The electric signals from an MC cartridge are extremely small, making them susceptible to electrical and magnetic noise from electronics, cables, and power supplies. To reduce noise—often heard as a mains network hum—careful placement of cables and components is essential. A compact phono preamplifier helps with this, allowing it to be positioned comfortably away from power transformers, such as those in power amplifiers. However, this ideal location might be distant from the main equipment table.
For this reason, a compact, low-power, closed device is preferred, utilizing transistors instead of tubes—a staple of Ancient Audio. While tubes are ideal for CD-based systems, lending a softer quality that mitigates digital harshness, vinyl requires the livelier response of transistors. Additionally, transistors have a significant advantage for this application due to their inherently low noise levels; tubes, by contrast, tend to introduce more noise due to their higher operating temperatures.
Building a tube MC preamplifier without a step-up transformer is challenging, as the additional component can introduce distortion. The MC preamplifier demands high gain—over 10,000x—while maintaining low noise and minimal distortion. To meet these requirements, the Silver Stage utilizes five stages of amplification, each with local feedback. This high gain made it essential to implement a fully balanced circuit, similar to the demanding vertical amplifier circuits found in oscilloscopes, which require high gain from DC up to hundreds of MHz with minimal distortion and temperature resilience. The balanced design allows for true XLR balanced outputs, rather than the phase-inverted RCA outputs common in other preamplifiers.
The circuit employs FET transistors for linear performance, but their variability poses a challenge; individual FET parameters can vary by 100–200%. Thus, each of the 26 transistors is meticulously hand-selected and tested across multiple temperatures, making the preamplifier’s manufacturing process complex and labor-intensive.
The RIAA network uses a multi-stage RC type with finely selected components, ensuring perfect left-to-right channel balance across the audio spectrum. All switches are hermetically sealed miniature relays with exceptionally low ON impedance, which is crucial given the low impedance of MC cartridges, akin to speaker impedance. For optimal signal integrity, all internal wiring is crafted from pure silver, consistent with Ancient Audio’s high-end standards.
To minimize interference, the power transformer is housed separately in a non-magnetic cabinet. The preamplifier is available in two versions: a silver stainless steel model, and a black and gold model crafted from brass and aluminum.
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