The Wheatfield Audio HA-2 Headphone Amplifier
We believe that the Wheatfield Audio HA-2 is the best-sounding headphone amplifier that you can buy.
The HA-2 is an all-tube, OTL (Output Transformer-Less) amplifier. It uses only triode tubes, and employs no negative feedback.
It uses a 6SN7 triode voltage amplifier stage, follower by a 7236 or 6080 cathode follower stage. It uses a 5U4 or GZ37 tube rectifier.
The design of the HA-2 had two main goals: one, to provide the best possible sound, and two, to provide it without excessive frills that add to the cost of the amplifier. We believe that we've succeeded in this delicate balance between sonic excellence and reasonable cost.
Connected to a good CD player, we believe that the HA-2, along with a good pair of headphones, can provide you with the best possible listening experience.
This is an oscilloscope screen shot of the HA-2's response to a 10 kHz square wave. The top trace is the input to the amplifier; the bottom is the output, into a resistive load.
Note the clean transitions and the lack of any overshoot or ringing. This is something that no transformer-coupled amplifier can duplicate.
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