Crown Audio MA-36X12, MA-24X6 operation manual Theory of Operation

Page 19

Macro-Tech MA-24X6 & 36X12 Power Amplifiers

6 Theory of Operation

Each channel is powered by its own power transformer, T100 or T200. Both channels share TF-1, a low voltage transformer. The sec- ondary outputs of each transformer are full- wave rectified by heavy duty bridge rectifiers and are filtered by large computer grade capac- itors. A thermal switch embedded in each transformer protects them from overheating.

The low voltage transformer TF-1 uses a sepa- rate fan motor winding. The TF-1 output is rec- tified by diodes D1-4, generates an unregulated

24volts. Monolithic regulators U1-2 provide a regulated ±15 volts.

For simplicity, the following discussion of the circuitry and operation will refer to one channel only. Please refer to the block diagram in Figure 6.1

The input signal at the phone jack passes directly into the balanced gain stage (U104- C,D). Use of a PIP module for input signal causes the input signal to pass through the PIP and then to the balanced gain stage.

The balanced gain stage (U104-C,D) causes balanced to single-ended conversion to take place using a difference amplifier. From there, gain can be controlled with a potentiometer. The error amp (U104-A) amplifies the differ- ence between the output signal and the input signal from the gain pot, and drives the voltage translator stage.

The voltage translator stage channels the signal to the Last Voltage Amplifiers (LVAs), depend- ing on the signal polarity, from the error amp U104-A. The +LVA (Q105,Q125) and the –LVA (Q110,Q126), with their push-pull effect through the bias servo Q318, drive the fully complementary output stage.

The bias servo Q318 is thermally coupled to the heat sink, and sets the quiescent bias cur- rent in the output stage to lower the distortion in the crossover region of the output signal. D301, D302, D303, and D304 are used to remove the charge on the unused portion of the output stage, depending on the polarity of the output signal.

With the voltage swing provided by the LVAs, the signal then gains current amplification through the Darlington emitter-follower output stage.

The bridge-balanced circuit (U104-B) receives a signal from the output of the amplifier, and differences it with the signal at the Vcc supply. The bridge-balanced circuit then develops a voltage to drive the bridge-balanced output stage. This results in the Vcc supply having exactly one half of the output voltage added to their quiescent voltage. D309, D310, D311 and a trimmer resistor set the quiescent current point for the bridge-balanced output stage.

The protection mechanisms that affect the sig- nal path are implemented to protect the ampli- fier under real-world conditions. These conditions are high instantaneous current, excessive temperature, and operation of the output devices outside safe conditions.

Q107 and Q108 act as a conventional current limiter, sensing current in the output stage. The allowable current level is also adjusted as a function of voltage. When current at any one instant exceeds the design criteria, the limiters remove the drive from the LVAs, thus limiting current in the output stage to a safe level.

To further protect the output stages, a specially developed ODEP (Output Device Emulation Protection) circuit is used. It produces an ana- log output proportional to the always changing safe operating area of the output transistors. This output controls the translator stage by removing any drive that exceeds the safe oper- ating area of the output devices. Thermal sen- sor S100 gives the ODEP circuits vital information on the operating temperature of the heatsink on which the output devices are mounted.

Should the amplifier fail in such a way that would cause DC across the output lead, the DC protection circuit senses this on the negative feedback loop and shuts down the power sup- ply until the DC is removed.

Operation Manual

page 19

Page 18 Page 20
Image 19
Page 18 Page 20
Contents Some models may be exported under the name Amcron MA-24X6MA Series amplifiers require Class 2 output wiring Important Safety InstructionsUse only with a cart, stand, bracket, or table Competent Body’s Name and Address Safety StandardCrown International, Inc TCF Technical Certificate No P4300CRI1.IWSTable of Contents How to Use This Manual FeaturesWelcome Unpack Your Amplifier Install Your Amplifier SetupYou may also stack amps without using a cabi- net Connectors Choose Input Wire Balanced LineDistance Wire Size Choose Output Wire and Con- nectorsSystem Wiring a Macro-Tech 36x12 is shown Wire Your SystemConnect to AC Mains Startup ProcedureTurn up the level of your audio source to an optimum level Operation PrecautionsEnable Indicator Front Panel Controls Indicators Dust FilterSignal/IOC Indicator Odep IndicatorGround Lift Switch Power CordReset Switches Input Sensitivity SwitchOutput Device Emulation Protection Odep Advanced Features OptionsStandby Mode Protection SystemsCircuit Breakers Transformer Thermal ProtectionCircuit Designs Grounded Bridge IQ-PIP-USP2 Adapter Replace the PIP module and restore the powerInput Ground Lift Switch Options PIP ModulesFront panel has several helpful indicator LEDs Figure TroubleshootingOdep and Signal/IOC Indicator States Theory of Operation Only ONE Channel Shown Specifications Output Impedance Power Draw at IdleDimensions WeightTypical Phase Response Following equation is used to calculate thermal dissipation AC Power Draw Thermal DissipationAC Power Draw Thermal Dissipation Service 12/01 WarrantyWorldwide Except USA & Canada Nature of Problem Crown Factory Service InformationThis page intentionally left blank This page intentionally left blank Macro-Tech MA-24X6 & 36X12 Power Amplifiers

MA-36X12, MA-24X6 specifications

Crown Audio is a renowned name in the professional audio industry, celebrated for its commitment to innovation and reliability. Two prominent offerings that stand out in their lineup are the MA-36X12 and MA-24X6 power amplifiers. Designed for versatility and performance, both models cater to a variety of applications, ranging from commercial installations to live sound environments.

The Crown MA-36X12 amplifier delivers 36 channels of robust power, making it an ideal choice for larger systems requiring multiple zones of audio distribution. Its ability to provide a solid output ensures that every speaker in a setup receives the necessary power, maintaining audio clarity and preventing distortion. The MA-36X12 is engineered with a focus on thermal efficiency, utilizing advanced cooling systems to minimize overheating during extended use. Additionally, its compact design allows for easy integration into various environments, whether it be schools, conference centers, or places of worship.

On the other hand, the Crown MA-24X6 amplifier offers 24 channels of audio powerhouse capability. With slightly less power than the MA-36X12, the MA-24X6 is still no slouch; it provides exceptional sound quality, making it suitable for smaller installations or setups requiring fewer channels but high-quality delivery. The MA-24X6 features an intuitive user interface, allowing for seamless adjustments and monitoring of each channel's performance. This amplifier also comes equipped with integrated signal processing capabilities that enable users to fine-tune audio output according to specific acoustics and requirements.

Both models incorporate Crown’s proprietary DriveCore technology, which combines superior sound quality with greater efficiency in amplifying audio signals. This technology minimizes power consumption while maximizing output, ensuring that audio reproduction is both dynamic and clear. Furthermore, Crown’s Smart Amp technology enhances reliability by incorporating self-monitoring functions that provide real-time feedback on performance and status.

In terms of connectivity, the MA-36X12 and MA-24X6 amplifiers come with a variety of inputs and outputs to accommodate diverse audio sources and speaker configurations. Their rugged construction makes them well-suited to endure the rigors of live events and installations, ensuring they deliver consistent performance over time.

In summary, the Crown Audio MA-36X12 and MA-24X6 amplifiers exemplify the brand's dedication to quality and innovation in professional audio solutions. With advanced technologies and versatile features, they respectively cater to both large and small installation needs, making them reliable choices for audio professionals around the globe.
Top Page Image Contents