging, and a 360-degree sound field. You may actually notice things in the mix that you never heard before in conventional stereo playback.

I said at the outset that purists may balk, and I don’t suggest that you who are purists listen in surround. It may annoy you. But if you’re feeling adventurous and you want to revisit some of your favorite stereo recordings, try some listening in surround sound. You just might like it.

Let me know what you think, and if you have stereo recordings that sound great in surround sound please share them with us in the related forum thread.