My Headphone Amplifiers


Here are some pictures of yesterday's project, a headphone amp I designed around the popular OPA627 and BUF634 from BB.

Note I could not find my box of metal films so the carbon films I had lying around had to do. Yes, I know for audiophile devices they are not prefered but I can't really tell much of a difference audibly anyway. :)

Sounds really good, good rail filtering and lack of ground loops = no audible noise at all even though I am not using regulated supplies.

All caps are misc Panasonic FC electrolytics and 0.1uF 1206 SMT for decoupling. The OPA are in sockets so I can swap between OPA134 and OPA627 to see the difference in sound quality.

Rails are +/- 15V.



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Here are my two headphone amps sitting by each other.

The one in the black case is a similar unit based on 4 x OPA627 that runs off two 9V batteries for +/- 9V. It is small and self-contained so as to take along with my portable CD player, note the headphone jack input on it.

I would say that they both sound about the same, I can't give an honest comparison through because I have not run the black unit from my reference CD player, just the portable. The opposite is true of the mains-powered unit, I have never run that one with the portable. If I got some adapters from headphone jack - RCA and visa-versa I could easily do a comparison between the two.



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