Martin Audio – MA900 Amplifier
E
NGLISH
12
MA90 0
- 40 dB
CLIP
PROTECT
ON
WARNING: To prevent electric shock, do not operate the amplifier with any of the loudspeaker cable
conductors exposed.
8
OPERATION
8.1
Operating precautions
•
Make sure that the power switch is set to “OFF” before connecting any input or output or operating the
switches on rear panel. See pages
8
about installation.
•
Make sure that the AC mains voltage is correct and the same as the one printed on the rear panel of the
amplifier. See pages
8
, about operating voltage and power consumption.
•
Make sure that the switches on the rear panel for operation modes, gain-switch and clip-limiter switch are
in the correct position. See page
6
about operation modes and page
13
about clip limiters.
•
It is always a good idea to turn down the gain controls during power-up, to prevent speaker damage in
case a high signal is present at the input.
8.2
Powering up – Soft start
•
W he n yo u p ow e r up th e am p lifier it ta ke s a cou ple o f se con ds to self-che ck. T his is kno wn a s the "soft-sta rt"
o r "slo w -sta rt" seq u en ce . T he fa ns th en b lo w a t h ig h sp e ed b e fo re g o in g into "id le " a nd the tw o b otto m g re en
L ED ’s illu min ate to sh ow th e am p lifie r is o p eration al.
8.3
Input attenuators
T he two in pu t level atte n ua to rs on th e fron t p an e l ad ju st th e sig na l leve l fo r the ir re sp ective a mp lifie r ch a nn el in a ll
m od es. T he y a re calibrate d in d B ’s to h elp settin g up a ctive lo ud sp e aker system s.
In brid g ed m o de , bo th co n trols m ust b e in th e sa m e po sitio n, so tha t the lo ud sp e aker lo ad w ill b e sha re d e qu a lly
b etwe en th e cha nn els.
8.4
Indicators
T he yellow L E D's at th e top ind ica te if a ny prote ctio n
circu its a re activa ted . T he se a re de scrib ed on p a ge
13
T he C lip /lim it LE D's ind ica te w h en th e am plifier ou tp ut is
clipp in g o r lim itin g . It ha s tw o d ifferen t ind ica tion states
•
W he n th e clip lim ite r is en ga ge d it h as a sh ort tim e
con stan t a nd illu min ates brie fly.
•
W he n th e clip lim ite r is no t en g ag ed it h as an
incre ase d tim e co nstan t a nd it illum ina te s for a lo ng er
p erio d.
The ”-40 dB” LED’s illuminate if the output signal is greater than -40dB (with 0dB as reference to full output power).
These LED’s also act as signal present indicators.
The two bottom green ”ON” LED’s indicate when the power supply and the output circuits are receiving the correct
rail voltage.
9
PROTECTION FEATURES
E ach MA R TIN A UD IO M A series a mp lifie r h as m a ny a d va nced prote ctio n fea tu res, th a t will prote ct b o th the am plifier
a nd the lo ud spe akers con n ecte d to it, sho uld a fa ult co n ditio n arise .
Under normal use these features are inaudible. All protection circuits operate independently.
All material © 2007. Martin Audio Ltd. Subject to change without notice.
