Heavily inspired by the tone and feel of legendary Marshall amplifiers, such as the non-master volume series PLEXI Super Lead (1959/1987) and Super Bass (1992), as well as the master volume series JMP (2203/2204), we have had the privilege of working on various Marshall amps over the years. Some came to us for repairs, while others came for customisation.

As devoted fans of the sounds these classic amplifiers produce—sounds that ignite passion in countless artists—we embarked on a quest to capture their essence, the very “mojo” that defines them, and distil it into a compact creation. Thus, Room #40 was born! Through the use of JFET technology, we aimed to stay true to the unparalleled tone and spirit of these iconic Marshall amps.

OBN emphasised the importance of replicating the compression and sag that occur in the power amp section when these amplifiers are pushed to their limits. At the same time, it offers access to two well-known modifications: mod #39 (PLEXI) and mod #34 (JMP™ & JCM800). Additionally, we wanted to pay tribute to the late, great Eddie Van Halen, who famously created the "brown sound" using an Ohmite variac (a variable transformer that adjusts the voltage supplied to the amplifier).

Lastly, we included a Presence control to ensure the sound is adaptable to any situation, whether you are plugged into the front of an amplifier with or without a bright cap or directly into a power amp.