The G312B was developed for audio engineers, producers, and musicians seeking the classic sound of legendary American preamps from the 1970s, combining punch, definition, and fast transient response in a modern, robust, and handcrafted unit.
Inspired by the classic architecture of American preamps that shaped the history of professional recording, the G312B delivers a sound with great presence—featuring tight lows, harmonically rich mids, and detailed highs—while preserving the full dynamics of the performance, even at high gain levels.
Its fully discrete circuit ensures an extremely fast transient response, a characteristic that made this architecture a benchmark in recording studios worldwide.
Whether capturing vocals, guitars, drums, bass, acoustic instruments, or any other sound source, the G312B delivers character, depth, and musicality from the very first moment.
The G312B delivers the sonic character that made one of the music industry's most respected preamp architectures famous.
Its tone is naturally full-bodied, with solid lows, defined and harmonically rich mids, and open, highly detailed highs. The result is a sound with presence, excellent definition, and dynamic response, capable of making any instrument stand out in the mix without losing naturalness.
Each channel employs an input transformer and an output transformer, both developed based on the originals found in classic 1970s American preamps. This configuration contributes directly to the unit's sonic signature, providing increased headroom, excellent transient response, and the harmonic richness characteristic of the finest analog consoles.
When pushed to higher gain levels, the G312B delivers smooth, highly musical harmonic saturation, adding depth, texture, and dimension without compromising signal fidelity. Transformers on each channel
One of the G312B's key features is the use of *two transformers per channel*: an input transformer and an output transformer.
Developed based on the transformers found in legendary American preamps from the 1970s, they play a fundamental role in the unit's sonic character, offering excellent impedance matching, fast transient response, and a sound rich in detail and harmonics.
Combined with the fully discrete circuitry, these transformers deliver a three-dimensional sound—full of character and the musicality that made this architecture a global benchmark in professional recording.
Unlike designs based on conventional integrated circuits, the G312B employs a fully discrete architecture, where every stage of the circuit has been carefully engineered to deliver maximum sound quality.
This construction provides greater headroom, excellent dynamic response, ultra-low noise levels, and a harmonic-rich sonic signature—qualities highly valued by audio engineers worldwide.
Each unit is hand-assembled and undergoes rigorous functional testing and calibration before leaving Greenbox Pro Audio.
Each channel features fully independent controls, offering maximum flexibility during professional recording and production sessions.
Gain control
Allows for precise adjustment of signal amplification while preserving the full dynamics of the sound source.
48V Phantom Power
Individual 48V phantom power for use with professional condenser microphones.
Line Input
Allows the channel to function as a line amplifier for external processors, keyboards, audio interfaces, and other line-level gear; it is also compatible with most musical instruments.
PAD
Reduces the input signal level, allowing you to work with high-intensity sources without overloading the preamp stage. Applications
• Vocal recording
• Acoustic guitar
• Electric guitars
• Electric bass via DI/Line
• Snare drum
• Toms
• Overheads
• Piano
• Acoustic instruments
• Synthesizers
• Re-amping
• Line-level signal processing
• Professional and high-end home studios
• Fully discrete circuitry
• Two independent channels
• One input transformer and one output transformer per channel
• Transformers developed based on classic 1970s models
• 100% made in Brazil
• Selected electronic components
• Heavy-duty metal chassis
• Low-noise power supply
• Excellent headroom
| General Info Section | |
|---|---|
| External Source | 110/220 Volts ~ (50/60Hz) |
| Power Consumption | +/- 18 Volts DC / 85mA (max.) |
| Signal Section | |
| THD | 0.0033% |
| Equivalent Input Noise (EIN) | -133dBu |
| Mic Gain | 65dB (approx.) |
| Hi-Z Gain | 20dB (approx.) |
| PAD | -10dB |
| Input Impedance (MIC) | 150 Ω |
| Input Impedance (Line) | 10k Ω |
| Output Impedance | 75 Ω |
| Audio Transformer | 320 Ω Turns Ratio |
| Frequency Response | 15Hz to 40kHz |
| Controls | |
| Funções | Gain, Phantom Power 48V, Phase Reverse, Line, Pad |
| Conections | |
| Mic Section | XLR Balanced |
| Line In | TRS balanced |
| Line Out | XLR Balanced |
| Components | |
| In Section | Audio transformer + American Style Dual Discrete OpAmps |
| Out Section | Greenbox Audio Transformers TT-75B |
| Dimensões | |
| Weight | 2,575 quilos |
| Dimensions | 1U x 19"x 12cm |
