I publish now as definitive after so many hours of listening test:
EARphone PURE AUDIOamp II
(upgrade of the EARphone PURE AUDIOamp AD826)
Self-made 100 mW
Desktop Headphone Amplifier.
- hi speed bipolar opamp ( AD826 & LT1364 )
- class A buffer input
- hi current parallel buffer output
- mixed type opamp output configuration for colorless tonality
- double output impedance
- dual board, separate channel circuits
- fine regulated dual power supply
- Schottky rectifiers in power supply
- NP (Non-Polar) power supply electrolytics
- film shunt capacitor
- low quantity and value rail capacitors
- constant impedance volume attenuator
- star grounding design
- AC/DC balancing resistor
- DC offset null circuit
- one year project
- components brand and value empirically selected
- more than 20 releases before the schematic approval
We everybody know that different brands of chips differently sound, but I never thought that they, once mixed and paralelled together, would sound better !!
This mixed configuration not only preserves but reciprocally enhances the clear and full harmonic midrange of the AD826 with the dynamic and accurate soundstage of the LT1364.
