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Martin Audio – MA200Q Amplifier
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limiter re du c es the in pu t s ig na l p ro p or tion a lly. No te th at, if th e s ig na l is dis to rte d or c lip pe d b efor e it r ea ch es
the a mp lifie r , th e c lip limiter will no t be ac tiv ated .
U nd er n o rmal op er ation th e clip limiter is ina ud ible. Th e limiter c a n be tu rn ed “O n” or “ Off” by pr es sin g th e
r elev an t c lip limit sw itc h. ( 3 s ee p a ge 5 )
Some ma n ufac tur er s o f lo u ds pe ak e r pr o ce ss or s d o n ot r ec o mmen d the u s e of clip limite r s in a mplifier s, a s it
c an e ffe ct th e tr ac k in g o f th e p ro ce s so r' s limite rs .
If th e a mp lifie r is be in g u se d w itho u t an y e xter n al limiting , Mar tin Aud io r ec omme n d le a ving th e clip limiter s
s witc he d " ON " ( bu tto n de p re ss ed ) .
9.2 Thermal protection
W he n th e a mp lifie r is dr ive n ve r y ha r d in to a lo w imp ed a nc e loa d, th e co o ling fa ns w ill r un at h igh s pe e d. If
the se o p er ating c on d itio n s co ntinu e, th e Pr o te ct in dica tor (s ) w ill illumina te in dica tin g th a t th e a mp lifie r is
a bo ut to g o into th e rmal sh utdo w n.
After five s e co nd s the a mplifie r w ill g o in to th e rmal p r otec t b y mu tin g the inp u t sig na l. Afte r 1 5- 20 s e co nd s
the a mp lifie r w ill h av e c oo le d d ow n e no ug h for th e amplifi er to c ome o ut of s hu tdo wn an d op e ra te as
n or ma l. If th e lo ad co nd ition s r emain u nc ha n ge d the the r ma l p ro te ction w ill b e r e - initiate d. Th er ma l
p ro te ction o c cu rs w h en th e h ea t s i n k t e m p e r a t ur e r ea c he s 90
°
C .
9.3 VHF protection
If a signal of more than 12kHz, at full power is detected, which lasts for more than five seconds, the VHF
protection mutes the input signal. (This is indicated on the front panel (4) by the LED labelled Protect).
After five seconds the outputs will un-mute and return to normal operation, unless the output signal has
remained unchanged, in which case the VHF protection will re-initiate.
9.4 Short circuit protection
All Martin Audio MA Series amplifiers are completely short circuit protected. The protection circuit permits
very high peak currents, but still holds the output devices within the safe operating area. If a sh o rt c irc uit is
maintain ed , the c ha n ne l a ffec te d w ill e ve ntu ally go into a th er ma l p ro te c t cy cle u ntil th e s ho rt circ uit h as
b ee n re mov ed .
9.5 AC mains voltage protection
If the AC mains voltage is outside the operational window (over or under voltage), the power supply will
automatically shut down. When the mains voltage is above the minimum start voltage and below its
maximum operating voltage the amplifier will restart.
The four green ”ON” LED’s indicate when the power supply is operating correctly.
9.6 DC protection
The re a r e tw o typ es of D C p ro te c tion :
• Fus es o n the su pp ly br an c he s of ea ch ch an ne l.
• D C cr ow b ar p r otec tio n th a t sh or ts th e o utpu t if mor e th a n 10 vo lts D C is be in g d etec ted o n the
o utpu ts . Both the se circ u its co me in to effe c t on c e a DC le ve l is de tec te d o n eithe r c ha nn el.
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