Go To Part #4
This series of articles
re-published from www.radio-guide.com
issues of February to August 2007 original on PDF format.
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
“History Repeats Itself. First as tragedy,
then as farce.”
(Radio-Guide April 2007)
Today, and Tomorrow
Talking with Today’s Masters
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
THE PAST AND FUTURE
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
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.
Are the Maxx Brothers worthy of respect or
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
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.
AN “OVERNIGHT” SUCCESS
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.
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?
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
first processor was actually an adaptation of an existing processor, was it not?
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
The original Vigilante was built on an Aphex
THE PARTS TOGETHER
the Vigilante an all-in-one, stand-alone box or did it require support by other
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.
processor designers influenced you most strongly at this time?
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.
THE PARTS TOGETHER
that progression makes sense. Now what was the Unity, and how did it differ from 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
approach is a sort of doubleedge sword, right? IMD not normally a desirable audio
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.
you were to point out the main weakness of the Unity, what would that be?
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”
REALLY TAKES THE STAGE
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!
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.
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?
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
Orban Optimod 8200, was the first Digital
THE FORMERLY IMPOSSIBLE
certainly sounds like a major jump forward. What sort of things were now possible using
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.
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.
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
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
The 8400 brought full DSP audio processing
to the market.
CREATES A STUDIO ISSUE
was some surprising feedback from the field from the effects of the look-ahead limiter.
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.
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.
HAD TO ASK
you care to take out your crystal ball and give us a few predictions on what we can expect
from Orban in the future?
would be telling! Seriously, I don’t want to say anything that might give away future
plans to my competition.
... and thank you for taking the time to share with us as much as you did.
ENTERS THE RING
how did your first DSP processor, the Omnia come about?
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
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.
you had a working prototype, how did you introduce it?
personally took the beta version of Omnia.fm 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.fm enters the DSP marketplace.
THAT QUESTION AGAIN
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?
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?
MORE FUNCTIONS FROM THE TECHNOLOGY
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.
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!
TO KEEP FACTS STRAIGHT
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