Headphones and Earphones
- Written by John E. Johnson, Jr.
- Published on 22 July 2010
All Burson products including the HA-160 share several unique design features, other than simplicity. The first and foremost Burson design philosophy is to use no integrated circuits anywhere in their products. Everyplace a typical manufacturer might use an op-amp, a voltage regulator or the like, Burson designs and implements that functionality from scratch using transistors. One of Bursonâ€™s signature items is the Burson HD Audio Op Amp, a custom built circuit board made with dozens of matched transistors and other precision discrete parts that provide the functionality of an IC op-amp. This component was originally designed for the DIY market to replace IC op-amps as an upgrade. Burson then began to build on this design in all their products. The PI-100 had this op amp as a major component in the preamp section, and it is also the core of the HA-160. The output stage is also both entirely discrete and fully Class A. In addition to the gain stage, the voltage regulators in the power supply are also entirely made from discrete components. The volume control is entirely passive, and is implemented as a 24-step attenuator with 1% resistors. This simple switchable voltage divider puts only a single 1% resistor in the signal path. Two high quality Â¼â€ phono jacks are provided, one for low impedance (25-150 ohm) headphones, and one for higher impedance (150-500 ohm) headphones. A single pair of RCA inputs is provided, along with an IEC power socket.
The quality of the electronics in the HA-160 is first rate, and the case is a great improvement over previous Burson products. The 6mm thick aluminum case is much beefier and well put together that the PI-100. The HA-160 let me down in two ways. The first was very minor: my 160 came with an Australian power cord and the power supply set to 230V. This was easily fixed since the HA-160 accepts any IEC power cord, and the power supply voltage changes with a flip of a switch. The second was a bit more annoying. One of the 24 steps in the attenuator (in the middle of the range) was shorted. When I selected this setting, the HA-160 went to maximum volume. With my Denon AH-D7000â€™s this resulted in very loud but not damaging volume level. Had I had a more sensitive pair of headphones, this issue could have gotten very expensive.