[sdiy] headphone amp

[Roy J. Tellason]

On Thursday 01 July 2004 03:52 am, Ryan Williams wrote:
> hi,
>
> I was thinking of adding a headphone amplifier and also an attenuator
> for the main output of my modular. this would be a simple little module.
> Can anyone point me to some deccent headphone amplifier schematics? I've
> found a few that seem quite complicated for such a little thing.

For headphones I'd just use the LM386,  though I'm no audiophile,  and some of 
those folks may have some objections to this part.  :-)

> Also, about output impedances, I want this module to have a output that
> will hook straight into my computer sound card (for now). Most of the
> synth schematics I've looked at have a small (few hundred ohm) output
> resistor. Is this neccesarry, or would a 1K that I use for every other
> module be ok? (sound card has max input +2.2dbV and > 10k input impedance)

Are you talking about a few hundred ohm resistor connected to say the output 
of an op amp?  I was of the impression that those were there more to prevent 
oscillations than anything else.  Output impedance doesn't matter all that 
much if it's significantly lower than whatever the input impedance of what 
you're driving...