O2: High Performance Portable/Home Amp

[NwAvGuy]

This has been in the works a while. At the request of friends (and a few critics) I've designed my own portable/desktop amp: The Objective2 (O2 for short).

It's a very objective approach (what would you expect from an electrical engineer?) at a low cost "one size fits all" headphone amp. The goal was to show how much performance is possible on a limited budget. It's designed to outperform even far more expensive desktop amps using solid engineering rather than audiophile designer parts or mythical circuit designs.

To put this amp in perspective it will overall outperform everything FiiO makes including the E9 and E11.

For now it's a DIY amp but it's a free open source design and a few commercial companies have already expressed an interest in offering it as a kit, pre-assembled circuit board (no soldering required) and possibly even as a complete amp. Some have called it the spiritual successor to the Cmoy but the performance is an entirely different league (sorry for not being more modest!). Some highlights:

• Enough output even for difficult headphones like the full size HiFiMan Planars and 600 ohm Beyers (7 V RMS and lots of current). It will drive nearly any headphone from 16 - 600 ohms to "live" levels.
• Completely silent even with the most sensitive BA IEMs (zero hiss with 131 dB S/N )
• Near zero ohm output impedance (0.5 ohms)
• Very low distortion of any kind--some tests push the lower limits of my dScope audio analyzer.
• ~8 hours battery life for the normal version & ~ 30 hours for the low power version
• Indistinguishable from Benchmark DAC1 in blind listening tests
• Switchable gain for use with different source/headphones
• Unique battery rundown protection
• DIY friendly, self contained on a single PC board, no surface mount parts
• Designed for a rugged inexpensive all aluminum case with a pre-made customizable front panel available.

Documenting everything has been a huge project. I've posted 2 articles so far (including detailed measurements) and the third and final article with the rest of the details should be online no later than this coming Wednesday. Bare boards should be available around the end of the month and pre-assembled boards and/or kits could be available as early as September or October.

http://nwavguy.blogspot.com/2011/07/...phone-amp.html

And just to be clear, I'm not selling anything myself, and I don't get a penny of revenue from this design. It's open source hardware licensed under a Creative Commons License.

For the DIY crowd, once I have the final article online, I'll be starting a thread on diyAudio for those interested in building one.

For everyone else, if the O2 is popular, there should be some options in the next few months to purchase it without any soldering or special skills required.

I know many are probably curious about the price, that will be in next article. But as a hint, it was designed to outperform its closest current competitor, the AMB Mini3, in every way including the price.