[Ask] Bridge amplier topology

[mulyo]

I'm still don't understand the advantage and this advantage between this two bridge topology. Can anyone explain the advantage and this advantage?

[Ian Finch]

The signal is fed to each of 2 amplifiers' input terminals in reversed phase. The output then, as measured between both positive terminals, is twice that from either single amplifier positive to negative terminal (in normal configuration). That is what "Bridge-Tied Load" means. That is also the same basic scheme for connecting 2 separate mono amplifiers or stereo channels in "bridge-mode" as you see in PA and automotive applications.

Thus you have twice the voltage swing and power for the same supply voltages but you don't have matching increased current capability, so the load impedance rating should be raised from say, 4R minimum to 8R minimum for an equivalent safety margin.

It is a popular means of extending a basic range of amplifier products by just adapting them to BTL connection but the limited current capacity requires better protection and careful planning. It could be said that it is better to use more appropriate designs in the first place.

[mulyo]

Thank you for the explanation

[AndrewT]

The bridged amplifiers deliver double the power to the doubled load impedance.
If you sum the total power delivered by each of the amplifiers to it's rated load, you will find that the two amplifiers deliver exactly the same power as the bridged arrangement. NOTHING is gained by bridging.

Two 50W into 4ohms amplifiers deliver 100W into the two 4r0 loads.
A bridged pair of these same amplifiers delivers 100W into 8r0.
Exactly the same power from both arrangements.

[FoMoCo]

Originally Posted by AndrewT

NOTHING is gained by bridging.

There is some cancellation of distortion by bridging. In theory, close to perfect. In reality, closer to nothing.

[sregor]

One advantage is that bridged amps can be run direct coupled with single PS voltage. One of the reasons it is so common in car amps.

[JMFahey]

NOTHING is gained by bridging

Well, no *extra power* is gained, but it can be achieved at a more convenient impedance.
That counts as "gaining" in my book.
Besides the classic car audio amps, I can offer another example from the MI world: the excellent Crate Powerblock guitar amp has two 75W/4r amps , which forces you to find two 4 r Guitar speakers (not very common) or carry two 2 x 12" cabinets (bulky) *or* , thanks to bridging, get 150W/8r , which allows you to make a single compact and very loud single 12" cabinet, using, say, an EVM12L or equivalent.

[DRC]

Am I looking at a different image ??

Configuration 1 clearly won't work but I could guess it is suppose to be an "Alexander" type amplifier ?

dc

[mulyo]

Originally Posted by DRC

Am I looking at a different image ??

Configuration 1 clearly won't work but I could guess it is suppose to be an "Alexander" type amplifier ?

dc

I got from electroschematics. 200W Transistor Audio Amplifier Circuit I don't know if it work or not. I'm still learning about audio amplifier

[Ian Finch]

That schematic is correct but difficult to understand unless you know what to look for. Try this:
Google Image Result for http://lenardaudio.com/education/images/a12/a12_bridge-management.gif