Designing a super low distortion headphone amp.

[00940]

Here's a super simple circuit. You can bias it low for headphone use or, with a large heat sink, bias it high enough for small speakers. Just be sure the heat sink is adequate. Today I'd use an LME opamp, but 5532 or 5534 is very good. MOSFET choice is non-critical and it's also nice because no P channel devices are needed. I'd also use a polypropylene cap rather than a mylar.

Nice, simple design but something bothers me. With the resistors values as shown, don't you have a huge offset with the ne5534 ? It would be fine with jfet opamps though.

 

[RocketScientist]

I think riding on the advanced isolated, complementary bipolar semi processing and development $, deep expertise of the A/DSL op amp designers is worthwhile - no audio "guru" has near the resources, institutional knowledge or budget that these chip designers do

That's very true. And National has demonstrated the same thing with their LME49xxxx line of audio parts. I was especially impressed that National went to the trouble and expense to build a high-end listening room with Wilson Watt speakers, a floating floor, tube traps, etc:

National Semi Audio Sound Room

That said, I'm still interested in further exploring the various schools of thought on headphone amps--both with measurements and blind listening. National, AD, Burr Brown/TI, etc. are mainly IC companies. So their solutions use IC technology. Some argue the old saying "when you have a hammer everything looks like a nail" applies here.

I suspect using the best audio ICs results in the best measured performance you can get in a headphone amp. But, I know many who argue it's still not the best sound.

So that's something I want to explore further by comparing an ultra low distortion IC-based headphone amp to a discrete comparatively low feedback Class-A design. What will blind testing reveal? What will differencing tests reveal?

Does anyone know if such a thing has been done and the results published somewhere?