bridging an LM4881 headphohne amplifier? Can it be done?

[soundNERD]

Hi, I have a some LM4881 chips and have built a headphone amplifier for my portable CD player. The sound is excellent, so I would like to bridge them. The problem, though, is that they only have one input. Is there any way to bridge them short of using something like a DRV134 to invert one amp's input?

thanks!
mike

 

[Alexander Rice]

just stick an inverting buffer before one of the amplifiers

 

[soundNERD]

like the DRV134 right? that takes one signal, invertes it, balences the inverted and non-inverted inputs then has two outputs of the same signal, inverted and non-inverted.

The only problem with that is I only have one and would need two for stereo. I don't think with headphones you would notice the difference when one amp is inverted and not the other, so I could just stick an inverting opamp before the input of one of the amps, right?

 

[Alexander Rice]

that is what i said - inverting buffer = inverting op amp with unity gain, any old thing'll do as long as it i unity gain stable since even TL072 will have a bandwidth well into RF, i reccomend the NE5532 for this type of thing for it's low noise and good value

 

[soundNERD]

OK!
Thanks!

-mike

 

[paulb]

Do you plan to modify your headphone cable to separate the common connection to each channel? Bridging won't work with a 3-wire cable; you need all 4 wires.

 

[soundNERD]

yes, my cable is from a standard pair of headphones, so the connector splits into two seperate cables, one with L and gnd, and the other with R and gnd.

thanks for pointing that out though.

-mike