Grado RA1 Headphone Amplifier Clone
Fancy making your own Grado RA1 amplifier clone. Well the circuit below is all you need. About £10 worth of electronic parts minus the case and regulated supply. Also very easy to make on veroboard or protoboard. The original circuit came from diyaudioprojects.com who I understand reverse engineered an original RA1. The design can be easily altered to use other better quality op-amps and more importantly E24 series preferred resistor and cap values.
The opamp used is the LM4562 or better still the OPA2134. You can use the cheaper original JR4556 but the OPA2134 should be easier to buy and is much higher quality than the JR4556.
Put it in a nice case with a power supply like Grado do and you have neat little headphone amp for little cost. Probably one of the simplest circuits to make based around an op-amp as it is a standard non inverting circuit.
Battery or Regulated Supply