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H2 Audio Helios 2128 Preamp & 5011 EQ

H2 Audio 2128 & 5011

H2 aim to put the legendary sound of Olympic Studios in your 500‑series rack.

H2 Audio is a new collaboration between engineers Al Sutton of Acme Audio and Rustbelt Studio, Tim Mead of Q2 Audio, and entrepreneur, recording artist and engineer/producer Perry Tell. They all share an appreciation for the sonic qualities of the golden era of British Rock music, and have devoted much of their recent design effort into producing modern recreations of equipment from this time, particularly the designs of Dick Swettenham. After beginning his career as a maintenance engineer at Abbey Road in the early 1950s, Swettenham moved on to another legendary London studio, Olympic, where he began to introduce his own designs under the name Helios Electronics. The Helios consoles that were installed at Olympic and elsewhere were used to cut tracks by countless famous artists, including the Rolling Stones, Led Zeppelin and Black Sabbath.


After sourcing a number of original examples, more than a year of experimentation followed before H2 Audio released the 0011, which is a faithful reproduction of the preamp, filter and EQ stages of the recording channel found on the Helios Consoles at Olympic. From there, H2 decided to port the design to the popular 500‑series modular format, and decided early on that it wouldn’t be possible to squeeze everything into a single module while maintaining the integrity of the circuit and overall design. As with many other vintage designs that have been migrated to this format, their solution was to create two separate products: the 5011 EQ and the 2128, which is a preamp with the high‑pass filter section.

Both units sport the same, understated, black styling, which is in keeping with the look of the original Helios modules. The decision not to attempt squeezing everything into one module seems sensible to me, not least because it means you can have proper‑sized switches and dials, but it’s also a more versatile approach than creating a ‘doublewide’ module with everything on board.

Looking at the 2128 preamp first, everything you’d expect to find on a good mic preamp is here. There are input and output transformers, a 20dB pad, polarity inversion and switchable 48V phantom power, and it’s all laid out nicely....

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