Jomo Audio Koyo Tri-Brid In-Ear Monitors

Artisanal craftsmanship. Advanced tri-brid engineering. High-end sound made more accessible.

Named after the vivid colors of autumn foliage, the Jomo Audio Koyo is a premium tri-brid in-ear monitor designed to bring together natural materials, sophisticated acoustic engineering, and exceptional value.

Koyo combines a 10mm dynamic driver, three balanced armature drivers, and a 6mm planar magnetic super tweeter within Jomo Audio’s graphene-infused AC2X Asymmetrical Co-Axial Acoustic Chamber. The result is a full-range presentation designed for powerful, textured bass, articulate mids, precise imaging, and airy, extended treble.

Beyond its acoustic performance, Koyo is built to be as distinctive as it sounds. Stabilized maple hardwood, stainless steel, and a gold-plated brass open-back faceplate give every pair a character of its own—one that continues to evolve with age and use.

Natural Stabilized Maple Shell

Koyo’s housing pairs stabilized maple hardwood with a precision-finished stainless steel frame, creating a distinctive balance between organic craftsmanship and modern engineering.

Rather than covering the wood beneath a glossy lacquer, Jomo Audio uses a carefully polished and waxed finish that preserves its natural grain and tactile character. This approach also retains more of the wood’s natural acoustic properties, contributing to Koyo’s warm, organic presentation and spacious sense of ambience.

Because genuine wood naturally changes over time, each Koyo can gradually develop its own patina, deepening in character with use. Natural variations in grain and appearance also mean no two pairs are exactly alike.

FlowMax Open-Back Design

A striking CNC-machined, gold-plated brass FlowMax grille forms the centerpiece of Koyo’s open-back architecture.

Engineered to optimize airflow and acoustic dispersion, the FlowMax design helps Koyo create an open, natural-feeling soundstage while reducing the closed-in presentation that can occur with conventional sealed IEM housings.

The intricate brass structure also provides a distinctive visual contrast against the natural maple shell and stainless steel frame, giving Koyo an unmistakably boutique appearance.

Sophisticated Tri-Brid Driver System

Koyo combines three complementary driver technologies, allowing each to focus on the frequencies it reproduces best.

1 × 10mm Custom Silk-Diaphragm Dynamic Driver
Produces deep, textured bass with satisfying physical impact and natural decay.

3 × Precision Balanced Armature Drivers
Deliver articulate mids, high levels of detail, and precise imaging.

1 × 6mm Nano Planar Magnetic Super Tweeter
Extends the upper frequencies with smoothness, sparkle, and an airy sense of space.

A 4-channel C.S.U. crossover circuit integrates the five-driver system for a coherent presentation across the frequency spectrum.

AC2X Graphene-Infused Acoustic Chamber

At the heart of Koyo is Jomo Audio’s AC2X Asymmetrical Co-Axial Acoustic Chamber, manufactured from graphene-infused 3D-printed resin.

The AC2X architecture places the bass and ultra-high-frequency drivers within a carefully engineered shared cavity while using an asymmetrical design to control interactions between the frequency extremes. This helps preserve low-frequency definition while maintaining clean, extended treble.

The chamber is also designed to create a stable operating environment for Koyo’s balanced armature drivers. Its graphene-infused resin increases structural rigidity and provides additional damping, helping suppress unwanted micro-vibrations and internal resonances.

The result is greater control, lower unwanted resonance, tighter bass, improved clarity, and a more natural tonal balance—allowing Koyo’s tri-brid driver array to perform as a cohesive system rather than a collection of individual drivers.

Oil-Infused OCC Copper & Silver Cable

Koyo includes a premium oil-infused coaxial cable constructed from OCC single-crystal copper and OCC single-crystal silver conductors.

The copper-and-silver blend is designed for highly transparent signal transmission, pairing the natural tonal qualities associated with copper with the excellent conductivity of silver. Its coaxial construction also provides shielding against electromagnetic interference for a clean signal path.

The supplied cable uses a 4.4mm balanced termination and connects to the monitors through 0.78mm 2-pin connectors.

Boutique Engineering Without the Flagship Price

Koyo brings together materials and engineering approaches more commonly associated with considerably more expensive boutique IEMs: stabilized hardwood, stainless steel and gold-plated brass construction, an open-back acoustic system, graphene-infused internal architecture, five drivers spanning three technologies, and a premium OCC copper-silver cable.

It is designed for listeners who want high-end acoustic engineering and artisanal construction without stepping into traditional flagship pricing.

Whether you value impactful bass, detailed vocals, expansive staging, extended treble, or simply an IEM that feels genuinely special in the hand, Koyo offers a sophisticated combination of performance, craftsmanship, and value.

Specifications