I have a multipart question for purposes of a self-tutorial.
Some of this "esoteric" audio information can drive you nuts and often times, is contradictory.....hence, my questions.
Ok....so I have this little USB DAC chip that I've breadboarded......the PCM2902 from TI.
It's really a neat device, taking my computer's WAV files through it's USB port and ultimately outputing a stereo analog signal....all in one chip.
Works great.....and for now I just have the output feeding (2) 47uf capacitors and some bleeder resistors right into my amplifier.
First of all, the chip shows a Vout peak to peak of .6v and an center voltage of .5v and an impedance of 10k ohms.
(Q) Does that mean the output swings between .2v and .8v? I'm not clear on that.
Secondly, I'd like to learn more about the "importance" of a buffer stage.....("unity gain" or otherwise).
Many of the circuits using this chip are taking the output into high quality opamps (analog devices and the like)....but I'm not clear on exactly "why". (This chip sounds damn good with just the caps...right into the amp). (and "maybe", less is better?)
(Q) Based on the .6v p-p figure (low?) and the 10k output Z -- would that mandate a buffer stage? Is there some loading going on that is affecting performance...(that I may not hear?)
(Q) Or are the opamps used to "tailor" the sound of the chip...using the various opamps available and coming up with your own preferred "recipe"?
(Q) Or I suppose, a combination of the two?
Thanks kindly for any education on this....I really appreciate it.