Montarbo GRAVIS 24, Руководство пользователя

Страница: 8 / 12

7
Protection circuits
1. CLIP/Limit
This feature has two protection functions:
1) Limiting the input signal level to prevent input signal overloading beyond amplifier rated input level,
thus causing square wave output damaging the speaker.
2) When the signal waveform distorts, it can automatically adjust gain and limit distorted signal output.
Note: If input signal is +22dBu (10V) even clip limit will be helpless, so do not increase input source
signal unlimitedly.
2. Soft clip
This function can be selected by rear panel ON/OFF dip switches. When the input signal exceeds the
set range, it will smoothly limit the input waveform range.
3. Overheat protection
1) When the amplifier works at full load for a long time, fans could reach higher speed. If this condition
continues and the amplifier transistor temperature rises to 95 degrees, the first-step power decrease
(halving output power) will be activated, to ensure that even overheating still there's program output.
Power reduction according to different music content, amplifier will be recovered to be original output
power in 3-10 minutes.
2) When the amplifier works for long time in overload, without ventilation or external temperature higher
than 35 degrees,the amplifier is in the first phase of power reduction and no eased, the amplifier
transistor temperature rises to 105 degrees, the fully protection will be activated and no signal will be
output. In this condition, the PROT (protection) LED and temperature LED are simultaneously on.
Suggestion: Do not connect to the amplifier loads under 4 ohms, don't place the amplifier in
high-temperature environment and without air flow.
4. VHF protection
If the amplifier output has reached a certain level and large amount of frequencies exceeding 10KHz,
like a mic feedback, then the amplifier may go into VHF protection after 3 seconds. In this case the PROT
(protection) LED on the front panel will be lit, the amplifier will have no output, but it will be recovered
automatically after 10 seconds protection circuit activation. If the output signal does not change , the VHF
protection will continue to be active.
5. Short-circuit protection
All our company Gravis series amplifiers are provided of short-circuit protection. This protection makes the
output transistors working in a safe range. When output is in short-circuit, the PROT (protection) LED on
the front panel will be lit and the amplifier has no output. The amplifier will be recovered 10 seconds after
the end of short-circuit removal.
6. AC Power Supply Protection
If the AC mains voltage is lower than the minimum allowed working voltage (~165V), the power supply will
be automatically turned off until when the mains voltage returns in regular range.
7. DC protection
1) In order to protect the speaker, the DC protection circuit will be activated, when the output signal has
large DC voltage (=2.6V). In this case the PROT (protection) LED on the front panel will be lit, and the
amplifier will have no output.
2) If there is DC output and the relay circuit is open, there's a protection circuit to force the amplifier output
to burn the fuse to protect the speakers.
Ex-factory settings
1. All the volume adjustment knobs were set at "-80dB" position. 2. Power switch was set "OFF".
3. Soft clip dip switches set "ON". 4. Working mode selector dip switches set at "STEREO" place.
5. Sensitivity selector dip switches set at "0.775V" place.
Use environment
1. The room temperature shall be kept around 25 degree when used indoor. The amplifier can't be used
at too high temperature environment or such temperature may cause components damages due to
over-heat.
2. If used outdoor, please avoid sunshine and rain damped, or it would shorten equipment's life.
3. a. Environment temperature: -10
°
C
～
40
°
C b. Relative humidity: less than 90%
c. Air pressure: 80kPa
～
106kPa
Applications
Gravis series has been designed for live concert, disco, night club, etc.