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


Go To Part #3

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

It is with great sadness that we note the passing of Jim Somich. Fortunately for us, he had just finished this series of articles before his untimely death. So, leading up to a focus on the current state of the art – and where we are headed – we continue Jim’s reflection on how the art of audio processing developed. (Radio-Guide March 2007)

Yesterday, Today, and Tomorrow
by Jim Somich

Part #2

Multiband Audio
Up to the 1970s, audio limiters and processors essentially were marketed only by the big companies: RCA, WE, GE, and CBS. However, that changed in the early 1970s –and in a big way.

This is an exciting business. The pioneers have led the way. But maybe you are one of those engineers or programmers who has a dream – who has become so strongly dissatisfied with the sound of his station that it becomes an obsession. One young recording studio engineer turned broadcast engineer, Mike Dorrough, was not a great fan of the famous “Maxx Brothers.” He knew broadband audio processing had severe limitations, especially when it was pushed hard in order to achieve a competitive sound in a market. After all, this was why those “backroom engineers” were developing Audimax modifications left and right. I first met Dorrough in the early 1970s and he was a young man with a dream under his arm called the DAP (Discriminant Audio Processor). I had never seen such passion about an inanimate object before. Little did I know how his ideas would revolutionize the sound of broadcasting. But even Dorrough could not imagine back then how far we would have come in thirty years. Undoubtedly, we have better tools today than ever before in broadcast history. But, in many ways, we are still learning how to use them.

The greatest problem with broadband compression is intermodulation, as when a heavy bass line modulates the mid and upper frequencies. “Pumpy” was one of the milder terms used to describe the effects wideband processing caused. Any abrupt audio spike could cause the whole audio package to “duck” – or worse. Dorrough remembered an old Altec-Lansing compressor from back in the 1950s that took a different approach to the intermodulation problem. It split the audio into two bands and processed them separately. The results were far superior to broadband designs and the idea for the Discriminate Audio Processor was born. Dorrough’s first prototype split the audio into eight bands with passive filters, processing the individual bands with Spectra Sonics modules. “The Monolith,” as this monster was dubbed, was put on the air at KRLA in Los Angeles and the results were spectacular. This 50 kW AM flamethrower became the most dominant sound on the LA radio dial! But the box was very tweaky. Each cut sounded quite different from the one preceding it. Dorrough learned two things from his prototype: Eight bands were just too many and the filter slopes had to be much more gentle, allowing the individual band control to be much broader. The DAP 310 was born. The Model 310 was a three-band processor with FET gain-control elements. Mike built a new prototype, and then embarked on a brilliant marketing campaign that was unique at that time.

The DAP310

Dorrough would not only offer broadcasters a free trial, but he would not put a time limit on it! And he “hit the road” with a car full of DAPs. Visiting markets, large and small, he made the acquaintance of hundreds of engineers in the field. On a one-to-one, personal basis he would install a DAP in their air chain and let them play with it. The marketing plan worked and the Model 310 became one of the most popular broadcast processors to date. To date, I do not know how many DAPs Dorrough ultimately sold, but it was in the thousands to be sure and it might be the all-time best-selling broadcast processor. In the 1980s Dorrough introduced the Model 610, a discriminate processor with digital control. While the 610 never achieved the blockbuster status of the 310, it was a decent processor that was ahead of its time. Dorrough’s passion was to make radio sound better. Not louder, but better. He achieved success with the DAP. However, the loudness wars of the 80s and 90s were right around the corner, and many DAPs became “secret processing weapons” with their own set of “special tweaks.” One interesting tactic was running two DAPs in parallel, setting one for light processing and the other for much heavier action.

About this same time, a young Stanford engineering graduate who had started a small company to build equipment for recording studios was also dissatisfied with the state of radio audio – FM radio audio in particular. While a freshman at Princeton, Bob Orban first decided to do something about how FM stations were processed. Up until that time, most processors were AM processors, with little or no modification to handle the 75 uS pre-emphasis curve employed on FM. The result was low average modulation and a lot of peaks – it was not uncommon to hear an overmod light relay clicking away behind the announcer. In 1972, after experimentation with existing products and different approaches, including FET gain control, program controlled time constants, nonlinear smoothing, and a preemphasized clipper, Orban built a self-described “contraption,” the “Overload Protection System.” Although not yet a complete processing solution, it stood out on the FM dial when unveiled on KPEN in Los Altos, California. The big hurdle in FM processing was the significant overshoot in the 15 kHz low-pass filters required to protect the 19 kHz pilot region. Orban reasoned that if he could integrate the FM processor and stereo generator “under one roof” he could effectively control this overshoot and be as much as 6 dB louder on the dial without overmodulation. The prototype in 1974 – the Model 8000 – brought the whole package came together and the next year, the Optimod 8000A production unit was released. To say it was an instant hit is an understatement. A legend was born! In fact, for many broadcasters, the name “Optimod” has become synonymous with FM processing. The Optimod 8000A made stations louder than anything that had come before and it had substantially less distortion than the Audimax/Volumax combos of the time. It is a tribute to Orban that there still are many 8000A’s running on the air today – over thirty years later.  

The Orban Overload Protection System


The Optimod 8000 the first FM processor with a built-in Stereo Generator.
Top: the prototype. Bottom: production model.

Also during the 1970s, an audio guru who owned a major studio in the Los Angeles area decided to give broadcast processing a go. Bill Putnam’s Universal Audio introduced the BL-40 AM Modulimiter. The Modulimiter combined Putnam’s patented, unique optical gain-control compressor that had achieved legendary status in the LA series of levelling amplifiers, with an FET limiter stage and proprietary “phase optimizer” circuit to maintain optimum polarity for maximum positive modulation. The BL-40 was a hit and along with Orban’s Optimod 9000A, gave the AM stations of the 70s a new, bigger sound.  

Urei Modulimiter
The Urei Modulimiter

Orban introduced the 8100A in 1981. It was a significant improvement on the 8000A, going on to become the most successful Orban product – and perhaps the best selling broadcast processor of all time, with approximately 10,000 units shipped. The 8100A improved on the 8000A by adding two-band processing with a unique cross-coupling scheme, an improved 15 kHz low-pass filter with distortion cancellation and an Orban designed VCA based on the RCA CA3280 dual Operational Transconductance Amplifiers. The improved design yielded greater loudness with less distortion and was used in several other Orban products. Over the years, Orban and other manufacturers have designed a variety of PC cards and pre-processors to enhance the Optimod’s operation. An optional six-band accessory processing chassis (XT) with was released in 1984, which included a distortion-cancelling clipper. With or without the add-ons, the 8100A is still the main processor at hundreds of stations around the world.

The Optimod 8100A/XT2

Aphex is a company best known for its recording studio equipment. However, they also ventured into the world of broadcast audio processing in the 1980s with Donn Werbach’s 2020 analog processors. Werbach’s team at Aphex proved, with the 2020, that analog was far from dead. This was a highly complex box that would define and redefine analog broadcast audio processing for some time to come. I believe the future is digital, but the 2020 proves that there is yet much that can be accomplished in the analog domain. The 2020 is a counterpoint to most of today’s broadcast processors and that is good.

Aphex 2020MKII

As loudness became more of a factor in processing decisions, program directors began to have significant input into the sound of a station – something unheard of in the past. During this period, several audio processors hit the market with the express purpose of increasing a station’s competitive edge on the dial. Notable among these processors were those by Greg Ogonowski (Gregg Labs), Ron Jones (Circuit Research Labs, or CRL), and Glen Clark with the Texar Audio Prisms, which were four-band gain riders with a gain platform. Users of the Gregg Model 2510 processors were passionate about their performance, especially the “killer bass,” and they became “secret weapons” at many highly competitive stations. Ron Jones developed a full line of processors, but his approach to AM processing was brilliant. He was the first to utilize pre-distortion in an AM processor to cancel out  transmitter problems and thereby increase modulation.

The CRL AM System

Glen Clark’s Audio Prisms became the backbone of Frank Foti’s new “Wall of Sound” at Z-100 in New York City and word of their performance spread like wildfire. A pioneer in digital processors, Clark’s digital Prism was adopted by many stations. Used in combination with the Optimod, some awesome levels of modulation were achieved. Anyone familiar with the New York City market knows that it places unique demands on audio processing. If you want to get lost on the dial, just try to apply conventional audio processing techniques to a New York City station. The market is loud and brash, just like the city itself. Foti was uniquely qualified to shake up the market with the new Z-100, a fast-paced, take no prisoners CHR format. He cut his processing teeth at The Mighty Buzzard in Cleveland, WMMS and he was ready for the big time. Foti put the prototype of his “Vigilante” processor on the air at “The Big Gorilla” in New Yawk and it was creating quite a buzz. The Vigilante – an extensively modified Aphex Dominator peak limiter – was loud, just what the New York market needed. WHTZ (Z-100) went from worst to first in less than two books and the Z-100 sound had a lot to do with it. When combined with Scott Shannon’s programming genius (he invented the “morning zoo”) the team was invincible. Toward the end of the decade word spread of a new form of audio processing, different from anything that came before. Around 1988, I saw a prototype of theAudio Animation Paragon digital processor and it gave me a glimpse into the future. Valley People, a recording studio equipment manufacturer, had also been showing a prototype digital processor. I do not know what eventually happened to either box, but we moved into the 1990s with dreams of digital audio processing, but nothing concrete.

Texar Prism
The Texar Audio Prism

aphex-vigilante.jpg (5105 bytes)
The Vigilante - Aphex Dominator 700

As we slid into the 1990s another significant change was in the air. We were on the verge of the digital revolution and new players would emerge to join some of the old. Many would drop out and some, like Steve Hnat and Ron Jones, would have succumbed to untimely deaths. Mike Dorrough had found new fame with his innovative loudness meters. Frank had left Z-100 and returned to Cleveland to strike out on his own building processors. Bob Orban had partnered with Greg Ogonowski to design the next generation of audio processing. It was an exciting time. Foti’s first commercial processor was the Unity 2000, an analog box that incorporated every trick that the master had learned at Z-100 and WMMS. It was a big hit and a terrific launch product for his new company, Cutting Edge Technologies. But more change was in store for Foti as, in the early 1990s, he joined forces with his best friend and DSP guru Steve Church, to bring his new vision to life – the Omnia!

The Unity 2000

The “Bob and Greg Show” in California was not letting moss grow beneath their feet either. They had to design a new box to replace the aging 8100A – a fabulous product that was, however, growing a bit long of tooth – and digital was on their minds. The result of the research of this super-charged pair of engineers was the digital Optimod 8200 – and it was revolutionary. It was the first Digital Signal Processing (DSP) audio processor to achieve commercial success, designed and built by the pioneers of analog processor design. Foti and Church’s “baby” was dubbed the Omnia and it was also a digital processor. But that is where the comparison with the Orban 8200 ended. The Omnia was a unique vision, born in the trenches of New York City radio and nursed to life by a DSP genius and a processing warrior. It is no wonder that the Omnia has been the most popular processor in the New York City market.

The Optimod 8200

The first Omnia

It is clear that audio processing has quite a heritage but, alas, we must move on. This series is not designed to be a comprehensive history lesson; and we are just covering the high points of processor development. I apologize for leaving out dozens of other processors and their developers. The past is gone forever, but it gives us a foundation to understand why we are where we are at today. Sometimes it is quite difficult to analyze that which is all around us. We all think we know all there is to know about the current state of the processing art. But we should not take for granted that which is all around us. With the advent of DSP (digital), the industry has reached the pinnacle of processor performance. Digital permits broadcasters to easily do things that were virtually impossible in the analog world. Yet, modern radio really does not sound all that good. Why not? That is part of what we will examine in the next installment in this series, a look at present day audio processing for radio.

Go To Part #3