# Bridge mode with amplifiers?

1. Jul 30, 2013

I read that bridge mode in amplifiers will, for example, take a 100 watt amplifier at 8ohms and turn it to a 200 watt amplifier at 4ohms.

I was going to use 2 tda2050 amps, each running one speaker, but if I use 2 amps in bridge running 2 8ohm speakers in parallel, would this give me double power into both speakers? So as if each speaker had it's own amplifier twice as strong?

If I didn't explain that well please tell me

2. Jul 31, 2013

### Crazymechanic

Well draw yourself a schematic , and you'll see that in bridge mode two channels which would normally run in stereo mode and be connected to separate speakers are now connected to the same speaker.
Can an amplifier do this depends on the circuit layout and transistors used etc but the thing you need to know is what is the lowest resistance it can drive in such a mode , as normally you would have an 8ohm load to a stereo channel for a bridge it will look like 4 ohms, because each of the channel sees only half the load.

About the twice as strong part I doubt that.
It is said that in bridge mode an amplifier can drive a maximum power which is higher than that if it connected in stereo or mono modes but that even though higher is not twice as high , you can't get power out of nowhere just magically connecting something in a different way.

If you have two of those integrated chips and you put them i bridge you can drive your one 8ohm speaker in mono mode with a higher power rating , so to drive 2 of those speakers you will need in total of 4 tda chips.And sufficient power supply ofcourse.

By the way as you mentioned two 8 ohm speakers in parallel would be one 4ohm speaker and putting those 4 ohm in bridge mode would mean a 2ohm load on channel, before you do this check the design specifications of the TDA chip!!!

3. Jul 31, 2013

I don't know much about bridge so I am not questioning you, but how does the 4 ohms make it 2 ohms, as you said in your last paragraph?
I that a rule in bridge mode that your resistance will cut in half or something?
And so If I put two 8 ohms in parralel with bridge mode, each speaker will not recieve the same higher power, and just draw twice the current?

4. Jul 31, 2013