help needed in Class AB amplifier output

[waqas5304]

hi
i am doing a project in which i am using class AB audio amplifier to drive 8 ohm headphones.
my project has two similar circuit cards one is the main card and second is the standby card . both have same SSM2211. the power supply is used to switch between the main and standby cards.headphone for both cards is same.
what i am doing is that i am connecting the headphone parrallel to both ssm2211. when the main card is selected the power supply is provided only to the ssm2211 on main card and the ssm2211 on standby card is switched off .i think it should work but in reality the circuit gets short . any body has some solution .
the circuit diagram is attached for reference
i hope someone will give a good suggestion
waqas

 

[Audioguru]

You should never short the outputs of two amplifiers together, powered or not.

Mixing of signals is done at the inputs to the amplifiers.

 

[waqas5304]

i think you did not understand the application i am trying to build . i have one headset and to drive it there are two SSM2211, one is the main and other is standby and the selection is controlled by a switch . if you have any other idea to implement the same kindly tell me.

 

[Audioguru]

The outputs of the amplifiers must not be shorted together. Use the switch to select which amplifier the headset connects to.

Your schematic does not show a switch. It shows some wires.

 

[FvM]

One could guess, that some kind of switch is implied with the "wires". There are however clear schematic symbols or terms as N.C., N.O. COM available to show switch operation. Without any clue like this, I just can say: The switch circuit may be wrong.

 

[waqas5304]

ok
i think i have to make the schematic for you people. what i hope you understand the issue???

 

[Audioguru]

Are you using a switch to connect the headset to only one amplifier at a time?

 

[waqas5304]

hi
the headphone is connected to both amplifier all the time . i am using the switch to switch the power supply 5 v to either ssm2211.

 

[Audioguru]

One or both of your amplifiers will blow up.
Disconnect the amplifier that is not being used.

 

[enjunear]

i think you did not understand the application i am trying to build . i have one headset and to drive it there are two SSM2211, one is the main and other is standby and the selection is controlled by a switch . if you have any other idea to implement the same kindly tell me.

I think something got lost with the latest replies. If I read your descriptions correctly, the "select" signal being supplied to the two amps is controlled by a single switch. The outputs of the amps are tied in parallel (I agree with Audioguru, this is a bad idea).

If you are still set on having your switch enable one amp and disable the other, then leave it as is. However, use the signal coming from the switch (maybe +5Vdc?) to also drive a DPDT relay that transfers the headphone High-Low lines to the output of one amp, or the other.