H2 Audio Helios 0011/Stereo Mic Pre/EQ

Some recording circuits earn their reputation by becoming part of the sound of an era, and the Helios 2128 preamp and EQ remains one of the most distinctive examples. The H2 Audio Helios 0011/Stereo mic pre/EQ brings that classic analog design into a dual-channel 2U rackmount production module, combining two recreations of the original 2128 microphone preamp with Lustraphone input transformers and inductor-based equalization. Each channel provides 25–75dB of preamp gain in 5dB increments, with the Lustraphone transformer supplying 20dB of gain ahead of the preamp. Balanced line inputs, -20dB pads, 48V phantom power and phase controls round out a flexible front end for stereo recording, individual sources and outboard processing.

Original Helios Circuitry Shapes the Signal Path

Both channels recreate the Helios 2128 preamp architecture and pair it with Lustraphone input transformers based on the original design. H2 Audio also adds an output amplifier and output transformer of original Helios design, allowing the 0011/Stereo to drive a 600-ohm load up to 25dB before clipping. This addresses a practical limitation encountered when adapting classic Helios modules for use in custom racks while retaining the underlying circuit approach. EQ Cut and phase controls, along with selectable 40Hz or 80Hz high-pass filtering, provide additional control over the signal as it moves through the production chain.

Inductor-Based EQ Provides Hands-On Tonal Shaping

The inductor-based equalizer combines selectable LF and MF bands with a fixed-frequency 10kHz high-frequency section for broad shaping or more focused tonal adjustments. Low-frequency boost is selectable at 60Hz, 100Hz, 200Hz or 300Hz, while the midrange provides eight selectable frequencies from 700Hz to 6kHz with peak or trough operation. The 10kHz section provides stepped boost or cut from -10dB to +10dB, while EQ bypass makes it easy to compare processed and unprocessed signals. Combining dual-channel 2128 preamp circuitry, transformer-coupled inputs and outputs and flexible inductor-based EQ, the H2 Audio Helios 0011/Stereo Mic Pre/EQ brings the classic Helios signal path into a modern rackmount studio format.