Good audio amplifier design combines the following aspects:

• What does it sound like?
• How linear can it be? (measurable specs)
• How much will it cost?
• Reliability, Esthetics and Ergonomics

Some of these aspects are more subjective than others, and can even contradict each other. MASCINI's design approach starts with a set of baseline criteria, anchored in technical rationale such as power rating, distortion thresholds, frequency linearity, targeted size/weight/cost etc.

Extensive proto-typing follows, where each prototype is being assessed by a listening panel of experienced music lovers and scored. The outcome informs the process of 'tweaking', where prototype modifications are being made, measurements and listening sessions repeated, and if required, new prototypes are being build.

You will notice that MASCINI GaN amps have larger than usual heatsinks for this type of technology. Through extensive listening it became clear that, contrary to the belief that GaN FETs need very little cooling, larger heatsinks contribute significantly to much more stable sound quality at all levels and improves overall reliability.

Through the highly iterative design process, MASCINI GaN amplifiers reach their final production state to be ready for your ears only after the perfect balance between the various design criteria has been met.

Class-D amplifier design with super fast GaN transistors requires significant insight and effort to produce stable, reliable, and good sounding results. Switching frequencies of hundreds of KHz occur at the PWM and power stages of the amplifier where timing sequences of nano-seconds are critical. Copper traces on component boards start to act as inductors, and interactions between metal layers and components introduce unwanted capacitance.

Designer Jan Mascini, has extensive experience with designing high frequency circuits, acquired during his years as an active radio amateur. Combined with his multi-year experience as an audio designer, this makes for valuable skills in the domain of fast class-D audio design.

Some highlights of technical design implementation are:

• 4-layer PCB's eliminates parasitic inductances through effective return paths
• 2 oz copper on all layers for low impedance and optimal cooling
• Component separation on both sides of the PCB decouples audio and HF
• Bridge Tied Load (BTL) with 4 GaN FETs per channel for highest power efficiency and best performance
• Optimized heavy GaN FET cooling for eliminating thermal instabilities
• Dual pre- and post-filter feedback for vastly reduced output impedance, stellar frequency linearity, and superior stability.

With today's modern technologies available to audio design engineers, and with proper design skills, it is relatively easy to build a GaN MOSFET based Class-D power amplifier that has stellar specifications. The market presents products with such low distortion and noise characteristics, that it challenges the most sensitive measuring equipment the industry has to offer. But do ever improved technical specifications also sound superior?

At MASCINI Audio we believe that a certain baseline set of technical specifications is a required foundation, but beyond that it is our hearing that drives further audible improvement. For example, through various empirical testing it has become clear that humans can no longer discriminate a total harmonic distortion figure below ~0.05%. Therefore any effort with sole focus on improving that particular metric wastes time & money. The race to produce ever-improved technical specs is meaningless and misleading, and often compromises other aspects of the design such as reliability.

Although MASCINI GaN amps have stellar technical specifications, the following design example demonstrates MASCINI's approach; our amplifiers utilize precision MELF (Metal Electrode Leadless Face) resistors in the signal path instead of the regular SMD components, because our extensive testing has confirmed a better sounding result, although no differences can be measured.