Product Overview

A Modern Vari-Mu Legend with Custom Parallel Tube Architecture

Unlike conventional variable-bias compressors loosely inspired by vintage radio-era broadcast gear like the Fairchild, Collins, or Gates consoles, the SPL Iron V2 introduces a completely rewritten hardware blueprint. It does not merely emulate old topologies; it redefines them.

By integrating a dual-tube design that features two distinct twin-triode tubes with conflicting response curves running in parallel per channel, the Iron V2 allocates processing depending entirely on the amplitude of the incoming mix. This results in an extremely musical, lively, and transparent compression that prevents full master tracks from ever feeling choked, flat, or over-saturated, even at high gain reduction levels. Equipped with total hardware recall functionality, it serves as an indispensable tool for commercial mastering houses and critical mixing setups.

Product Description

120V High Dynamic Tech and Cryogenic Tube Perfection:

At the foundation of the Iron V2 is SPL’s iconic 120-volt rail operating platform. Running at a continuous DC voltage that quadruples the operating capacity of standard semiconductor IC op-amps, the unit yields an astronomical +32.5 dBu of headroom and an expanded dynamic soundstage.

For the V2 revision, SPL updated the core tube network. The parallel signal flow marries matched 12AU7 tubes with hand-selected Wathen CryoTone™ 12AX7-WCM Long Plate tubes. These specialized tubes undergo a rigorous cryogenic freezing treatment that reorganizes their molecular structural alignment, culminating in an ultra-low noise floor, enhanced longevity, and exceptional depth of field. High-level, double-core Lundahl mu-metal-iron transformers frame the tube architecture to weave subtle harmonic richness throughout the entire frequency spectrum.

Six-Position Switchable Rectifier Matrix:

The behavior of the variable-bias tube control circuit is dictated by an integrated rectifier switch featuring six distinct diode selection matrices (incorporating Germanium, Silicon, LED, and mixed configurations):

• Germanium (1 mF, 2 mF, 220 nF)

• Silicon (330 nF)

• LED (3.3 mF)

• Germanium/Silicon Mixed (100 nF)

Swapping rectifiers dynamically recalculates the envelope tracking, modifying the internal Attack and Release curves. This allows the engineer to tailor transient responses on the fly—from fast, transparent tracking for classical or acoustic music to slower, fat, vintage saturation behaviors suited for rock and pop records.

Upgraded XLR Sidechain and Timbre-Shaping EQ Filters:

The Iron V2 advances internal control capabilities with four on-board sidechain EQ filter curves plus an external sidechain matrix. In the V2 hardware, previous TS inputs are replaced with premium, fully balanced XLR Send and Return Sidechain Inserts, making it easier to route external vocal or instrument equalizers directly into the control signal path.

To add a final analog polish before printing, a built-in passive filter network provides two master EQ presets:

• AirBass: Grants a gentle 1.5dB to 2dB lift on both the extreme sub-bass regions and high-frequency air spectrum for massive scale and expensive-sounding top-end shine.

• Tape Roll-Off: Deploys calibrated high- and low-cut filters that accurately emulate the warm, smoothed-out high transient response of a vintage analog tape deck.

Key Features

• 120V RAIL PLATFORM: Delivers ultimate dynamic response, high-end headroom, and a quiet noise floor.

• PARALLEL DUAL-TUBE CIRCUITRY: Uses a dual twin-triode concept per channel to assign compression duties based on incoming signal amplitude.

• CRYO-TREATED WATHEN TUBES: Outfitted with perfectly matched Wathen CryoTone 12AX7-WCM Long Plate tubes for pristine imaging clarity and extended lifecycle.

• LUNDAHL MU-METAL TRANSFORMERS: Custom dual-coil high-level transformers embedded in the signal path for rich analog depth.

• SIX RECTIFIER PRESETS: Front-panel switch toggles through combinations of Germanium, Silicon, and LED diodes to remap Attack/Release behavior.

• BALANCED XLR SIDECHAIN INSERTS: Upgraded dedicated XLR Send/Return infrastructure to feed custom equalization arrays into the detector path.

• AIRBASS & TAPE EQ PROFILES: Built-in passive filter settings to add instant low-end body, high-frequency sparkle, or tape-machine emulation.

• STEPPED CONTROLS FOR RECALL: Every parameter operates via high-quality switches or a 41-step detented potentiometer (for Threshold) to ensure precise session repeatability.

• INTEGRATED VACTROL OPTOCUPLER: Independent feed-forward opto-isolator absorbs radical transient spikes to keep compression characteristics transparent and musical.

• INTUITIVE AUTO BYPASS: An adjustable audition timer automatically toggles processing on and off for unbiased listening assessments.

Technical Specifications

Analog inputs & output; XLR (balanced)

Maximum input & output gain

32,5 dBu

Input impedance

20 kΩ

Output impedance

75 Ω

Frequency range (-3 dB)

10 Hz bis 40 kHz

Common mode rejection (0dBu, 1kHz)

> 80 dBu

Crosstalk (1 kHz)

-108 dBu

THD (+10 dBu)

0,002 %

Noise (A-weighted)

-98 dBu

Internal Linear Power Supply with Shielded Toroidal Transformer

Operating voltage for analog audio

+/- 60 V

Operating voltage for relays and LEDs

+ 12 V

Mains Power Supply

Mains voltage (selectable, see fuse chamber)

230 V AC / 50; 115 V AC / 60 Hz

Fuse for 230 V

T 1 A

Fuse for 115 V

T 2 A

Power consumption

max. 60 VA

Dimensions & Weight

W x H x D (width x height x depth)

482 x 177 x 300 mm

19 x 6,97 x 11,8 inch

Unit weight

11 kg

24,25 lbs

Shipping weight (incl. packaging)

12,9 kg

28,44 lbs

Referenz: 0 dBu = 0,775V. Technische Änderungen vorbehalten.

What’s Included in the Box

• 1 x SPL AUDIO Iron V2 Two-Channel Tube Mastering Compressor Main Unit

• 1 x Standard AC Grounded IEC Power Cable

• 1 x Set of Premium Rackmount Chassis Washers

• 1 x Official SPL Mastering Series Operation and Calibration Manual