AGD Production AGD Gran Vivace MkIV

A Personal Note on the AGD Gran Vivace MKIV

From the very beginning, my goal has been simple: to bring together perfection and beauty in the art of audio reproduction.

Every AGD design is a continuation of that pursuit—an ongoing dialogue between technology and music.

The AGD GaNTube™ platform reflects this journey. Now in its fourth generation since its introduction in 2020, the new GaNTube120KT MKIV represents a meaningful step forward. At its core is a new generation of high-voltage GaN HEMT devices, combined with refined thermal management and an improved low-noise linear regulator stage—each element carefully engineered to elevate performance without compromising musical integrity.

The Gran Vivace MKIV delivers an even deeper sense of control and authority when compared to the MKIII. The latest GaNTube implementation, together with a newly developed 100% GaN-based power supply—capable of delivering up to 6kW peak power—allows the MKIV to respond with remarkable speed and composure, even under the most demanding conditions.

The result is a greater clarity, lower distortion, and a more effortless presentation. Music unfolds with enhanced transparency and dynamic precision, revealing nuance and space with a natural, unforced quality and holographic imaging that define the AGD sound.

Every detail has been considered to preserve what matters most: a sense of realism, emotional connection, and ease, while at the same time, the Gran Vivace MKIV retains the elegance, simplicity, and upgradeability that define the AGD philosophy.

Alberto Guerra

Evolution of Speed, Control, and Musical Truth

The Gran Vivace platform has always occupied a unique position in high-end amplification,  not  simply as a powerful Class-D design, but as a deliberate rethinking of how modern power electronics can serve music.

With the Gran Vivace MKIV, that philosophy reaches a new level of maturity, where engineering refinement and sonic expression converge more seamlessly than ever before.

At the heart of the Gran Vivace architecture lies AGD’s distinctive GaNTube™ platform, a modular approach that integrates the entire power stage into a compact glass enclosure.

This is not merely an aesthetic gesture; it is a deliberate engineering choice aimed at maintaining consistency across revisions and delivering unprecedented easy of upgrade.

Earlier generations of the Gran Vivace (and Audion) already demonstrated the advantages of GaN (Gallium Nitride) switching devices and the Gran Vivace MKIV builds upon this foundation with a new generation high-voltage GaN HEMT MOSFETs, new PCB layout optimized for speed and thermal efficiency, and improved device integration and high-reliability components.

The system continues to operate at ~800 kHz PWM switching frequency, a regime that pushes switching artifacts well beyond the audible band and allows for a more benign output filtering process.

The Gran Vivace has always been known for its ability to control demanding loudspeakers, and the MKIV reinforces this strength.

With 400W into 4 ohms and high current capability, the amplifier delivers bass that is:

• Deep
• Controlled
• Free of overhang

Importantly, this control does not come at the expense of weight or texture.

The bass remains articulate yet substantial, avoiding the overly damped character sometimes associated with high-feedback designs.

What ultimately defines the Gran Vivace MKIV is not any single parameter, but the way its capabilities integrate into a cohesive listening experience.

Music is not pushed forward; it simply unfolds.

Large-scale dynamics are delivered without strain, while delicate passages retain their nuance and intimacy.

This duality—power and finesse—is what elevates the MKIV beyond a purely technical achievement.

One of the persistent challenges of Class-D amplification has been the trade-off between speed and musicality. Earlier implementations often impressed with precision but fell short in tonal density or harmonic naturalness.

All the AGD designs address this balance with notable success, a success we committed to further extend.

That goal was set during the development of the MKIV. The most immediate impression with the Gran Vivace MKIV is speed, not in an artificial or etched sense, but in the amplifier’s ability to follow the signal envelope without lag or overshoot.

Fast transients are rendered with clarity and control, allowing percussive elements and leading edges to emerge with natural definition. With the improved regulation and reduced noise floor, the Gran Vivace MKIV reveals micro-information with greater ease. Ambient cues, decay trails, and spatial information become more apparent, not spotlighted, but simply present.

This contributes to a soundstage that feels less “constructed” and more organically layered. There is no sense of dryness or analytical thinning. Instead, the presentation retains body and harmonic completeness, allowing instruments to sound convincingly real.

All the improvements are not limited to switching behavior, but extend to overall system integration, including the new output filtering and the new GaN based power supply.

• A breakthrough in the MKIV is the introduction of a new 600W continuous, fully GaN-based power supply, capable of delivering up to 6kW peak power (100ms, 60Apk).
• The new advanced AGD PS design, has a resonant topology for the primary stage and a dual-stage PFC front-end, (which ensures and optimal sinusoidal current absorption and enhanced voltage supply stability).
• Unlike conventional designs, this 100% GaN implementation provides ultra-fast transient response, dramatically reduced switching losses, and exceptional power density.
• The result is an amplifier that responds instantly to dynamic demands while maintaining absolute control and low noise.

By allowing existing users to upgrade the core power stage, AGD effectively decouples technological progress from product obsolescence—a rare and meaningful approach in high-end audio.

The Gran Vivace MKIV is not a radical departure from its predecessors, nor does it attempt to redefine its identity. Instead, it represents a systematic refinement of an already sophisticated concept.

By improving the key areas that matter most—switching behavior, thermal stability, power delivery, and noise performance—AGD has created an amplifier that advances both measurable performance and subjective experience.

In listening terms, the result is clear:

• Greater transparency
• More precise dynamics
• Improved tonal naturalness
• Effortless control across all conditions

The Gran Vivace MKIV stands as a mature expression of AGD’s vision—where technology serves music without calling attention to itself, and where performance is defined not by spectacle, but by coherence and realism.

The New AGD GaNTube120KT MKIV

• In this new AGD GaNTubeTM120KT, a pair of the newest and most advanced generation of 650V rated HEMT Gallium-nitride power MOSFETs are at the core of the design. These new advanced components are the key to the improved efficiency and power capabilities and the reference musical  performance of the AGD “Gran Vivace” MKIV.
• A refined thermal management and an improved low-noise linear regulator stage, with increased passive component reliability, with each element carefully engineered to elevate performances.
• The refinement of the upper frequency operation delivers a direct and positive impact on the overall outstanding sonic and musical performances with sublime mid-high range realism.

• New Gallium Nitride Design Power Stage with the most advance 650V GaN MOSFET device.
• Enhanced thermal design.
• Redesigned power stage with optimized layout, 400W 4ohm, ~800KHz PWM.
• 400W 4ohm, 800KHz PWM, 60Amp peak.
• New linear supply rails with increased capacitor bank and long-life high reliability grade passive components.