Component Reviews

Surround Master Processor

A very effective pseudo-surround processor for any stereo source, lacking proper switching into an already-existing surround system.

Published on May 6, 2013

Surround Master Processor

Surround Master processor
SRP: $395





Involve Audio

First of all, these Australians—some of whom were involved with Lake and other Aussie companies specializing in surround sound and acoustic effects—have come up with a really successful pseudo-surround processor for two-channel sources.  It is much more effective and less gimmicky than either Dolby Pro Logic IIx or Circle Surround. In fact, it is similar to the Circle Surround processor which I used to have in my old car, in that it even creates some surround effect from mono sources as well as stereo sources.

All stereo recordings have L-R or “difference” information which this type of pseudo-surround processor uses to pull out the out-of-phase information which can then be directed to the surround channels. This differentiates them from the “hall,” “jazz club” and similar processors in most multichannel preamps and receivers, which only add artificial reverb and EQ to the signal and are nearly always ineffective and unnatural-sounding. Today we have many different surround sound processes: the discrete three-to-six-channel systems of SACDs and DVD-Audio, the lossless multichannel systems of Blu-rays, the lossy systems of DVDs, and even some processes for Net downloads in surround.  Then there are the analog two-channel surround codecs of Dolby Surround and Circle Surround which are pretty much obsolete by now.

There are audiophiles who play all their music-only sources as only stereo via their front left and right speakers, using their surround systems strictly for playback of movie soundtracks with that feature.  As our readers are probably aware, AUDIOPHILE AUDITION supports Surround Sound for Music, and believes that since sound comes to us from all around us, listening to music in surround makes a lot of sense. The Surround Master makes it possible to achieve a very convincing surround effect from any stereo source with just four speakers and amps, and without any investment in discrete audio playback or specialized recordings.

The Surround Master is powered by a 9-volt wall wart and comes with a clear 12-page manual in English. The connection cables are included. It has only an on-off switch and another on the front which can be set for either 2-channel or 4-channel. (You must switch it on before you power on your amps; otherwise it creates a loud pop.) The 2-channel setup—which I did not test—creates a semi-surround effect from any stereo sources with just two speakers in front (probably similar to some of the soundbars). The 4-channel setup is specialized for playback via four similar speakers equidistant from the listener, and an optional subwoofer if you wish. However, since many users will have a 5.1 surround speaker setup already in place, it will also work with a center channel, and also with the two surround speakers placed more to the sides rather than directly behind the listener. Involve feels there is really no need for a center speaker nor additional rear speakers of a typical 7.1 setup (and I agree on the latter).


SM-VectorscopeSampleThe Surround Master comes with a demo DVD which has two repeats of sections from various action movies, and encourages the listener to play the first one without the Surround Master in the circuit (or set to 2-channel) and then use it in the 4-channel mode for the second repeat. It includes on-screen moving images from their “vectorscope” which shows the sounds you are hearing in visual form, using various processes in comparison to the Surround Master. I must say, the Surround Master processing often creates a surround field even superior to many DTS-HD MA 5.1 tracks. Some of the images are very interesting, such as the ProLogic II one showing no surround signal at all, which I don’t agree with—although Surround Master is much better, with less emphasis on the center channel.

The big problem here is that there is no way to switch the Surround Master in and out of one’s system for comparisons and to properly play actual 5.0 or 5.1-channel sources. One must disconnect the cables for channels 3, 4 & 5 plus the subwoofer from your preamp or receiver and reconnect them directly to the rear of the Surround Master. Its two-channel input signal must come from the two-channel outputs on your preamp or receiver; you cannot feed it multichannel signals. (The Involve tech person was concerned that I might not be getting the center channel signal into the Surround Master—even though I had selected “Multichannel Mix-Down to Stereo” in my Integra preamp. He advised me to move the two-channel feed to directly from my Oppo deck; an odd piece of advice since that meant no volume control whatever. Once my hearing returned I went back to the output from my Integra preamp.)

I do have level controls on the amplifier connected to my surround speakers, and there is a main level control on the Integra preamp for the two-channel feed. However, without the preamp there is no level control for the center channel, which goes directly to a tube monoblock amp.  Therefore it is extremely difficult to set balanced levels on all the speakers when using the Surround Master. No matter how I set the levels of the left and right front speakers, the Surround Master seemed to provide more of a frontal signal on the left side and more of a rearward signal on the right side. Not only was I unable to use my side-height speaker feeds, but I could only audition all my multichannel SACDs as two-channel sources. I had to change the option on my Oppo deck from multichannel to stereo only.

However, the surround field from most two-channel sources was phenomenal. Many 5.0-channel SACDs have extremely subtle surround channels, which often have to raised in level to create more of a surround field. I never had that feeling from playing two-channel sources thru the Surround Master.  Not only was there an excellent surround signal extracted from the original, but there was a more seamless surround field to the sides than achieved with most multichannel sources, even with my surround speakers to the rear. Occasionally there were instruments very specifically located at various points between the left front speaker and the left surround, and vice versa. There were not any artifacts or unusual equalization of the sound at any point. It appears that the higher the resolution of the stereo source (such as 2-channel SACD or 96K/24-bit) the more difference information the Surround Master processing has to work with and the more convincing the surround field it creates. (There are also some superb discrete 5.0-channel SACDs which capture the acoustics of the concert hall or performance venue with startling realism.)

In addition to providing a much better surround field (using the stereo layer) from those multichannel SACDs lacking a sufficient signal on the surrounds, the Surround Master created terrific sound fields from older 2-channel Dolby Surround CDs, UHJ Ambisonic CDs and LPs, and Circle Surround CDs. Sometimes I even had to turn down the level on the surround speakers for an improved balance. Then there are many stereo-only pop and jazz SACD reissues and even some mono SACDs, which would create a surround field, rather than be restricted to only the front left and right speakers, as when playing in normal SACD mode. (Most preamps unfortunately don’t allow using Pro Logic on the discrete stereo SACD sources.) If you’ve already discovered the terrific surround placement you can achieve with the standard stereo releases of the Beatles and Beach Boys using Pro Logic IIx, you’re in for a real treat with the stepped-up spatial positioning of the Surround Master.

If I were an independent audio buff without the magazine connection, I think I might even consider purchasing (probably used) one of those stereo-only high end SACD decks from Denon and others, set up four identical full range high-quality speakers and use the Surround Master to create the surround field from all two-channel recordings, both standard and hi-res.

Involve is to be commended for keeping the price reasonable for such a convincing surround experience.  But meanwhile I will await a future model of the Surround Master that will allow for proper integration into an already-existing discrete surround system, as well as replacing and allowing comparison with Dolby Pro Logic II using stereo sources.

—John Sunier

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