In Praise of Analog - a Visit with the Beyerdynamic Revoluto

Digital is fun. Digital is sexy. Digital is what gives us the tools to manipulate sound and video in ways which would have been impossible not too long ago. Today video switchers are digital. Audio mixing consoles are digital. Fancy speaker arrays and even mic arrays are digital. The world is so digital that it becomes easy to forget that the world is, at its core, analog and that, especially in the case of audio, the analog can be the most important. With this in mind, 

(aside - I am aware that the world might, in fact, not be analog. The hypothesis of quantization holds that increases in any entity - be it matter or energy - is by a multiple of discrete smallest increases, or quanta. This means that the universe is, as we measure things, digital - albeit with a very high sample rate and quite a few bits of precision. Some have taken this a step farther and hypothesized that all which we see is a digital simulation running on some form of computer in a parent universe. This has very little impact on audio processing, so we can all go back to pretending that we live in a real, analog universe with no antecedents. End of aside).

Microphones and Microphones
Last year we had a nice visit with the ClearOne Beamforming ceiling microphone. This remains an impressive piece of technology,  but one with the inherent limitation of a need to be paired with an associated digital processing device. It is a very nice device, but at a very high cost. Is there another way to create a microphone array? Would I even be asking the rhetorical question if there wasn't?

German microphone manufacturer Beyerdynamic thinks that there is. One of their flagship products - the Revoluto - consists of seventeen microphone elements on a curved circuit board with analog summing elements. Nothing else. No digital processing, no magic. Just analog signals added together to create a single mic-level output. Beyerdynamic appears quite proud of this project, and has been adding "Revoluto technology" to its line of delegate mics.

As there are really few better ways to engage my skepticism than to make up a word and then promise the made-up-word technology in other products, I was glad to get my hands on a Revoluto and play with it. No, this won't be a product review and I didn't perform rigorous, technical measurements on it (what was the fate of our demo Revoluto? See here, on ExpresSHENs).

What I can say about it is this: it gives very clear voice reproduction at a surprising distance, with pick-up dropping off sharply as sources move off-axis. This makes it an especially interesting choice for huddle spaces in noisy rooms, assuming the noise sources are off-axis from talkers.

Test setup. Revoluto sitting in the pen tray, ceiling mic
hanging from the ceiling.

Does it actually work? On one simple set of tests (detailed above), the mic array certainly seems to perform as Beyerdynamic claims that it does. I didn't test it rigorously or thoroughly enough for a formal review or product comparison, but in a quick and basic setup it did a far better job than an analog ceiling microphone of rejecting the noise from an adjacent equipment rack full of noisy AV gear.

Overall, it's an interesting product and a nice reminder that thoughtfully crafted analog devices still have a very important place in our digital world.

Did you hear what's up? A morning with a ceiling mic

I remember my first ceiling speaker experience. I was the project manager on a simple bid-build job for a local presentation space. In addition to the usual VGA, composite video, and DVD/VHS combo deck (this was quite some years ago), the client wanted some way to record local meetings. No video conferencing, no audio conferencing, portable furniture to be plugged in via floor-boxes. With no good options for placement of microphones and lacking the budget for wireless boundary mics, the consultant decided to take a pair of omnidirectional boundary microphones and screw them to the ceiling. It worked pretty much as you'd expect; Recordings in this room were absolutely perfect if your goal was to replicate the feeling of talking to someone from across the platform at a medium-busy railway station. If you wanted the actual content to be louder than the HVAC noise you were pretty much out of luck.

There are, of course, better solutions, but the end result always seems the same; the ceiling is not the optimal place to locate microphones. They're far from the talker. They're close to all kinds of ceiling noise. The best results one could hope for are "barely adequate". So it was with hope but some degree of sketicism that I took part in a test of Clear One's new digital beam-forming ceiling mic array.

It's neither a bird nor a plane, but a ceiling mic array.

Physically, it's a nice looking piece of hardware. It's thirty inches long, five and three-quarters wide, by only one inch deep. On the bottom (if ceiling-mounted) are cutouts for the individual mic elements and two LED/touch buttons, one of which has the Clear One 'C' log discretely wrapped around it. It connects to a Clear One Converge DSP (and only a Clear One Converge - more on this later) and power-injector through two Cat5-type cables which can be neatly managed through the hollow rectangular support pole. It also comes with a tile-bridge to easily mount to a standard two-foot drop-ceiling. It's certainly a nice physical package.

The big question, of course, is what it sounds like. We set one up in the center of a fifteen by thirty foot room and made calls from various positions. Sitting at a table. Standing next to the table. Walking around the room. Standing in the corner. We turned on a projector about five feet away from it on the ceiling. Then we did a quick-and-dirty A/B test with some wireless boundary mics (from the good folks at Revolabs). Remember that bit of skepticism I mentioned? It turned out to be completely unwarranted. In as unscientific a test as could possibly be devised in which we were absurdly unfair to the hardware under test (passing it through an extra DSP to avoid having to reconfigure an existing system) it performed splendidly. Intelligent tracking software built into the mic follows the sound of voices, giving a clear and even signal as one of us walked in a circle around the room. Audio was clear from all four corners of the room. Clear One's noise cancellation dealt nicely with the projector noise, although at the expense of slight artifacts perceived by those of us with the most sensitive ears for such things.

Those LEDs light blue when the mic is live, red for muted, off for off (and can be turned off entirely via software). Sadly, there's no ability to actually direct the beams although one can switch them on or off. Switching off a beam pretty effectively would cut off audio to half of the room, making the mic somewhat more directional. Configuration is relatively simple through Clear One's Converge Console software.

There are two issues I saw with this mic array; first is that it connects to the Clear One DSP through a proprietary expansion bus. The ability to daisy-chain three of them together is nice, as is the cleanliness of the installation. It's an additional nice touch that even if you inadvertently switch the power and link wires (we tried) you'll not let any of the magic smoke out of the unit; it'll just  hang there until you get the wiring right. The problem is that it locks you into one DSP option, which wouldn't be my preferred option for all applications.

The other concern is that it isn't an inexpensive option. MSRP is close to $4000, and the DSP will be another four. You could get eight nice boundary mics for half of that, assuming you have anywhere to put them. So it's not the budget choice, but is one of the best I've seen thus far. If anyone's interested, perhaps some more on this after some more experimentation.