Recording engineers and producers choose different microphones for different sound sources. It is intriguing that, in the 1950s and 1960s, the variety of available microphones was relatively limited compared to what we have available today. Yet, recordings from that era remain exemplary even now. The microphones used at the time were primarily vacuum tube models. Through discussions at AES Conventions on improving phantom power supplies and my own experimentation with tube microphones myself, I began to realize that defining attribute of their sound might not stem solely from the tubes themselves. Instead, the type of power supply appeared to play a crucial role in shaping the final sound quality. This hypothesis was confirmed with the introduction of high-voltage DPA 4003 and 4004 microphones, compared to their phantom-powered counterparts, the 4006 and 4007. In direct comparisons, the microphones with external, more current-efficient power supplies consistently delivered superior sound. Having worked extensively with numerous AKG C12 and C24 microphones I identified two pairs, one of C12s and one of C24s with identical frequency characteristics. For one C12, we designed an entirely new, pure Class A transistor-based circuit with an external power supply. Reflecting on my 50-plus years as a sound engineer and producer, I sought to determine which microphones were not only the best, but also the most versatile. My analysis led to four key solutions extending beyond the microphones themselves. Since I had already developed an ideal Class A equalizer, I applied the same technology to create four analog equalizers designed to fine-tune the prototype microphone’s frequency characteristics at the power supply level.
