Locomotive Audio L72P-1 – 500 Series Tube Microphone Preamp

The Locomotive Audio L72P-1 brings the unmistakable sound of legendary V72-style German broadcast preamplifiers to the modern 500 series format. Inspired by the classic console amplifier modules originally made for the German radio network, the L72P-1 delivers solid, deep lows, rich, creamy mids, and smooth, never aggressive highs, characteristics that have made these vintage circuits highly prized in professional recording studios.

Designed for sound engineers seeking authentic vintage character with the flexibility of modern systems, the L72P-1 combines internally wound transformers, a carefully recreated plate choke, flexible gain control, a dedicated line input, and reliable modern tube options. The result is a characterful tube preamplifier, capable of capturing the essence of the original V72 sound while offering practical functionality for contemporary recording and mixing workflows.

The Heart of the V72 Sound

At the core of the Locomotive Audio L72P-1 are three fundamental components:

• Custom input transformer
• Custom output transformer
• Three-chamber plate choke

These elements were developed in-house by Locomotive Audio to closely mimic the behavior and response of the vintage modules that inspired the design. They contribute significantly to the unit’s sonic character, providing punchy lows, rich low-mids, smooth highs, and the musical saturation typical of classic German tube preamplifiers.

Increased Gain and Level Control

The L72P-1 offers up to 54 dB of gain adjustable in 4 dB steps, providing significantly more flexibility compared to the original vintage modules, which offered up to 34 dB of gain.

A 5-position rotary output attenuator allows for fine-tuning of the final level in 2 dB increments, enabling the preamp to be driven for color and saturation while maintaining precise level control throughout the signal chain.

Line Inputs and Pad for Greater Flexibility

To adapt to various studio situations, the L72P-1 includes dedicated XLR line inputs, as well as two attenuation levels:

• 20 dB Pad
• 34 dB Pad

This configuration makes the unit suitable for both use as a microphone preamplifier and as a color amplifier for line signals, useful for mix processing, stereo bus coloration, or for adding V72-style weight and depth to already recorded tracks.

Modern Tube Technology

Instead of using the now rare EF86 or EF804 pentode tubes, the L72P-1 employs:

• 2x 6922 / E88CC tubes
• Dual-triode cascode configuration

This solution was chosen to replicate the behavior of the original pentode circuit, while offering a quieter, more reliable, and readily available solution.

The design is optimized for 6922/E88CC, but also supports other common dual triode tubes like the 12AU7.

Two Different Transformer Configurations

The L72P-1 comes standard with the input transformer in the "S" configuration, which offers a slightly more linear high-frequency response compared to the non-"S" broadcast version.

For those who prefer an alternative response, a version with a non-"S" transformer is available. Additionally, a jumper on the board allows selection of the input transformer load between:

• 400 kΩ
• 200 kΩ

a modification commonly associated with "S" configured modules.

Applications

The L72P-1 is suitable for:

• Vocals
• Acoustic instruments
• Drums
• Electric bass
• Guitars
• Synthesizers
• Stereo or line-level sources from mix

Key Features

• V72-style tube microphone preamplifier in 500 series format
• Inspired by classic German broadcast modules
• Up to 54 dB of gain in 4 dB steps
• Internally wound transformers and plate choke
• 2x 6922/E88CC tubes in cascode configuration
• Also compatible with tubes like 12AU7
• Dedicated XLR line inputs
• 20 dB and 34 dB pads for line-level signals
• 5-position output attenuator in 2 dB steps
• Standard "S" input transformer
• Optional non-"S" version
• Selectable transformer load (400 kΩ / 200 kΩ)
• Sound with solid lows, rich mids, smooth highs, and low distortion