Mastro Valvola Pedals Mastro Valvola Millibar mk2

The Mastro Valvola Millibar mk2 is a studio-grade optical compressor pedal for guitar and bass, unveiled by Mastro Valvola Pedals on March 3, 2017¹². It is handcrafted in Italy and was sold at launch directly through the Mastro Valvola online store at www.mastrovalvola.it¹². The mk2 is a revised version of the original Millibar, and its single most important change is a new attack control, which Mastro Valvola says gives players "maximum flexibility and control over compression characteristics"³¹.

An optical compressor uses a light-dependent element to control gain reduction rather than the transistor or FET circuits found in many other compressor pedals. Mastro Valvola says the Millibar's design draws on two classic studio units: the Universal Audio 1176 and the Teletronix LA2A¹². In the maker's words, the result is compression that leaves the instrument intact:

What the Millibar mk2 does

The Millibar is built to deliver what Mastro Valvola calls "optimal compression control on both guitar and bass alike"¹². Compression evens out the difference between a player's loudest and quietest notes, raising sustain and tightening dynamics, and the Millibar's optical approach is aimed at doing that transparently, with what the maker describes as "tone-full" qualities and no loss of sound frequencies¹.

The maker positions it as an extremely versatile pedal rather than a one-trick effect. Its separate compression and sustain controls allow a range of dynamic combinations that Mastro Valvola says are suitable for arpeggios, solos, grooves and many other styles and effects³². In practice, that means a player can dial in light leveling for clean arpeggio work, or heavier compression with long sustain for lead lines, from the same set of knobs.

The controls and the added attack knob

The control layout is where the mk2 differs from the original Millibar. The core of the design is two independent knobs⁵²¹:

The separate compression and sustain controls are the Millibar's defining feature. On many compressor pedals a single "sustain" or "level" knob handles both jobs, which couples how hard the pedal squeezes with how long notes ring. Here the two are decoupled, so a player can set strong compression with short sustain, or light compression with long sustain, and any combination between⁵¹.

The attack control is the mk2's addition. Attack time determines whether the compressor reacts to a note's initial transient or lets it through before clamping down. A fast attack tames pick attack for a smooth, even output; a slower attack lets the front of each note through, preserving percussive snap while still leveling what follows. Mastro Valvola added the knob specifically so players can place that behavior anywhere on the scale themselves, rather than living with one fixed response³¹.

What is new in the mk2

The original Millibar already had the separate compression and sustain controls and the optical circuit inspired by the Universal Audio 1176 and Teletronix LA2A⁵¹. The mk2, announced on March 3, 2017, keeps that design and adds the attack control³¹². No other circuit or feature changes are given in the maker's material for the mk2.

Where it is made and what it costs

The Millibar mk2 is handcrafted in Italy¹². At launch it was available directly from the Mastro Valvola online store at www.mastrovalvola.it¹². The launch price was €185 with VAT included¹²; a later listing on the maker's site shows the Millibar optical compressor at €193,00²¹⁴. No US dollar price is given. The maker's product page currently lists the pedal as "Temporarily Out of Stock"⁵, and the maker provides a downloadable manual for the Millibar on that page³.

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