[sdiy] Headphone amps using op-amps

Scott Gravenhorst music.maker at gte.net
Wed Dec 12 19:13:58 CET 2012

Tom Wiltshire <tom at electricdruid.net> wrote:
>Hi all,
>If I'm driving a pair of cheap headphones from a standard op-amp 
>(I've got a TL072, a MC1458 or a LF353 available - you don't get 
>much more 'bog standard' than that lot) is there anything special 
>I need to do? 
>Currently I've got a simple differential amp boosting signals 
>from my dsPICs DAC output. That works fine, but plugging 
>headphones into it distorts the output terribly. 
>I've looked at the various "headphone amp" circuits I can find on 
>the web, and none of them seem that extraordinary. For example, 
>classic CMoy: 
>	http://tangentsoft.net/audio/cmoy-tutorial/misc/cmoy-tangent-sch.pdf
>Is this just a case of me trying to blast too much output into 
>the headphones? I've got about 8Vpp. In which case, sticking some 
>resistance in series with the outputs should do the trick, right? 
>Sorry if these seem like pretty basic questions, but I haven't 
>really dealt with headphones before. 

I'd have to wonder if perhaps insufficient current is the problem.  If so, perhaps
after the differential amp, maybe using more than one of those opamps in parallel
might work?  Or maybe that's too cheesey?

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