I built my first headphone amp

[Fixion]

My onboard nForce2 could barely drive my headphones when I was listening to music with lots of drums and bass, so I figured I needed a headphone amp.

A few weeks ago I had to propose a project for class (EE255 Electronics 1 Lab) and design/build it for a semester project. So I designed a 3 stage (per channel) class AB headphone amp, and just last night got around to actually building an audio quality version... well... the transistors are still lacking in quality but the rest is good.

Here's a pic of my first version:

The headphones in this pictures aren't mine, they're my brothers Sennheiser HD 497s

Specs:
-2 channel
-Buffered input
-10x Gain
-2x MAX412 opamps
-4.5V/us slew rate (in theory)
-2.8MHz bandwith (10x gain)
-Gain steady from 15Hz to about 100kHz (measured with an oscilloscope)
-Class B power amp stage biased into class AB with active loads
-Works with low impedance headphones (although I wouldn't try anything lower than 16 ohms with these transistors, they might start burning up).

Unfortunatly I only had generic transistors, if I get some higher quality transistors and match their gain by hand, it may sound even better. But the quality difference with the amp is noticable, especially in loud music with an abundance of brums and bass. I'm not sure if this is considered a "good" design, but it sounds good to me. When I settle on a final design, I'll make a circuit board for it and make one that fits in my pocket

Now I just need some better headphones...

What kind of amps do you guys use?

 

[FiZ]

Nice! Next semester I am going to need to do a project for a similar class. I may just steal your idea . I have made a couple CMOY amps and currently I use a HeadRoom Micro amp.