The Box Soundstage Monitor
This curious looking metering system was invented by the late and much loved Frank Fox, who devised an ingenious way of combining level and stereo width metering on a single display. Having used one of Frank's original Boxes for many years, I'm delighted it's in production again, this time under the brand name ITZA, a small audio company run by recording guru Mike Skeet. Still hand-built in limited numbers, this new, mains-powered version of The Box is cosmetically different from the old in that it now resides in a plastic case rather than a wooden cube, and the circuit design has been updated to allow manufacture at a lower cost. There's also a button on the rear panel which switches the display to mono for calibration purposes.
The input to The Box is a stereo, unbalanced jack socket, which most users find convenient to feed from the headphone socket of their mixers. Unlike a standard LED meter, The Box utilises a diamond-shaped matrix of 100 LEDs: green, yellow, amber and red. The vertical centre row is coloured red, and in the presence of a mono signal, only a vertical display is visible — similar to what you'd expect to see on a normal meter. But feed the unit a stereo signal and the display widens to produce a flickering flame pattern which changes with the programme dynamics and pan positions; in the case of a mix where the left and right channels are balanced in level, the pattern will be nominally symmetrical about the centre. This provides an instant check that the output is indeed stereo, that the stereo image is adequately wide, and that the two channels are in balance.
If the phase of one channel has accidentally been reversed, the display changes to a V shape, which behaves like two conventional meters joined together at the bottom. Should a correctly-phased stereo mix contain a high level of out-of-phase components, caused by signal processing or artificial stereo widening, this characteristic V-shape tends to overlay the normal flame display. In fact, with experience, it's surprising how much The Box tells you about your mixes that your ears don't always appreciate. It's also instructive to watch the display as a single mono signal is panned from one side to the other. It starts life as a line running up one side of the display (one leg of a V) and then gradually moves across, passing through the central, vertical position, then moves to the other side (the other leg of the V). Stereo delay effects show up quite clearly, with differently panned delays popping up at different parts of the display.
The Box can also be used instead of an oscilloscope to compare the relative phase of two test tones — ideal for setting up tape machine azimuth. Just feed one channel with the test tone from track one, the other channel from the highest numbered track, and then go through the adjustment procedure. Minimum phase difference is indicated by a straight, vertical line on the display. Other uses include checking that left and right channels of a stereo compressor are behaving in the same way and checking for accidental phase inversions in a balanced patchbay system.
On paper, The Box might seem like a rather quirky luxury, but being a regular user, I can vouch for its genuine usefulness. Many is the time it's warned me of something amiss before my ears picked it up, and it offers constant reassurance that all is well on the stereo mix front. I think I'd rather mix with one ear in a sling than go back to working without my Box!
The Box £350 including VAT.
ITZA, (Contact Details).
Review by Paul White
Previous article in this issue:
Next article in this issue:
mu:zines is the result of thousands of hours of effort, and will require many thousands more going forward to reach our goals of getting all this content online.
If you value this resource, you can support this project - it really helps!