UltraDisc One‐Step (Mobile Fidelity Sound Lab)

Series manufactured with the intent of presenting music from master tape to consumer in order to present the average consumer with the closest musical presentation they can have to hearing the actual master tape. Presented in box sets with special inserts and 45 RPM records.

Details from MOFI site:
Instead of utilizing the industry-standard three-step lacquer process, Mobile Fidelity Sound Lab's new Ultradisc One-Step (UD1S) uses only one step, bypassing two processes of generational loss. While three-step processing is designed for optimum yield and efficiency, UD1S is created for the ultimate in sound quality. Just as Mobile Fidelity pioneered the Ultra High-Quality Record (UHQR) with JVC in the 1980s, UD1S again represents another state-of-the-art advance in the record-manufacturing process. MFSL engineers begin with the original master tapes and meticulously cut a set of lacquers. These lacquers are used to create a very fragile, pristine UD1S stamper called a "convert." Delicate "converts" are then formed into the actual record stampers, producing a final product that literally and figuratively brings you closer to the music. By skipping the additional steps of pulling another positive and an additional negative, as done in the three-step process used in standard pressings, UD1S produces a final LP with the lowest noise floor possible today. The removal of the additional two steps of generational loss in the plating process reveals tremendous amounts of extra musical detail and dynamics, which are otherwise lost due to the standard copying process. The exclusive nature of these very limited pressings guarantees that every UD1S pressing serves as an immaculate replica of the lacquer sourced directly from the original master tape. Every conceivable aspect of vinyl production is optimized to produce the most perfect record album available today.

In July 2022, three Mobile Fidelity mastering engineers were interviewed and admitted that ALL One Steps were transferred to DSD digital for mastering purposes, so the One Steps are not a 100% analog transfer from the original master tapes.