Cloud Microphones TRUE BLUE 520 500 Series Precision Microphone Preamp

Co-designed with Tim Spencer of TRUE Systems, the TRUE BLUE CL-520 brings 25 years of high end engineering into a single-slot 500 series format. The CL-520 features a fully balanced topology delivering an ultra-wide -3dB bandwidth of 6 Hz to 630 kHz, near-zero phase distortion, and an extended 76 dB gain range for quiet ribbons and low-output dynamic mics.

Engineered for accuracy, the TRUE BLUE 520 captures authentic 3D depth and detail without colour. Its fully balanced topology provides ultra-low THD+N, wide bandwidth, and rapid transient response to guarantee fidelity.

Key Features

• Collaborative TRUE Systems Design: Built upon the high-resolution architecture of the TRUE Systems Precision 8, refined for modern 500 series racks.

• Dedicated Dynamic & Ribbon Mode: Increases input impedance to $10\text{ k}\Omega$ and bypasses front-end capacitors for total DC signal path transparency.

• Extended +76dB Total Gain: Provides a base gain range of $+6\text{ dB to }+60\text{ dB}$, with a touch-activated $+16\text{ dB}$high-gain boost for low-output transducers.

• Patent-Pending Cloud Touch Interface: Illuminated capacitive controls trigger high-grade telecom relays with over $100\times$ the operational life of traditional mechanical switches.

• Continuously Variable High-Pass Filter: Smooth $6\text{ dB/octave}$ low-cut filter sweepable from $25\text{ Hz to }420\text{ Hz}$ to tame proximity effect without destroying low-end warmth.

• Front-Panel Instrument DI with Thru: Unbalanced $1/4"$ input routes directly to the preamp core while the Thru jack passes clean signal to external amplifiers or secondary processors.

• Safety Blink-Delay Protocols: Prevents accidental phantom power pops or high-gain jump scares with timed engagement holds.

Technical Specifications

• Form Factor: 1-Slot 500 Series Module

• Gain Range: $+6\text{ dB}$ to $+76\text{ dB}$ (Base $+60\text{ dB}$ + $+16\text{ dB}$ Touch Boost)

• Frequency Response (Bandwidth): $6\text{ Hz}-630\text{ kHz}(-3\text{ dB})$ / $10\text{ Hz}-250\text{ kHz}(\pm 0.25\text{ dB})$

• Maximum Output Level: $+26\text{ dBu}$

• Total Harmonic Distortion (THD+N): $<0.0004\%@+28\text{ dBu output}$

• Intermodulation Distortion (IMD): $<0.0005\%\text{ (MOD) }@40\text{ dB gain}$

• Equivalent Input Noise (EIN): $-133\text{ dBu}$ (unweighted, 20 Hz−20 kHz,Rs=0 Ω) / $-135\text{ dBu}$ (A-weighted)

• Phase Response: 2.5∘ @ 30 Hz to 20 kHz ($+26\text{ dBu output, }40\text{ dB gain}$)

• Slew Rate: 54 V/µS

• Common Mode Rejection (CMRR): $92\text{ dB}$ ($30\text{ Hz}-20\text{ kHz},+10\text{ dBu CMV input}$)

• Input Impedance: $5\text{ k}\Omega$ (Phantom Power Engaged) / $10\text{ k}\Omega$ (Dynamic/Ribbon Mode)

• High-Pass Filter: Continuously Variable $25\text{ Hz}-420\text{ Hz}$ ($6\text{ dB/octave}$)

• Front Panel I/O: 1x $1/4"$ Instrument DI Input, 1x $1/4"$ Thru Output