Crown Macro-Tech MA-2402 User manual

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Celebrating the Crown
Macro-Tech Series
Your Macro-Tech®Signature Series amplifier is the
culmination of a long heritage of Crown®products
and design ideas that began in the early 1970s.
In these pages you can explore how the Macro-Tech Series came to be, understand its advanced features, and enjoy stories and sales literature from its colorful past.

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Sometimes a product fits an application so well, it
is deemed a classic. The term is synonymous with the Crown®Macro-Tech Series of power amplifiers.
That product line, and its predecessor Micro-Tech®, sparked
innovative technologies that provided lower distortion, less thermal stress, higher output power, greater reliability, more power density and superior audio quality. No compromises, no gimmicks. Just brilliant engineering backed by superior manufacturing, support and an unsurpassed commitment to quality. Like all Crown amps, the defining characteristic of the Macro- Tech Series is sonic accuracy. A tight, rock-solid low end, with smooth, detailed highs and a well-defined midrange. In short,
Crown Macro-Tech Series
Enjoy!
the most accurate reproduction of an audio signal you’ve ever heard. And because we put the quality of sound above all else, Crown amplifiers are the most coveted in the business. When it comes to manufacturing amps, our work is based on one simple fact: there are no shortcuts to quality. And our Macro- Techs have proven this time and time again in some of the most demanding applications in the world. For this special, limited Macro-Tech release, we wanted to bring you more than just the typical operation manual. This brochure goes much further, delving into the Macro-Tech’s development, design philosophy, and advanced technical features. We’ve also included some brochures from the past, a bio of Crown’s chief R&D engineer Gerald Stanley, customer statistics, anecdotes and more.
Since 1984, Crown has shipped approximately 272,625 MT and MA amplifiers to date. That’s approximately 54 million watts into 4 ohms or 65 million watts into 2 ohms!

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Crown Macro-Tech amplifiers were used at the 64,640-seat Sangam Stadium in Seoul, South Korea, during the 2002 World Cup.

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A Sampling of Crown Macro-Tech Users
THEME PARK Universal Studios Everland (Korea) Six Flags of America FIXED INSTALL Club Capitale Sydney 2000 Olympics Crystal Cathedral Official All Star Cafe Hard Rock Live Experience Music Project Spirit, Roxy Deep night clubs
TOUR Neil Diamond tour Pro Show, SPL Sound, XFL Seoul Word Cup 2002 Audio Analysts Morgan Sound Clair Brothers Disturbed (band) Art Garfunkel Tour Maryland Sound Gemini Sound On Stage Audio Enterprise Live
STADIUM / ARENA American Airlines Arena American Airlines Center Ralph Engelstad Arena Key Arena Xcel Energy Arena Conseco Field House Coors Field Volkswagen Stadium Hong Kong Stadium Racks of Crown Macro-Tech amplifiers power this 2001 extravaganza staged in Salt Lake City’s Salt Palace for the Annual Gala held by Utah Governor Mike Leavitt. Rocky Mountain Audio Visual chose Crown Macro-Tech along with JBL Vertec speakers to provide concert-quality sound for the event. (Find out more at http://www.jblpro.com/pressroom/rmav_utah.htm.)

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Crown Macro-Tech amplifiers power the premium sound system employing JBL PD Series speakers in the 400,000 sq. ft. Ralph Engelstad Arena in Grand Forks, North Dakota.

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The Macro-Tech Design Philosophy
The Macro-Tech product line, and its precursor
Micro-Tech®, awed the audio industry with new
technologies that reduced distortion and thermal
stress — while increasing reliability, audio quality, power density and power output. Three patented technologies invented by Crown’s Gerald Stanley led to those benefits: •Grounded Bridge™topology provided 4 times the power of
existing power transistors without sacrificing reliability.
•Junction Temperature Simulation (JTS), otherwise known
as Output Device Emulator Protection (ODEP®), protected
the power transistors from overheating and maximized their potential power output by keeping them at the optimum temperature.
•Variable Impedance or VZ®power supply, also called bi-level
power-supply switching, was used in the MA-3600VZ and MA- 5000VZ Series. The supply changes its impedance to adapt to the signal voltage and current. This technology permits large amounts of power in a compact package while achieving ultra- low distortion and without generating excess heat.
How It All Began... The brainstorming for this whole family began with collaboration between engineers Gerald Stanley and Jim Wordinger. In considering the drawbacks of current power amplifiers, they were looking for ways to: •pack more power into a smaller rack space •improve reliability by preventing overheating •lower the cost per watt. Gerald’s Grounded-Bridge design and Junction Temperature Simulation were already in his toolkit. In 1975, JTS was employed in the SA-2 and PSA-2 amplifiers, while Grounded Bridge was used in the M-600. Gerald and Jim thought, “How about taking our two best technologies and putting them in the same product?” The Micro-Tech Series was born. The original name of this series was to be HVA for High Value Amplifier.
How about
taking our
two best
technologies
and putting
them in the
same product?”

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In those days, Crown was recognized as a manufacturer of home hi-fi products. But the HVA Series was intended for pro audio Touring and MI, not for the living room. It was a new direction for Crown. Crown’s president at that time, Max Scholfield, recognized that Crown’s marketing needed to be shaken up, so he hired Dr. Clay Barclay to drive change in Crown’s marketing and sales divisions. Clay realized that the MI and Touring industries needed a product like this, and he sold the idea to Crown and to potential customers.
A 1983 schematic by Gerald Stanley of the Grounded Bridge circuit.

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Micro-Tech Jim and Clay used to share ideas over lunch, where Jim told Clay about the concept. Clay came up with the name “Micro-Tech” because the goal was to put high technology into a micro-sized amp. It was a new packaging paradigm as well as a new market. In the early 1980s, Jim Wordinger went to Showco, one of the major touring sound companies. At that time they were doing sound for David Bowie using PSA power amps. According to Jim, “We asked them what they would like to see in an amplifier.” “They said, ‘We’d like them smaller and lower-cost.’ I couldn’t say anything about what we were working on, but their comment certainly vindicated our design goals. Showco was one of our first customers; they used a lot of Micro-Techs. We had a relationship with them. They would find any problems first and then we’d fix them.” Eventually Clair Brothers bought Showco. Now they are using over 2000 MA-3600VZs.
The MT-700 (never released) was the first Micro-Tech amp. Then came the MT-1000 which provided 1000 watts into 2 ohms. Next was the MT-1200 which produced 1200 watts, thanks to bigger power transformers. The technology in Micro-Tech products helped Crown develop amps for Magnetic Resonance Imaging (MRI). General Electric asked Crown to make amplifiers with more voltage and current than what was available. We created bigger amps for GE, such as the 7780, using JTS and Grounded Bridge.
An early sketch by Jim Wordinger showing a proposed chassis layout of a pre-Micro-Tech power amplifier.

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Macro-Tech Building on our experience with the MT series, Gerald and Jim developed the Macro-Tech Series in 1987. It added Plug- In-Processors (PIP™cards) and offered a better appearance.
Jim Wordinger remembers, “In the early days we’d compare MA amplifiers side-by-side with competitive amps. Ours had more punch and deeper bass, which I attributed to more output voltage and current.” The huge Macro-Tech 10,000 amplifier was basically an MRI amp modified for audio use with a new audio interface and front panel.
It was developed for John Royer and Tom Allebrandi who did sound for the Indianapolis 500. Three of these amps were modified to drive the race track’s 240V distributed-speaker system — replacing two huge war-surplus amplifiers from a battleship.
“We supplied the first Macro-Tech prototypes to John McBride of MD Systems, doing a tour for Garth Brooks. At one gig, the FOH engineer noted that he had to keep pushing the level up in the midrange. The problem wasn’t with the amps. Actually, MD had burned up
two-thirds of the midrange drivers because they weren’t used to seeing that kind of power. Crown shipped in 24 drivers, installed them, and wired them differently. Problem solved. That’s the kind of support Crown would do.”
Crown Macro-Tech 10,000.
...they weren’t
used to seeing
that kind of power.”

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In 1992, Crown engineer Andy Archias worked on the MA-5000. Crown’s upper management was delighted that the amp had such a positive impact on the company, the music industry, and the audio world. MA-5000s were even used on destroyers and aircraft carriers (and still are today). A major supporter of MA amps was Sam Helms, manager of Sigmet, a premier pro audio representative in New Jersey. Sam put Crown amps through all sorts of torture tests. As he says, “We put low-frequency square waves into the amp and drove a subwoofer with that signal. This was to show how the MA’s damping factor controlled speaker-cone motion compared to the competition. It was no contest.” “Using a signal generator, we put 60 Hz in the front end of the amp, ran the level controls up, got high-power out of the amp and welded pieces of metal with it! Or we’d take an AC cord, cut off the end of it, put on a banana jack, plug it in the back of the amplifier, and run a drill off it. The competition would shut off and the Crown amp would just keep going. You could drill through a 4x4 with no problem at all.” Crown’s elite studio amplifier, the Macro- Reference™, used the same main board as the
MA-3600VZ, but with remote load sensing for higher damping factor. It was the best-measuring
MA-5000s are used on
destroyers and aircraft carriers.”
amp Crown ever made. Around 1992, Crown introduced the MA-24x6 and MA-36x12 amps with a different power rating in each channel for bi-amping woofers and horn drivers. VZ technology (with bi-level power supply switching) was first prototyped in an MA-1200. It was feared that the switching would affect the audio, but that did not happen. The first bi-level amps were MRI units custom-made for Picker International, a medical imaging company. Jim Stembel, Crown’s International Business Development Manager, recalls: “At the trade show in which we introduced the MA-3600VZ, it was the first amp with that much power in two rack spaces. One of our biggest competitors asked, ‘Why put all that power in two rack units?’ We replied, ‘Because we could.’ That power density was unheard of at the time. It was quite a significant landmark.” “When we introduced the MA-5000, one of our major customers asked, ‘Why does anybody need that much power?’ Again it was an amplifier ahead of its time — it was so large compared to anything else on the market. At the time, nobody appreciated the power of the MA-5000. Of course, the MA-5000 has gone on to become a wildly successful amp in touring sound — a standard. They really were trend-setting amplifiers.” 10 years ago in Pro Sound News, a poll reported that 9 out 10 of the major tours used Crown, mostly MA amps. We still have die-hard customers who refuse to use anything else. So, starting with Grounded Bridge, invented in 1971, and JTS, invented in 1974, those two key pieces of technology enabled the Micro-Tech and Macro-Tech family. After a long lifetime, most of those products are still running. That’s what we think they should do.

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About Gerald Stanley The mastermind behind the Macro-Tech Series, and
all Crown solid-state electronics for over 40 years, is our senior vice president of R&D Gerald Stanley.
Gerald recalls, “When I was a kid I used to go around to neighbors to get old radios. I liked to get parts out of them, and I liked to soup them up.” This early interest in electronics led to an amazing career. This brilliant engineer joined Crown part-time in 1964, first working as a tape-recorder tech, draftsperson and engineer, when he designed the SA-20-20 and SA-60-60 — the first solid-state Crown amplifiers. In 1965 he received a BSE from Michigan State (Honors College) and MSE from the University of Michigan in 1966 (State College Fellowship). Gerald has this to say about the SA-60-60: “It was a dual 60W 8-ohm amplifier. Only a few were made. They were unreliable, using only high-speed fuses for protection. The SA-20-20 was a 1-rack-space amp that soon became the SA-30-30. The SA- 20-20 used smaller versions of the SA-60-60 output devices. The 60-60 was DC coupled throughout and the 20-20 was AC coupled at the input. The DC-300 was not the first DC audio amp, but it was the first that was reliable.” Gerald went on to invent the technology behind all of Crown’s power amp series. He holds a huge number of patents: 31 in the U.S. alone, and many more in other countries.
Gerald comments on Crown’s success over the years:
In an era of cookbook
designs and buggy software, it would seem that the most basic lessons of history have been forgotten. Crown’s recipe is simple: design, build and service each product as if you were the customer. This approach not only drives the product to excellence, it drives the people to be the best that they can be.”
Crown’s Vice President of Research and Development, Gerald Stanley.

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Macro-Tech Advanced Features The Macro-Tech Series employs a number of innovative, patented technologies. Let’s look at them in detail. IOC®(Input Output Comparator)
The IOC circuit compares the output signal of the amplifier with the input signal. If there is any difference other than gain, then it is considered distortion and the IOC indicator flashes. This LED lights whenever there is distortion of 0.05% or more. (Note that amplifier clipping is typically close to 3% THD.) An IOC condition also is sensed by an IQ-PIP module installed in PIP-compatible amplifiers. IOC is designed to report any form of distortion. IOC not only checks the waveform for distortion, but also reports input overload and even a protective action that mutes or shuts down an amplifier. With all of these features, IOC monitors the entire amplifier. When the IOC indicator is off, the amplifier is definitely operational and undistorted. IOC provides a real-time proof of performance.
Output Device Emulation Protection (ODEP)
Gerald invented ODEP to solve two long-standing problems with amplifier designs: •Preventing amplifier shutdown during demanding operation, and •Increasing the efficiency of the output transistors. ODEP limits the signal when necessary to prevent overheating and failure of the amplifier output transistors. Crown engineers established a rigorous program to measure the safe operating area (SOA) — related to temperature — of each output transistor before installing it in an amplifier. Gerald also designed intelligent
circuitry to simulate the instantaneous operating conditions of those output transistors. Its name describes what it does: Output Device Emulation Protection or ODEP. It not only simulates the operation of the output transistors but it also compares their operation to their known SOA. If more power is about to be asked of the output devices than they are capable of delivering under the present conditions, ODEP immediately limits the drive level until it falls within the SOA. Limiting is proportional and kept to an absolute minimum — only what is required to prevent output transistor damage. When ODEP limiting begins, the IOC circuitry will see that the input waveform does not match the output waveform, and an error signal is generated. If the compressors are on, they will see the error signal and compress the input signal to correct the problem. When this happens, there is no audible signal degradation. Compression is subtle, and not noticeable unless the system is driven to extremely high levels. How does ODEP limiting increase the efficiency of the output transistors? It keeps them at the optimum temperature. The transistors are neither overheated, nor overprotected. Overprotecting results in transistors not being driven to their full output level. In short, ODEP enables the amplifier to use the output transistors more efficiently while greatly increasing their reliability. Finally, the status of ODEP is monitored in two ways. First, the front panel ODEP indicators show whether the amplifier is functioning correctly or if ODEP is limiting the drive level. Second, ODEP data is fed to the PIP connector at the back of the amplifier so advanced
One of Gerald Stanley’s many patents.

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PIP modules like the IQ-PIP-USP3 can use it to make decisions and control the amplifier. With ODEP you get the maximum power with the maximum protection — the show goes on! Grounded Bridge
Crown’s Grounded Bridge topology makes the amplifier deliver peak-to-peak voltages to the load that are twice the voltage seen by the output devices and twice the voltage generated by the power supplies. In other words, the amplifier can produce louder sound without stressing the output transistors. The results are higher efficiency, lower distortion and superior reliability.
Class AB+B Crown invented the Class AB+B amplifier design, which provides both high efficiency and low distortion. AB+B circuitry draws less AC power and wastes less heat than Class A, and has less distortion than Class B or Class AB. To explain how AB+B works, first we need to explore other amplifier classes. Audio power amplifiers are classified primarily by the design of the output stage (the transistors and related circuitry that send signals to the loudspeakers). Classification is based on the amount of time the output devices (power transistors) are made to operate during each cycle of the signal. Amplifier classes are also defined in terms of output bias current (the amount of current flowing in the output devices with no signal present). In Class A operation, both output transistors conduct continuously for the entire cycle of signal swing, so the bias current flows in the output devices at all times. Both devices are always on. Class A amplifiers are single-ended designs with either PNP or NPN output devices. Class A is the most inefficient of all power
Grounded Bridge theory for electronics-savvy readers The power-supply bridge rectifier is not ground referenced, and the transformer secondary is not center- tapped. This allows the power supply to deliver +VCC and -VCC from the same bridge rectifier and filter as a total difference in potential regardless of their voltages with respect to ground. Composite output devices are arranged to function as gigantic NPN and PNP devices. Each output stage has two composite NPN and two composite PNP devices. The devices connected to the load are referred to as “high-side NPN and PNP” and the devices connected to ground are referred to as “low-side NPN and PNP.” Positive current is delivered to the load by increasing conductance simultaneously in the high-side NPN and low-side PNP stage, while decreasing conductance of the high-side PNP and low-side NPN in synchrony. Imagine a graph of current versus voltage (I versus V) in an output stage of a power amplifier. This graph has four quadrants: +V and +I, -V and +I, –V and –I, +V and –I. Grounded Bridge is a four-quadrant amplifier topology. Resistive loads only use the first and third quadrants (+V, +I and -V, –I). Reactive loads also use the second and fourth quadrants (–V, +I and +V, –I).
amplifier designs, averaging only 20%. Because of this, Class A amplifiers are large, heavy and run very hot. That is because the amp runs constantly at full power. On the other hand, Class A designs have the least amount of distortion. Class B operation is the opposite of Class A. Both output devices are never allowed to be on at the same time. The bias is set so that current flow in a specific output device is zero when not stimulated with an input signal. Each output device is on for exactly one half of a complete sinusoidal signal cycle. Due to this operation, Class B designs show high efficiency, but poor linearity around the crossover region. This is because it takes time to turn one device off and the other device on, causing extreme crossover distortion. All of this restricts Class B designs to applications with low power consumption, such as battery operated two-way radios and other communications equipment.

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Class AB operation allows both devices to be on at the same time (as in Class A), but just barely. The output bias is set so that current flows in a specific output device appreciably more than a half cycle, but less than the entire cycle. That is, only a little current is allowed to flow through both devices — unlike the complete load current of Class A designs — but enough current to keep each device operating so they respond instantly to input voltage demands. Thus the inherent non-linearity of Class B designs is eliminated, without the gross inefficiencies of the Class A design. It is this combination of good efficiency (around 50%) with excellent linearity that makes Class AB the most popular audio amplifier design. Class AB+B design involves two pairs of output devices. One pair operates Class AB, while the other (slave) pair operates Class B. Class AB+B designs are just as efficient as Class AB, but have even less distortion. To summarize, AB+B circuitry draws less AC power and wastes less heat than Class A, and has less distortion than Class B or Class AB. Variable Impedance (VZ)
VZ is the name of Crown’s patented bi-level power supply technology. It allows Crown to pack large amounts of power into a compact package while achieving ultra-low distortion and without generating excessive heat.
An amplifier power supply must be large enough to handle both the maximum voltage and maximum current the amplifier needs to drive its rated power into a specified load. In order to meet this requirement, most conventional supplies are heavy, large, and produce lots of heat. In contrast, the VZ supply gets more current AND voltage out of a smaller, lighter, and more efficient package by dynamically adapting to both signal and load requirements in real- time. This provides the best power match to the widest range of loads. The VZ power supply is divided into two segments. When the output stage requires high voltage, the segments are arranged in series to deliver twice the voltage of a single segment. When the output stage requires high current, the segments are arranged in parallel to deliver twice the current of a single segment. Sensing circuitry “watches” the voltage of the signal to determine when to switch VZ modes. The power supply continuously adapts to the output signal: high voltage or high current. The switching circuitry is designed to prevent audible switching distortion to yield the highest possible dynamic transfer function.
It allows Crown
to pack large
amounts of power
into a compact
package...”
A Circuit Diagram from the VZ Patent.

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Normally, the power supplies operate in the high-current (low-impedance) mode for maximum thermal efficiency. When the voltage demand spikes, the supplies quickly shift into high-voltage (high-impedance) mode. Because voltage and current requirements vary with the output level and frequency content of the source signals, the power supplies are designed to be able to continually switch between the two modes as needed with no degradation to the audio signal. With VZ, you get not only maximum power, but also the best power matching to your load. ILoad/ILimit (MA-5000) This LED indicates the maximum real-world load that you can put on your amplifier. The ILoad/ILimit feature is designed to help you get the maximum power out of your amplifier. In the real world, loudspeaker impedance varies with frequency, and loudspeaker impedance ratings are only approximations. Without ILoad/ILimit, you have to do some lengthy calculations to approximate the maximum number of loudspeakers you can drive with the amplifier — and this does not allow for a 4-ohm loudspeaker whose impedance drops below 2 ohms at 80 Hz. This is why your amplifier has ILoad/ILimit. The ILoad function turns a channel’s ILoad/ILimit indicator green when it senses that current is flowing to the load. The ILimit function turns the indicator red when it reaches maximum current output. This makes it possible to connect real loudspeakers and conduct realistic tests to find the maximum number of loudspeakers that should be connected. To do a test like this, you can operate under worst- case conditions and continue to connect additional loudspeakers in parallel with each output until the ILoad/ILimit indicator turns red. The optimum load is achieved before the ILoad/ILimit indicator turns red, so disconnecting the last added loudspeaker gives you an optimized load.

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Loudspeaker Offset Integration Loudspeaker Offset Integration (LOI) protects speakers from damaging asymmetrical waveforms, DC and ultrasonic signals. LOI circuits use double integrating filters in the amplifier’s feedback circuitry to protect loudspeakers in several different ways. First, they center asymmetrical audio waveforms that cause off-center woofer cone movement. Off- center cone movement increases loudspeaker heating and distortion while reducing the loudspeaker’s power handling ability. Second, LOI filters unwanted DC and subsonic frequencies using a third-order Butterworth filter with a 35- Hz corner frequency. Third, LOI filters unwanted ultrasonic frequencies (RF) that can cause tweeter burnout using a second-order Bessel filter with a 50-kHz corner frequency. LOI does NOT protect loudspeakers from large transient voltages or excessive power levels for prolonged periods of time. For information on techniques to protect loudspeakers, refer to the Crown Amplifier Application Guide, available online
at www.crownaudio.com.
PIP™ Modules
PIP (Programmable Input Processor) modules provide features that can be added to customize the amplifier. PIP modules plug into the connector inside the back panel of the amplifier. Features range from error-driven compressor/limiters to remote control and monitoring via System Architect or IQwic™. Your amplifier is a PIP2 amplifier, which means it can take advantage of the many advanced features found in PIP2 modules, as well as all standard PIP modules. Visit the Crown website at www.crownaudio.com, or contact Crown Customer Service, for descriptions of available PIP and PIP2 modules.
Reference articles on Macro-Tech amplifier technology Go to the Crown website’s Amplifier Technical Information page at this address: http://www.crownaudio.com/amp_ htm/ampinfo.htm. Under the heading “Other Crown Amplifier Technologies” check out these articles: •IOC Distortion Detector •Understanding Damping Factor •Grounded Bridge Topology •ODEP (Output Device Emulator
Protection).
In the 1990s, nearly 9 out of 10 major touring companies chose Macro-Tech amplifiers to power their sound systems.

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•1971: Gerald Stanley invents Grounded Bridge topology. •1974: Gerald invents Junction Temperature Simulation (JTS). •1975: M-600 was the first amp to use Grounded Bridge. SA-2
and PSA-2 first used JTS.
•1984: MT-1000 was the first combination of Grounded Bridge
and JTS, and Crown’s first amp intended for the MI and Touring Sound markets.
•1985: MT-1200 was a higher power version of MT-1000. MT-
600 also was released. MT-1200LX and MT-600LX had a fancy extruded front panel and more displays.
•1986: MA-10K provides 10,000 watts of power. The first MA-
10K application is to power 465 speakers at the Indianapolis 500 Motor Speedway.
•1987: MA-1200 and MA-600 (with PIP panels). •1991: MA-3600VZ featuring Variable Impedance (VZ) bi-level
power supply switching. VZ technology was first prototyped in an MA-1200. The first bi-level amps were MRI units custom- made for Picker.
•1992: MA-5000VZ also features Variable Impedance.
MA-3600VZ and MA-5000VZ quickly become the touring standards. MA-24x6 and MA-36x12 for bi-amping are introduced.
•1999: MA-602, 1202, 2402 and MA-5002VZ.
Crown Amplifiers Time Line
VZ theory for electronics-savvy readers VZ offers a simple way to apply Class-H operation to a Grounded Bridge circuit. Class H changes the power supply voltage from a lower level to a higher level when larger output swings are required. Class H also modulates the higher power-supply voltage by the input signal. This allows the power supply to track the audio input and provide just enough voltage for optimum operation of the output devices. The Grounded Bridge has a particularly simple supply needed for Class H in that only one supply needs to be rail switched, whereas a common half-bridge (totem- pole) output stage needs two such switched supplies per channel. The bi-level (VZ) supply is further elegant in that the power supply is always fully utilized in both high- and low-voltage configurations. No segments of the power supply are wasted.
Amp room at SooYoung Ro Church in Pusan, South Korea.

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A page from Audio Engineering Society Preprint 959 (N-1), “What Watt in Amplifier Testing” by Gerald Stanley and Robert McLaughlin.
An early sketch of a Micro-Tech schematic by Jim Wordinger.