Who did the maths first

Lineage

The Lotus M3 stands on other people's work, and says so.

Randall Aiken

Randall Aiken's writing on attenuators is the ground John Hewitt's maths builds on.

John Hewitt, the JohnH design

John Hewitt ("JohnH") did the maths and the schematic of the Simple Attenuator, developed in the open on the Marshall forum since 2017, in the thread Simple Attenuators – Design And Testing. His design intent is the heart of the Lotus.

The Lotus JohnH M2

Fromel Electronics built JohnH's design as the Lotus JohnH M2: three switches, −7 dB to −31.5 dB in 3.5 dB steps. Fromel builds the Lotus under a licensing agreement with John Hewitt.

The Lotus M3

The M3 is a significant departure from the M2: the first stage refitted so it lands on its 3½ and 7 dB labels, a 1¾ dB stage for 1.75 dB steps, four impedance models scaled from one set of ratios, and a fan supply powered by the speaker signal. JohnH's name stays on the panel.

The hands

• Design maths: Randall Aiken, John Hewitt.
• Design, direction and the bench: John Fromel, Fromel Electronics.