Relentless Series
Four years after setting the measure for amplifier excellence, the Relentless Mono Amplifier has undergone an upgrade—the Epic. Combining new circuit sections and components, the Relentless Epic 1600 Amplifier resets the standard in power amplifier performance. The Relentless Epic 1600 Mono Amplifier is a true balanced design but unlike conventional bridged amplifiers, the Relentless Epic 1600 Mono Amplifier uses a single front end topology, based on current mirror circuitry to derive the symmetrical plus and minus rails.
In the new Relentless Epic 1600 amplifiers, the driver transistor has been upgraded to a new device that handles 33% more power per device. Additionally, the driver transistor count has doubled thus minimizing demand on each individual device and lowering overall amplifier output impedance without resorting to global negative feedback.
With its 5.5-kilowatt power supply feeding over 100 output devices, the Relentless Epic 1600 Mono Amplifier easily delivers 1,600 watts into 8 ohms—and when connected to a 220-volt or greater AC mains outlet, it doubles its output to 3,200 watts into 4 ohms and 6,400 watts into 2 ohms.
This power output is maintained with the same musical composure at full power as it is at 1 watt.
The Relentless Epic 1600 Mono Amplifiers’ unique heat sink combines copper and aluminum in a thermal engine that wicks away heat from the connected devices. The elaborate elliptical design expands on the venturi heat sink first explored in the Momentum series and makes certain that the Relentless Epic amplifiers run safely and reliably even when delivering its full rated power.
Dan D’Agostino Master Audio Systems set the standard for amplifier performance with the Relentless Epic 1600 Monoblock Amplifier. Now, the Relentless Series expands its reach with the Relentless 800 Monoblock Amplifier. Every major section of the Relentless Epic 1600 has been incorporated into the Relentless 800, whose design is further enhanced by new power management topology that isolates the power supply from the entire audio circuitry, providing extra protection from noise generated by the amplifier’s massive power transformers.
The Relentless 800 Monoblock Amplifier employs all-new, fully complementary topology based around a precision input stage that maintains a perfect balance between the positive and negative components of the signal. Gain circuits operate in the current domain, assuring that performance does not fluctuate, regardless of speaker demand. New input stage devices deliver a 300% increase in current as compared to the devices previously employed. These wider-bandwidth, higher-power components extend low- and high-frequency performance with reduced distortion. Global negative feedback is not required, as the amplifier’s open-loop linearity eliminates the need for this performance-robbing technique. Crucial to the new circuit are the bipolar transistors powering the front end. Activating the driver stage is a new bias stability circuit providing a nearly 50% increase in operating bias. Increasing Class A operation directly correlates to better sound quality. The new bias scheme ensures bias consistency, preventing excessive temperatures even under the greatest demand. Additional regulation circuitry prevents any AC power anomalies from upsetting the amplifier’s input circuitry.
A critical element of any amplifier output topology is the driver section, and here, the driver transistor has been upgraded to a new device that handles 33% more power per device. Additionally, the driver transistor count has doubled, minimizing demand on each device and lowering overall amplifier output impedance without resorting to global negative feedback. Individual transistors are used for the positive and negative signal elements, nearly doubling the current drive necessary to maximize the enhanced output stage. The output stage features the same new transistor used in the driver section for sonic and technical consistency. As with all Dan D’Agostino Master Audio Systems components, the Relentless 800 features discrete, direct-coupled, balanced circuitry—the most accurate circuit platform possible.
The entire chassis of the Relentless 800 is machined from solid aluminum for superior shielding, thermal stability, and vibration damping. High-precision milling allows the entire chassis to fit together solidly, with no visible fasteners. Each Relentless 800 Mono Amplifier is hand-built and individually tested in D’Agostino’s Arizona factory by their team of technicians and craftsmen.
The new Relentless Preamplifier is the ultimate in preamplifier design. The preamplifier plays a critical role in musical playback; the point in the reproduction stage when the music signal is particularly susceptible to compromise through noise and distortion. The use of three separate chassis in the design of the Relentless Preamplifier—a dedicated audio chassis for each channel separated by a power supply/control section—addresses these challenges and brings other benefits as well.
Positioned between the two audio channels, the power supply makes use of extensive electrical and magnetic shielding to keep radiated interference out of critical preamplifier circuits. Internal line conditioning circuitry filters RF noise on the AC power and compensates for asymmetric power waveforms and DC on the mains. Power for the preamplifier stages comes from two 150 VA toroidal transformers – one dedicated to the analog circuitry and one for the digital and control circuitry.
The Relentless Preamplifier has nearly as much power supply capability as many power amplifiers.
Arguably, the most striking element of the Relentless Preamplifier is the pair of volume controls fronting the two audio chassis. Volume control circuits are often overlooked, if not actively minimized, in preamplifier designs. This is not the case in the Relentless Preamplifier. Each volume control is constructed using 14 separate metal components ensuring the smoothest response and control of the military-grade, high-linearity solid-state switches and discrete precision resistors employed in the volume circuit.
Featuring only balanced XLR inputs the Relentless Preamplifier topology rejects common-mode input noise over an unusually wide bandwidth. All signal gain is realized in the current domain using proprietary multiple-output current mirrors with nearly 30 times the linearity of other designs.
Utilizing no negative feedback anywhere, core D’Agostino circuit concepts include a signal path that is fully complementary and balanced from input to output achieving a frequency response flat to 120 kHz.. The overall result is a musically dense and dynamically rich signal presented to the balanced outputs.