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Positive Feedback ISSUE 47
january/february 2010


AES 2009
by Scott Dorsey



I always enjoy talking about the pro audio shows from the standpoint of the high end audio community, and it's very interesting to see how things overlap in interesting ways.

This year has been a good one for that kind of thing. The AES show, I will point out, consists of two different things going on at the same time. Upstairs there is a trade show with people talking about products, and downstairs there is a set of paper sessions and workshops with people talking about theory and technological development.

This year, in great part due to the economy, the trade show upstairs had about half the normal space. A lot of vendors pulled out, and many of the vendors had radically reduced the size of their booths. Belden went from a huge booth, for instance, down to a small table. Most of the semi-pro manufacturers and sound reinforcement product companies pulled out completely.

The thing is, even though there was half the floor space, the people who were left were mostly the more interesting companies, the smaller companies, and the people with quality products rather than music store junk. In addition, the actual number of attendees didn't seem down at all, so there were the same number of people packed into half the space. This made for a very crowded show but it made for a show where a lot of people got to see stuff they wouldn't have been able to see before. And for me it meant that I got a little more time to see the paper sessions.

A note about the papers here, by the way: the paper presentations are selected by the convention organizers based upon the abstracts only, rather than by a full peer review as would a journal article. This is a good thing, because it means we get to see presentations of preliminary research years before a final journal report is available. However, because of the lack of careful review, sometimes crazy stuff slips through, and sometimes the crazy stuff can be the most interesting, too.

I'm going to describe here the stuff that I saw, and being only one person I can't give a complete description of everything. I'm going to talk about some papers and some workshops and a whole lot of products, and if I miss something important or I get something wrong about a product, you shouldn't be too surprised because I'm trying to cover a huge event with a lot of different things going on, by myself in only four days.


Trident Audio Developments was showing off a pair of small nearfield monitor speakers called the HG3, and they actually sounded good. It wasn't prone to any of the painfully obvious issues that most small monitor designs are. Now, I've only heard them under show floor conditions and not in a proper room, but they definitely show enough promise that I am going to go out and give them a listen.

Adam Audio and Focal both had elaborate 5.1 demonstrations set up which didn't sound very good, which is tragic since the speakers they were showing were actually very fine products which deserved better presentation.

Community was showing off a small line array called the Entasys, more or less like a modern version of the old Bogen Sound Columns. Modern dsp technology has tightened some things up a bit, and it's very clear that the radiation pattern is very directional vertically with these. There is a lot of audible comb filtering as you move up and down, though.

The Sennheiser booth was showing off the Klein and Hummel monitor speakers. These are some of the best sounding box-type speakers I have used, but unfortunately they didn't really have any way to demo any of them and they really didn't do justice to the product. Sennheiser also had a small line array like the Community mentioned above, which they called the K-Array. It's really one of the newer and more interesting Sennheiser products, and they had them on display, but they didn't have any way to listen to them, any documentation about them (they pointed me to the website) or anyone who really knew about them.

A similar state of affairs existed at the American Music and Sound booth, where the description in the Exhibitor Directory promised demonstration of the full line of Wharfdale Pro loudspeakers. When I got there and asked about them, though, they had only a couple of the Wharfdale monitor speakers, no information about them (they weren't even sure what model they were), and no way to demo them.

There were a lot of interesting loudspeaker papers this year. In New Induction Drive Transducer Designs, Marshall Buck, Patrick Tummire, and David Graebner describe two loudspeaker drivers that operate like an induction motor, with a fixed voice coil that generates an induced current in a shorted turn on the cone. It's an old design but one that hasn't been explored in a while and which has some real advantages when talking about long driver excursions. Preprint 7847.

With a coaxial loudspeaker where the tweeter is in front of or behind the woofer cone, the movement of the woofer cone moves the boundary behind or around the tweeter and therefore modulates the high frequencies. This causes an intermodulation distortion effect which was described and empirically measured by Paul Klipsch in 1976. Edward Dupont from the University of Waterloo recently did his master's thesis on a mathematical model of this effect in which the woofer is considered a flat boundary behind a single point tweeter source. The model corresponds well with both his own measurements and Klipsch's original measurements. He summarizes the thesis work in Modeling the Intermodulation Distortion of a Coaxial Loudspeaker which he presented with his advisor, Stanley Lipshitz. Preprint 7840.

Folks have long known that there is some effect on the loudspeaker suspension caused by displacement; the presence of a lot of low frequency information causing a long throw of the woofer will briefly alter the stiffness of that driver and move the resonant frequency down a bit. This behavior isn't really very well understood and it may be responsible for some of the effects that people may mistakenly attribute to driver break-in. In Time varying behavior of the loudspeaker suspension: Displacement level dependency, Finn Agkarvist and Bo Pederson make a first cut toward modeling what is going on. Preprint 7902.

Another interesting paper on loudspeaker theory was Comparison Between Measurement And Boundary Element Modelization of Subwoofers. In this presentation, Manuel Melon and friends from the CNAM in Paris talk about how subwoofers are very difficult to measure accurately because even the largest anechoic chambers aren't large enough to be really anechoic in the bottom octave. Consequently, a lot of designers have to rely on computer modeling to predict response rather than use a measured response. These folks described a system called the Field Separation Method which allows the acoustic field from the loudspeakers to be separated from the field reflected from the room walls, using an array of microphones configured to determine the individual pressure vectors at different points. They compared results from these measurements with a computer model of a subwoofer and found them to match fairly well. This is a very interesting method that has a lot of promise for accurate loudspeaker measurements in the real world. Preprint 7845.

In Subwoofers in Rooms: Effect of Absorptive and Resonant Room Structures, Juha Backman gave a good introduction to the mathematics of small room acoustics at low frequencies. He used finite element models to demonstrate well-known wave propagation principles. Preprint 7957.

On the other side of the frequency range, there is an increasing use of large line arrays for touring sound systems, because they provide a lot of flexibility in changing the radiation pattern. Many systems just run all the speakers in the array full-range and just use physical geometry to adjust the pattern, but that's inconvenient. It's also possible to use FIR filters to adjust the pattern, but setting it up is nontrivial. Ambrose Thompson of Martin Audio looked at this as an optimization problem in Improved Methods for Controlling Touring Loudspeaker Arrays, and came up with a generalized system for calculating filter coefficients given a particular requirement. Preprint 7828.

In a big line array, what happens if not all the speakers are quite identical? In The Effect of Sample Variation among Cabinets of Line Array on Simulation Accuracy, Stefan Feistel and Wolfgang Ahnert go through the full statistical error analysis and then use a simulation model to see how different errors in cabinets affect the total system behavior. They find the overall effect of a single error drops rapidly as the number of cabinets in the array go up, and they do some actual testing of a small line array and find it fits their model. This is actually very important information because it provides a real mathematical basis for an assumption that array designers have made in the past without actual support. Preprint 7842.

People familiar with high end loudspeakers in the past decade or so probably remember the Gallo Acoustics speakers which used semi-cylindrical tweeters made from a piezoelectric film material. In A Thin and Flexible Sound Generator Using Electroactive Elastomer, Takehiro Sugimoto and some other people from NHK in Japan described a similar tweeter configuration and went through the principles of operation giving a good mathematical model for the driver for predicting linearity and radiation pattern. Preprint 7848.

Another unconventional tweeter design is the old Heil AMT, which is starting to come back somewhat. A number of manufacturers including Beyma and Adam are making these devices now, but some of the response and distortion issues with them aren't very well understood. In Target modes in moving assemblies of a pleated loudspeaker, J. Martinez from Beyma and some other folks both from Beyma and the Universidad de Alicante in Spain construct a preliminary finite element model of the device to help find resonances and to see how adjusting the geometry will change them in a useful manner. They don't model the air flow, though, but that's their next step. While their model is still rather crude, it's already useful. Preprint 783

More Speaker Papers

Back on the show floor, PMC was showing some high grade mastering monitors but because of their proximity to some very loud sound sources it wasn't really possible to hear anything there. Unity Audio in the UK was also showing off a monitor speaker called The Rock, which employed some new sort of ribbon tweeter design, but again it wasn't possible to get a very good demo because of the sound levels.

Not exactly a speaker paper, but something I'll mention here anyway because it's as relevant here as anywhere else was Mack Kahrs' paper SPICE simulation of headphones and earphones. Since the early 20th century it's been common to describe electromechanical systems in terms of electrical analogies, treating the various mechanical part of the system in terms of lumped-sum resistors, capacitors, and inductors. In the late 1980s, Marshall Leach at Georgia Tech started using the SPICE circuit simulation program combined with electrical analogies to simulate loudspeakers and microphones. Mr. Kahrs begins to extend some of this work to modeling headphone and earphone drivers. His models are somewhat rudimentary but it's an important start, and this is work that has been long overdue. Preprint 7843.

Lipinski Sound, which should be better-known in the high end world than they are, were showing off an extended version of their L-707 speaker. You've probably seen the L-707 before... the L-707A is similar, with an amazingly clean tweeter and two small woofers. They have also come out with the L-707A Signature which is the original L-07A with two additional linear woofer arrays added. The sound at the demo was very clean and these are definitely worth checking out.

A Digression

In addition to making speakers, Mr. Lipinski also owns a record label, and he handed me a copy of their new Blu-Ray audio release of the Gorecki 3rd symphony. The sound quality is excellent, as you would expect.

But most interesting is that this is one of three Blu-Ray discs that people handed me at the show. Nobody has ever given me an SACD disk or an HDCD disk or a DVD-A disc with a new release or a demo on it. Over the years I have received lots of demos and new releases on CD and CD-R, on various sizes of vinyl and quarter-track tape. And now, Blu-Ray. This indicates to me how the market is going.

In fact, a number of folks like Minnetonka Software were talking about Blu-Ray authoring systems, and I didn't see a single mention of SACD anywhere on the show floor.

So... I think Blu-Ray might actually be a winner.

Acoustical Stuff

There was a lot of cool acoustical stuff this year, more so than usual. The usual folks like Acoustical Solutions out of Richmond which makes some excellent and very reasonably-priced acoustical treatment, but also some new people. A company called Jocavi out of Portugal was showing what looked like a great line of inexpensive diffusion panels that were roto-molded from plastic, as well as some nice-looking absorbers and bass traps. The plastic diffusion panels are sold under the Acoustic Shell line and they were looking for US distribution for them.

Primacoustic was showing off their line of absorbing materials, as well as the Recoil Stabilizer speaker stands which are intended for use for table and console-mounted speakers so they could be pointed properly while still isolating them well from the surface under them.

Taytrix had a great demo, with some fairly loud musicians playing inside their mobile isolation booth. These guys make gobos and modular isolation booths for all kinds of studio applications.

And, a company called Acousticorp was also new to the show this year. These guys had a thing called an Acoustack, which is a sound absorbing banner that can be rolled and unrolled automatically under the control of an electric motor, much like some projection screens. While it's thin enough to be not very effective in the low end, the ability to control it remotely is incredibly powerful. This is a great tool for theatres that need to be used both for amplified and acoustic music; you can leave it up for the classical concerts, then drop it down for rock music where the reduced room RT60 is important. In a world with limited budgets where people are trying to do more kinds of things in a single room, this is a great tool to improve versatility of a hall.

Outdoors, of course, you have the exact opposite problem, and the lack of room acoustics makes it very difficult for classical ensembles to play in outdoor situations, as well as difficult for the audience. There's a commercial system called LARES that provides artificial reverberation in a hall to allow room acoustics to be adjusted, and Steve Barber at E-Coustic Systems has adapted this system for use outdoors. In Inside Out-Time Variant Electronic Acoustic Enhancement Provides the Missing Link for Acoustic Music Outdoors he details several different installations both permanent and temporary and describes the benefits and problems encountered with each of them. Positioning speakers well above the audience to provide simulated ceiling reflections is done in a number of ingenious ways. This sort of thing is a huge advance in terms of sound reinforcement for acoustical music, and even though it's describing a commercial product application was the runner-up for best paper just because it solves such a severe and common problem. Preprint 7831.

Back in 1981, Oscar Bonello gave a simple rule for selecting room dimensions for small listening rooms and studios, based on the frequency distribution of resonant modes in the rooms. It seems reasonable on the face of it and it's very easy to calculate, but nobody has done much work on determining whether the empirical tool actually predicts room performance. Todd Welti from Harman International did some testing in Investigation of Bonello Criteria for Use in Small Room Acoustics and found it didn't correlate very well at all with some more complex but well-respected methods for predicting room low frequency performance. Preprint 7849.

In a small listening room, if all other technical issues were possible to ignore, what would be the best possible radiation pattern for a loudspeaker to give the most accurate phantom image? In The Challenge to Find the Optimum Radiation Pattern and Placement of Stereo Loudspeakers in a Room for the Creation of Phantom Sources and Simultaneous Masking of Real Sources, Siegfried Linkwitz doesn't actually answer that question. But he does explore the effects of placement and why that question is so difficult to answer, as well as proposing some listening test methods to help answer it. Preprint 7959.

Another worthwhile study was David Clark's Measurement of Audio System Imaging Performance. Mr. Clark points out correctly that imaging seems to be the most elusive attribute of sound systems to describe and measure, and he demonstrates a simple dummy-head system combined with some analysis based on a simple perceptual model of imaging, which allows a given room and speaker system to be measured. He didn't show a controlled study of effectiveness where the system would be correlated with listening tests, but once that's done this could turn into a useful tool. Preprint 7936.


A lot of companies were showing off Cat-5 cable, since there is an increasing amount of interest in technology to put all kinds of signals over Cat-5 and similar twisted pair materials.

Belden had a very small booth, but they also had probably the two most exciting cable products of the show. First off, they had an HDMI cable which could be run for a hundred feet without problems. This is a HUGE deal in the home theatre world. It may not seem exciting to audio guys, but it makes a lot of previously impossible configurations entirely usable. Secondly they had a tactical Cat-5E cable called 130BA... that's four bonded pairs in a quarter-inch Kevlar sleeve that you could run a tank over without a problem. An excellent thing for anyone running live audio systems or computer networks in the field where they need to be deployed and then rolled back up and transported to be deployed elsewhere the next day. It looks to be very tough stuff. Belden's Steve Lampen was very enthusiastic about it.

Mogami was also showing off a slightly lighter cable for similar applications called Mogami 3306. It doesn't look quite as well protected but it looks also a lot easier to carry around.

Zaolla Silverline was selling some cables which were aimed at the high end audio market. Zaolla is actually a division of Hosa, which is a company that makes inexpensive cables for the music store market, so it's interesting to try and watch them trying to get their feet wet in the high end audio world. The folks at the Hosa booth had a sign up about them but didn't seem to really know much about their products.

A much more reasonable high-end cable company was Essential Sound Products, which was showing off their line of power cables. I continue to be very skeptical about the ability of power cables to change the sound, but that's a subject of another article. Some other folks in PF have reviewed the ESP cables and liked them a lot and even I will admit they're nicely built.

Subjective Testing

This is sort of an interesting category here, but I'm adding it this year because not only were there a number of interesting papers about testing, but also a pretty cool new product from Manley. These guys have come out with the MicMAID, and MAID stands for My Assistant is Dead. It's a matrix switch with gain controls on the matrix, so you can take four microphones, four preamps, and evaluate any one with any other, quickly switching from one to the next on the fly while keeping levels constant. All the switching is done with relays, so the box itself is very transparent. I think a lot of people over the years have built a lot of different kinds of test boxes for this sort of application, but this is a commercial product that is very well thought-out and not only allows you to conduct accurate formal tests but also can be used every day in the field for quick selection of combinations without much effort.

Down in the paper sessions, John Boley and Michael Lester were talking about Statistical Analysis of ABX Results Using Signal Detection Theory. These guys aren't doing anything innovative, but they're talking about proper statistical measures to make sure that A-B tests actually mean something. The signal detection theory method is well known in the experimental psychology community but needs a lot more publicity in the audio world, and they did a great job of explaining it. Preprint 7826.

Objective Testing

RTW was showing off their line of great audio level meters, phase meters, and surround monitor displays. Dorrough was showing off their line of audio level meters; not quite as slick as the RTW meters, but less expensive and with better distribution in the US.

Coleman audio had a number of nice metering systems as well as control room monitoring systems with meters, talkback, and monitor switching. As people move further into digital workstations and don't have the nifty monitoring features that typical mixing consoles made available, this sort of stuff becomes critical. They also had a pumpkin with meters in it.

Stanford Research Systems was showing the SR1 Audio Analyzer, which is the great-grandchild of the old GenRad 2615 analyzer. It's a signal generator, a digital scope, and an FFT analyzer with digital inputs and outputs, but it also has some functions for analyzing physical properties of digital signals (ie. jitter measurement, eye pattern display, etc.)

And NTI had their line of miniature analyzers which fit in your pocket, and provide a wide variety of handy functions.

On the subject of levels, I was very upset to see that there was little to no discussion this year about aggressive compression and limiting in mastering, which is as severe an issue as it's ever been before and still needs to be addressed.

However, Mat Easley and some other people from THAT gave a talk on A Survey of Broadcast Television Perceived Relative Audio Levels in which they went through the bands with an automated system and measured audio levels on different television programs. They point out that different stations have different level standards, that fake stereo and fake surround processing can exaggerate level differences, and that programs seem to vary a lot in the degree to which they are compressed. They found differences of up to 20 dB between two programs when skipping channels (by the ITU1770-1 standard which does a pretty good job of modeling perceived sound level). Everybody knows TV levels are all over the place, but these guys spent the time to show how severe the problem really is. Preprint 7896.


One of the more interesting things this year is that Nevaton microphones now has US distribution again, through FDW Worldwide. Nevaton is a Russian company that has made some very fine condenser microphones for decades, but which has struggled with poor US distribution. It will be good to see their products available here again. Lonya Nenashev at FDW Worldwide is the person to call.

Shure has purchased Crowley and Tripp, and is selling the Crowley and Tripp ribbon mikes under the Shure name. It's a good thing to see Shure selling some ribbons again after many years of absence. Also on the ribbon front, Audio-Technica is making two ribbon mikes, the AT4080 and AT4081. Both are based on the same mechanism which is a stamped high-tension ribbon like the Beyer microphones, but with a very thin ribbon material.

Cloud Microphones was showing off a new ribbon design that was designed by Steven Sank, the son of the RCA engineer Jon Sank who designed the later RCA ribbons. This mike is derived from the classic RCA BK-11 design with some body and grille changes, and looks quite promising.

Telefunken was showing off their new M-80 stage microphone, which I would definitely like to check out; it seems like it has a fairly tight pattern, as well as one can figure out on the show floor. They also have introduced the "AR-51 Tube Microphone" with a rather amusing press release which basically claims that it's the same as their classic ELAM 251, except with different electronic layout and a different capsule. Which is to say that it's a totally different microphone. Telefunken now has on board Mr. Bonsai and Fletcher (formerly from Mercenary Audio), both of whom have good ears, so hopefully it'll turn out to be a good one.

TAB Funkenwerk was showing their "Lucas CS-1" microphone, with transformer and electronics designed by them and the capsule and body provided by Terry Manning. German capsule, metalwork by the fine folks at Latch Lake Music, it also looks worth checking out.

3 Zigma Audio was showing off their "Hybridmic system" which was a modular set of different capsules and bodies. If anything it looked like a Chinese adaptation of the original Oktava 012 system.

Miktek Audio was also showing off a new line of microphones which they are making in Nashville, from parts sourced all over the world. They have the CV4, a multi-pattern tube condenser, the C7, a multi-pattern FET mike, and the C5, a small diaphragm cardioid condenser that also looks reminiscent of the Oktava 012 design.

JZ was showing off a line of condenser microphones made in Latvia, along with a booklet entitled "A General Guide to Understanding and Using Microphones" which contained a lot of bad information, including the reference to the "3:1 placement rule" with regard to spaced omni stereo miking. Sheesh. I hear enough misinformation about the "3:1 rule" without anyone helping by trying to apply it to stereo miking as well. They did have a new modular mike system called the BT-201.

MH Acoustics was showing off a prototype they had of a steerable beam microphone. Tony Agnello, the company chairman, didn't really have a demo room open (though it was mentioned in the exhibitor list), but he was very willing to show the device off. It's an array of 16 omni-directional microphones around the surface of a four or five inch diameter sphere, and with dsp it's possible to synthesize arbitrary patterns, up to a very narrow third-order pattern. What's even more interesting is that it's possible to synthesize multiple patterns from the same array at the same time, so you can, for instance, have a second order cardioid pointing at the mouth of a singer and another cardioid pointing at his guitar. There was some audible comb filtering in the upper registers, but the system worked well enough that it could be marketed right now, I think, perhaps with a little nicer user interface on the dsp side.

Incidentally, Grace Audio came out with a modular stereo bar system for positioning microphone pairs and arrays. These things have accurate and repeatable distance and angle markings on them, so you can set things up so they sound right and then instantly return to the same position when you work in that hall again. Yes, I know Schoeps has done this before, but the Grace Spacebar system is more versatile and much less expensive.

There weren't very many papers this year on microphones, and the only one I really got to see was Measurement Techniques for Evaluating Microphone Performance in Windy Environments, in which the authors, Simon Busbridge and David Herman, talk about how to measure wind noise in an anechoic chamber, and how to separate real wind noise from the noise caused by the wind source. They also addressed the issue of the frequency response of the microphone being irregular, and used the response chart and a wind noise spectrum to generate a wind to signal response plot, then derived a wind rejection ratio from that. This is really the first attempt I have seen to create a general standard. It has some issues in that it doesn't address wind direction; for some directional microphones (like the classic RE-20), wind from the side may be more of a problem than wind directly impinging the diaphragm. Still, it's an excellent start and should get people thinking more seriously about the problem. Having a universal measurement standard means being able to do actual comparison between different manufacturers' products. Preprint 7889.


Zaxcom was showing off a stereo digital wireless system using the unlicensed 2.4 GHz band. What's interesting is that their transmitter also had a small receiver in it for foldback, which is very useful for folks doing film sound work and electronic news gathering, but could be useful for a lot of other applications where an actor might need to be cued. They also had a tiny recorder, the ZFR100, which was about the size of a wireless mike pack and could easily be concealed under clothing.

Lectrosonics was showing off their complete line of very tiny wireless packs, as well. They make some cool things, like UHF transmitters that can be set up to transmit properly to a wide variety of different manufacturers' receivers, all of which use different emphasis and noise reduction configurations. They are also showing some digital wireless systems as well, using the 902 Mhz unlicensed band where multipath and interference issues aren't quite as bad.

On the opposite side of the camera, HME was showing off some 2.4 GHz wireless intercom systems. These are headset and table intercom units that can be connected to existing clearcomm and telex wired intercom networks, or used alone in production situations.

There were a couple good workshops about wireless systems, none of which I actually got to attend, unfortunately.


Analogue Tube was showing a beautifully-made recreation of the old Fairchild 670 stereo mastering compressor. It's in a new case with modern parts, and they seem to have taken some of the sum and difference stuff off, but there was a serious attempt made to duplicate the original circuits and transformers. They are using modern versions of the original 6386 variable mu tubes. Very fine workmanship, and considering the crazy prices original 670s sell for today, it may even be a major cost savings.

Slate Pro Audio was showing their Dragon compressor, which is a classic FET VCA compressor design but with some odd effects trickery built in. It looked like a very versatile unit.

Something that I missed but which apparently happened some time ago is that Studio Products has brought back the Joe Meek line of equipment. They have a stereo compressor and several channel strip configurations available now.

And on the other end of the price spectrum, Weiss was showing off some very impressive standalone digital processors, including a 7-band equalizer, a compressor, a de-clicker, and A/D and D/A converters. Weiss makes some of the most carefully designed systems out there and I have found their converters to be extremely transparent.

Down in the papers sessions, Nicolas Tsingos from Dolby was talking about Using programmable graphics hardware for acoustics and audio rendering. I found this fascinating; consumer video cards are now employing very high speed parallel processing engines that are optimized for 3-D video rendering, but scientific computing people in a number of disciplines are figuring out ways to use them as general purpose parallel processors. The author did a clear overview on the kind of architectures found in modern graphics cards, and how people are using them for audio dsp. This is a great thing because it's a very powerful resource for very little money, and the more folks doing software development who know about these tools, the better. Preprint 7850.

Another unusual paper was Automatic equalization of multi-channel audio using cross-adaptive methods by Enrique Perez-Gonzales and Joshua Reiss. These folks have come up with an automatic equalizer to do a first cut equalization for multi-track mixes, but unfortunately their view of the aims and constraints of the process seem somewhat misguided. Rather than attempt to dissect the method that would be used by an engineer in taking apart an arrangement and equalizing sounds to fit into it, they use a general method that seems less than useful even as a first-cut approximation. Preprint 7830.

Sidelight: The 500-Series Module Phenomenon

A few years ago, API made public the pin-out, geometry, and power requirements of the modules for their 500-series mixing consoles. This allowed other companies to make modules which could drop into API consoles, into rackmount card cages designed for API modules, and it also allowed them to build their own consoles and drop API modules into them.

This was a big deal at the last show, but this year the idea seems really to have taken off. Sales apparently aren't all that high, but they don't have to be because it is remarkably cost-effective to make small runs of these modules since the cabinets are standardized and the power supplies are external.

Brent Averill Enterprises was showing off some very nicely made rackmount card cages and small lunchbox card cages, as well as a 500-series version of their 312A mike preamp. Their 312A module uses a discrete op-amp and a high ratio Jensen transformer.

Lipinski had their L-409 discrete, transformerless, dc-coupled microphone preamp on display, as well as their L-629 compressor module as well.

Pete's Place Audio was showing the Brad Avenson Compressor, a FET VCA-based compressor that's intended to be subtly colored.

Matrix Audio Systems was showing their HO-5 mike preamp, which uses their 1205 hybrid op-amp. They also had a FET-based compressor-limiter called the FTC and a stereo version of that called the FTC-2.

Electrodyne had a discrete two-stage mike preamp, the 501, and also their 511 two-band inductor equalizer, both based on the original Electrodyne console electronics.

A-Designs has a whole line of different microphone preamps with different transformers and gain structures, as well as their EM-PEQ which is a Pultec-style equalizer in a 500-series module. These are the modules that say "erickson montessi" on the side if that helps you identify them.

Roll Music makes a real tube preamp that fits into a 500-series space. They use a 12DW7 tube so they can get good linearity with the limited available current, and a little baby switching supply to create a reasonable B+ from the DC rails. It's the real thing, with a real transformer input and a couple tube gain stages. Only the output section is solid-state.

Great River, by the way, is now making a thing called the 32EQ. This is the equalization section from a Harrison 32-series mixing console, cut down to fit into a 500-series module. It's a classic sound, and it's a good thing to have in a small form factor.

Chandler Limited had their Little Devil, a combination 3-band equalizer with adjustable centers (but fixed Q), and compressor. The compressor is a solid state VCA design.

John Hardy is working on a 500-series version of their Jensen Twin Servo preamplifier. It's not out yet, but he showed off a few parts and the preliminary designs.

Alternate Soundings had a whole line, the MDI2 dual guitar and bass preamp with a high-Z input, the MP2, a dual mike preamp with Sowter input transformers, the M2M, an 8X2 summing module for mixing consoles, and the MP1 mono mike/line preamp and input section.

Prodigy Engineering was showing their Bella remote-controlled 500-series mike preamp. These can be controlled off a USB interface, and you can stick several of them in a rack and hide them someplace because you don't need physical access to set the gains.

Purple Audio had lots of 500-series stuff. They had the TAV, a 10-band graphics EQ with inductors, the LilPEQR, a three-band program EQ, and the Purple Action, a compressor.

Overall, I was pleased to see the explosion in 500-series modules this year. It's a very versatile sort of form factor that you can put into a lot of systems.


There were a lot of both digital and traditional analogue mixing consoles at the show, and all the big names like API and Neve were there. The one interesting thing I saw, though, was the APB Dynasonics ProDesk-4. It's a small PA console with a lot of care and attention made to construction and sound quality. In a world where most of the smaller consoles are low budget cheapies, it's nice to see something like this. It is simple and straightforward without a lot of junk in the signal path, and it's modular and field-repairable unlike the cheapies.


The transformer situation was interesting this year. First off we have Lundahl Corporation, which has long exhibited at the show. They always have great stuff including some of the best C-core tube amp output transformers around. This year they were introducing a filament choke, for unregulated DC filament supplies, which are used to keep leakage hum down in a number of tube amp designs. They also had a very nice looking 600 ohm output transformer that they are coming out with.

There were some newcomers too, though. Keen Ocean Industrial from Hong Kong was showing off a large line of power transformers from cheap wall warts to nicely made large toroids. They didn't have any broadband audio transformers on display although John Lew there said they could make them on request. They seemed a bit out of place.

Also a bit out of place was Payton Planar Magnetics, Inc. These guys actually do make some conventional power transformers but most of what they sell are very compact high frequency transformers made with stacked planar coils. These are very high grade transformers for switching supplies and have a lot of applications for Class D audio amplifiers, but it seemed that this year the interest in Class D stuff wasn't as high as it has been at the last few conferences.


Electroswitch was their with a nice line of switches. Cirrus Logic had a booth with their name on it, but nobody ever showed up to man it.

Neutrik was there, and in the past the Neutrik booth has been fairly famous among attendees for their promiscuous giveaways of free sample connectors. This year... no free samples. If there is any sign that vendors are tightening own on their marketing budgets, that's number one.

Tad Rollow, who used to be from Digidesign, is now working for ARDA Technologies and was talking a bit about their very high quality A/D and D/A converter chips. If the numbers on the datasheet are to be believed, their AT1201 gets closer to actual 24-bit performance than anything else I have ever seen.

THAT is still making really nice preamp chips and transistor arrays. They didn't have anything new, but that's okay. Just the fact that ANYONE is making large area low-noise transistors for audio today is wonderful.

What was most interesting was that Rosalfonso Bortono and Wayne Kirkwood from THAT did a short presentation called The 48 Volt Phantom Menace Returns. They went through all the various possible current paths of a typical preamp front end, showing where current travelled when the phantom power was turned on and off with various microphone loads, and showed that typical protection diodes (rail to signal line) don't actually provide much

protection for the input transistors under a lot of conditions. They then went to show some various methods that would work for each of the possible conditions. Absolutely essential information for anyone building a mike preamp, and it's definitely worth reading the preprint if you are doing so. Preprint 7909.

Also on the semiconductor front, Dialog Semi had a booth and they were showing their new DA7210 ultra-low-power stereo audio codec. This is a very low power stereo A/D and D/A combined with a switching amplifier that can it's drive 40mW into a pair of headphones. All on one chip. I'm inclined to dismiss this sort of thing as very low-fi but in fact the majority of listeners today are listening on portable players and so any effort expended on improving those miserable things is probably well-spent.


Phil Paske from RMGI and Mike Spitz from ATR Magnetics were both showing off high quality audio recording tape in various widths from 1/4" to 2".

JRF Magnetics wasn't there at the show this year, but John French was still seen wandering around and talking to people about tape head designs and about their excellent tape head products.

Endless Audio was selling a thing called the "CLASP" which allows you to route audio through a multitrack tape machine within Pro-Tools.... from the user's perspective, the tape machine just looks like any other plug-in. I think the idea is a misguided one, but it does sound good.

Digital Recording

One kind of neat gadget was the Blackbox Recorder by JoeCo. This is a 1U box with a set of three DB-25 connectors, each wired to carry eight audio inputs and outputs, unbalanced. It's supplied with cable harnesses to plug into the 1/4" inserts of typical PA consoles.

You stick it in the rack, plug it into your console, and with the press of a button it records all of the channels on the console to a regular USB disk, creating Broadcast WAV files.

This is a very convenient and inexpensive solution for any sound system operator who wants to record concerts on the fly without a vast amount of effort. There's really nothing like it on the market now.


Richard Tollerton from Isomorphic Software gave a talk on Digital Simulation of Phonograph Tracking Distortion in which he provided a good geometrical model for how tracking distortion happens, and then implemented it in software to demonstrate that tracking errors cause sidebands to be formed around pure tones in a mechanism much like jitter in digital systems or fast flutter in analogue systems. His simulation allows easy manipulation of parameters, which could in the future allow people to get actual listening tests done to determine the audibility of tracking distortion and figure out what levels are problematic. It may also make digital cancellation of existing tracking distortion possible in the future. Preprint 7924.


A company called Neyrinck was showing off a de-reverberation plug-in for Pro Tools, written by a company called Tacsystem in Japan. It actually worked. It left behind some artifacts and it appears to be mostly usable only for dialogue, but it actually took out reverb below the noise floor. This is the first someone someone has actually sold a de-reverberation system commercially before, and if it doesn't work perfectly (and it doesn't), it can be forgiven in the amazement that it works at all.

Another really impressive thing was Odeon's room acoustics modeling software. This is a serious raytracing system that can do a surprising job of modeling rooms before they are actually constructed, and one of the interesting features is that it will generate an impulse response of a proposed room design and then use it to process a source signal so you can get a sense of what the room effects will sound like. This is a GREAT tool for anyone building any kind of listening room or studio, and they have a free demo version available which is limited in many ways but still a very useful tool. This is an amazing tool for predicting how a system will perform and how a room will perform. It doesn't look to be an easy thing to sit down and learn quickly, but nothing really powerful ever is.

Sound Ideas had their demo of royalty-free production music and sound effects on a handout CD-ROM containing MP3 files.

Also, Charlie Pilzer from Airshow Mastering was giving a little presentation about their new facility in Takoma Park, MD, which looked very impressive. It's a studio purpose-built for mastering work, but also with a small tracking and mixing facility on the side for dealing with some of the things that today sometimes don't turn up until the mastering begins. Their presentation was sponsored by the Sonic Studios folks, who made some of the first mastering software for CD and who still make some of the best.


The usual suspects where there this year, Recording Magazine, EQ, and Mix. All of them are getting thinner and thinner, although I am pleased to see Recording is holding their own better than many of the others. Pro Audio Review was there, and they are down to almost nothing these days. If anyone is doing well, though, it's Tape Op which still seems to be growing in spite of the poor state of the economy.

Audio X-Press (formerly Audio Amateur) was there, and they had copies of their World Tube Directory which is one of the better sourcebooks for makers of tubes and parts for tube electronics on a commercial scale. They also are now distributing Elektor magazine in the US as well, and they have a really nifty magazine for the loudspeaker industry called Voice Coil. Unfortunately at the show they announced that due to economic conditions, Voice Coil would, like PF, be going to online editions only.

Sound On Sound, the British audio magazine was there, and they seem to be doing well. Also there were the large format Pro Audio Asia and Pro Audio Middle East magazines which are both published by a British firm for the overseas markets.

FOH magazine was there, and they were handing out copies of their Event Production Directory, which is another very handy sourcebook for anyone looking for event providers anywhere in the US.

Sound Synthesis

Paul D. Lehrman from Tufts University gave a great talk called The Wii Remote as a Musical Instrument: Technology and Case Studies. He described the interface of the wii remote and accessories, and gave a brief historical view of how people had reverse-engineered the interface and set them up as synthesizer controllers. Preprint 7888.

In TheremUS: The Electronic Theremin, Andres Gomes and others designed an instrument that used ultrasonic sensors that detected hand positions from round-trip arrival times of ultrasonic pulses, then used the hand position information with a digital FM synthesis algorithm. They also provided a MIDI output. Definitely a neat trick. Preprint 7860.

On a very different synthesis front, Jussi Pekonen and Antti Jylha from Helsinki University took two things and put them together. They took an existing model of insect swarming behavior and an existing algorithm for the synthesis of a honeybee sound, and produced a system that develops a 3-D sound field representing the sound of a swarm. In 3D Sound Synthesis of a Honeybee Swarm they then use various methods to sample the 3D field as a stereo signal so you can hear bees around you. It seems like a silly intellectual exercise at first until you think about the sheer number of motion picture and game sound applications for a system like this, especially if it is expanded to other sound sources, such as birds and automobiles. Preprint 7883.


I don't know where any of this stuff really goes, but it's all interesting so I'm putting it here.

Core Sound is now selling a thing called the HeadLine... it's a battery powered D/A with an integral headphone amplifier, gain control, and line level stage (and that includes a source selector). You can put in three S-PDIF signals, and one line level analogue signal, and get a headphone output. The headphone output is competently designed with enough current to drive Grados and still sound good. The A/D can run up to 192 ksamp/sec. This is high quality monitoring in the palm of your hand, and while it's intended for the field recordist, it's only around $500 which makes it an excellent thing to add to your laptop or portable music player for good sound.

The Audio History Library in NYC is attempting to collect any documents and recorded interviews that establish the chronology and narrate the development of audio equipment and audio as an industry, and to make those available to the public. They were very interesting to talk to.

And... while this is an audio conference and not a music industry conference, I thought it was interesting that for the first time we saw a music public relations outfit at the show. Eric de Fontenay of Mi2N and Musicdish had a wide variety of album-plugging services available, which is a big deal in this brave new world of small labels with limited budgets.

Ever had someone thump on your back while you're trying to talk? If you try this, you'll find that the vibration affects both the pitch and amplitude of your speech. This is a real problem for people trying to talk over communications systems in high vibration environments like aircraft and rockets. C.W. Nixon did some work on this in the early 1960s, but a more extensive analysis was performed by Durant Begault at NASA Ames Research Center in Effect of Whole-Body Vibration on Speech, Part I: Stimuli Recording and Speech Analysis. Preprint 7820.

In Audio-over-IP Acceptance test Strategy, Matthew J. O'Donnell from BSkyB gave a good introduction to the TCP/IP and UDP/IP protocols and what happens to both under various network conditions. It's all stuff that can be found in the original RFCs but which may not be so well-known in the audio community and needs to become better known as IP transmission of audio becomes more widespread. Preprint 7944.


It was a small but very intense show, more crowded than I have seen in a long time in spite of the fewer vendors, and the vendors that remained were mostly the ones I wanted to see. I was pleased to see the paper presentations, workshops, and student sessions hadn't been affected by the drop in size of the trade show floor. It was a good show. You should have gone. The next one is in London and then there's another one in San Francisco next fall, so you can start planning your trip now.