UPDATE: New batch arrived today!

The Objective2 (O2) amp was designed by NwAvGuy to have better performance than any commercial headphone amp under $1000 on the market today. He realized this goal with a DIY design that costs only $30 in parts to build.

This PCB will get you started on building this amp yourself (just add $30 in readily available parts). Detailed building instructions including a detailed list of parts with part numbers - which you can use to quickly order all the required parts - is available on NwAvGuy's website (see links on the right under Documentation).

Specifications

• Output impedance less than 2 ohms
• Input impedance >= 10K
• Frequency response +/- 0.25 dB 20 hz – 20 Khz 400 mV 16-600 Ohms
• Phase response less than +/- 2 degrees error 100 hz - 20 Khz 16-600 Ohms
• Absolute phase: Preserved
• Slew Rate greater than 3 V/uS using 10 Khz square wave near full output 600 Ohms
• Distortion under 0.01% 20hz – 20 Khz into 16 – 600 ohms from 10 mV – 400 mV RMS
• Channel separation better than -40 dB @ 16 ohms and –60 dB @ 150 ohms 400 mV RMS
• Channel balance error less than 1 dB at any setting down to –45 dB below max volume
• Noise under –105 dBv (103 dBu) unweighted (5.6 uV or -97 dBr referenced to 400 mV)
• DC offset under 5 mV typical, and ideally, under 20 mV worst case
• 100% stable with any realistic reactive load from 16 – 600 ohms
• Transient ringing and overshoot tightly controlled with all realistic headphone loads and 0.01 uF
• 166 mA per channel, both channels driven, peak current capability at < 1% THD
• 6.25 volts RMS on AC power at < 1% THD into 150 ohms
• 4.5 volts RMS on DC power (nominal battery voltage) at < 1% THD into 150 ohms