Briged amp from Balanced Input Signal

[barnabas1969]

Jer,

You seem to be missing what I'm saying. You are correct that you cannot do it the way I explained IF you use the POSITIVE OUTPUTS on both the left and right channel of the amplifier. If, however, you wire the inputs the way I explained and use the POSITIVE OUTPUT on one channel AND THE NEGATIVE OUTPUT on the other channel, it will work just fine, I promise.

[geraldfryjr]

Yes, you may have been confusing me in your explaination,

"the POSITIVE OUTPUT on one channel AND THE NEGATIVE OUTPUT on the other channel"

If you are referring to the source output then yes you are correct.

But this is were you had started to confuse me,
"The + outputs of the amp will be IN PHASE, but the opposite outputs will be OUT OF PHASE" and,
"connect the + output from the source to BOTH the + inputs of RIGHT and LEFT"
I also definitely read this one wrong as well,
" your speaker would be connected to + on the right and - on the left."

You must try to be exact when explaining such things as sometimes things can get quite confusing,I know I have been there before and I have had to spend many hours retyping an explanation before.

In my last explanation I had caught an error in #5 were I had used a (+) when it should have been a (-). he,he

Sorry for the confusion.

jer

[barnabas1969]

Here's what I was saying:

1) Connect the + output from the source to both amplifier + inputs.
2) Connect the - output from the source to both amplifier - inputs.
3) Connect the speaker + to the Left + output of the amplifier.
4) Connect the speaker - to the Right - output of the amplifier.

This will have the affect of summing the left and right amplifier power. It will do exactly the same thing as this:

1) Connect the + output from the source to the left amplifier + input.
2) Connect the - output from the source to the right amplifier + input.
3) Ground the - inputs of the amplifier.
4) Connect the speaker + to the Left + output of the amplifier.
5) Connect the speaker - to the Right + output of the amplifier.]

I've highlighted the main difference between the two approaches in red, bold text.

[geraldfryjr]

No,I don't think that you are understanding correctly.

The signals of the amplifiers must be out of phase to work in a bridged mode.
The - outputs of the amplifiers are tied to ground and bare no signal at all.

Unless it is an amplifier that is already configured in a BTL mode as in Car audio devices, in which if that were the case this would bare no advantage at all.

In a bridge configuration only the + outputs are connected to the load and are the only points that are active.

The - outputs of the amplifiers are just GROUND the same ground that is connected to the input side (source) of the amplifier,A simple continuity test can confirm this.

The only exception to this is when if the amplifier has a balanced input and is configured for unbalanced operation,where the - input (source) gets tied to ground as well.
Otherwise it would be just a matter of swapping the - and + input signals on one of the amplifier inputs (source output) in order to run them in a Bridged mode.

In a bridged mode configuration the output voltage will be twice the voltage of a what single amplifier can produce, With of course all things being equal.
Therefore supplying 4 times the power output providing that the amplifiers can produce the current that is demanded from them.
Or it will produce double the power of a single amplifier at an 8 ohm load into a 16 ohm load when configured as bridged .

jer

[barnabas1969]

Originally Posted by geraldfryjr

The - outputs of the amplifiers are tied to ground and bare no signal at all.

And there is where you are wrong. I haven't seen an automotive audio amplifier with the - speaker output tied to ground since the 80's.

The OP was asking about connecting his factory head unit to an aftermarket amplifier, no?

[paulb]

Originally Posted by geraldfryjr

Unless it is an amplifier that is already configured in a BTL mode as in Car audio devices, in which if that were the case this would bare no advantage at all.

Originally Posted by barnabas1969

I haven't seen an automotive audio amplifier with the - speaker output tied to ground since the 80's.

If the speaker outputs' - terminals are not grounded they are already BTL and there is no point in trying this.