Crown Audio 2400 Voltage Amplification, Grounded Bridge Topology, Last Voltage Amplifiers LVAs

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Micro-Tech 2400 Amplifier Service Manual

Theory

amplifies the difference between input and output

The ODEP transistors steal drive as dictated by the

signals, any difference in the two waveforms will

ODEP circuitry (discussed later). The control/protec-

produce a near open loop gain condition which in turn

tion transistors act as switches to totally shunt audio to

results in high peak output voltage. The output of the

ground during the turn-on delay, or during a DC/LF or

Error Amp, called the Error Signal (ES) drives the

Fault protective action.

Voltage Translators.

 

VOLTAGE AMPLIFICATION

Last Voltage Amplifiers (LVAs)

The Voltage Translator stage channels the signal to

The Voltage Translator stage separates the output of

the Last Voltage Amplifiers (LVA's) in a balanced

the Error Amp into balanced positive and negative

configuration. The +LVA and -LVA, with their push-pull

drive voltages for the Last Voltage Amplifiers (LVAs),

effect through the Bias Servo, drive the fully comple-

translating the signal from ground referenced ±15V to

mentary output stage. The LVAs are configured as

±Vcc reference. LVAs provide the main voltage ampli-

common emitter amplifiers. This configuration pro-

fication and drive the High Side output stages. Gain

vides sufficient voltage gain and inverts the audio. The

from Voltage Translator input to amplifier output is a

polarity inversion is necessary to avoid an overall

factor of 25.2.

polarity inversion from input jack to output jack, and it

 

allows the NFb loop to control Error Amp gain by

Voltage Translators

feeding back to its non-inverting input (with its polarity

A voltage divider network splits the Error Signal (ES)

opposite to the output of the VGS). With the added

into positive and negative drive signals for the bal-

voltage swing provided by the LVAs, the signal then

anced voltage translator stage. These offset reference

gains current amplification through the Darlington

voltages drive the input to the Voltage Translator

emitter-follower output stage.

transistors. A nested NFb loop from the output of the

GROUNDED BRIDGE TOPOLOGY

amplifier mixes with the inverted signal riding on the

offset references. This negative feedback fixes gain at

Figure 2 is a simplified example of the grounded

the offset reference points (and the output of the Error

bridge output topology. It consists of four quadrants

Amp) at a factor of -25.2 with respect to the amplifier

of three deep Darlington (composite) emitter-follower

output. The Voltage Translators are arranged in a

stages per channel: one NPN and one PNP on the

common base configuration for non-inverting voltage

High Side of the bridge (driving the load), and one

gain with equal gain. They shift the audio from the

NPN and one PNP on the Low Side of the bridge

±15V reference to VCC reference. Their outputs drive

(controlling the ground reference for the rails). The

their respective LVA.

output stages are biased to operate class AB+B for

 

ultra low distortion in the signal zero-crossing region

Also tied into the Voltage Translator inputs are ODEP

and high efficiency.

limiting transistors and control/protection transistors.

 

 

BGS

VGS

Error

+15V

 

 

 

Voltage

+VCC

 

 

 

 

 

Translators

 

Audio

+

+

Amp

Divider

 

 

 

 

NPN Outputs (+HS)

+

 

 

 

 

 

 

 

 

 

 

Q100

Q121

Q101

Q105

 

 

 

 

 

 

 

Inputs

 

 

 

Voltage

 

 

 

Q102

-

-

-

 

Q103

 

 

PNP Outputs (-HS)

 

 

 

 

 

 

 

 

 

 

Q122

 

Q110

 

 

 

 

 

 

 

 

 

 

 

 

 

- +

Mute

 

 

-VCC

 

 

 

 

-15V

ODEP

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

NFb Loop

 

LVA's

Figure 1. Typical Amplifier Front End and Voltage Amplification Stages.

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Contents MICRO-TECH-2400 Avis Table of Contents Warranty IntroductionScope Parts Information Power SpecificationsVoltage Conversion Theory FeaturesOverview Front END OperationGrounded Bridge Topology Voltage AmplificationLast Voltage Amplifiers LVAs Voltage TranslatorsLow Side LS High Side HSOutput Device Emulation Protection Odep Positive Electrical Checkout Procedures Test 12 Output Power Test 7 Phase ResponseTest 6 Voltage Gain Test 8 Level ControlsPost Testing Test 16 Signal to Noise RatioTest 14 Odep Limiting Test 15 LF ProtectionPower Supply Parts List Non-ModuleOutput Assembly ONE PER Channel Supplimental ItemsOutput Assembly CONT. ONE PER Channel Back Panel AssemblyChassis Front Assembly Miscellaneous Main Chassis AssemblyModule History Module InformationMain Modules Fuse ModuleDiodes M46330-3 Fuse Module & Q43327-8 Display Module Parts ListLeds ResistorsCapacitors Q43354-2 Output Module Parts List P10429-2 BoardInductors TransistorsQ43328-6 MT-2400 Original Main Module Use Schematic J Q43328-6 Main Module Parts List D8679-9 BoardResistor Networks Q43328-6 Main Module Parts List Cont. D8679-9 BoardTest Points SwitchesQ43328-6 Main Module Parts List Cont. D8679-9 Board Q43399-7 MT-2400 Main Module Use Schematic J Q43399-7 Main Module Parts List D8827-4 BoardQ43399-7 Main Module Parts List Cont. D8827-4 Board TP1 TP2 U103A U203A Open

2400 specifications

Crown Audio is a well-respected name in the audio industry, known for its powerful and reliable amplifiers. Among its notable products is the Crown Audio 2400, a high-performance amplifier that has garnered attention for its impressive range of features and technologies.

The Crown 2400 is part of the XTi series, which is renowned for delivering exceptional sound quality and performance. A key feature of the 2400 is its innovative Class-I technology. This design allows the amplifier to remain highly efficient while producing substantial power output, making it suitable for a variety of applications, from live sound to installation settings. With a power rating of 2400 watts per channel at 4 ohms, the XTi 2400 provides ample power for driving multiple speakers, ensuring that audio can fill even the largest spaces.

Another standout characteristic of the Crown 2400 is its built-in DSP capabilities. This onboard digital signal processing allows users to tailor the audio output to their specific needs. The DSP features include adjustable crossover settings, EQ adjustments, delay settings, and limiting functions, all accessible through an intuitive LCD interface. This user-friendly design enables quick adjustments in real-time, which is critical in dynamic live performance environments.

The amplifier also boasts advanced connectivity options, including both XLR and 1/4-inch input connectors, allowing for versatile integration with various audio sources. Additionally, the inclusion of Speakon outputs provides secure and reliable connections to speakers, minimizing the risk of accidental disconnects during performance.

Thermal management is another area where the Crown 2400 excels. The amplifier is equipped with a comprehensive cooling system, which includes a variable-speed fan and extensive heat sinking. This design ensures that the amplifier operates efficiently even under heavy load, prolonging its lifespan and maintaining optimal performance.

Finally, the Crown Audio 2400 is designed with durability in mind. Its rugged construction makes it suitable for the rigors of touring and demanding live environments, reinforcing Crown's commitment to quality and reliability.

In conclusion, the Crown Audio 2400 stands out as a powerful and versatile amplifier, offering Class-I technology, robust onboard DSP, excellent connectivity options, advanced thermal management, and durable construction. These features make it an ideal choice for audio professionals seeking reliability and high performance in their sound systems.
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