Anyone tried to build LME49600 Headphone Amplifier Evaluation Board??

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It sounds to me, a little bit flat.. needless to say I use as a backup amp :)

Anytime you use the LME49600 you can expect the sound to be "flat" and "lifeless" regardless of the op-amp(s) used in front of it.

Been there done that. I eventually threw my board in the trash after trying many op-amps in front of the '49600.

Too bad T.I. doesn't discontinue it like they have already done with some of National's better sounding offerings.
 
If you look at a sinewave plot then cut it in half (mentally) along the X axis, you get two series of 'lumps' with sharp edges where the cut happened. Those lumps are what the current flow looks like into the LME49600. Such sharp-edged pulses generate rather a lot of high frequency noise at the zero crossing. Then imagine that for music there are many, many more zero crossings than with a sinewave - or rather the density of zero crossings is much much higher.

Since no power supply is perfectly zero impedance the sharp-edged current pulses turn into sharp-edged changes to the voltage on the supplies. When those get into the opamp, 'flat sound' is the result IME.
 
Here's the schematic, its not that complicated - you'll normally need two of these, one for each rail.

On the left that's your input (shown as a voltage source) which is the LME supply, the output to the opamp is to the right.
 

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Here's the schematic, its not that complicated - you'll normally need two of these, one for each rail.

On the left that's your input (shown as a voltage source) which is the LME supply, the output to the opamp is to the right.

Thanks for your help.

In my design, I planned to use two LME49710 and LME49600/BUF634 (For one channel). One LME49710 serve as voltage gain and the other one serve as DC servo, so I need to separate each one with LC filter as the schematic attached??
 

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In my design, I planned to use two LME49710 and LME49600/BUF634 (For one channel). One LME49710 serve as voltage gain and the other one serve as DC servo, so I need to separate each one with LC filter as the schematic attached??

No, you'll only need two filters (so two Ls, two Cs) unless you're adopting separate L,R channel construction (when you'll need four). Both the LME49710 on a single channel can be powered on the same rails as their outputs are barely loaded.

On the schematic you've shown you only need L1 and L4 and C1,C4. L2,L5,L3,L6 are replaced with wires and C2,C3,C5,C6 are omitted.
 
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