Huge power supply capacity and Class A biasing do not guarantee reference level performance nor do the parts themselves that make up the internal circuitry. The choice of circuit topology and implementation of said methods may be the most critical to preserving signal integrity. The circuit design itself along with the implementation of the design are paramount to the success of a product. A long history of trial and error is important to the design of audio circuitry, as there are many ways to create an audio gain or power circuit. Choices in regards to gain device types i.e. Vacuum tubes, Bipolar Transistors, FET transistors and their variants are important for a number of reasons. The first of which is availability, Vacuum tubes have limited life spans and are not widely manufactured in the 2010’s. FET and Bipolar transistors are currently in production but as we speak the devices that were notably utilized in many successful audio products are being phased out without replacement devices being offered.
BSC Audio uses devices that are current, “off the shelf”, and readily available. In the event a commenly used device should be obsoleted, we have the ability to implement and substitute quickly without negative effects on the circuitry. We also do not rely on specialty components to create the sound presentation we are known for, as to rely on a component to create your sound is to limit design possibilities.
All of the BSC circuitry is designed using primarily discrete through-hole components configured in very low distortion complementary topologies. Through-hole components are larger, leaded parts that can handle higher power and heat when compared directly with surface mount (SMT) parts. SMT parts were created to maximize circuit density minimizing the space required on a particular circuit board, the creation of these miniature parts albeit practical for many electronic products requires special tooling to place and service. The use of through-hole components minimizes the number of parts in the signal path. This, coupled with the reduced heat and increased power handling ability, awards little signal degradation and increased life expectancy. Through-hole components also enable the simple repair of the circuit boards they are attached to. Any qualified technician with proper documentation could potentially service a BSC Product without the use of specialty tools or equipment.
Discrete circuitry - unlike the use of Integrated Circuits (IC's) - allows the designer to optimize individual sections of a circuit or layout and not rely on that particular device to dictate the sonic or electrical signature of a product. In many instances the pre-packaged devices add a level of simplicity to a circuit design but also can negatively affect the overall performance. At BSC Audio we lean toward discrete circuit implementation particularly in the areas we find most critical to sound reproduction.
Complementary circuitry is utilized in the most critical sections of the audio signal path. Complementary circuits use electrically matched NPN and PNP transistor pairs optimized in a push-pull like configuration. An ac (audio) signal swings both positively and negatively through a common reference point. Using a transistor that is specifically designed to work natively with a positive referenced signal and respectively the same with a natively negative referenced device allows a more natural relationship. Using a non-complimentary circuit raises the level of circuit complication that in most cases results in poor sonic performance overall.
In certain sections of a circuits signal path such as the amplifier or preamplifier input stage, preamp volume control, and some output stages, it is best to separate these signals even further and use differential circuit paths. In a differential circuit, the positive and negative signals are carried through their own respective channel, or a specialized and independent plus and minus signal path. Differential signal paths offer increased common mode rejection and superior noise characteristics when compared to single ended designs. Using differential or balanced interconnection between components yields superior performance, virtually eliminating external contamination. This is especially true when using long cable runs.
Attention to the details is what separates a good musical performance from a magnificent one, and even at the very lowest levels BSC Audio has considered and implemented concepts that make noticeable improvements to the final presentation.
When Bret D'Agostino was in his early twenties, he did some work for a friend that worked in the Film Special Effects Industry. On site, there was a Scanning Electron Microscope. Bret was able to observe for the first time electrons moving through a printed circuit board. Because the power of this particular circuit (wrist watch) was very low, he was able to watch the electrons move through the circuit traces. He observed there were sections of the circuit traces that would glow much brighter compared to the rest of the signal path. This was due to the electrons colliding into the corners of circuit traces that were particularly steep or right angled. This made a permanent impression on Bret, today all the audio signal traces in the 5 series products are gently curved and free from right or steep angles. In our listening sessions the curved traces have greatly improved the low level detail along with a lightning fast, liquid, and effortless presentation. We plan to design future power supply and communication circuitry in the same way, with the prospect of further improving what we have already achieved.