Micro-Tech 2400 Amplifier Service Manual

Electrical Checkout Procedures

TEST 6: VOLTAGE GAIN

Spec 26dB Gain: Gain of 20.0 ±3%.

Spec 0.775V Sensitivity: ±6%.

Spec 1.4V Sensitivity: +12%/–6%.

Initial Conditions: Controls per standard.

Procedure: No load connected. Inject a 0.775 VAC 1 kHz sine wave with the Sensitivity Switch in the 26 dB position. Measure 15.5 VAC ±0.5 VAC at the amplifier output. Inject a 0.775 VAC 1 kHz sine wave with the Sensitivity Switch in the 0.775V position. Measure 64.5 VAC ±3.9 VAC at the amplifier output. Inject a 1.4 VAC 1 kHz sine wave with the Sensitivity Switch in the 1.4V position. Measure 64.5 VAC +7.7/-3.9 VAC at the amplifier output. Return the Sensitivity Switch to the 26 dB position.

TEST 7: PHASE RESPONSE

Spec: ±10° from 10 Hz to 20 kHz at 1 Watt.

Initial Conditions: Controls per standard, 8 ohm load on each channel.

Procedure: Inject a 1 kHz sine wave and adjust for 1 Watt output (2.8 VAC). Check input and output signals against each other, input and output signals must be within 10° of each other.

TEST 8: LEVEL CONTROLS

Spec: Level controlled by level controls.

Initial Conditions: Controls per standard.

Procedure: No Load. Inject a 1 kHz sine wave. With level controls fully clockwise you should see full gain. As controls are rotated counterclockwise, observe similar gain reduction in each channel. When com- plete, return level controls to fully clockwise position.

TEST 9: CURRENT LIMIT

Spec: Current Limit at 38 Amps, ±3 Amps

Initial Conditions: Controls per standard.

Procedure: Load each channel to 1 Ohm. Inject a 1 kHz differentiated (or 10% duty cycle) square wave. See figure 4. Increase output level until current limit oc- curs. Current limit should occur at 38 ±3 Amps (38 Vpk) with output device Vce less than 40 Vpk. Ob- serve clean (no oscillations) current clipping.

InOut

.047 uF

1K Ohm

Figure 4. Differentiator Circuit

TEST 10: SLEW RATE & 10 KHZ SQUARE WAVE

Spec: 17 - 25 V/µS.

Initial Conditions: Controls per standard.

Procedure: Load each channel to 8 ohms. Inject a 10 kHz square wave to obtain 64 volts peak-to-peak at each output. Observe the slope of the square wave. It should typically measure 17 to 25 V/µS. Also, the square wave must not include overshoot, ringing, or any type of oscillation.

TEST 11: CROSSTALK

Spec: -60dB at 20 kHz.

Initial Conditions: Controls per standard. Terminate input of channel not driven with 600 ohms. Procedure: 8 ohm load on each channel. Inject a 20 kHz sine wave into the Channel 1 input and increase output level to 62 VAC. Measure less than 62 mVAC at the output of Channel 2. Inject a 20 kHz sine wave into the Channel 2 input and increase output level to 62 VAC. Measure less than 62 mVAC at the output of Channel 1.

TEST 12: OUTPUT POWER

Spec at 8 Ohm Stereo: >= 520W at 0.1% THD.

Spec at 4 Ohm Stereo: >= 800W at 0.1% THD.

Spec at 2 Ohm Stereo: >= 934W at 0.1% THD.

International 8 Ohm Stereo: >=515W at 0.1% THD.

International 4 Ohm Stereo: >=745W at 0.1% THD.

International 2 Ohm Stereo: >=925W at 0.1% THD.

Initial Conditions: Controls per standard.

Procedure: Load each channel to 8 ohms. Inject a 1 kHz sine wave and measure at least 64.5 VAC at the output of each channel. Load each channel to 4 ohms. Inject a 1 kHz sine wave and measure at least 56.6 VAC. Load each channel to 2 ohms. Inject a 1 kHz sine wave and measure at least 43.2 VAC. All power measure- ments must be at less than 0.1% THD.

TEST 13: REACTIVE LOADS

Spec: No oscillations. Safe with all types of loads.

Initial Conditions: Controls per standard.

Procedure Capacitive: Load each channel to 8 ohms in parallel with 2 µF. Inject a 20 kHz sine wave with 55 VAC output for 10 seconds.

Procedure Inductive: Load each channel to 8 ohms in parallel with 159 µHenries. Inject a 1 kHz sine wave with 35.8 VAC output for 10 seconds.

Procedure Torture: Load each channel with the primary (red and black leads) of a DC-300A transformer (D 5781-6). Inject a 15 Hz sine wave at sufficient output level to cause 3 to 5 flyback pulses, for 10 seconds.

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Crown Audio 2400 service manual Test 6 Voltage Gain, Test 7 Phase Response, Test 8 Level Controls, Test 9 Current Limit
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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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