[_atari_]

I am currently working on an dac/headphone amp project (something quite simple). Currently I am working on a grounding and got two questions:

1) Is it better to separate the headphone and circuit ground like this:
/-->opamp->GND
TLE2426-
\-->opamp->buffer->headphone ground

or

TLE2426->opamp->GND->opamp->buffer->headphone ground
(can in the later case the 2nd opamp left out?

2) any recommendations for the opamps (the second one probably the same as for the left/right channel (classic OPA627? - still not decided)?
I am current thinking of an OPA551 for driving GND.

The whole circuit (without driving headphones via buffers) will have something like 100-150mA (PCM2702 + 3 opamps)

Thanks for your help!

more details (schematics) will follow soonish (some weeks).

 

[heatmizer]

I'm thinking tle to a opa551 would make for a good ground or go 3 channel.
Either way "virtual ground" will have to be separate from the dac ground.

 

[_atari_]

Quote:

Originally Posted by heatmizer /img/forum/go_quote.gif I'm thinking tle to a opa551 would make for a good ground or go 3 channel. Either way "virtual ground" will have to be separate from the dac ground.

Why this (really curious)?

Should not the signal ground of the DAC be the same as the ground of the amp?

All papers about grounding suggest using shared ground for DAC and analogue circuit. A split ground is said to introduce more noise.

 

[HIPPOhifi]

Quote:

Originally Posted by _atari_ /img/forum/go_quote.gif I am currently working on an dac/headphone amp project (something quite simple). Currently I am working on a grounding and got two questions: 1) Is it better to separate the headphone and circuit ground like this: /-->opamp->GND TLE2426- \-->opamp->buffer->headphone ground or TLE2426->opamp->GND->opamp->buffer->headphone ground (can in the later case the 2nd opamp left out?

Just keep your digital ground seperate from you analogue ground, then connect them using a couple of vias and a thin track.

Quote:

Originally Posted by _atari_ /img/forum/go_quote.gif 2) any recommendations for the opamps (the second one probably the same as for the left/right channel (classic OPA627? - still not decided)? I am current thinking of an OPA551 for driving GND.

I recommend AD843's for the ground channel, 627/637's for the left and right, personal preference though.

 

[Bjornboy81]

Quote:

Originally Posted by HIPPOhifi /img/forum/go_quote.gif Just keep your digital ground seperate from you analogue ground, then connect them using a couple of vias and a thin track.

I agree to keep them seperate and then reconnect them (if they can be...same potential and all), but please explain why you would use a couple of vias and a thin trace.

As long as they are connect back at the PS, as close to the ground rereference as possible, then there isn't any special way of connecting them.

Curious as to technique.