If you mean for a specific speaker impedance, that is not correct. Bridge amps are used specifically to increase output power for a given impedance by increasing the voltage swing at the load. A single stereo amp used in a car (14V rail) is biased to center line (7V) and swings about 5V up and down from 7V. That means the speaker sees a signal voltage swing of 10V (p-p) which is AC coupled to the speaker whose other terminal is grounded. In a bridge with the same 14V rail, the speaker terminals "float" and one side goes up and the other goes down. It can swing about 12V each way, so that makes 24V (p-p) possible voltage excursion creating much more power for the same speaker impedance which is P = V(sq)/R where R is the speaker impedance.
I'm going to run some simple numbers here...
assume your amplifier is designed for a 10Vpp swing:
Single Amp: 10Vpp into 8Ω = 1.25App --> 1.25A*10V = 12.5W = 20V^2/8Ω
Bridge Amp: 20Vpp into 8Ω = 2.50App --> 2.50A*20V = 50.0W = 20V^2/8Ω
Parallel Amp: (each amp "sees" half the load of an 8Ω speaker):10Vpp into 4Ω = 2.5App --> 2.5A*10V = 25W = 10^2/4Ω
(This assumes the amps are perfectly matched, just for sake of calculation)
So a parallel amp will double the power of a single amp, whereas bridge configuration power goes as V^2.
However if your amps are limited in current drive to, say, 1.25A, the only way is to parallel them...
That is something that is not intuitive... that although you have two amplifiers one configuration has more power than the other.
The power of the chip the OP posted about is doubled when run in mono mode, which speaks of paralleling to me!
The
**broken link removed** shows application circuits for both bridge and parallel schemes; the parallel connection uses some load-balancing resistors to get around the matching problem. Simple enough solution, if not efficient. Should have thought of that a few posts ago.
My guess is that the output stage is limited in its current-drive abilities so if you go for the bridged configuration you will run into some nasty problems above 120W.