The "Prophetic" Processing History
Yesterday, Today and "Beyond"


Go To Part #4

This series of articles re-published from
issues of February to August 2007 original on PDF format.

Before his recent death, Jim Somich was very interested in just how audio processing has changed over the years – but even more so in considering what is to come in the future. Of course, understanding the current technology and the reasoning behind it is what gives us the foundation to discuss the future. In preparation for this article, Jim had conversations with some of the current masters of processing – and some of the future masters.
 “History Repeats Itself. First as tragedy, then as farce.”
– Karl Marx
(Radio-Guide April 2007)

Yesterday, Today, and Tomorrow
by Jim Somich

Part #4
Talking with Today’s Masters

Today, we may deride the Audimaxes and Sta-Levels of the past and assure ourselves that we are “state of-the art” all the way. After all, digital is perfect is it not? And we do have digital boxes, do we not? Well, perhaps it is time to break a few eggs: I predict that in thirty years we will look back on the DSP processors of today in much the same way as we smile condescendingly at the mention of an Audimax or Volumax of yesteryear. What will it take to develop the first 21st century audio processor? We sure do not have all the answers today. In fact, we do not even know many of the questions. But let us give it a try!

The digital processors of today are based on the best analog designs of the past. Those digital boxes, introduced in the last millennium, have been enhancements and improvements on older designs. We are still waiting for the first breakthrough processor of the 21st century! Most stations which can afford anything they want are using either Orban or Omnia digital processors. Processing strategies that are virtually impossible in analog are relatively easy in digital. Each box has its own unique processing strategy; these new strategies will be the hallmark of the first major processor of the new millennium, and so we want to discuss those strategies. Yet, it is important that we do not embrace digital just because it is digital. Many analog designs from the past are still performing exceptionally well on the air, proving that you do not need the latest digital box to sound great. The ultimate goal of this series is to speculate on the future, but our task today is to take a cold, hard look at the world around us: what is good and what is bad about broadcasting in general – and audio processing in particular.

CBS Audimax & Volumax
Are the Maxx Brothers worthy of respect or derision?

Designing and building broadcast processors is a highly competitive business, so it is not so unusual that the guys at the top of the field are usually closed mouthed about anything but their companies’ standard talking points. Therefore, having the opportunity to sit down and talk with the men behind the leading processors of our day is really something. Of course, given everyone’s schedule, we have to settle for a virtual roundtable, a combination of live, email, and telephone conversations. Still, the chance to chat and learn something about their thought processes is pretty neat, no matter which way we accomplish it. We were fortunate to be able to interview Bob Orban, a living legend in the processing world, Frank Foti, the challenger to the throne, and Cornelius Gould, a young turk who might just develop the first great processor of the 21st Century. So, let us take a break from my pontificating. Maybe these three guys will give us some insights on the present state of audio processing – and what we can expect in the years ahead.

We will start by listening to the reigning champs, Bob and Frank, in this article. Next time, we will push into the future with Corny Gould. If we are fortunate, we might learn something that we did not know before.
Jim Somich: Frank, I know you are not the overnight sensation that many people think you are. What were your early influences, and how did the Vigilante, your first processor, come about?
Frank Foti: During my stint at Z-100 (1983-1987) we had the Texar Audio Prisms. Up until that time, FM audio processors generally employed pre-emphasis before the (multiband) limiters. Upon grasping the full understanding about how that multi-band system worked, I kept thinking about a limiter system that managed pre-emphasis after the multi-bands, rather than before them. My thinking was that the control loops in that architecture were essentially tilted upwards a bit, due to the emphasis, and that was causing uneven processing in the upper frequencies. Essentially the upper range of each audio band had a lower limiting threshold. The question – and quest – became finding out what happens if the control loops are flat and the limiters are set to manage pre-emphasis via differing threshold levels?  

Frank Foti
Frank Foti

Jim Somich:
Your first processor was actually an adaptation of an existing processor, was it not?
Frank Foti: The Vigilante, as most know, grew out of the Aphex Dominator, Model 700. I had seen the prototype Dominator at NAB 1985, but it was a lot more elaborate than the finished product. The prototype appeared to be a direct answer to the Orban Optimod 8100, but with auto-adjusting crossover frequencies, and a few other new tricks. I never knew why that version never appeared. However, upon playing with the original Dominator – which sounded very good if not pushed too hard – it became apparent that the timing was the same in all three bands. That caused the unit to become “busy” sounding quite rapidly, especially when set aggressively. Before ever having a schematic at hand, I found the R-C networks that governed the timing and began playing. It did not take long to “tune” the unit for a CHR station. Eventually, a schematic was acquired. I began playing with the ALT (Automatic Limiting Threshold) circuit and more advancement in the Vigilante’s gestation occurred. Being able to modify the threshold settings in the Dominator empowered the box to manage pre-emphasis very consistently. The “attack” and “release” functions were brought out to the front panel via three-position switches. The limiting thresholds were also brought out via numeric “dial pots” that, in fact, were suggested to me by you! But – the key sonic element and improvement that we heard on-the-air was how much the high frequency domain opened up. This was the result of pre-emphasis insertion after the multi-bands. 

The original Vigilante was built on an Aphex foundation.

Jim Somich:
Was the Vigilante an all-in-one, stand-alone box or did it require support by other processors?Frank Foti: At this early stage the unit only did the dynamic limiting. We used the clippers (cards 8/9) from the Orban 8100, which worked quite well. Upon launching “Cutting Edge,” and building these fulltime, radio stations wanted an integrated solution; I designed our first distortion-controlled clipper, which was added to the Vigilante sometime in 1989.
Jim Somich: Which processor designers influenced you most strongly at this time?
Frank Foti: The influence here was mainly Glen Clark. I thought his Audio Prism concept to be very good. I used to tell him that he needed to create a multi-band limiter version of the Prism. While the Dominator was multi-band, that was not the idea that was lurking in my head. Upon the modifications to the Dominator, it got closer, but those ideas eventually manifested themselves in the Unity – and eventually in the Omnia.

Jim Somich:
OK, that progression makes sense. Now what was the Unity, and how did it differ from the Vigilante?
Frank Foti: The Unity was our attempt at putting the rack of individual processor units in one box. The technology used was known as “digitally-sampledanalog.” The idea was to clone a rack of gear that would have been a wideband AGC, multi-band compression, multi-band limiting, pre-emphasis, distortion controlled clipping, and the stereo generator. It worked quite well. The clipper design came right from the Vigilante. The stereo generator included a composite clipper that performed clipping before the pilot was inserted. The entire system was governed by a microprocessor; it could save and recall a default, as well as user presets. A concept we introduced with Unity, and carried forward to Omnia, was the idea to employ differing architecture into the dynamic sections. The Unity had feedback control on the lower two limiters and feedforward on the upper two bands. This enabled the system to maintain the warm IMD-ish sound on lower frequencies, which feedback limiters tend to offer.
Jim Somich: That approach is a sort of doubleedge sword, right? IMD not normally a desirable audio component.
Frank Foti: That is true. IMD is quite irritating on presence and high frequencies. On those bands, we utilized feed-forward control, which is inherently much lower in IMD. This type of processing offers a clean, open, and smooth high end, while retaining a rich fullness to the low end. We still use this method within Omnia processors.
Jim Somich: If you were to point out the main weakness of the Unity, what would that be?
Frank Foti: In hindsight, the Unity never had the internal flexibility that a DSP box has. As such, there were many hindering factors that kept me from getting it to where the ideas that were still lingering up in the foggy grey matter needed to go. Of course, the Unity was successful enough in that it made the worldwide broadcast industry aware of our efforts. If anything, it got the company noticed when we introduced the Omnia, which was our first full DSP processor.

The Cutting Edge “Unity”

Jim Somich:
That brings us to the dawn of DSP audio processing – and Bob Orban. Bob, I always thought of you as an “analog guru.” How did you make the transition into the digital age? It seems like you got real good, real fast!
Bob Orban: I don’t write DSP code, but I create the algorithmic architecture and do most of the coefficient computations – in other words I create “schematic diagrams with parts values” that other engineers at Orban turn into actual code. I credit my ability to learn DSP in mid-career to an excellent engineering education at Princeton and Stanford that emphasized timeless engineering fundamentals, particularly math. I learned DSP myself by studying textbooks and journal articles, but I couldn’t have done it without the university education that I got.
Jim Somich: The Orban 8200 Optimod was the first DSP broadcast processor in the world to achieve commercial success – and that was quite an accomplishment. Bob, what were the influences that moved Orban from being an analog company into the digital era?
Bob Orban: The 8200 project originally started as a DSP model of the Orban 424 compressor using the then-new Motorola 56001 24-bit DSP chips. (It was the Motorola 24-bit architecture that finally allowed high-quality DSP filters suitable for pro audio applications.) We got far enough along with that to realize that we could build a complete DSP broadcast audio processor that modeled our analog processors and had a few “DSP-only” innovations besides. At that time, Greg Ogonowski, a long-time friend and “friendly competitor” in the Gregg Labs days, was formally hired as a consultant on the 8200 project and we decided to make the 8200’s multi-band algorithm five-band (as it was in the Gregg Labs processors) instead of six-band as it has been in the XT2. Overall, though, most of the influences for the 8200 came from earlier processing I had developed, including the 8100 and the XT2. We learned a lot doing the 8200, and I combined this with new ideas that could finally be realized because we now had enough DSP power to pull them off. The 8400 was the end result. I should add that the 8400 project was the first Orban DSP-based processor that really exploited the things that one could do in DSP that were impossible in analog.

Robert Orban
Robert Orban

Orban Optimod 8200, was the first Digital Processor.

Jim Somich:
That certainly sounds like a major jump forward. What sort of things were now possible using DSP?
Bob Orban: In my opinion, the big advantage of DSP compared to analog  processing is that one can implement look-ahead processing economically because making delay lines is just a matter of writing data to memory and reading it out later. By being able to “look into the future,” the DSP-based processing can make intelligent decisions that are impossible in analog designs. Look-ahead limiting is just one example of lookahead processing. The 8400 and 8500 use lookahead processing for clipping distortion control and for our “half-cosine interpolation” composite limiting, among other functions. Another important thing we did in the 8400 was to add a speech/music detector, which allowed the processing to be optimized separately for speech and music. Some of the most sophisticated of the old-school, major-market processing chains actually had separate speech and music processing because these really require separate adjustments. DSP allowed us to do this automatically within one processor.

The 8400 brought full DSP audio processing to the market.

Jim Somich:
There was some surprising feedback from the field from the effects of the look-ahead limiter. What happened?
Bob Orban: The most important decision that we had to make before designing the 8400 was whether it was acceptable to make a processor with a throughput delay so long that it was impractical for talent to monitor its output through headphones when speaking. We assumed that the improvements in processing would be more important to broadcasters than the inconvenience of arranging a separate monitoring chain for talent headphones. Unfortunately, we were surprised when the 8400 was released – we got lots of complaints about headphone monitoring. Accordingly, in version 2.0 of the 8400 software, we cut the delay in half without compromising the look-ahead algorithms by looking at every delay in the chain and getting rid of the ones that were not actually necessary to implement the look-ahead processing. We also allowed users to configure the 8400 to emit a low-delay headphone monitor signal from an unused output. And when we designed the 8500, which maintained a 64 kHz minimum sample rate (as opposed to 32 kHz in the 8400), we further reduced delay by about 4 ms by eliminating 64/32 and 32/64 kHz sample rate conversions in the signal path. However, even with all this effort, the best-quality processing available in the 8500 (using lookahead in the most favourable way to reduce distortion) exhibits a 37 ms delay, which is too long for headphone monitoring. Fortunately, most of the advantages of lookahead processing are still available with a 17 ms delay, which is the delay of most of the 8500 factory presets. Additionally, we made available a separate ultra-low-latency processing chain without look-ahead for those applications where the low delay was considered necessary, such as remote off-air cueing.

Jim Somich:
Would you care to take out your crystal ball and give us a few predictions on what we can expect from Orban in the future?
Bob Orban: That would be telling! Seriously, I don’t want to say anything that might give away future plans to my competition.
Jim Somich: Understood ... and thank you for taking the time to share with us as much as you did.

Jim Somich:
Frank, how did your first DSP processor, the Omnia come about?
Frank Foti: Omnia was an outgrowth of the Unity, along with input from all those who were critical of the Unity. Moving into DSP illuminated many things for us; most notably was the whole notion about how to clip pre-emphasized audio without causing aliasing distortion. Steve Church and I put a solid two years into researching that one alone. Omnia’s lineage follows my thinking all the way back to Z-100 and the rack of gear we had in NYC. The first goal – and what would have been the dealbreaker – was to create a hard-limiter (clipper) that didn’t generate that awful grunge effect that was obvious to the sound of other units and was giving DSP-based processing a bad name. Within the dynamic sections, we were able to take advantage of the DSP processing power to add functions like “Make-Up Gain.” This allows the compressors to operate with slower overall timing, but “knows” when softer segments are occurring and will speed up the system only during those intervals. Additionally, Omnia offers gating that is very intelligent. It can reset the dynamic gain to a preset platform level or just freeze gain during periods of gating. Stereo-EFX was designed to enhance stereo without destroying the natural soundfield or exaggerate multipath due increased RMS levels of the L-R signal. The composite clipper that is incorporated into Omnia also contains a DSP version of “The Dividend” which keeps composite clipping products in the SCA region down to a minimum. This was a first for an integrated audio processor.
Jim Somich: Once you had a working prototype, how did you introduce it?
Frank Foti: I personally took the beta version of to those customers who were not fans of the Unity. I figured if we could please the critics, then we were on to something. With all honesty, I can say that we visited close to 25 customers (the world over) and every one of them purchased the Omnia!

The enters the DSP marketplace.

Jim Somich:
That is quite an achievement for any product. So, looking ahead – can I get any predictions from you? What can we expect out of you and your team in the future?
Frank Foti: Looking into the future is always fun. Here in 2007, we now live in a coded-audio world. Thus, audio processing is becoming more focused on that transmission method. Still, I feel there’s still at least one more, if not two, conventional broadcast processors yet to be designed for FM and AM (at least from our company). I’m not sure that those will be focused on more loudness. As we all know, processing creates L-O-U-D audio today, all the way from the CD source straight through to the eardrum. My view is that we employ algorithms that will diagnose the signal and modify the architecture in order to reduce sonic artifacts. (We’re doing this already in the codec world with our SENSUS Technology.) Reduction of distortion, THD, and IMD, while maintaining competitive audio is the goal. Then again, hasn’t that always been the goal?

Depending upon how the digital transmission services settle, we could see META data come to radio, and that opens a whole new frontier. HDTV has this already with Dolby-Digital, but I foresee a method that would be far more sophisticated and comprehensive, not just a wideband method, as the TV counterpart employs. Processing platforms are already beginning a paradigm shift. We’re moving towards a transition period from where we have dedicated boxes into the early stages of doing all processing as a PC application. We have already developed a processing farm where many instances of an audio processing application are operating within one “engine” – a single box that allows up to a preset number of audio processors to run independently of one another. All I/O is Ethernet to the station’s infrastructure or can be routed to dedicated nodes that are AES or analog. Additionally, utility  unctions regarding processing are becoming more elaborate. The ability to display detailed information about a signal, or segment thereof, is now available. Processing power, which once was a premium in cost, is now quite affordable in the digital domain, just as the lowercost, high-performance opamps and VCA’s became during the analog years.
Jim Somich: Thank you, Frank. Talking with you is always an education. Folks, I hope you have enjoyed this discussion with Bob and Frank – today’s masters of audio processing. Join us next month when we will take a look at the way the next generation of audio processor designers is thinking. I promise it will be interesting!

Memories are a tricky thing. As we try to recap the history of audio processing over the past 70 years, it is inevitable our memory cells will fail once or twice. Last time, in discussing the BL-40 Modulimiter – indeed a revolutionary product – I attributed the patent to Bill Putnam. However, as Paul Gregg kindly pointed out, while Putnam did own the patent, it was originally issued to Jim Lawrence, who first used the optical gain control in his Teletronix LA-1 and LA-2. Shortly thereafter, Teletronix (and the patents) was sold to Babcock Electronics and then Bill Putnam’s UREI.

Go To Part #4