Classic 47 Headphone Amp – Reloaded

Common Chinese headphone amp circuit with a few modifications. I have yet to test different resistors that set the output impedance… i may change the 100k resistors to 1M.

Can use NE5532 chips or upgrade to OPA2134PA – both sound great,

You will need a regulated fixed voltage power supply to run this circuit.

This circuit runs on 9-18v – i tested it with 12v works great. You should be able to run this on 2 x 9v batteries… in which case no power supply needed.

An LM78xx & LM79xx power supply can be found HERE

AN LM317 & LM337 Power Supply can be found HERE

Etch at home files for large capacitors can be found HERE

Etch at home files for standard capacitors can be found HERE

This circuit in the current stage its in… Sounds great. There has been talk of the original Chinese version being very susceptible to EMI… You will need some sort of metal case, or simply keep away from close proximity of phones and power lines,

A side note… the 10k potentiometer works great with my input source (Line Level) the attenuation on my iphone is not great, you may have to play around with a larger value potentiometer to suit your input device… this is directly in relation to the volume control.

Classic 47 Schematic – with jumpers.
Board Layout with larger input capacitor.
Layout standard capacitors.