VT-9M

Mastering-Grade Compression
Provides smooth, controlled dynamics for individual tracks or complete stereo mixes.

All-Tube Audio Path
Uses Class-A vacuum tube circuitry to deliver a clear, transparent sound with natural warmth.

Stereo Operation
Two channels can work together for consistent compression across stereo material.

Flexible Compression Character
Adjustable compression shape lets you move between gentle, natural control and a firmer, more noticeable effect.

Adjustable Attack
Controls how quickly compression responds, allowing transients to remain lively or be more tightly controlled.

Adjustable Release
Shapes how quickly the signal recovers after compression for anything from natural dynamics to a denser sound.

Sidechain High-Pass Filter
Reduces the compressor’s sensitivity to bass, helping prevent heavy low frequencies from causing unwanted pumping.

Make-Up Gain
Restores level after compression so the processed signal can be properly balanced.

True Bypass
Provides a direct comparison between the processed and unprocessed signal and allows audio to pass even when the unit is powered off.

VU Metering
Displays output level or gain reduction for straightforward monitoring while making adjustments.

Transformer-Balanced Audio
Uses high-quality input and custom output transformers for professional studio connectivity and sound quality.

Hand-Built Construction
Individually assembled, tested, and evaluated with high-quality components for long-term professional use.

General Specifications
Device Type: Dual-channel mastering compressor
Audio Path: Class-A triode vacuum tube
Channels: 2 independent channels
Nominal Input Level: +4 dBm
Gain: Unity to +15 dB
Gain Reduction Range: 0 to 20 dB

Input
Input Type: Transformer-balanced bridging
Input Connector: XLR-3 female
Input Load Impedance: 32 kΩ
Nominal Source Impedance: 600 Ω
Maximum Input Level at 20 Hz: +25 dBm
Input Transformer: Jensen
XLR Pin 1: Ground
XLR Pin 2: High / +
XLR Pin 3: Low / -

Output
Output Type: Low-impedance transformer-balanced
Output Connector: XLR-3 male
Output Source Impedance: 115 Ω
Maximum Output Level: +22 dBm into balanced or unbalanced bridging input
Recommended Load Impedance: 20 kΩ or greater
XLR Pin 1: Ground
XLR Pin 2: High / +
XLR Pin 3: Low / -

Audio Performance
Frequency Response: ±0.2 dB, 20 Hz–20 kHz
Extended Frequency Response: ±0.5 dB, 11 Hz–28 kHz
-3 dB Bandwidth: 0.5 Hz–65 kHz
THD + Noise: <0.05%, 20 Hz–20 kHz
Signal-to-Noise Ratio: 78 dB minimum

Compression Controls
Threshold: Adjustable
Make-Up Gain: 0–10 dB, 1 dB per step
Attack: Adjustable
Release: Adjustable
Compression Shape: Softer–Harder
Sidechain High-Pass Filter: Off / Low / High
Bypass: True bypass

Metering
Meter Type: True VU
Meter Standard: ASA C16.5-1954
Meter Modes: Left output / Right output / L+R output / Gain reduction
Output Reference: 0 VU = +4 dBm
Gain Reduction Indication: Average gain reduction
Output Level Indication: Average output level
Output Meter Reference Adjustment Range: -20 dBm to >+20 dBm

Circuitry
Input Amplifier Tube: 6072A
Input Amplifier Configuration: Class A
First Input Amplifier Stage Gain: Approximately 20
Second Input Amplifier Stage Gain: Approximately 15
Input Amplifier Output Stage: Cathode follower
Input Amplifier Output Impedance: Approximately 450 Ω
Gain Control Circuit: Pulse Width Modulator
PWM Loss Without Gain Reduction: Approximately 20 dB
PWM Loss at Maximum Gain Reduction: Approximately 30 dB
Output Amplifier Tube: 6072A
Output Amplifier Configuration: Class A
First Output Amplifier Stage Gain: Approximately 30
Second Output Amplifier Stage Gain: Approximately 20
Output Amplifier Output Stage: Cathode follower
Vacuum Tube Quantity: 8
Vacuum Tube Type: 6072A
Interstage Coupling Capacitors: Polypropylene
Output Transformer: Custom transformer
Power Supplies: 5 solid-state fully regulated supplies
Filament Supply: 12 V
Low-Voltage Supplies: +15 V / -15 V / +5 V
B+ Supply: 8 separately regulated voltages

Electrical
Mains Voltage: 115 V or 230 V AC
Supported 230 V Range: 220–240 V AC nominal
Mains Frequency: 50/60 Hz
Power Consumption: 85 W
120 V Fuse: 2 A slow-blow, 3AG 6.3 × 32 mm
220–240 V Fuse: 1 A slow-blow, 3AG 6.3 × 32 mm
AC Connector: IEC
Power Transformer: Toroidal
Chassis Ground: Rear-panel grounding terminal

Dimensions and Weight
Rack Width: 19 in (48.26 cm)
Height: 5.25 in (13.34 cm)
Depth: 13 in (22.9 cm)
Weight: 22 lb (9.55 kg)
Shipping Weight: 28 lb (12.27 kg)

Installation
Rack Format: Standard 19-inch rack
Vertical Rack Space: 5.25 in
Recommended Ventilation Clearance: At least 1 rack unit above and below
Cooling: Passive airflow through bottom and top ventilation slots