4 Pin Amp output to 3 Pin headphone jack?

[strays2k]

Hello- I'm new here and wondering if anyone can help me out with making a small circuit...

I have a four pin amplified audio output on a prototype motherboard and I am looking to convert this to a 3 pin output so I can then attenuate and use standard headphones.

The one caveat is that the amplifier is push/pull. Therefore, there are no grounds- AC is fed to each speaker as the polarities have opposite sin waves. I understand they make 4 pin headphones but this will not suffice. Using one channels ground will not work either as it sounds quite distorted.

Is this possible? If anyone can point me in the direction of a component or circuit that would do this I would be SO greatful! It seems simple but in reality....its over my head!

-JEFF

[robertkd]

so what you have is a balanced output (differential drive) any clue as to what exactly it is that you have ?

does it run single rail or dual rail supply ?

what solution are you really looking for

simple might be as simple as putting a capacitor with the a' output and return to ground.

A transformer

a balanced to unbalanced circuit, although it may well be easier to replace the whole circuit.

[rickcr42]

If I understand correctly you want to use a balanced bridge amplifier to power "normal" headphones that use a common ground ?

Well the easiest solution would be to use headphones with a "custom" cable like those meant to be used with "balanced" headphone amps (HeadRoom and others)

The other option is to wrangle up a resistor matrix to load and isolate the "hots" but on this I am not positive (need to think on it a bit more )

Remember-with a balanced bridge amplifier you are using ALL "Hots" and NO actual ground the "+" amp driving the "+" terminal of the loudspeaker and the "-" output post the "-" terminal so ANY device that has a common ground connection (some speaker selectors,hafler type ambience devices) if used on the output of such an amp will in fact create a dead short from the left side to the right side "-" polarity amplifiers that depending on the protection circuits built into the amp may or may not blow up that "Side" of both channels