Bob Leonard wrote on Sun, 06 January 2008 00:55 |
No, there are 3 power supplies. One for each side and one common to both sides. Not 3 sides silly.
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Not to continue harping on this, but...
There is little if any practical benefit from two small power supplies vs. one big one. I can even argue that one big one is better. If we visualize what is going on in bridge mode one channel is drawing only from the plus rail(s) while the other channel only from the negative, and vice versa. Using a common PS means each channel can draw upon the full capacity of the whole amp's available current.
I suspect the supplies were split up for packaging reasons. Putting the rail capacitors right next to the output stages could reduce internal wiring losses, and the two could still be wired together, so they will share like one big one during peaks.
I'm not trying to mystify amp design, technology can make a difference but IMO design execution is very important. The lads at QSC have plenty of practice and by now have pretty much figured out what works or not. Their different models are dialed in for different applications and pocketbooks.
JR
PS: Some audiophools will argue separate supplies improve crosstalk between channels but how do you measure crosstalk in bridge mode?