Crown POWER-TECH 3 Instruction Manual download pdf (Page 9)

Power-Tech .1 Series Power Amplifiers

Page 9Reference Manual

3 Operation

3.1 Precautions

Although your amplifier is protected from external faults,

the following safety precautions are recommended:

1. There are important differences among the Stereo,

Bridge-Mono and Parallel-Mono operating modes.

Please refer to Section 2 for additional information.

2. WARNING: Do not change the position of the

stereo/mono switch unless the amplifier is first

turned off.

3. CAUTION: In Parallel-Mono mode, a jumper is

used to connect the red binding post outputs.

Be sure to remove this jumper for Bridge-Mono

or Stereo mode, or high distortion and exces-

sive heating will occur. Also, make sure the ste-

reo/mono switch is set to the proper position.

4. Use care when making connections, selecting sig-

nal sources and controlling the output level. The

load you save may be your own!

5. Do not short the ground lead of an output cable to

the input signal ground. This will form a ground

loop and may cause oscillations.

6. Operate the amplifier from AC mains of not more

than 10% variation above or below the selected

line voltage and only the specified line frequency.

7. Never connect the output to a power supply

output, battery or power main. Such connections

may result in electrical shock.

8. Tampering with the circuitry by unqualified person-

nel or making unauthorized circuit changes may

be hazardous and invalidates all agency listings.

Remember: Crown is not liable for any damage that

results from overdriving other system components.

3.2 Indicators

When lit, the red enable

indicator shows that the amplifier

has been turned on. It is driven only by the low-voltage

power supply and does not indicate the status of the

high-voltage supplies.

The SPI/IOC indicators flash green in sync with the audio

input signal, and flash yellow if the input waveform differs

from the output by more than 0.05%. IOC reports any

distortion over 0.05% introduced by the amplifier

including harmonic distortion, intermodulation distortion

and clipping distortion.

3.3 Protection Systems

Power-Tech .1 Series amplifiers have extensive

protection systems, including ODEP, ultrasonic/RF

protection, drive protection, transformer thermal

protection and fuses or circuit breakers to protect the

power supplies.

3.3.1 ODEP

Crown invented ODEP to keep the amplifier working

under demanding conditions and to increase output

efficiency. To do this, Crown established a rigorous

program to measure each transistor’s

safe operating

area

(SOA). Intelligent circuitry was then designed to

simulate the instantaneous conditions of the output

transistors. Its name describes what it does: Output

Device Emulation Protection, or ODEP. In simple terms,

ODEP compares transistor conditions to their known

SOA. If more power will be asked of them than they can

deliver under the existing conditions, ODEP limits the

drive until conditions fall within the SOA. Limiting is

proportional and kept to an absolute minimum—only

what is required to prevent output transistor damage.

Under normal conditions, no limiting is required and

ODEP is transparent to the audio signal.

ODEP makes possible a quantum leap in output

efficiency and reliability—with ODEP, the show goes on.

3.3.2 Ultrasonic and Radio Frequency Protection

An amplifier’s slew rate only needs to be large enough to

deliver the maximum voltage at the highest required

frequency. Higher slew rates actually allow undesirable

ultrasonic and radio frequencies to be reproduced. By

design, Power-Tech .1 Series amplifiers have a

controlled slew rate to limit the highest frequencies that

they reproduce. Limiting occurs well above 20 kHz, so

there is no audible effect on performance. This approach

protects the amplifier from radio frequencies and can

even protect some sensitive loads (including some

tweeters).

3.3.3 Drive Protection

The drive protection system temporarily removes output

drive to protect the amplifier and its loads. Drive

protection can be activated in two situations. First, if

dangerous infrasonic frequencies or direct current (DC)

is detected in the amplifier’s output, the unit will activate

its DC/low-frequency protection circuitry which puts the

amplifier in drive protection mode. This protects the

loads and prevents oscillations. The unit resumes normal

operation as soon as the amplifier no longer detects

dangerous output. Although it is extremely unlikely that

you will ever activate the amplifier’s DC/low-frequency

protection system, improper source materials like

infrasonic square waves or input overloads that

excessively clip the input signal can activate this system.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 ... 18 19

Comments to this Manuals

No comments

Crown POWER-TECH 3 Instruction Manual Page 9

Comments to this Manuals

Related products and manuals for Musical Instrument Amplifier Crown POWER-TECH 3