Objective 2: The open source headphone amp

o2 Objective 2: The open source headphone amp

NwAvGuy is a man who recently made quite a few enemies in some audio communities and got banned from some enthusiast/audiophile forums as well. He’s rather outspoken and doesn’t beat around the bush when it comes to pointing out flaws in shoddily designed – and often overpriced – gear (which sometimes goes against commercial interests of said sites, unsurprisingly).

Since some of his adversaries asked if he can only criticize other people’s designs or if he indeed has the skills to create better performing devices, he now has a point to prove, it seems. The result is known as the O2 – short for “Objective 2″ – headphone amp.

NwAvGuy was very transparent on his blog regarding the design process of the O2, and he open sourced the schematics under a Creative Commons license. He will not be selling finished amps, but everyone is free to build their own – no matter if for personal use, or for commercial purposes.

Some design principles of the O2 are:

  • State of the art audio performance with most any headphone out there, from the most sensitive multi-armature IEMs to full-sized high-impedance headphones
  • Usage of inexpensive quality parts instead of overpriced “boutique” components
  • Easy to solder and assemble (no SMT components)
  • Precise volume control (no crackling or audible imbalance at low volume levels)
  • No dangerous clicks/pops at turning on/off
  • Usable as a portable or a desktop amp (batteries and AC power)
  • Switchable gain
  • Battery rundown protection

In the end, the price of the parts used in the O2 should come to about $30 (without enclosure, panels, or wallwart) – and according to NwAvGuy the audio performance should be indistinguishable from top quality studio gear like the $1600 Benchmark DAC1. I, for one, am very interested in building my own O2 to find out how it performs.

Detailed info on NwAvGuy’s blog: Part 1, Part 2, Part 3 – and we also got an ABI forum thread about the O2 going on.


MarvintheMartian on August 8, 2011 5:31 PM

I hope it lives up to expectations, so that it delivers a wake-up call to some of those snake-oil vendors that sponsor that website that banned him.

And after that, I hope people post pictures of the finished product over there.

Corinn on August 8, 2011 5:42 PM

lol b& from headfi…

I just might build me one of these. :)

tds101 on August 8, 2011 5:45 PM

This is why I’m so proud to be a member here @ABI – the truth is spoken & no bullshit is tolerated!!! I can’t wait to see the backlash created by this,…well worth it IMO!!!

Jorge on August 8, 2011 8:55 PM

hah! I second tds101, “no bullshit is tolerated” :D

Otacon239 on August 8, 2011 9:32 PM

Wow. I can finally look toward a realisticly priced headphone amp. I was looking at a pair of Sennheiser HD595s, but have been kind of avoiding them due to the fact that I don’t have a player powerful enough to pull it off. So much for that. Time to start saving…

Confispect on August 8, 2011 9:41 PM


kasrhp on August 9, 2011 9:38 PM

Martin, I look forward to hearing about your opinions on this when you build your own. No rush;)

TheGame21x on August 10, 2011 3:46 AM

Well, my interest is officially piqued. I consider myself an audiophile but one with a reasonable budget. I don’t indulge in those stupidly expensive amplifiers that barely outclass my $60 CMoy (if at all) and the promise of an amp that outperforms those stupidly expensive amps for about $30 is intriguing indeed.

Now I just need to learn how to solder…

Dale Thorn on January 27, 2012 2:31 PM

I got the Objective2 already assembled, which is an option now. Very small, beautiful, dangerous if you try using an AC to DC adapter recharger (use AC to AC only!). The sound is flawless. I used a German Maestro 8.35D headphone and it was quiet, well controlled, totally clean at all volumes and with huge dynamics did not have any distortion I could hear.

Giorgio on August 16, 2012 5:54 AM

sorry, but i cant believe its so good, isnt?

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