Crown 280ma Manual Suplementario

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Crown International
1718 W. Mishawaka Rd.
Elkhart, IN 46517-9439
TEL: 574-294-8200
FAX: 574-294-8FAX
www.crownaudio.com
 280MA
12/07                                                        138058-1B    
Specifi cations subject to change without prior notice. Latest 
information available at www.crownaudio.com. 
Crown and Crown Audio are registered trademarks of 
Crown International. 
Printed in U.S.A.
© 2007 Crown Audio
®
, Inc.
Architectural & Engineering Specifi cations
C O M M E R C I A L   A U D I O   S E R I E S
280MA
The Crown
®
 280MA shall be a mixer-amplifi er for commercial and 
industrial audio. It provides 4-ohm and constant-voltage outputs (70V and 
100V).
The 280MA has 8 inputs and dual 80W power amplifi ers for two-zone 
systems.
Specifi cations
The 280MA shall have the following specifi cations:
Minimum guaranteed power into 4 ohms or 70V/100V output: 80W maxi-
mum power at 1 kHz with 0.5% THD. Frequency Reponse (at 1 watt from 
4-ohm tap, 70 Hz - 19 kHz): +/- 1 dB. Frequency Response (at line out, 
20 Hz to 20 kHz): +/- 1 dB. Power Bandwidth (at 4-ohm tap, 2 dB below 
maxium 1 kHz power): 50 Hz to 20 kHz with < 0.5% THD. Signal to Noise 
Ratio (ref. to rated power, master volume at minimum): 85 dB. DC Output 
Offset:  < ±5 mV. THD: Less than 0.5% at rated power at 1 kHz. Input 
Sensitivity (for full output at maximum gain): Balanced mic inputs 3 mV, 
balanced line inputs 800 mV, RCA connectors 400 mV.  Input Impedance 
(nominal): Mic 400 ohms, line 100 kilohms, RCA 50 kilohms. Crosstalk:  
–70dB at 1kHz. Line Output Level (nominal): 1V into 10 kilohms. Phantom 
Power: 15 VDC. AC Line Voltages Available: 100V  50/60 Hz, 120V  60 Hz, 
220V  50/60 Hz, 230V  50/60 Hz, 240V  50/60 Hz. Operating Temperature/
Humidity: 0 degrees C to 40 degrees C at 95% relative humidity (non-con-
densing). Storage Temperature: –20 degrees C to 85 degrees C. 
Front Panel Controls and Indicators
Front panel controls and indicators shall include the following:
Power Switch: Pushbutton on-off switch. Input Volume Controls: eight 
microphone/line, detented potentiometers with knobs. Output Volume 
Controls: One per output channel, detented potentiometer with knob. Tone 
Controls: Bass and Treble non-detented recessed potentiometers on each 
input channel, Bass ±10 dB at 100 Hz, Treble ±10 dB at 10 kHz. Power Indi-
cator: Blue LED indicates power on. Input Signal Presence Indicator: Green 
LED, one for each input channel, illuminates when input signal exceeds 
100 mV (45 dB below full power) from the 4-ohm tap; shall not respond to 
signals from the AMP INPUT connector. Output Signal Presence Indica-
tor: Green LED, one for each input channel, illuminates when input signal 
exceeds 100 mV (45 dB below full power) from the 4-ohm tap; shall not 
respond to signals from the AMP INPUT connector. Clip Indicators: Red 
LED, one per output channel, illuminates at threshold of audible distortion, 
shall not respond to signals from the AMP INPUT connector. 
Rear Panel Controls and Connectors
Rear panel controls and connectors shall include the following:
Reset Switch: Resets the circuit breaker that protects the power supply; 
220/230/240V units shall have a fuse instead. AC Power Inlet: Detachable 
IEC. Auxiliary Power Input: 2-position terminal strip for 24 VDC(±10%) 
backup power; accepts up to 14 AWG terminal forks. Amplifi er Outputs 
Connectors: One per channel, 4-position terminal strip with Com, 4 ohms, 
70V and 100V terminals; accepts up to 14 AWG terminal forks, non-touch 
cover included. Output VCA Connector: 4-pin Phoenix-type connector for 
two VCA control lines of +10 VDC and ground; compatible with Crown 
1-VCAP and 4-VCAP modules. Amp Confi g Switch: A DIP switch with 
two functions which shall be 1. Assign an input as the priority input for 
each output, thereby temporarily muting the remaining inputs; muting is 
activated by contact closure.  2. Global enable switch for phantom power, 
shall not affect RCA inputs.  Priority Connector: 3-pin Phoenix-type con-
nector shall allow Input 1 or Input 5 to mute other input signals by contact 
closure. Input Routing Switch: DIP switches shall assign each input signal 
to each output, two switches per input. Line Out Connector: One 3-pin bal-
anced Phoenix-type connector per output channel,  post master, pre-VCA, 
with level control. Input Connectors shall include a Mic/Line Connector of 
3-pin Phoenix-type, balanced, one per input channel, and a dual RCA Input 
Connector for stereo music signals, unbalanced, summed together, two 
connectors per input channel.  Mic/line Switch: Selects mic-level or line-
level signals, one switch for each balanced input. Link In/Out Switch:  Slide 
switch, one per channel. With the Link Switch IN, any signal applied to the 
Amp Input connector shall be mixed with the input signal(s). With the Link 
Switch OUT, only the signal from the Amp Input Connector shall appear at 
the amplifi er output. 
Miscellaneous
Cooling shall be by convection. Included protection mechanisms shall 
be current limiting, over-temperature thermal cutout, and DC-fault load 
protection. 
Included accessories shall be a power cord, detachable rack ears, screws 
for rack ears, non-touch cover for output connectors, Phoenix-type con-
nectors, and spade lugs. Optional accessories shall be a 1-VCAP remote 
volume control for one channel, and a 4-VCAP remote volume control for 
four channels.
The dimensions of the mixer-amplifi er shall allow for 19 inch (48.3 cm) 
EIA standard (RS-310-B) rack mounting. The mixer-amplifi er shall be 3.5 
inches (8.9 cm) tall, and 12.2 inches (31 cm) deep behind the rack-mount-
ing surface (not including the non-touch cover).
The mixer-amplifi er shall weigh 25.3 lb (11.5 kg).
The mixer-amplifi er shall be designated the Crown 280MA.