TRUE BLUE 520 Precision Mic Preamp
TRUE BLUE 520 Precision Mic Preamp
TRUE BLUE 520 Precision Mic Preamp
TRUE BLUE 520 Precision Mic Preamp
TRUE BLUE 520 Precision Mic Preamp
TRUE BLUE 520 Precision Mic Preamp
TRUE BLUE 520 Precision Mic Preamp
TRUE BLUE 520 Precision Mic Preamp
TRUE BLUE 520 Precision Mic Preamp
TRUE BLUE 520 Precision Mic Preamp
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New Made in USA
Precision Mic Preamp / Instrument DI

TRUE BLUE 520 Precision Mic Preamp

Experience stunning musical accuracy with this next-generation preamp. Built in collaboration with True Systems, the True Blue 520 features up to +76 dB of ultra-clean gain and the patent pending Cloud Touch Controls. 

Read more about the True Systems legacy

+76 dB gain API 500 Series Variable HPF DI + THRU
Channel Count
Quantity

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TRUE BLUE 520 Precision Mic Preamp

$1,498.00
$1,498.00
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Guaranteed performance
30-day returns
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Description

The CL-520 Microphone Preamplifier / Instrument DI is engineered to deliver stunning musical accuracy, practical and innovative features, outstanding value, and long-term reliability. Every element of its design has been refined through extensive critical listening evaluations and comprehensive user feedback.

The CL-520 features an updated TRUE Systems preamplifier core design, providing ultra-high-resolution musicality and optimized performance with condenser microphones, dynamic microphones, ribbon microphones, and self-powered tube microphones. The original TRUE Systems preamplifier core has been trusted for over two decades in studio, live sound, post-production, and educational environments - supporting virtually every genre of voice and music production.

A unique illuminated Cloud Touch-ControlTM User Interface replaces conventional pushbutton and toggle switches. This advanced interface enables microprocessor-controlled, high-reliability telecom relays for signal and function switching, resulting in significantly shorter signal paths and reduced sensitivity to electromagnetic interference (EMI). The illuminated controls also enhance visibility of preamp status from a distance or in low-light environments.

To enhance operational safety, the CL-520 includes a Blink-Delay feature that helps prevent unintended activation or deactivation of Phantom Power and High-Gain modes.
When either function is selected, its status indicator briefly blinks as a visual warning before activation is engaged after a short delay.

The DI IN and THRU jacks function as a signal split for simplified system integration. The DI IN routes the instrument signal directly to the preamp core, while the THRU jack passes the signal to an amplifier, additional DI, or 500-series module without interruption.

The continuously variable High-Pass Filter (HPF) provides precise low-frequency attenuation across a range of 25 Hz to 420 Hz. This control allows fine adjustment to compensate for microphone proximity effect and is highly effective in reducing low-mid frequency buildup or “mud” in vocals, bass instruments, and other sources.

When the HPF is disengaged, the low-frequency response extends down to 6 Hz, ensuring full bandwidth performance.

Features

◆ APITM 500 Series Module Format
• Compatible with standard API 500 series racks and power supplies.


◆ Fully Balanced Topology - Designed for superior noise rejection and signal integrity:
• Exceptional immunity to ground noise and ground loops
• High resistance to external EMI and interference from adjacent modules or power
supplies
• Ultra-low distortion performance, no capacitors in the signal path (Dyn/Rib mode)


◆ Rail-to-Rail Circuit Design - Optimized for maximum headroom and dynamic range:
• Increased internal operating headroom
• High maximum input level without pad (up to +21 dBu)
• Elevated output level capability without transformer coupling or excessive current
draw


◆ 0.1% Precision Resistors - Ensuring consistent, accurate performance:
• Outstanding common-mode rejection and output signal balance
• Excellent unit-to-unit sonic consistency


◆ FET-Based DI IN and THRU Jacks - Designed for flexible integration:
• Simple connection to amplifiers for simultaneous DI and mic’d tracking or live sound
• Easy routing to additional DI units or effects processors for parallel signal paths


◆ Continuous Detented Gain Control - Precise and repeatable gain staging:
• Detented control for accurate resettability
• Dual gain ranges for optimized control
• Up to 76 dB of total available gain


◆ Cloud Touch-ControlTM User Interface - Advanced reliable control architecture:
• Illuminated controls and status indicators
• Microprocessor-controlled, high-reliability signal and function relays
• Blink-Delay to protect against accidental phantom power or gain switching


◆ High-Pass Filter (HPF)
• Continuous, detented adjustment from 25 Hz to 420 Hz
• Precise low-frequency management


◆ 4-Level Signal Metering
• -20dBu (signal present), +4dBu, +14dBu and +24dBu (OL)
TRUE BLUE 520 Precision Mic Preamp
TRUE BLUE 520 Precision Mic Preamp

Channel Count: Stereo Pair

TRUE BLUE 520 Precision Mic Preamp
TRUE BLUE 520 Precision Mic Preamp
TRUE BLUE 520 Precision Mic Preamp
TRUE BLUE 520 Precision Mic Preamp
TRUE BLUE 520 Precision Mic Preamp
76 dB
Max Gain
25–420 Hz
HPF Range
1 MΩ
DI Input Impedance
2 Yr
Warranty
See It In Action

Hear the 520 for yourself

True Blue 520 Precision Mic Preamp Overview
True Blue 520 Precision Mic Preamp Overview
BRAND NEW SONG with the Cloud True Blue 520
BRAND NEW SONG with the Cloud True Blue 520
True Blue 520 at Phat Planet Studios
True Blue 520 at Phat Planet Studios
"They give exactly what you put into them" - True Blue 520 Precision Mic Preamp
"They give exactly what you put into them" - True Blue 520 Precision Mic Preamp
Capture Your TRUE Sound - True Blue 520 Precision Mic Preamp
Capture Your TRUE Sound - True Blue 520 Precision Mic Preamp
Cloud Mics Dropped Something Special - True Blue 520 Mic Pre
Cloud Mics Dropped Something Special - True Blue 520 Mic Pre

Cloud Touch-Control™

Touch Control. No switches to wear out.

Every function on the CL-520 lives behind illuminated glass — relay-switching and high visibility in dark environments. Hover over the buttons to see what they do!

CL-520 Cloud Touch-Control panel

+16 Lifter Mode

24–76 dB · Blink-Delay armed

Touch and hold to add 16 dB of extra gain on top of the main control. The pad blinks before it engages, so it can't be switched on by accident mid-take.

Phase

180° invert

Flips output polarity with a tap. Handy when a second mic on the same source is fighting the first one in the mix.

HPF Range

25–420 Hz · detented

Sets exactly where the low end starts rolling off. The detented knob clicks back to the same spot every time, so settings carry over session to session.

High Pass Filter

–6 dB/octave

Switches the filter in or out. Off, the preamp runs full bandwidth down to 6 Hz — on, it follows the frequency set by the range knob.

Dynamic / Ribbon Mode

10 kΩ input · caps out of path

Engages automatically whenever phantom power is off. Input impedance rises and coupling capacitors drop out of the signal path — built for dynamic and ribbon mics.

48V Phantom Power

Blink-Delay armed

Hold to send 48 volts to a condenser mic. The red light blinks first as a warning, then holds solid once power is live.

The Core

A 25-Year Legacy Returns

Built on the TRUE Systems Precision 8 core — trusted for two decades across studio, live sound, post-production, and education.

Working with True Systems' Founder, Tim Spencer, the updated TRUE Systems preamp core delivers ultra-high-resolution musicality tuned for every microphone type you own, so the CL-520 sounds like your source, not like itself.

Kennedy Center Warner Bros. Coachella FOH Bonnaroo Remote

Condenser

Full-bandwidth detail

Dynamic

10 kΩ optimized mode

Ribbon

Capacitor-free path

Tube (Self-Powered)

Clean high-headroom gain
Under The Hood

For The Engineers In The Room

Every measurement below exists because someone on our team refused to ship the version that just sounded "good enough."

01

500 Series Compatible

Drops into any standard API™ 500-series rack and power supply — no proprietary chassis required.

02

0.1% Precision Resistors

Tight-tolerance components hold common-mode rejection and unit-to-unit consistency to a standard most preamps don't bother with.

03

Rail-to-Rail Design

Maximized internal headroom supports up to +21 dBu input without a pad, and elevated output without transformer coupling.

04

Capacitor-Free Signal Path

DYN/RIB mode removes input capacitors entirely and raises impedance to 10 kΩ — a cleaner front built specifically for dynamic and ribbon microphones.

05

Fully Balanced Topology

Exceptional immunity to ground noise and EMI, even in racks crowded with other modules and power supplies.

06

4-Level Metering

Signal present, normal, high, and overload — gain-stage with confidence instead of guessing.

Technical Specifications

Microphone Input
Gain (MIC In)
  • +6.5 to +60 dB (+16 "lifter" mode OFF)
  • +22 to +76 dB (+16 "lifter" mode ON)
Maximum Input Level
@ min gain setting
  • +21 dBu (60 dB range)
  • +3 dBu (76 dB range)
Input Impedance (MIC)
  • 5.5 kΩ (+48V phantom power ON)
  • 10 kΩ (+48V phantom power OFF — RIB/DYN mode)
High Pass Filter (HPF)
  • 25 Hz to 420 Hz, 6 dB/octave (HPF ON)
  • 6 Hz (HPF OFF)
Direct Input (DI)
Gain (DI In)
  • -9 to +43 dB (+16 "lifter" mode OFF)
  • +7.5 to +60 dB (+16 "lifter" mode ON)
Maximum Input Level
@ 20dB gain, +26dBu out		 +6 dBu in (THD+N = <0.0007%)
Input Impedance (DI) 1 MΩ
Audio Performance & Distortion
Frequency Response
@ 40dB gain, +26dBu out
  • -3dB BW: 6 Hz to 630 kHz
  • Flatness: ±0.25 dB (10 Hz to 250 kHz)
Maximum Output Level
@ 40dB gain		 +28 dBu (THD+N = <0.0004%)
CMRR
@ 40dB gain, +26dBu out		 92 dB (30 Hz to 20 kHz, +10dBu CMV in)
Output Balance
@ 40dB gain, +26dBu out		 80 dB @ 1 kHz
Phase Shift
@ +26dBu
  • 2.5° @ 30 Hz to 20 kHz (40 dB gain)
  • 2.5° @ 30 Hz, 3.3° @ 20 kHz (60 dB gain)
THD + N
@ 40dB gain, +26dBu out		 <0.00036% @ 1 kHz, 20 Hz to 20 kHz (Note 1)
THD
@ 40dB gain, +26dBu out		 <0.0002% @ 1 kHz (Note 1)
Intermodulation Distortion
@ 40dB gain, +20dBu out
  • <0.0005% MOD (u1–u9) (Notes 1, 2)
  • <0.001% DIM 30 (Notes 1, 3)
Noise
Rs=0
  • -133 dB unwtd (20 Hz to 20 kHz)
  • -135 dB A-wtd
Slew Rate 54 V/µS
Power & System
Common Mode Output Offset
@ max gain		 40 mVDC
Differential Output Offset
@ max gain		 5 mVDC
Power Consumption
+26dBu out
  • +16VDC @ 80 mA, -16VDC @ 55 mA (10 kΩ load)
  • +16V @ 90 mA, -16V @ 65 mA (1 kΩ load)
  1. Actual value is at or below the measurable limitations of the Audio Precision APX555-B test system.
  2. Similar measurement to SMPTE/DIN 4:1 7kHz/50Hz, but with more detail.
  3. Measures high frequency linearity, stability, and "edginess" related to transient response.

* Typical performance specifications, subject to change without notice.