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<blockquote data-quote="zako" data-source="post: 7917926" data-attributes="member: 629735"><p>The PPI P900.4 is one of the most efficient amplifiers in its class, which means that for a given power output level, it&#039;s current draw is relatively low. It&#039;s about 85% efficient at maximum power powering 4ohm speaker. However, there is no way around the fact that if you need big power, you also need big current draw. The P900.4 comes with 75A fusing, but it needs this because at the highest output testup (all channels either running at 2ohms or bridged at 4ohms), it will produce over 900watts RMS with 14.4V battery. If you need this kind of power, then there is no way around the fact you need a fuse at least as big. However, if you run the channels at 4ohms, the amps total output configuration being about 600watts with ALL channels running full tilt, you would need a fuse that&#039;s half as big. Even that kind of scenario is unrealistic. If you have four speakers connected to it, assuming each can actually handle 140watts RMS, you actually never need to send so much power to them continuously.. Even if half of channels are bridged for subwoofer, I wouldn&#039;t worry honestly. If a larger box can be installed, I might have preferred to use a 10 inch ported subwoofer just to maximize the SPL for a given amount of power, but 8 ported could still produce satisfying bass on 450watts.</p></blockquote><p></p>

[QUOTE="zako, post: 7917926, member: 629735"] The PPI P900.4 is one of the most efficient amplifiers in its class, which means that for a given power output level, it's current draw is relatively low. It's about 85% efficient at maximum power powering 4ohm speaker. However, there is no way around the fact that if you need big power, you also need big current draw. The P900.4 comes with 75A fusing, but it needs this because at the highest output testup (all channels either running at 2ohms or bridged at 4ohms), it will produce over 900watts RMS with 14.4V battery. If you need this kind of power, then there is no way around the fact you need a fuse at least as big. However, if you run the channels at 4ohms, the amps total output configuration being about 600watts with ALL channels running full tilt, you would need a fuse that's half as big. Even that kind of scenario is unrealistic. If you have four speakers connected to it, assuming each can actually handle 140watts RMS, you actually never need to send so much power to them continuously.. Even if half of channels are bridged for subwoofer, I wouldn't worry honestly. If a larger box can be installed, I might have preferred to use a 10 inch ported subwoofer just to maximize the SPL for a given amount of power, but 8 ported could still produce satisfying bass on 450watts. [/QUOTE]

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