Audio Engineering Society (AES) 125^th AES Convention
San Francisco, CA      October 2 through 5, 2008
Report By Clarke Robinson

   The Audio Engineering Society (AES), now in its sixth decade, is the only professional society devoted exclusively to audio technology. Its membership of leading engineers, scientists and other authorities has increased dramatically throughout the world, greatly boosting the society's stature and that of its members in a truly symbiotic relationship. Unlike more consumer-oriented trade shows, the meat & potatoes of AES conferences are in the presentations rather than the exhibits. I only had one day at the conference, and splitting my time between the sessions and the show floor only gave me enough time to catch a talk and a half. The “half" was a longer talk by Søren Bech of Bang & Olufsen and Nick Zacharov of SenseLab about perceptual audio evaluation, a topic about which the pair have recently published a book. Targeted towards audio professionals who evaluate their products by conducting listening tests using a large number of subjects, it wasn’t exactly up my alley, but it was interesting to hear about the statistical challenges of designing such a test.

I left that one early and went to another that proved much more useful to an audio journalist involved in doing subjective equipment evaluations. Bill Waslo of Liberty Instruments (maker of Praxis audio evaluation software) was demonstrating his new freeware application, Audio DiffMaker. In short, DiffMaker takes two nearly identical audio signals, subtracts one from the other, and creates a new audio file out of the difference. For example, you could record a track using one set of interconnects, record it again with another set, and the resulting audio file would contain the actual, audible difference the cable change made. If the “difference" file is completely silent, it would prove the change made no difference at all.

I had heard of this software (which is available as a free download from www.libinst.com) before and was skeptical, as it requires the signal to run through a computer soundcard. Hearing Waslo’s presentation allayed my concerns. The software is very sensitive, and getting two audio files (even two identical files) to produce a null result is not trivial. The examples Waslo played in his demo are available on the website for download, including (among others) the results of a capacitor comparison, different levels of mp3 compression, and the infamous “green pen CD tweak".

The software has a “playback boost" feature to make audible even the faintest differences. Using Waslo’s capacitor comparison as an example, the distortion created by a cheap Z5U capacitor was audible (just barely) on my laptop speakers without any boost at all, but 30dB of boost was required to hear the sonic impact of an “audio grade" polypropylene cap. The biggest benefit of DiffMaker is that the end result does not depend on measurements, but in actual evaluation by ear. I suspect that many of the more controversial topics in the age-old “subjective vs. objective" debate would turn out like the poly cap: a difference exists, but it is at such a low level, each audiophile can decide for themselves if they want to be concerned.

I’m looking forward to trying out DiffMaker in future reviews, but now, on to the show floor:

EveAnna Manley shows off her latest effort in the pro space, the Manley Mastering Backbone. Manley has been building custom mastering consoles for years... this is an insert switcher for use with them, of course built to exacting audiophile standards. While I was standing there, recording guru Doug Sax dropped by to invite the perennially cool Manley to an after-show party.

It’s a bird, it’s a plane, it’s a subwoofer! Eminent Technology’s TRW-17 Rotary Woofer picks up where mundane old box subwoofers roll off, covering the 0Hz to 40 Hz range. You may be asking, as I did, “why bother?" Eminent had a demo in a hotel across the street to answer that very question. It turns out that, yes, you can hear below 20Hz, and yes, there is program material available that does so. Eminent estimates that about one third of all DVD movies have content in the 8Hz to 20Hz range. Their demo reel had some wall-rattling examples, including an actual recording of a San Francisco earthquake that was quite lifelike (frighteningly so, considering I was on the 8^th floor). SPLs in the demo were not especially high, but the impact of this unit is so great that they didn’t need to be to make a very big impression.

M-Audio was showing a ton of new products designed in partnership with Digidesign (Avid, Digi’s parent company, purchased M-Audio a few years ago). This workstation was demonstrating their new Studiophile DSM2High-Resolution DSP Reference Monitors. The monitors were fine, but the real fun was in their demo material…the actual Pro Tools files for Joss Stone’s “Tell Me About It", sitting there for all the world to screw around with. I made myself a fairly benign remix artist, just turning the handclaps on and off and such, but oh man…talk about giving a geek the keys to the kingdom.

To celebrate their 80^th anniversary, Neumann has released a modern version of their classic U-67 microphone, the TLM 67. “TLM" stands for “transformerless microphone", and it uses an electronic circuit instead of a conventional output transformer. According to the marketing materials, this circuit “closely reproduces the sound characteristics of the classic U-67, without the use of tubes". The marketing materials do not say how this is done, and their man in the booth was similarly mum. It will be interesting to see if this technology takes off, however I don’t expect studios will be ditching their vintage U-67s any time soon.

Cirrus Logic had the evaluation board of their new digital receiver on display, the CS8422. The key selling point here is an on-board sample-rate converter, which, according to the rep I talked to, eliminates the need of running the signal through a dual-pll loop for ultra-low jitter applications.

All-around nice guy Elias Gwinn was working Benchmark Media’s booth, with typically nice things to say about everything and everybody. Their chief engineer, John Siau, was on hand as well to introduce me to the new MPA1 preamp, and explained the technical hurdles he jumped through to have an on-board power supply in Benchmark’s characteristic small-footprint enclosure, and still maintain a very low noise level.

Nagra, the classic manufacturer of field recorders (ever see Blow Out?), was showing their new six-channel recorder, the Nagra VI. Considered their most advanced recorder ever, it records everything to an internal IDE hard drive, features analog and digital inputs, microphone preamps with an integrated “vortex" filter for use in windy conditions, transfers files via USB or compact flash card, and, as if that weren’t enough, comes in three different colors.

Representatives from the Burr-Brown wing of Texas Instruments were showing off prototypes of their next-generation op-amp, the OPA1611. The spec sheet scored high marks on all of the requisite criteria: unity gain stable, usable across a wide voltage range (down to 2.25V), and insanely low distortion (0.000015%). The evaluation board shown here uses the single-channel op-amp for both analog output and I/V conversion. A stereo version, the OPA1612, is coming as well.

Live sound gurus Meyer Sound were showing a number of new products, not the least of which was the large, stop sign-shaped SB-3F Sound Field Synthesis Loudspeaker (the unit is about four feet across), a sonic telescope capable of projecting sound over 1 kilometer. Also present in their booth was the new 500-HP Compact High-Power Subwoofer, at only (only) 28 inches wide, it brings high output, low-distortion bass to a wider range of Meyer’s groundstacked or flown loudspeaker arrays. Listen for bass that is better integrated with the mids at a state-of-the-art performance space near you!

France ’s Focal Professional had their new CMS 65 and CMS 50 studio monitors on display. The most affordable powered monitors in the Focal Professional line-up, they feature heavy aluminum enclosures and a newly designed aluminum/magnesium tweeter.

Lundahl Transformers were not only giving out some very tasty Swedish chocolates, but were also talking up their line of amorphous iron core output transformers. Amorphous iron is created, I learned, by spraying molten iron onto an extremely cold surface: the iron cools into a thin film before any of its crystal structure has time to form, hence amorphous, or “lacking form". The transformers on display (and in the picture above) are their more traditional silicon iron variety, but amorphous core models are available in most of the popular voltages.

Telefunken | USA has been refurbishing vintage Telefunken microphones for years, and has more recently started building recreations of some of the classics. Their booth featured a demo where passers-by could compare the sound of a vintage U47 (of Frank Zappa’s Joe’s Garage fame) with their new recreation, the U47AE. Out of production since 1965, aging U47s have never been known for their consistency and this was no exception: even on the noisy show floor, the modern U47AE had an obviously more extended top end. A fun and popular demo nonetheless, Telefunken’s booth was a fun people-watching spot.