What’s Right About Discrete Circuits
All discrete circuits are custom-built for specific applications rather than an op-amp’s jack-of-all-trades-master-of-none specifications. The art of circuit design yields superior sound in every way in comparison to simple plug-a-chip engineering.
A system can only sound as good as its weakest link. All our products use thick, quality, temperature-stable printed circuit boards with high-purity copper traces and gold-plated soldering pads. An extra coating is applied to both sides of the PCB to prevent oxidation. The boards are hand-built use high-spec metal-film resistors and other audio-grade parts using as few hand-matched components in the signal path as possible.
- Custom circuitry designed for specific application
- Significantly reduces component count to better preserve signal integrity
- 0.1%-matched metal-film resistors and silver mica capacitors
- Extremely temperature stable
- Each transistor is chemically optimized for its application: NPN or PNP
- Each transistor tested and matched before hand-soldering onto the PCB
What’s So Entirely Wrong With IC Op-Amps
Integrated chip op-amps are simple building blocks created for the PC industry and designed to work in a wide range of equipment and temperatures. To achieve such versatility the densely-packed circuits inside an op-amp have over 50 micro-components that are chemically formed and inferior in every way to discrete components. Plus many ICs have built-in components and corrective networks that aren’t even used for audio amplification further spoiling the signal.
The conductive layer in commercial op-amps is formed with a layer of aluminum-vapor that’s thinner than the water vapor left on a foggy windshield! The close proximity of components creates electromagnetic interference or EMI that further dirties the audio signal.
An IC op-amp is entirely constructed on a single slice of silicon wafer smaller than a grain of rice! Limited by size and heat dispersion it’s impossible to incorporate top quality audio transistors like the A970 or K170 which feature in Supreme Sound discrete designs.
Furthermore, all components on the commercial op-amp’s silicone are formed by droplets of chemicals like an inkjet printer. This process just can’t create parts like the 1%-tolerance metal-film resistors, or the super-stable silver mica capacitor. Since they’re all connected (thus integrated), they also can’t be individually tested and matched.
During construction of a discrete transistor a chemical optimization process take place for each piece of silicon according to its application (NPN or PNP). This process is critical to the performance of the final product. But it can’t be done on an integrated circuit as all transistors are fabricated on the same piece of silicon, a major drawback compared to a discrete circuit.
For example, a standard IC op-amp like the OPA2064 is designed to work between 4.5 to 24V which means a lot of compensation has to be applied to the power input circuits. Supreme Sound designs, on the other hand, knows precisely what voltage is required for our applications and so our custom circuits supply ideal voltage without needing any compensation.
And What’s Wrong With Class-D
Most modest footprint power amplifiers are class-D or variations like class-T or Z. Such designs are wholly inconsistent with Burson ideals on two counts. The first is our steadfast refusal to use IC-based audio building blocks as we’ve described above. The second is that class-D and class-T chips were created for the car audio industry and subsequently for mobile phones where power efficiency, size and budget are the driving design parameters so audio performance is secondary if that.
Instead of going with the flow, we refused to compromise and gave ourselves the difficult task of creating a class-D sized power amplifier with an IC-free class-A output stage with a custom transformer and a linear power supply. Burson’s wonderful-sounding Timekeeper amplifier successfully challenges the established beliefs about size vs. performance.
Class-A designs are simpler than other modes so there are a reduced number components in the signal path that preserves the purity of the signal. The transistors in this design operate in the most linear portion of their transconductance curve hence deliver less distortion. Because the transistor is never ‘off’ there’s no “turn on” delay or problems with charge storage. And generally class-A has better high frequency performance and a stable feedback loop. Lastly, class-A doesn’t suffer the crossover distortion that’s associated with class-D designs.