Set Input Sensitivity, Set Ground Lift Switch

Micro-Tech Series Power Amplifiers

3 Setup

SENSITIVITY SWITCH INSIDE ACCESS HOLE

1.4 V

26 dB

0.77 V

THIS AMPLIFIER IS EQUIPPED WITH SELECTABLE INPUT SENSITIVITY. REMOVE COVER PLATE (ABOVE) TO ACCESS SENSITIVITY SWITCH.

		6		CH-2					CH-1	6
	5	6	7						5	6	7
	4			8					4			8
	3			9					3			9
BALANCED	2			10		INPUT GROUND LIFT			2			10	UNBALANCED
INPUT WIRING	1			11		INPUT GROUND LIFT			1			11	INPUT WIRING
INPUT WIRING	1			11					1			11	INPUT WIRING
+ TIP	0		12		INPUT	LIFT		INPUT	0		12		+ TIP
– RING	GAIN				INPUT			INPUT	GAIN
– RING						(AFFECTS PHONE	INPUTS ONLY.)	(MONO)
GND SLEEVE						(AFFECTS PHONE	INPUTS ONLY.)	(MONO)					GND SLEEVE

GROUND LIFT SWITCH

Figure 3.7 Input Sensitiviy and Ground Lift Switches

3.7 Set Input Sensitivity

The three-position input sensitivity switch is located inside the amplifier behind the MT-XLR module (Figure 4.2 letter “I”). The switch is set at the factory to a sensitivity of 0.775 volt for standard 1 kHz power into 8 ohms. (Factory setting for International versions is 1.4 V.) If desired, the sensitivity can be switched to 1.4 volts for standard 1 kHz power into 8 ohms, or a voltage gain of 26 dB. The 26 dB gain setting is equivalent to a sensitivity of 2.1 volts for the Micro-Tech 600, 2.5 volts for the Micro-Tech 1200 and 3.2 volts for the Micro-Tech 2400.

To change the input sensitivity:

1.Remove the back panel cover plate (or input connector accessory).

2.Locate the access hole for the sensitivity switch inside the chassis opening (Figure 3.7). The sensitivity switch will not be vis- ible because it is mounted below the hole. Use your little finger to reach it.

3.Set the switch to the desired position noted on the label beside the access hole.

4.Replace the back panel cover plate (or input connector accessory).

3.8Set Ground Lift Switch

The ground lift switch (Figure 3.7) is located on the back panel and can isolate the input sig- nal grounds from the AC (chassis) ground. It affects only the phone jack inputs and has no effect on accessory input connectors. Sliding the switch to the left isolates or “lifts” the grounds by placing an impedance between the sleeve of each phone jack and the AC ground.

The Micro-Tech 2400 has two reset switches for its high-voltage power supplies. Refer to the Troubleshooting Section in the unusual event of a tripped breaker.

3.9 Connect to AC Mains

Connect your amplifier to the AC mains power source (power outlet) with the supplied AC power cordset.

WARNING: The third prong of the power connector (ground) is an important safety feature. Do not attempt to disable this ground connection by using an adapter or other methods.

Amplifiers don't create energy. The AC mains voltage and current must be sufficient to deliver the power you expect. You must operate your amplifier from an AC mains power source with not more than 10% variation above or below the amplifier's specified line voltage and within the specfied frequency requirements (indicated on the amplifier's back panel label). If you are unsure of the output voltage of your AC mains, please consult your electrician.

3.10 Startup Procedure

Use the following procedure when first turning on your amplifier:

1.Turn down the level of your audio source.

2.Turn down the level controls of the ampli- fier.

3.Turn on the “Power” switch. The Power indicator should glow.

4.Turn up the level of your audio source to an optimum level.

5.Turn up the Level controls on the amplifier until the desired loudness or power level is achieved.

6.Turn down the level of your audio source to its normal range.

If you ever need to make any wiring or installa- tion changes, don't forget to disconnect the power cord.

For help with determining your system's opti- mum gain structure (signal levels) please refer to the Crown Amplifier Application Guide, available online at www.crownaudio.com.

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Operation Manual