A New Level In Our Understanding
Most headphone amplifiers use standard IC Opamps in their designs. Such opamps are very cheap and easy to apply, however they are inferior (learn more). This is because they are not tailored for a particular audio circuitry, and they contain many low quality and unnecessary components (learn more) which degrade audio signals.
Three years ago we developed the HA-160 headphone amplifier. Instead of using standard IC opamps on the signal path, we designed tailor made circuitry using high quality discrete components. Because of this, we were able to reduce components on the signal path to optimise its operation. It offered higher resolution and superior dynamics to any IC based design, and yet presented a mid range intonation that many thought only possible from top-tier tube amps. It was good, like a properly designed solid state should, and many in the industry saw it as a benchmark.
Instead of celebrating and introducing "newer" versions each year with small refinements, we have been studying and developing circuitries that can realise more of our ideals. Now, our dream of an even more idealistic circuitry, with even less components on the signal path is realised. And it sounds more beautiful than any of us could have conceptualised at the beginning of this project. We named this new headphone amp Soloist!
The New FET Input Stage
The input stage of the Soloist is a symmetrical current feedback circuit with only 21 components on its signal path (compare that to a typical IC Opamp of over 50). It's signal path is so short and with so little blockage on it, that it can achieve amazing sound. Also because we only had to select and match 21 components, the Soloist sounds absolutely amazing.
Less Blockage, More Music
It is a common misperception that a standard IC opamp is a single active device. In fact we sometimes get comments such as "less is more!, so why not just use an IC opamp on your circuitry, just like so many other audio companies?"
We agree that less is more, it is precisely why we can never accept IC opamps. Each IC opamp is densely packed with over 50 micro components and audio signals travelling through them. These micro components are chemically formed and inferior in every way to even the cheapest of discrete components. Furthermore, even Wikipedia knows that IC opamps were created for the PC industry, and were designed to work in a vast range of equipment and temperatures. To achieve such versatility, the tiny circuitry inside the opamp contains many components and corrective networks that are useless to audio amplification. As a result, audio signals travelling through them are tainted beyond repair. We sit squarely in the less is more camp. In the first generation HA-160 input stage we were able to achieve ideal operational levels with 32 carefully selected and matched discrete components. By reducing the number of components on the signal path, more micro details were able to get through. The result is a higher definition and more organic sound compared to any IC chip based design.
During the development of the Soloist, one of our theories was confirmed. That even the best discrete and most matched components introduce distortion when used on the signal path. But, every time a component is removed from the signal path, a veil is lifted between us and the music. The design objective therefore was to remove as many components from the signal path as possible while still maintaining ideal operational levels.
At the end, Burson developed a brand new Field Effect Transistor (EFT) circuit for the Soloist. It has only 21 components on the signal path. It was an absolute breakthrough for us, and the result was breathtaking.