Dan D'Agostino Master Audio Systems announced the launch of Relentless preamplifiers. As a supporting model of Relentless mono amplifier, Relentless preamplifier combines innovative power and audio circuits, elegant architecture and a series of innovative features.
The breadth of the Relentless preamplifier design requires the use of three separate enclosures-a dedicated audio enclosure for each channel and an independent power supply in between to keep the power feed as short as possible. The three chassis are interlocked by a special mechanism in each chassis mounting foot. The 30-pin interlocking 20-amp gold-plated connector eliminates the wiring normally used in these applications and the associated anomalies that may occur. This unique structure physically and electrically isolates the audio signal from the power supply and digital control part. Physical isolation provides additional space to maximize power and audio circuits. This mono structure also separates the two audio channels from each other, ensuring the final channel separation.
The power supply is located between the two audio channels, and extensive electromagnetic shielding is used to prevent radiation interference from entering the critical preamplifier circuit. The internal circuit conditioning circuit filters the RF noise on the AC power supply and compensates for the asymmetric power supply waveform and DC on the power supply. The power for the preamplifier stage comes from two 150 VA toroidal transformers-one dedicated to analog circuits and the other to digital and control circuits. These transformers drive an 8 amp bridge rectifier and 26,400 microfarad filter capacitors. The two regulators in the analog stage are reduced versions of the regulators used in Relentless Mono amplifiers.
The input stage in each mono preamplifier is the result of design experiments on circuits that have not been used by any D'Agostino preamplifier before. The audio circuit topology starts with a completely unique new discrete differential FET input stage with 30 volt voltage input signal capability. With an input impedance exceeding 1 MOhm, the front end of the Relentless preamplifier is not affected by electrical problems related to the signal source. In normal operation, heating of the components will cause performance and sound attenuation. Specially developed for Relentless preamplifiers, the unique circuit maintains a stable bias to offset temperature-related anomalies, thereby maintaining performance during long listening sessions.
The Relentless preamplifier topology has only balanced XLR inputs, which can suppress common-mode input noise in an exceptionally wide bandwidth. All signal gains are realized in the current domain using a proprietary multi-output current mirror, and the linearity is nearly 30 times that of other designs. A four-layer circuit board is used to achieve excellent signal quality. Compared with the more common two-layer circuit board, the use of a four-layer circuit board significantly reduces the level of distortion and propagation.
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The analog and digital circuit components are isolated from each other, including the ground plane. When necessary, the digital control signal is optically coupled to the analog circuit. The signal switch relay is hermetically sealed and uses gold-plated contacts for maximum signal integrity.
There is no negative feedback anywhere. The core D'Agostino circuit concept includes a fully complementary, directly coupled and balanced signal path from input to output, achieving a frequency response that is flat to 120 kHz.
"The new Relentless preamp is an important moment in our quest to produce audio components that can provide as much musical performance as possible. This is a pursuit for more than 40 years. The Relentless preamp is a shining jewel in my career. "Co-founder and chief engineer Dan D'Agostino said.
It can be said that the most striking element of the Relentless preamplifier is the pair of volume controls on the front of the two audio boxes. In the design of preamplifiers, the volume control circuit is often overlooked, if not actively reduced. In Relentless preamplifiers, this is not the case. Each volume control is constructed with 14 independent metal components to ensure the smoothest response and control of the military-grade, high-linearity solid-state switches and discrete precision resistors used in the volume circuit. The bandwidth and transient response of the Relentless preamplifier are completely unaffected by the volume setting. The volume setting is displayed by an elegant Swiss watch-style volume wand, or can be displayed digitally, from 0 to 99.
The Relentless preamplifier is a dual source/two zone preamplifier. This means that Relentless preamplifiers can simultaneously control the switching and volume of two sources in two separate rooms or areas. This may be two analog sources, or when equipped with a streaming digital module, one digital source and one analog source. In a single zone system, the volume control will adjust the volume of the main room or zone 1. If two areas are required for operation, the upper volume control manages the volume of area 1, and the lower volume control adjusts the volume of area 2.
The Relentless preamplifier remote control is made of machined aluminum and copper, and has a comfortable design that can be operated via a touch panel. The Bluetooth VI technology expands the usable range of the remote control and eliminates the line of sight problems that plague traditional infrared designs. The new two-way remote control function reflects all the adjustments made on the front panel of the Relentless preamplifier to the remote control's display, including input, volume and balance selection.
Optional Digital Streaming Media Module (DSM)
The Relentless preamplifier is the first D'Agostino preamplifier with optional DSM. This digital enhancement adds connectivity to traditional sources, USB capabilities, and first-class streaming capabilities. DSM can be upgraded on site, adding SPDIF coaxial, optical, USB-A, RJ-45 and Wi-Fi network inputs. For the delay-free playback of high-resolution network content, 10/100/1000 Gigabit Ethernet is supported.
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Apps customized for iOS devices can easily control music collections, streaming content, and device control. Subscription streaming services Tidal, Qobuz and Spotify are native in the app. For appropriately encoded music files, MQA decoding is standard. In addition, Roon Music Management can also be used as an alternative music management program.
The DSM is completely isolated from the analog circuit and is installed in the power supply/control box. Three independent circuit boards are required. The core component is a pair of DACs configured in differential mode, and each DAC is configured to process the positive and negative signals of each channel. Capable of processing the highest resolution signal sources available today, PCM signals up to 32-bit/384 KHz and DSD signals up to DSD256 (11.2MHz) can be decoded locally. The analog part of the DAC is often overlooked or downplayed, significantly affecting the final sound performance of digital music. The internal balanced connection transmits the final analog signal to the connection pins and continues to each audio chassis. From here, the analog music signal utilizes the entire power supply and analog circuits in the three chassis of the Relentless preamplifier.
The Relentless preamplifier is priced at £165,000 (including VAT and installation) in the UK and will be shipped in November 2021, with silver, black or custom painted finishes.