Ruby 3
by Acustica Audio · EQ · Tube EQ
Not rated yet
Ruby 3 is a tube EQ based on Doug Fearn's VT-5, sampled from Fearn's own early reference unit with Acustica's NOVA hybrid modeling.
It works on tracks, buses and masters, and costs €109 (about $123.77) on sale, regularly €235.
Best for: Vocals, Acoustic Instruments, Bass, Mix Bus, Mastering. Genres: all genres.
Keywords: tube, mastering, auto-gain, vocals, full mix, hardware emulation, mid/side, smooth, analog-sounding, bass, bus processing, mix bus, mixing, sampled hardware, static.
What it does
Ruby 3 is Acustica Audio's tube EQ based on the D.W. Fearn VT-5, a passive equalizer with class-A triode tube stages. This version was captured from Doug Fearn's own hand-built VT-5, one of the earliest units made and his personal reference.
- Source unit: an early VT-5 with the high-grade parts of the first production run, which the developer chose for this third version.
- NOVA hybrid engine: Neural Optimized Volterra Audio modeling of the tube stages, so harmonics and response follow the input level.
- Deep Resampling: Acustica's capture method for more detail in the EQ curves and their analog behavior.
- Listening modes: Left-Right, Delta (hear only what the EQ changes), Mid and Side.
- Auto Gain: automatic gain compensation for level-matched before and after checks.
- Display and presets: a real-time EQ display and factory presets for tracks, buses and mastering.
It works at 44.1 to 96 kHz. Current Ruby owners get version 3 as a free upgrade. The store showed a sale price when checked. The product page does not mention a demo.
Source: Acustica Audio product page
When to use it
Ruby 3 models a boutique American tube EQ that few studios own, with Acustica's sampled detail of the preamp and curves. Compared with the Pultec Passive EQ Collection and PuigTec EQs, the classic passive tube choices best for broad low and high shelves with simple controls, and Manley Massive Passive, the flexible tube EQ for mastering, it offers a rarer tube sound. It adds Delta, Mid and Side listening and auto gain, which make it practical on the master as well as on single sources. Unlike Pro-Q 4, the clean, precise standard, it is the pick for smooth, colored tone shaping rather than corrective work.
- Best for: smooth tube EQ on vocals, acoustic instruments, buses and masters.
- Genres: any; it is a general high-end tube EQ that suits acoustic, jazz and pop work especially well.
- Look elsewhere if: you need dynamic bands or narrow surgical cuts (Pro-Q 4 or TDR Nova) or a classic Pultec low-end trick (Pultec Passive EQ Collection).
Where to buy
- Acustica Audio: $123.77 (regular $266.84) (€109 (regular €235) converted to USD (ECB rate, 29 Sep 2026))
Tutorials and reviews
- Ruby 3 Tube EQ by Acustica Audio (No Talking)
- RUBY 3 - Acustica Audio // This is Still The KING
- RUBY 3 - “Closer Than Ever to the Original”
- MANO... A ACUSTICA AUDIO FOI LONGE DEMAIS! (RUBY 3)
- [VST REVIEW] "RUBY" (By Acustica Audio)
Similar plugins
- Summit Audio EQF-100 by Softube · Tube EQ · $159
- Rule Tec Heritage Pro by NoiseAsh · Vintage passive tube EQ (3 models) · $59.90
- Soma by Knif Audio · Tube equalizer emulation · $200
- Rule Tec EQ5M by NoiseAsh · Vintage passive midrange EQ · $39.90
- D.W. Fearn VT-5 by MixWave · Tube passive EQ · $189
- GYRATEC XIV by Antelope Audio · Stereo passive tube EQ · $169
- Purple 4 by Acustica Audio · Passive EQ and tube preamp collection · $237.32
- TE-100 by Lindell Audio · Tube EQ · $75
- Rust 2 by Acustica Audio · Passive 7-band EQ · $73.81
- Pulse-Tec EQs by Nomad Factory · Pultec passive EQ emulation · $24.99
More from Acustica Audio
- Ash by Acustica Audio · Clipper · 7.5/10 · $89.70
- Magenta 5 by Acustica Audio · Channel Strip · $225.96
- Finn by Acustica Audio · Channel Strip · $89.70
- Sydney by Acustica Audio · Channel Strip · $130.58
- Gold 6 by Acustica Audio · Channel Strip · $225.96
- Mystic 2 by Acustica Audio · Channel Strip · $89.70
- Cream 3 by Acustica Audio · Channel Strip · $225.96
- Grey Pro 2 by Acustica Audio · Compressor · $78.35