Conrad-Johnson Design writes: “In December of 1975 fellow economist Bill Conrad loaned me his Dyanco PAS3 preamp to compare to my Marantz Model 7 (running into a pair of MacInstosh MC60s and KLH9 electrostatic speakers). To my surprise, there was no clear winner – each had its merits and weaknesses (perhaps Bill, whose capacity for remembering details far exceeds mine, will weigh in with a brief description of the differences).
Convinced that it should be possible to combine the best attributes of both, we decided to explore that possibility. Initially a few upgrades to the PAS3 resulted in noticeable improvements, but the tight chassis and small transformer clearly limited the possibilities. Analysis of the circuitry of a few highly regarded tube preamps, including the Dyanco and Marantz, along with consideration of theoretical advantages of each led to our circuit design. Starting from scratch, I hand-built a new platform – forming a chassis using a cheap metal brake from Lafayette (anyone else remember them?) and making my own PC boards. The resulting new platform was dubbed Phoenix One.
The next several months were devoted to establishing the parameters of the circuit and selecting the component parts, all determined through exhaustive listening sessions. One evening, Bill showed up at my home with a tangle of wires, diodes, transistors, capacitors and resistors which he announced was a discrete regulated power supply, and proceeded to carefully spread it out on the floor, instructing me on connecting it. (Bill called this technique floorboarding, as opposed to breadboarding). There was no question that his DC regulator was a clear improvement and it was incorporated into the design.
Confident that the end result handily surpassed the PAS3 and Model 7, we believed that there might well be a market for a preamplifier based on this design. We knew from experience that measured performance was no guarantee of musically satisfying performance, but expected that impressive technical performance would come as a natural consequence of circuit designs based on judicious application of theory and extensive subjective evaluation – an approach that served us well for the next four decades. But before committing to a business venture, we needed to confirm that the design was in fact technically competent. Lacking adequate equipment for precise measurements of the technical performance of the Phoenix One, we turned to a local audio repair tech, Bill Thalmann**. His measurements confirmed that the Phoenix One achieved excellent performance in bandwidth, linear frequency response and low distortion.”
** More on Bill Thalmann’s important role in the building of conrad-johnson as a business will come in the next installment. Bill recently passed away. He will be missed by a great many whose lives he touched.