Steve Lees: John Stronczer is the owner and product designer at Bel Canto. Starting out designing tube based amplifiers, John has moved his company firmly to the forefront of audio with a range of digital control centers (DACs) and Class D amplification. In this interview I ask John about that progression.
SL: How did you get into designing audio products?
John Stronczer: I started designing audio products as a hobby while I was working at the Honeywell Research Center in the early 1980s. I’ve been interested in audio and music since I was 12 years old and built my first Dynakit system at that age.
SL: Which aspect do you enjoy the most, digital or analog product design and why?
JS: My background is in analog design. Although I am getting more into DSP design for custom FIR filters and loudspeaker crossover and EQ. The critical focus in digital audio design for high performance playback mostly comes down to analog issues of jitter, power supply and the analog input or output stages anyway so my analog background serves me well here.
SL: You started using tubes for your amplifiers, why the switch to transistor and why class-D?
JS: I actually designed my first tube amp in 1986. It was a single ended 845 triode with about 20 watts of power. I’ve owned push-pull triode and pentode audio amps but they never performed to the level that I wished. There always seemed to be a veil between me and the music with push-pull amps.
The SE operation of the output transformer goes a long way to removing this veiling effect. I also like the inherent elegance of the SE amplifier and called these amps my Physics Experiment. My first exposure to a modern class-D amp was the Tripath architecture. My initial impression was that through the bass and lower mid-band it came close to that direct connection to the music that SE triodes offer. I also was attracted to the elegance and efficiency of class-D and saw that it would be the future of audio amplification.
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