Omnia Audio Unity AM Operating Manual
Cutting Edge
Unity AM Broadcast Processor
Cutting Edge Technologies
2101 Superior Avenue
Cleveland, OH 44114 • USA
(216) 241-3343• Fax (216) 241-4103
Manual Version: Preliminary AM (4.0.0)
Jan 1995
1
A letter from Frank Foti,
Dear Cutting Edge Customer,
Personally, I would like to thank you for selecting the Unity AM! What you have in your possession
right now is, not only years of research and development, but years of my passion for broadcast audio
processing. Add to that, a multitude of ideas, thoughts, and opinions of the many associates, friends,
and yes, even foes that I have encountered along the way! Who knows maybe even you yourself have
at sometime helped with a suggestion or idea! Again my heartfelt thanks!
You and I share a good common bond, radio! Before beginning Cutting Edge in 1988, I too was on
your side of the fence, in radio. As a broadcast engineer, I can totally relate to the day to day life in a
radio station. I have been there in the trenches just like you are right now! That’s why I am so excited
about the Unity AM, because someone designed it in the trenches, for radio, in radio!
Early concepts and ideas for this project actually began in the early 1980’s while I was enjoying the
life of great Album Rock at WMMS-FM, the Home of the Buzzard, right here in Cleveland! A brief
stint in San Francisco at Country music KSAN-FM and KNEW-AM gave me the opportunity to hone
my processing skills on something other than Rock-N-Roll! But the true test of ability, and far and
away the most pleasure and success, was achieved at that tiny Flamethrower atop the Empire State
Building, WHTZ-FM, better known as Z-100!
As a designer, engineer, and user, I know only too well how subjective audio processing is. There is
no right way, or wrong way to do it. As the sneaker manufacture Nike would say, “Just Do it”. (I
love the “Can Do” attitude!) We all know when it does not sound right, but to just “get it right” can
take quite an effort. So as you proceed with the installation of our product, I can only hope that you
will approach this endeavor with an open mind, patience, and time. Why? Because sometimes what
you desire, and what you initially receive may be two different things altogether!
For the majority of our customers, the Unity AM has made a big difference right off the bat. But I’d
be lying if I told you that, just by installing the Unity AM, your station would immediately be far and
above all the rest. It may take some time, but fear not, our goal is to get you to that point!
Well, enough of carrying on about myself. Here is where I would like to acknowledge the “known”
many who helped in delivering to you the Unity AM: Mozie, my Family, Pete Townshend, Steve
Church, Neil Glassman, Raymond Douglas Davies, Matthew Connor, David Reaves, M.D.D., David
“Zeke” Booth,“Don” Corleone, Doug Howland, Cate Cowan, John Granchi, F.Joseph Foti, Margot
Daly, Kevin Nosé, Dan Mettler, Marc Augis, Phillipe Legros, Bob Martin, Mark Hoageson, Mike
Maczuzak, Bruce Vanek, Don Coulter, Todd Linderman, Mary Dennis, Roz Brazleton, Danielle
Kreinbrink, Dee Oulds, Rich Matanowitch, Tom Petty, Madonna, John Alan, Judy Chamberlain,
Carlos Baerga, Dwayne Burlison, Paula Abdul, Emmylou Harris, Dean Thacker, Christine McVie, the
Cleveland Orchestra, The Who, Don Williams, the Bellamy Bros, Hiroshima, Frank Sinatra, Amy
Grant, Janet Jackson, The Kinks, Geary Morrill, Barry Thomas, Bonnie Riatt, James & Mary Anne
2
Duffy, Quincy Jones, Bernie Kosar, Dorothy Fuldhiem, Billy Joel, Roxette, Chief Wahoo, Dire
Straits, Jack Barnes, Steve Pepe, Wickliffe Sr. High, and the many, many individuals who helped
make this project a reality!
Kindest Regards,
Frank Foti
Jan 1995
3
About this manual
You have just opened the carton of a one of the most sophisticated pieces of broadcast audio
equipment. And we know how you feel. You don’t want to sit around a read a manual. You want to
plug it in and hear what it can do. You want to start pushing all the buttons and exploring the full
range of processing possibilities the Unity AM presents. We know how you feel, because when we
get a new, expensive toy, we feel the same way.
As much as we understand your excitement, we ask you to please try to demonstrate some selfcontrol.
This manual is designed to first introduce you to the capabilities of the Unity AM and then clearly
instruct you on its installation and operation. (Unlike most other manuals, large sections don’t even
require you to be sitting in front of the product.) We hope you will take the time to read the manual.
We trust you will enjoy it and that it will provide you with new and useful information on audio
processing.
Not yet convinced to wait a few hours? OK, here is where we have to warn you that we are not
responsible for anything that may happen to the Unity AM or the equipment to which you connect it
or to your station’s on-air sound or to your job if you do not read the manual.
4
Table of Contents
Introduction 1
A little history
Just what the world needs, another audio processor
A word about loudness
The bottom line
Unity AM Overview 11
Unified Processing
User interface
Processing functions
Special features
Processing Concepts 15
Why our processor sounds better
Processing designed for the ears
Feedforward control
Quality versus loudness
Keep and open mind
Installation 21
Clarify your objectives
Available time
Installation considerations
Installation checklist
Mounting and connections
Setting pre-emphasis
Rear panel connections
Setting de-emphasis
Operation 32
The obvious
The LCD display
The jog wheel and buttons
Security
The real time clock
Orientation to the Main Menus
Setting the Unity AM input levels
Setting the Unity AM output levels
5
The Processing Display 42
Input level meters
Wide Band AGC display
Level indicators
Limiter indicators
Display Interpretations
Processing Presets 46
Loading factory presets
Before you make adjustments to the presets
Modifying and adding presets
Loading user added presets
Updating user added presets
Deleting user added presets
Renaming user added presets
Main Menu Reference 54
Leveler Menu
Limiter Menu
Clipper Menu
Other Menu
In Case of Difficulty
Technical Descriptions 69
Troubleshooting Guide 81
Appendix 83
Remote Operation
Worksheets
Schematics
6
Introduction
A little history
Like most of us with a passion for radio, Frank Foti started young. He was six years old when he first
dismantled and successfully reassembled his AM/FM radio. (His father is a little vague about how
many radios he took apart before he figured out how to put them back together.) By the time he was a
teenager, Frank was building Heathkits in his basement and, as a high school senior, designed and
built his own stereo system. After his high school graduation, Frank received a full scholarship to a
Cleveland, Ohio broadcasting school and earned his FCC First Class Radio Operator’s license in
1974.
His first job was with WELW, a small AM station located in Willoughby, Ohio. He was not only the
engineer, but also wore the hats of production director, morning disc jockey, play-by-play announcer,
and music director. When the grass needed cutting, he did that too! Honestly!!
In 1978, after answering a blind ad in Broadcasting , Frank was hired as Assistant Engineer at Malrite
Communications’ WHK/WMMS in Cleveland. This was more than just a better position at a bigger
station. For a rock & roll junkie like Frank, working at legendary album rock station WMMS was a
dream come true. When his boss was fired, Frank was promoted to Chief Engineer of the combo.
Frank did more than hone his engineering skills during the three years he spent at WHK/WMMS. He
began to explore processing, the art and science of enhancing audio and tailoring sound to fit
programming needs. It was here in Cleveland that Frank first tinkered with various processing
theories and “hot rodding” existing audio components.
In 1981, Malrite shipped Frank west to be Chief Engineer at country formatted KNEW/KSAN in San
Francisco. But the “city by the bay” was not his only assignment. Frank was flown to several stations
in the group to work on their processing chains. He gained experience in a wide variety of formats
and every station he visited experienced a ratings increase due in part to Frank’s processing.
In July of 1983, Frank was assigned to New York to be Chief at Malrite’s just purchased WHTZ-FM
(Z-100). Frank, along with a team that included programming wizard Scott Shannon, had the
responsibility of pulling the lowest rated station in the market out of the basement.
When Z-100 went on the air one month later, it skyrocketed from worst to first in just 74 days! Z100’s rise to the top was due to three factors: the format, the promotion, and the sound. Frank
combined several off-the-shelf processing products with some of his own inventions to create a larger
than life sound. (Frank borrows the word of Roger Daltry of The Who to describe the sound as
“getting punched in the nose and having somebody say I love you.”)
In 1985, Frank started to sell his first product to other engineers. The Vigilante multi-band limiter
7
was initially sold by word of mouth. Stations that used the Vigilante kept this “secret weapon” behind
security covers so that the competition would not know what they were using. Frank discovered that
radio stations with the most successful audio chains (and the improved ratings) were the ones that had
all the separate components working in concert. Every part of the system had to be tuned for
maximum benefit; the sum of all the parts.
Frank returned to Cleveland in 1987 to become Malrite’s corporate Director of Engineering and
supervise the technical aspects of its seven radio properties. A “hands-on” manager, Frank traveled
the country to work with his engineers. Processing remained his primary interest and he was
frequently solicited to consult with other stations. His reputation as radio’s number one expert in
broadcast processing was now well established.
At home, Frank kept tinkering. And the tinkering soon became serious research. What he learned
from scores of engineers and programmers and from listening to stations all over the country was that
radio could sound better. And that better sounding radio meant more listeners.
Frank left Malrite in June of 1988 to create his own company and called it Cutting Edge
Technologies. More traveling, more consulting, and more research in the basement. Frank knew what
kind of processor radio demanded. And in 1994, he delivered it. The Unity AM.
Just what the world needs, another audio processor
Next to the fates and fortunes of local sports teams, nothing causes more arguments at radio stations
than processing.
In one corner there is the group who wants to burn a hole in the dial. In this day of high octane,
“Tastes Great… Less Filling,” extremely competitive, kill for the last dollar radio, the tendency in
many cases, has been towards creating a behemoth over-the-air. Utilizing as much of the latest,
greatest, tweaked, modified, and super-charged products available, we crank them up until we achieve
a sound that is “louder than anyone can ever be, but is totally clean.”
Who are we kidding? Hopefully, by now, we all know that all this does is create the potential for
fatigue, tune-out, and decreased time spent listening. The bottom line is that the listeners go
somewhere else.
On the other side of the debate are the sonic purists who want to transparently reproduce the source
material, just as it was recorded. Too little processing can be as bad as too much processing. Listeners
are more sophisticated and in the age of CDs (and now MDs) they know what sounds good. The
transmission chain and the receiving radios significantly effect audio dynamics and quality. It takes
careful, adequate processing to keep music sounding, well, musical.
The main reason this debate exists is that the processors you have been using don’t let you get the
8
sound you want and need for your station. Yes, they sound all right in most circumstances and each
processor does have a sweet spot that performs satisfactorily in many circumstances. But they also
have built-in limits on what you can creatively accomplish. This, however, is the real world of
competitive radio… you can’t afford to sound “all right.” You have to stand out on the dial. With
traditional processors, whether you crank the processing up or down, you lose musicality.
Until Frank Foti (with the help of a couple of hundred radio engineers, programmers, and managers)
designed the Unity AM, you had only two options. Live with what you had or add another processor
to the chain. Or perhaps two more processors. Or perhaps… well, you get the idea. Adding on to the
processing chain was the way Cutting Edge got started. But it is not where we ended.
Frank determined that, when the optimum sound could not be achieved in a multiple box processing
system, the weakness was often the inability of the audio chain, as a system, to work in an integrated
manner. The strengths of one box did not always compensate for the deficiencies of the others.
The bottom line was that the world did need another audio processor. A device that has an open,
accurate sound over the full range of processing. It took Frank a long time to get the Unity AM right.
The proof that he got it right is the way the Unity AM sounds.
A word about loudness
Making this confession is a little like telling your parents you dented the car. But here it goes.
It is OK for your station to be loud. Very loud.
In the past, loudness was a problem due to the limitations of the processors you had available to you.
If you processed more heavily, then you either had to adjust your single box outside of its “safe”
range or use multiple boxes and risk their conflicting with each other.
Frank Foti and the Unity AM have changed all of that. Frank knows how to get a station sounding
loud without the artifacts or grunge created by your current processor when you try to make it loud.
And he knows how to make loud an option for all formats.
One more confession. It is also OK for your station to not sound loud. Because the Unity AM has
given you the choice. Our intention is to provide you with a system that will maximize the audio
quality of your signal, yet at the same time maintain your competitive requirements.
The bottom line
The Unity AM is unique in its approach to audio processing. It sounds better and is easier to use than
any other processor available.
9
And how has the market reacted? As we look back over the past few years, the reaction has not been
unlike that to other “edge of technology” products like the original Apple computer.
• First, the Unity AM was ignored.
• Then it was accused (by other processing manufacturers) of being ineffective.
• Gradually, it was accepted by users with tolerance for risk and novelty.
• And now the Unity AM, is being accepted by large numbers of users.
You won’t find the Unity AM on the air at every station. But at the stations where it is installed, you
will find engineers, programmers, and managers happier than ever with their on-air sound.
Today, Cutting Edge is more than just Frank Foti. While Frank is glad to have someone else build the
boxes and keep the books, he’s still a busy guy. And we don’t mean spends the summers watching
Cleveland Indian games. No, he is still working on new ways to improve the sounds of broadcast
audio. And he is still spending a few hours each day talking with other broadcasters.
If your processing has you baffled, or you think you have a system that sounds better than Frank’s,
give him at call. The number is (216) 241-3343. His fax number is (216) 241-4103 if you are located
outside of the United States or a shy person. He’s a good talker and a great listener.
10
Unity AM Overview
Unified Processing
We reassembled the pieces of the processing puzzle to get more out of the system as a whole; sort of
rearranging the furniture to get better use of the room. We call it Unified Processing. This
arrangement allows us to “unify” all functions of a broadcast audio chain into one package. In one
seven-inch tall chassis is the processing flexibility and power of at least three, and as many as six,
different pieces of equipment.
To help you get begin to adjust a processor that sounds great at all settings, Frank has provided
presets for a number of formats and programming requirements. These are used as a starting point for
your processing adjustments. Once you have found a setting you like, there are fifty user memory
locations provided for safe keeping. Comparing two setups is as easy as pushing a button.
User interface
Total operation of this system is accomplished through microprocessor control. With the Unity AM,
we have strayed from the conventional methods of operation. Gone are mechanical switches and pots.
In their place are a button pad, jog wheel, and LCD screen. Through user menus, you can achieve
better flexibility as well as rapidly store and retrieve settings.
In designing our user menus, we have avoided creating too many “layers” that would require
excessive navigation. Most processes and functions are accessed in three steps and the menus are
arranged in a logical manner that can be learned in minutes.
The Unity AM presents extensive set-up metering in the Processing Display. At all times, you can see
the activity of all processing functions so that you can determine the overall effect of any changes you
make. Our display is uniquely designed to provide a significant amount of easy to interpret
information.
Processing functions
The Unity AM provides eight processing functions, all are operated by a single control interface.
When you create a processing setting, you have the advantage of doing so for every part of your
processing chain.
The Unity AM’s eight processing functions are:
1) Selectable Wide Band AGC that reacts as if it was a “slow hand” on the output of the audio
console so that the levels coming into the Unity AM are always within a consistent window.
11
This slow acting gain control circuit provides ±10dB of leveling. Imagine, if you will, someone
that would continually insure that the output of the audio console was always within a specific
level. The “platform leveling” control circuit for the AGC is intelligent enough to know that if the
incoming audio level is correct it will shut down its operation and wait until gain correction is
needed. The AGC is therefor only operating when needed, eliminating the constant seeking of
unneeded level changes.
2) Selectable Phase Rotator circuits that, when utilized, can assist in eliminating vocal distortion
during periods of heavier processing needs.
These specialized delay circuits create a “flywheel” effect on a certain range of frequencies. In this
case, audio within the main vocal range of 300Hz to 2kHz will change in phase as frequency
increases through the stated passband.
The reason we incorporate phase rotators is a problem created by the human voice. Most human
voices are asymmetrical in nature, meaning one side of the waveform is larger than the other. The
delay circuits of the phase rotators synthesize the symmetry of the waveform for vocal audio
through the passband. By doing this, the upper and lower crests of the vocal waveform are
processed more evenly.
For heavier processing situations, use of the phase rotators helps cut down on clipper induced
distortion on voices. For lighter processing requirements, the phase rotators can be defeated.
3) Selectable and adjustable low frequency Bass Enhancer circuit that provides a deep, full, and rich
texture to the bass line.
This is not just another low frequency equalizer. This section provides up to a 12dB boost to the
bass frequencies as well as the harmonic rich sub-bass region. The enhancement scheme used here
generates that deep, rich, and full low end that is sought after by so many contemporary
programmers. Unlike the use of conventional equalizers, there is no exaggeration of the upper low
frequency range causing the bass to sound unnatural and “tubby.”
4) The Selectable Matrix Processing Option allows the Unity AM to operate in either discrete
left/right or matrixed L+R/L-R processing for AM Stereo broadcasting. For detailed explanation
about matrix processing please refer to the technical description in the back of this manual.
5) Phase linear 4-way Adjustable Crossover Networks that allow all processing to be tailored to
any format requirement. This network provides perfect linearity as well as ±.5dB of flat response
when summed back together. Frequency response along with harmonic integrity are totally
maintained with this network. Since the crossover frequencies are adjustable, all crossover points
can be tuned for the appropriate programming format.
12
6) Four band Processor/Leveler that “intelligently” levels each audio band in an effort to generate a
high modulation average, while at the same time creating spectral consistency.
Our unique leveler circuit actually “learns” what it needs to know about the incoming audio signal,
makes some decisions on what to do, feeds the information forward to a dynamically adjustable
gain block, and then makes whatever any necessary changes. All functions are performed in the
digital domain.
This feedforward approach allows the signal processor to operate at a constant ratio. The benefit
is consistent leveling for whatever amount of processing employed. This is the key reason why the
leveler is almost always in its “sweet-spot” of operation. Also because each section works off a
platform, the control circuitry has the ability to produce ±7.5dB of RMS leveling. Since all
operation is RMS, only the average level is analyzed and corrected. This yields a better
modulation average for each audio band.
The processing display on the front panel of the Unity AM shows the state of all leveler bands.
Each leveler band also has the intelligence to wait or cease operation if the incoming audio level is
correct for that moment. The output of the four leveler bands can be independently adjusted to
create a custom spectral mix that will feed their respective limiter bands.
7) Four band multiple time constant Limiter that is dedicated to each Processor/Leveler band to
provide consistent peak control and low dynamic distortion.
Each limiter band operates in a fashion similar to the leveling scheme described above. The
exception is that the limiter bands deal predominately with peak level information and work at
higher, yet consistent, ratios.
Each band is fed directly from the preceding leveler band. Adjustment is available for attack,
release, and threshold levels for each limiter band. An output mix function allows contouring of
the spectral levels that are sent to the subsequent clipper section.
The utilization of multiple time constant networks allows each limiter to reduce dynamic
distortion through delayed release times. When a quick transient peak comes along, the limiter will
react and dynamically adjust the peak level. Once the peak has passed, the initial release time is
contoured somewhat fast, and then much slower. If during this slower period another transient
comes along, the limiter is still at some level of gain reduction and has already accomplished some
of its work. It does not have to begin limiting again from the initial processing point.
Multiple time constants offer a significant advantage over single time constant limiters. In the
scenario described above, a single time constant limiter will only apply a fast release time to a
quick transient peak. When another peak comes along, the limiter, which has totally recovered,
will be forced to limit again from the initial starting point. The sonic benefit of multiple time
constants are significant. Listeners will not hear the fast dynamic level changes so typical of peak
13
limiting schemes. .
8) Integrated Clipper/Low Pass Filter system that self-controls distortion to achieve clean,
competitive audio while providing exceptional bandwidth control.
This static circuit plays a large role in mediating the quality versus loudness debate. With ±5dB of
drive, a wide window is provided to suit all programming needs. From virtually no clipping to a
“wall of sound,” just about any sonic texture can be realized. Using proprietary circuitry, the
clipper will “self-control” clipping induced distortion products, allowing the audio to sound
cleaner at higher clipping levels.
The phase linear non-overshooting 10kHz low pass filter provides an exceptionally clean
spectrum. The upper frequency spectrum is protected to at least -80dB by ninth order topology.
With the suppression of upper spectrum energy, coverage in “fringe” signal areas may improve.
There are also two selectable Interface Ports that will allow ancillary audio equipment, if needed, to
be inserted. You may want to insert reverb, stereo enhancement, or whatever else you require. One
port is located just after the Wide Band AGC and the other is between the Processor/Leveler and
Limiter.
Special Features
All of the Unity AM’s features can be accessed by an IBM compatible computer through the Serial
Communications port. With a modem connected to the computer, you can control the Unity AM from
virtually anywhere. Compare processing settings in your home or even your car to get know how your
station will sound in the real world.
Another benefit of the Unity AM is Day-part Processing . This function allows the system to
automatically change its processing setup at specific days and times according to a schedule that you
create. For example, processing can be programmed to a preset best suited for the “morning drive”
and automatically change to a different preset that better complements the “mid-day” programming.
Up to fifty events can be scheduled in two formats. The Weekly Calendar Format is used for regularly
scheduled day-to day programming. For special event programs, such as remote broadcasts and
concerts, a Specific Date Format is also available.
The Unity AM features a multi-level password protection scheme. This station personnel to have
access to only those programming areas appropriate to their job.
14
Processing Concepts
Why our processing sounds better
The Unity AM utilizes advanced digital processing techniques that expand the performance ability of
the system. A single bit, digital gain block is employed to provide all dynamic processing functions.
Processing functions are a true representation of any gain changes that are implemented. This allows
the gain block to create dynamic level changes that are determined by the control circuitry only. This
is unlike typical analog processors where unwanted sonic artifacts are attributable to the limitations of
the gain stage.
The crossover networks, filtering, and NRSC low pass filter are all of a true phase linear design.
Sonic integrity is maintained in both frequency response and group delay/harmonic response.
A key important feature to the sound of the Unity AM is the unique Linear Response Algorithm
(LRA). This function provides intelligent high frequency control before the insertion of pre-emphasis.
Competing systems provide high frequency control after pre-emphasis, which compromises sonic
clarity and can sound dull, harsh, or lacking in natural content. LRA, on the other hand, yields
improved transparency in the presence and high frequency bands. As the ear is more sensitive to
fatigue and distortion in these ranges, thanks to LRA the Unity AM sounds more musical.
Processing designed for the ears
We won’t pretend that we have the answers to all of the audio processing questions that exist in our
industry. But we do think that the experiences and research of Frank Foti and our other engineers
have provided us with an understanding of many processing issues. What follows are some concepts
that should help guide you through the operation and adjustment of the Unity AM. These issues are
important because no matter how much we tell you in the manual, not matter how much time we
spend speaking with you on the telephone, and even if we visit you, you are ultimately responsible for
making the Unity AM sound best for your stations format and requirements.
What device is used to recognize the perception of audio loudness? If you answered the ear, you are
correct! The ear perceives loudness by sensing how much average (RMS) level is present in the ear
canal. The higher the average, the louder the perception. On the other hand, peak level by definition
is very low in average level and therefore less noticeable to the sense of hearing.
15
To translate the same concept to broadcasting, perceived loudness is directly related to the RMS level
of the modulated signal. This is commonly know as the peak to average ratio. the greater the level of
average modulation maintained, the louder it will sound to the listener. The secret then, is to discover
what method to use to achieve high average modulation, while maintaining excellent sonic quality as
well. The key word is RMS. If we can utilize processing to build a good RMS base, then we can
accomplish the goal of high average modulation while sustaining quality.
In a broadcast processing system, we can accomplish this with three stages of operation. In the Unity
AM, we begin with a gently operating, RMS controlling device, the Processor/Leveler. This first
section is able to generate a semi-controlled output that is high in both average and peak level.
Because it is “gentle” in control, quality is maintained. Since RMS adjustment ignores the peak
content of the signal the Limiter, which operates more aggressively follows and yields a better
controlled output. Now our signal is high in average level, but with peak level reduced. The final
stage is the Clipper, set to remove the remaining peak excursions. This results in a signal that is very
high in average, with little or no peak energy.
LEVELERS LIMITERS FINAL LIMIT
RMS
Control
Peak
Control
Clipping
Figure - This diagrams a simplified system that produces an
RMS signal that will yield a high peak to average ratio.
The above illustrated system can produce both quality and quantity (dBs) of audio. The perceived
processing artifacts are minimized by the gentle, qualitative, operation of the RMS stage, which the
ear recognizes. Since the ear is less perceptive to peak levels, harder limiting and clipping on peak
information can therefore be performed in an inaudible manner. Competitive loudness is generated
from the combined efforts of all three stages.
Many present processing systems, which operate without an RMS stage, rely on large amounts of
limiting and clipping to achieve high average modulation. Although accomplished, a noticeable loss
in quality occurs due to the aggressive action of the limiting and clipping functions.
The figure on the next page expands our concept of maintaining a high peak to average ratio to help
you further understand a basic philosophy behind the Unity AM.
Consider, if you will, the audio signal as it exists at the output of your audio console. Generally it is
of wide dynamic range. We know that, for it to be transmitted in a qualitative, yet competitive
manner, the dynamic range must be reduced. The wide dynamic range needs to be funneled down to
the smaller range. In other words, we are using the processor system as an audio funnel to accomplish
the desired goal.
16
If we were to break down the funnel into sections, we could assign a different function to each area.
Controlled Output Signal
In making use of each function, we could funnel down the dynamic range of the audio signal as it
passes from one area to another.
Wide-Band AGC
Multiband Leveling
Multiband Limiting
Clipping
Dynamic Input Signal
Figure - Audio Processing Funnel Concept
The less aggressive RMS functions, (AGC and Leveling) are assigned to the wider dynamic range
areas. This permits the funnel effect to begin without causing the perception of being affected. As the
dynamic range is reduced, more aggressive peak functions (Limiting and Clipping) can be added to
complete the process, again without the perception of affecting the audio.
From this brief discussion, you may be able to see why the aggressive functions, such as limiting and
clipping, can sound overly aggressive, or even offensive, if used within the wrong stages of a
processing system. Later, we will put this concept to use with respect to making adjusts of the
parameters on the processing system.
Feedforward Control
Vital to the great sound of the Unity AM is our use of feedforward control circuitry in all the
dynamic processing functions, i.e., the Wide Band AGC, Multiband Levelers, and Multiband
Limiters. This enables the processing ratio to remain constant across all levels of processing. By using
feedforward control, the Unity AM will always operate at the same processing ratio, providing a
wider range of operation. This yields improved sonic consistency, regardless of the amount of
processing employed. Feedback systems, found in most other processors, have “sweet spot” windows
that narrow with the changing of ratios as the amount of processing varies. This is why most, if not
all, feedback processors develop a thick, dense, mushy, and unnatural quality to their sound as they
are driven deeper and deeper into gain reduction.
17
Gain Element
F EEDFORWARD CONTROL
Audio In Audio Out
•
Control Information
CONTROL
CIRCUITS
Figure - Feedforward control circuitry
In feedforward dynamics control, the input audio signal to the gain control circuits is monitored, and
adjusted if necessary, before the gain element. The resulting control information is then “fed forward”
to the element. This produces dB linear gain control at a consistent ratio that remains constant
regardless of the amount of processing is employed.
For example, if the low band leveler is operating with a compression ratio of 4:1, any amount of
control, whether it is 3dB or 23dB, will operate the 4:1 ratio. Because the developed control
information is derived from the input side of the gain element, all corresponding control reaches the
gain element as it happens in real time. As the incoming input audio changes, the gain element is able
to make the same corresponding level adjustment change at the same time.
The gain element in a feedforward control scheme is a “dumb” device. It only does what it is told to
do by the control information and nothing more. If the control circuits are able to develop the correct
information, then the gain element is capable of providing a very natural and smooth effect to the
audio that is available over a wide operating range. If the control circuits develop the wrong
information, i.e. incorrect time or ratios, the gain element will produce an unnatural audio effect. The
Unity AM utilizes feed forward control which aids in creating its natural unprocessed sound.
As you can see from the figure below, when using a feedback gain processing technique the control
circuits develop the control information after the audio has passed through the gain element. The
information is then “fed back” to the element to accomplish gain control. Gain control operates in a
dB log/linear fashion. This changes and increases the processing ratio and continues to do so as more
processing is employed. For example, when 3dB of audio crosses the processing threshold the ratio
may be 3:1, but at 23dB the ratio may have increased to 20:1.
18
FEEDBACK CONTROL
Gain Element
Audio In Audio Out
Control Information
•
CONTROL
CIRCUITS
Figure - Feedback control circuit
Notice that the gain element is operating within the closed loop of the control circuits. By the time the
control information reaches the gain element, the level that required adjustment has already passed
the point of control. This is especially problematic when transient peak information occurs. The gain
element never really adjusts the leading edge of the peak, leaving the peak to be processed by a
subsequent stage. If a dynamic limiter follows, the limiter should take care of the peak, although the
resultant sound may be perceived as “dense” due to high limiting ratios. If a feedback limiter follows,
that limiter will not be able to control the leading edge of the waveform resulting in added, and
sometimes excessive, clipping of the waveform.
If the audio levels to be adjusted and the control information generated to process that audio vary over
a wide range, the gain element will generate increased intermodulation distortion. This is a key reason
why feedback gain control circuitry yields a “denser” and more fatiguing sound the harder it is driven
with audio level. This explains why these systems always will have a narrow “sweet spot” of
operation that is usually ranges only a few dB.
This discussion may lead you to ask why feedforward control is not more prevalent. The reason is, in
part, to the difficulty in designing the needed control circuits within the true analog domain. In order
for this style of circuit to operate, true dB linear adjustment is necessary and, for this to take place in
analog, log circuits are needed to create the dB linear control. In the past, such analog circuitry
usually was very unstable, cumbersome, and costly and could cause inconsistency within the
processing circuits. Since this dB linear function is performed digitally in the Unity AM, simple,
consistent, and reliable operation is achieved.
Quality versus loudness
The tradeoff between quality and loudness is primarily affected by the use of the limiting and clipping
sections. While either function will generate more “dial presence,” they both offer differing artifacts
and side-effects. With additional use of limiting, intermodulation distortion is increased. The added
dynamic activity of the limiters causes the audio to sound as if it is “overly controlled.” This can be
perceived to the ear as “pumping,” “breathing,” “dense,” or “mushy.” When the clipping is raised,
19
harmonic distortion is increased. The audio level is in effect “running into the brick wall.” This may
causes to sound “broken-up,” “torn,” “rough,” or “edgy.” As you might imagine, the harder limiters
and clippers are driven, the louder the perception…and the more likely you have increased
intermodulation and harmonic distortion.
Through the careful use of the multiband Leveler sections, high RMS levels can be created. This will
allow consistently controlled amounts of limiting and clipping to be used without the cost of added
distortion. If increased loudness is the goal, two possible methods should be experimented with. The
first makes use of the multiband Levelers and Limiters. By increasing the output of the multiband
Leveler sections, you are raising the controlled RMS levels to the Limiters. This will build increased
loudness by, in effect, driving the Limiting harder. The second possibility will be to increase the
amount of Clipping. With either of these two options, it is suggested that when making changes, work
with small 5% increments.
Keep an open mind
The Unity AM, is a different kind of processing system. We realize that many of your views on audio
processing are based upon your experiences with products with which you have previously worked.
You may find that the techniques and procedures that you have utilized up until the present, may not
create, perform, or have the same affect with the Unity AM. Because of this, we ask that you proceed
with the installation, setup, and operation with an open mind.
While the Unity AM operates around concepts that are not being utilized in other processing systems,
this is not a reason for you to be concerned. In fact, we have created a whole new realm of
possibilities. Here is a chance for you to master new processing techniques. And whatever your
processing requirements, needs, or desires are, the Unity AM can achieve them.
It would have been easy for us to “repackage” old technologies and stick the word “digital” on the
front panel. Instead, with the Unity AM, we have created something completely new. Once you have
has a chance to use the Unity AM, we know you will appreciate our efforts.
20
Installation
Clarifying Your Objectives
Your success in installing and getting the most our of a processing product is, or lack of, will be
directly related to how well you have developed your objectives for the product. With a clear set of
objectives, your tasks will be more clearly defined. Whether you are seeking better overall quality or
specific spectral improvements, try to articulate and write down your goals. Do you want a little more
loudness or “presence” on the dial? Are there certain characteristics of the sound of other stations in
your market that you want to emulate? Are there any you want to avoid? If you are installing the
Unity AM on evaluation, it is equally important to have a list of specific factors you are going to use
to make your comparison.
Engineering, programming, and management should all participate in the development of these
objectives. After all, processing can have a direct effect on the bottom line of your station. A little bit
of agreement before installation can save you a whole lot of disagreement afterwards.
Available time
Let’s get one thing straight: It takes time, a good deal of serious time, to process your station. We
realize in our business today, time is a precious commodity. Our Unity AM, and its competitors, are
expensive and multifaceted. We hate to sound like we are nagging, but don’t try to install the Unity
AM in between other major projects or the week your boss or your assistant is on vacation. Make
certain in advance that the staff members who helped you set your objectives will be available to
consult with you when you adjust the Unity AM.
How much is enough time? Good question! We feel that working with a system for at least a week is
a good starting point. (Look at the clock and see how long it has taken you to read the manual to this
point. And we have not even told you how the turn on the Unity AM!) We don’t suggest that you
drop everything for a solid week. What we do recommend that you install the Unity AM during a
week when you can spend a few hours day on the project.
Installation considerations
Installing the Unity AM requires a bit more than mounting it in the rack, connecting some cables, and
then putting it on the air. (We modestly believe, however, that our processor is the easiest to install in
its class.) Among the factors you should consider are:
1) Monitor Location You should have a good location in which the system, once on the air, can be
21
monitored. We suggest a good tuner, with good reception, feeding a set of studio monitor speakers
to be sufficient. While car radio and other “typical listener situation” settings are important, they
should not be the main reference points.
2) Good, Clean Source Material A well respected processing colleague once said, “Garbage in,
produces more garbage out!” He was not kidding. If you are using poor source material, or poor
performing playback equipment, you will not get maximum sonic benefit from your demo.
Anomalies that you perceive to be processing problems, may be source problems that the
processing is exaggerating! Make sure that you start out with a good first step - good source
material!
3) Mic Processing This may appear trivial, but the perceived sound of “live” voices over the air can
change dramatically with different processing systems. Whatever the effect your on-air
microphones will probably change when you change your processing. If you utilize mic
processing, you may have to adjust it to suit the operation of the new processing system. Most
announcers develop a “comfort zone” with respect to the sound of their voice over the air. When
that “comfort zone” is changed or modified, the common response is that something is wrong.
Mic processing can be a very important part of your overall station sound.
4) Operating Levels This is another simple area where trouble can develop. Make sure the input
and output levels of the Unity AM are at the operating at the proper level within your system.
(Did you know that operating a processor with insufficient level into an STL system will cause
loss of modulation and loudness? I only mention it, because we’ve seen it happen more than a
few times!) If you are comparing the Unity AM with another processor, be sure they are both
operating at the same levels. Your modulation monitor is an important tool in any processing
comparison.
Installation checklist
The following checklist will further assist with installation:
1) Finish reading this manual. (Sorry, we could not resist slipping this in one more time.)
2) Quickly revisit your goals and objectives, and decide upon whom is to assist with the evaluation.
3) Mail or fax the initial warranty registration to Cutting Edge. This way we will know who you are
if you call for assistance.
4) Perform the physical installation and initial set up. Start with one of the factory presets.
5) Once on the air, proceed from a processing level similar to that currently used by your station and
then if desired, become more aggressive. This is less likely to draw hasty, and negative, opinions.
22
6) Listen for awhile, then adjust. Try to avoid the temptation to “fiddle” with adjustments, moments
after getting the system on the air. Remember you should evaluate the operation over time, not
moment to moment! When it is time to adjust, the provided worksheets that can assist in
establishing improved settings of operation.
7) In making changes to the system, do not make hasty or radical changes. Also, do not make
too many different adjustments all at once. If too many parameters are changed at one time, it
is hard to determine which change made the difference. That can be frustrating whether the
change made you station sound better or worse!
8) A procedure we have found successful is the “sleep on it” method. Spend time adjusting and then
listening, and when the system gets to a point where it sounds good, stop for the day. In making
changes, there does come a time when the ears become less and less sensitive to adjustments
performed. The ears sort of “burn out.” That is why spreading the adjustment period over a
number of days is recommended. If it still sounds good after you have “slept on it,” quit
adjusting. If it does not, continue with this method until you’re satisfied. If the procedure is
working, you will find that each day the discrepancies are smaller and you’re making fewer
adjustments.
9) When you get it where you like it, STOP! Nothing more said!
10) Send in the second registration card. Now we know who you are an how you are using the Unity
AM.
A Word About Relative Phase
If the relative phase relationship of this system is different to your existing system, or the system you
are comparing it too, it could cause your announcers to sound “weird” in their headphones. If this
happens, then the relative phase of the Unity AM is 180 degrees different than what your announcers
are used to. To remedy this, just reverse the polarity to both of the inputs on the Unity AM.
Mounting and connections
Before rack mounting the Unity AM, review all items in this section. Some require that you change
jumpers on the cards located inside the unit and we know you will say nasty things about us if we
didn’t warn you.
We recommend installing the Unity AM with at least one rack height of space open above the unit.
This will enhance ventilation and prolong component life.
Setting pre-emphasis
For AM broadcasting worldwide, some form of pre-emphasis boost is employed. Generally it is 50µs
23
or 75µs. For North and South America, the modified 75µs NRSC standard is used. The NRSC
standard provides a 10dB boost at 10 kHz. A shelving response for frequencies above 10kHz, along
with a tight 10kHz low pass filter, is employed to control out of band emissions.
The factory default pre-emphasis setting in the Unity AM is the modified 75µs NRSC standard. The
pre-emphasis can be changed will relative ease.
Before going on to the next step, be aware sophisticated microprocessor controlled products like the
Unity AM do not like to be zapped by static electricity. Please take all required precautions to create
a static free environment before opening the Unity AM.
To change the pre-emphasis, locate and remove card #8, the eighth card from to the right of the power
supply, and set the “berg” jumpers according to the diagrams that follow:
24
x x
x x
x x
x x
x x
x x
x x
x x
x x
x x
x x
x x
NO PRE-EMPHASSIS
50 us PRE-EMPHASSIS
x x
x x
x x
x x
x x
x x
75 us PRE-EMPHASSIS
Rear Panel Connections
AC connection
AC power is applied to the EIC style connector. The Unity AM will operate from 100 to 240VAC.
Voltage selection is made using the jumper located in the fuse compartment of the AC connector
assembly. The default voltage shipped by the factory is 120VAC. We may have changed the
operating power setting at your request before shipping the unit.
25
Always turn the Unity AM off and disconnect the power cord before attempting to replace the fuse or
change the operating voltage. Always replace the fuse compartment before applying power to the
unit.
To access the fuse compartment, insert a small screwdriver into the tab just below the power
connector and pull the fuse compartment gently towards you. Grab the compartment on both sides to
remove it. Slide out the small circuit card with the jumper on it. Locate, on the top of the board, the
voltage to which you want to set the Unity AM. Orient the jumper so that it points in the direction
opposite that label. Insert the board with the side indicating the proper voltage first so that the jumper
sticks out towards you. Replace the fuse compartment and check that the jumper is displaying the
operating voltage you need. To change the operating voltage, locate the white jumper at the bottom of
the compartment.
When changing the operating voltage to 220 or 240VAC, change the fuse value to .200 amps.
Audio input
Before connecting audio to the Unity AM, you need to choose either -10dB or +4dB as your input
operating level. The factory default setting is +4dB. If you want the input sensitivity to be configured
for an input level of -10dB, you will need to change some “berg” jumpers on the input board.
Before going on to the next step, be aware sophisticated microprocessor controlled products like the
Unity AM do not like to be zapped by static electricity. Please take all required precautions to create
a static free environment before opening the Unity AM.
To change the operating levels, remove the cover. Lift out Card 2, the second board from the left hand
side. With the board facing you and the connectors facing down, you will notice two “berg” jumpers
to the left side. They are located near U101 and are labeled J101 and J102. The “berg” jumpers are
mark for either +4dB or -10dB input level. To change the input level sensitivity, move the jumper
from the +4dB to -10dB position.
Connect the input audio to the female XLR jacks on the back. The input circuitry is active balanced,
pin #2 high, pin #3 low, and pin #1 ground. Make sure to connect accordingly. If unbalanced, make
sure to use pin #2 as high, and tie pin #3 to the system ground. Ground loop “hum” can develop if this
is not done.
26
Discrete Left/Right Audio Outputs and De-emphasis Selection
Individual Left and Right channel outputs are available on the male XLR jacks. This signal is the
output of the final processing function of the system, the Clipper/Low Pass Filter. The output circuitry
is active balanced, pin #2 high, pin #3 low, and pin #1 ground. Make sure that pin #2 is connected to
the “+” terminal of the audio input on the transmitter. If not, incorrect modulation polarity can result.
It is important in AM broadcasting to observe correct output polarity. Since the Unity AM is capable
of modulating asymmetrically , incorrect polarity, coupled with asymmetrical operation, could
actually cost modulation. This would occur by modulating the asymmetrical waveform in the negative
direction. Thus yielding positive modulation of about 80%, having an adverse affect on signal
coverage.
Under normal circumstances the output signal is pre-emphasized, but through jumpers, located on the
motherboard, the signal can be de-emphasized for installations that require a “flat” response as would
be the case when feeding land lines.
It should be noted that through the system jumpers, two different “flat” response audio conditions
could be created. The first, is when no pre-emphasis or de-emphasis is used. Passing the audio signal
through the system without any specified boost and complimentary cut to the high frequencies. The
second, is when a specific amount of pre-emphasis is utilized to boost the high frequencies, and then
the corresponding de-emphasis is used to reduce to the high frequencies to an “overall” flat response.
If there are two options, what are the differences, and why use them? Good question! In the first
instance, there is never any boost to the high frequencies. Because of this, any subsequent preemphasis boost employed AFTER the Unity AM will cause unwanted overshoots in the signal. This
occurs because there is not any final limiting control that follows the pre-emphasis curve that is used
AFTER the processing of the UNITY. These overshoots cause “lost” modulation because their
amplitude must be accounted for in the total modulation of the system.
The second option, where pre-emphasis and de-emphasis is used, makes use of the final limiting
system within the Unity’s processing structure. Since this follows whatever pre-emphasis has been
selected, tight control of the high frequencies is accomplished. Even though the signal is subsequently
de-emphasized, any post pre-emphasis that will then be employed will only boost the high
frequencies to the already previously controlled level. This will allow the system, as a whole, to
modulate with relatively low, or no overshoots.
When, or where is either of these options applied? The answer is determined by what type of system
follows the Unity AM. If any portion of the following system does not employ ANY form of preemphasis, then the first option can be used. Applications might be: final limiting before power
amplifiers, final mixing, and final limiting for mastering purposes.
27
The second option must be used in any application that will utilize sort form of emphasis. This would
include: broadcast applications where land lines or some form of STL must be connected to a second
party stereo coder/modulator that will provide pre-emphasis. Any satellite uplink or digital converter
that uses an emphasis technique for improved S/N ratio.
Setting De-emphasis
The jumpers for the de-emphasis options are located in the upper right-hand corner of the
Motherboard. If you are facing the unit, it would be the area to the right, in the rear. Position the
jumpers as described in the following diagrams for the desired de-emphasis.
UNITY MOTHERBOARD
CONNECTOR
JUMPERS
JUMPERS
X X
X X
X X
AD 713
X X
X X
X X
NO DEEMPHASSIS
UNITY MOTHERBOARD
CONNECTOR
JUMPERS
X X
X X
X X
JUMPERS
AD 713
X X
X X
X X
NRSC DEEMPHASSIS
28
Loading...