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Spatializer HTMS 2510

3D Sound Processor By Paul White
Published October 1996

Paul White experiments with mind expansion '90s style, and discovers no harmful side effects!

A number of low‑cost, so‑called 3D sound systems have appeared on the market recently, mainly aimed at those setting up home cinema systems or playing computer games. These systems vary in cost and effectiveness, but because they're built for a mass market, they're very cheap compared with pro‑audio equivalents.

The Spatializer HTMS 2510 was created by the company responsible for the Spatializer TDM software for Pro Tools TDM systems, and as far as I can tell, it works on the same principles as the software, to give a 3D effect to the material being processed. Physically, the Spatializer unit is about the size of a typical rackmount box, but without the mounting 'ears', and is designed to operate at a nominal 4V signal level, making it compatible with ‑10dBV systems; +4dBu users need to be aware that they will have very little headroom, though having said that, I ran the Spatializer using my +4dBu insert points without any problems. The audio ins and outs are on phonos, and a second pair of switchable inputs is fitted so that you can switch the processor from TV to hi‑fi. Power comes from an external adaptor.

The Controls

The Spatializer's control system is incredibly simple. Essentially, the effect is either bypassed or on, with three switchable effect 'levels' accessed from the front panel. A large, green, sci‑fi style indicator displays three concentric LED semicircles, and the number of arcs lit indicates the process setting. There's no dynamic display or metering of any kind, but a supplied cordless remote allows you to adjust the effect without leaving the listening position. A further button adds extra bass for the benefit of those who think that too much bass is the same thing as hi‑fi sound quality; this is best left firmly in the 'off 'position.

The Effect

The hype that comes with the Spatializer box sounds pretty much like the claims made for almost every other 3D processor, but I'll tell you now that this one really works. I tried it on a few mixes, and as soon as I pressed the 'On' button, sounds and effects panned left and right moved way out beyond the speakers, and sounds which were previously buried in the mix seemed to find a space of their own in which to exist. The process isn't entirely tonally neutral at the highest settings — there seems to be a low‑mid boost which warms everything up quite noticeably — but this isn't a violent tonal effect and can be compensated for by rolling off the low end a little. More surprising is the fact that the effect has good mono compatibility, a further indication that equal and opposite components are added to the two outputs. When you switch to mono, these components cancel, leaving the original signal. This effect seems to work particularly well on orchestral sounds, where a real concert hall ambience is created, even without reverb or delay. If there's reverb in your original mix, it wraps right around, and although the system fails to position sound behind you, it does have you looking to the sides on occasion.

The Verdict

This box is aimed at home entertainment, and is capable of making a dramatic difference to a stereo TV soundtrack. In the studio, used with care, it can add a completely new dimension to music: I think it would be fair to say that the effect it produces is comparable to what you'd expect from the big‑money pro systems.

Though you can simply process your whole mix, I'd be more inclined to patch the Spatializer into a couple of mixer group inserts, to process selected instruments and effects returns. This maintains contrast and avoids the possibility of tonal changes on sounds that don't need widening.

At under £250, the Spatializer is a bargain, and as far as I'm concerned, it's a must‑have box in that I must have one! I'd be happier if a recording Spatializer was available, operating at +4dBu with jacks instead of phonos, but in the meantime this one will do just fine.

Space Oddity: Analysing The Spatializer

No precise description of the Spatializer's processing method is provided, though the documentation says that aural cues normally suppressed in conventional stereo recordings are restored by the process. There are only so many ways in which this can be done, and all involve filtering off‑axis sounds, introducing phase shifts between the two channels, or both. This particular system shows signs of directly out‑of‑phase L/R components when connected to my phase meter, but there's also a lot of frequency domain manipulation going on. The design also probably includes some kind of intelligent processing, because previously expanded material isn't over‑processed, and central dialogue sounds aren't allowed to become swamped.


  • Relatively inexpensive.
  • Staggeringly effective stereo expansion.
  • Simple to use.


  • Phono, ‑10dBV connections.
  • No level metering.


The Spatializer is sheer magic on a stick — I must possess it!