After years of painstaking research and development and exhaustive listening trials the Spectral DMC-30SV “Super Veloce” Reference Preamplifier is now here. The new DMC-30SV succeeds the classic DMC-30SS reference preamplifier, for eight years our most popular product and one of the most highly regarded audio components in the high-end audio industry. Developed over the course of three years, the DMC-30SV is our fourth generation of the DMC-30 family which music enthusiasts worldwide have come to regard as the gold standard in state-of-the-art performance and top value. The DMC-30SV utilizes new Spectral exclusive technologies and componentry to raise the bar in signal control and amplification to a new level of precision and musical realism.
Since the establishment of our company in the 1970sand the introduction of our very first audio component, high performance preamplifier design has occupied the highest engineering priority at Spectral. Our special focus on high-end preamplifier development over the years is based on the major design challenges which low-level amplifier and control circuitry can represent. At these critical signal levels minute amplifier distortions and signal control colorations are passed on and magnified by power amplifiers to dominate the sonic signature of the best audio systems. Spectral engineers have spent the last four decades pursuing ideal performance and signal transparency in audio preamplifiers to realize ultimate fidelity in high-end music systems.
The Super Veloce Preamplifier
In the DMC-30SV Reference Preamplifier, Spectral engineers evolve the renowned DMC-30 topology with our most advanced amplification circuits to date. Utilizing recent breakthrough understanding in high speed transistor behavior, new semiconductor designs exclusive to Spectral address historic limitations in amplifier linearity and banish low-level distortion products to previously unattainable levels. These devices and a new family of exotic custom made passive components are utilized in a new generation of high-speed, wide-band input stage and high-level line sections with unprecedented results.
Thermal Memory and Super Transistors
For years Spectral engineers have investigated the fleeting signal memory distortions found in certain semiconductor devices known as “thermal tails”. These elusive non-linearities occur at high speeds in transistors during switching as junction behavior changes as a function of heating and cooling. This change in semiconductor switching behavior affects amplifier circuit linearity until the device recovers from transient heating. This “thermal memory” distortion has long been a recognized phenomena in high tech amplifiers circuits for RF and microwave but is ignored by conventional audio engineers. In high resolution audio amplifiers, however, we find these small transistor distortions problematic as they compromise signal linearity and transient settling. Having isolated and observed these distortions in our own high-level driver circuits, Spectral engineers first addressed their elimination in our reference standard amplifier designs. Solving these subtle distortions which blur transient waveforms requires uniquely precise test and measurement systems and specific semiconductor designs which do not change their linearity under transient signal conditions. The results of this development are the finest performing amplifier circuits we have designed. Now our goal in the DMC-30SV is to successfully apply the benefits of this new semiconductor technology to the challenges of low-level amplification for the first time.
The SHHA Generation 3 Analog Line Modules
Just as the preamplifier is the essential heart of the finest music systems, the ‘Spectral High-speed Hybrid Amplifier' line module is the essential heart of our high resolution preamplifiers. For this reason, the modular architecture of Spectral preamps has been developed to accommodate the design evolution of our SHHA technology with convenience and ease. Now the new SHHA G3 line module takes our wideband, fast-settling discrete circuitry to a new level of refinement and signal resolution. Spectral engineers have continued to optimize the dense surface-mount FET topology of the SHHA module with new ultra premium custom semiconductor devices, exotic custom passive components and new circuit refinements. The input cascode of the SHHA G3 module utilizes our own proprietary FET technology. These new dual J-FET devices developed for Spectral, provide higher gain with ultra-fast transient settling. In addition, Teflon SMT precision film capacitors provide ultimate signal transparency in critical circuit locations. Custom ultra low value polystyrene film capacitors and Teflon film trimmers adjust each module for ideal transient response and wideband stability. These and other advances in the SHHA G3 module assure uncompromising sonics and extended reliability. Musical results include higher resolution, greater dynamics and improved harmonic structure. Vastly improved imaging and focus have resulted from the elimination of transistor thermal-tail distortions.
The Case for Uncompromising Attenuation
Certain devices in a high-end preamplifier fundamentally determine the ultimate performance possible in the component. Since a preamplifier basically amounts to an adjustable line amplifier, the role of the volume control or gain attenuator system is especially critical and will have a strong influence over the final sonics of the component. Most of today’s high-end preamps incorporate various digital and IC based attenuator systems to control gain, while a minority still use mechanical controls, potentiometers, switches or relay arrays. In our experience all of these approaches have serious compromises which limit signal transparency, dynamic range, step resolution or reliability. Today, digital based IC attenuators are ubiquitous in modern audio design. But even the most exotic of these digital and solid-state attenuators color the sound in various ways. Spectral engineers have long experience researching digital and DAC attenuators and find that none of these gain controls are really up to the demands of high-end preamp use, let alone for critical recording applications. We find the best relay and switch based resistor attenuators to be much better sonically than any digital control. Unfortunately, they in turn suffer from dynamic range and contact life limitations, more importantly they are not a realistic option when continuous gain adjustment is required. Since digital attenuators are not sonically transparent and stepped resistor attenuator controls have step size, contact life and dynamic range limitation, the ultimate gain control would have to be a continuously variable potentiometer or fader. Unfortunately, no pot or fader currently available is transparent or linear enough for the most critical gain adjustment applications in audio.
The Spectral Super Fader Technology
To solve the problems of existing gain control systems Spectral engineers have been working with a leading aerospace contractor. Out of this multi-year effort comes an extraordinary ultra-precision gain control. The Spectral ‘Super Fader’ combines mechanical precision, advanced materials science and unrestricted use of exotic materials to create a level control that behaves like an infinite number of theoretically ideal resistors. Inside, the critical moving parts are precision machined from solid precious metals. These wipers have many surfaces that are spring pressured as a group to contact micro-polished optically flat resistance elements. Exemplary mechanical design and fabrication alignment is used to prevent localized heating from circulating currents. Ultra-pure contact metal eliminates solid-state or junction distortions which occur from plated parts used in other controls. When such precision and material commitments are combined, noise and error in the presence of test signals is immeasurable and other performances are very near to ideal thermal accuracy limits. With polished custom element and ball-bearing construction, there is every indication that this superior performance will remain intact even after 100 million operations. The ‘Super Fader’ potentiometer outperforms all existing gain control systems with virtually infinite service life. We hear a clarity and transparency, as if a wire has been substituted for the control.
The Floating Power System
Music and theater systems are becoming larger and more complex so that stray interferences from other components and environmental sources must be prevented from entering and contaminating sensitive audio signals. A common path occurs from power cords that transmit noise residue and harmonics from large amplifiers, video equipment and other components. Higher frequency digital noise may propagate through signal cables to add further sonic loss. The floating power or battery-like regulator was developed for the SDR-4000 Reference CD Processor and it has demonstrated a superior isolation of noises that occur from power line and audio/video sources. Its combination of dense physical size and electrically open circuit character, out performs batteries and other devices to provide very pure floating power. Amplifier circuits within the DMC-30SV receive highly regulated voltages as if from small batteries. But unlike batteries, the floating shunt regulator isolates both low and high frequency noise contamination so circuits are neither subject to outside noise, nor pass residue from amplification of contaminated audio signals. This environmental isolation improves performance from complex sound systems as well as assures unhindered performance from the DMC-30SV itself. The Spectral ‘Floating Power’ regulator is a superior approach to noise isolation. While some interferences can be blocked by various AC line isolation products, their use is often problematic with unpredictable sonic side effects and additive distortions. Spectral ‘Floating Power’ is an integrated system for noise suppression which outperforms external AC line conditioning products which impose their own sonic colorations.
A Missing Link
With the widespread use of integrated circuit op-amp topologies in current high-end digital processors and digital source components, the role of the preamplifier to optimize the component interface has never been more critical to final system performance. Today's digital converters have a challenging task delivering precision conversions of music files and downloads while also driving complex cables and low-impedance input loads utilizing rudimentary analog circuits and basic power supplies. Without the benefits of discrete, high-bias analog amplifiers, digital processors struggle to provide optimal drive and load isolation when faced with the full dynamics of high-resolution recordings. In addition to these output drive limitations, IC based digital processors require balanced output operation to avoid higher distortion levels which occur when used single-ended. It is also important to recognize that digital audio processors are not equipped to perform the role of preamplifier in high-end audio component systems. Power amplifiers require robust drive capabilities from the best discrete class A preamplifier line sections to avoid impedance mismatching, current limiting and cable reflection problems associated with low bias IC op-amp output sections.
The Model 304 Balanced Input Amplifier
To address the shortcomings inherent in the output sections of todays high-end digital processors, Spectral engineers have developed the model 304 balanced input amplifier. The model 304 is a discrete, high-speed class A unity gain buffer operating on unusually high voltage rails. This fully push-pull topology is derived from our innovative SDR-4000 I/V balanced amplifier and features superior performance to any IC buffer. The model 304 is design optimized as a discrete buffer amplifier unlike conventional IC input buffers. Custom discrete buffers are a rarity in audio today but still are found in the best ultra-premium recording consoles. Although difficult to design and hugely expensive compared to op-amps, the optimized discrete input buffer is the only uncompromised solution for interfacing digital audio components and amplifiers. Spectral engineers have taken the discrete input buffer to the next level in the 304 balanced input amplifier. Custom matched J-FET transistors are employed in the cascode front-end. Built to Spectral specifications for low gain applications, the hand built devices lower crossover distortion, noise and improve common mode rejection. Bandwidth, slew rate and distortion are all vastly superior to conventional buffers. The speed and resolution of the 304 balanced input buffer are exemplary and perfectly compliment the superlative performance of the new G3 line section of the DMC-30SV.
The Result: Instantaneous Accuracy
In the DMC-30SV reference preamplifier, Spectral brings together some of the most accurate and sophisticated circuits yet developed for music reproduction. Through painstaking research and development, new active input stages and line-level output stages employ next generation instrumentation technology, which addresses historic distortion problems in solid-state semiconductor design, with heroic results. Amplifier topologies in the DMC-30SV are the fastest and deepest settling that we have developed. Premium passive component technologies used in critical locations are of unsurpassed quality. Today, no other preamplifiers have the ultra-fast signal response and the instantaneous signal extinction achieved in the DMC-30SV. This “instantaneous accuracy” sets the stage for remarkably transparent, articulate and vividly immersive sonics.
The DMC-30SV Reference Preamplifier - At the Leading Edge
We are pleased to see more and more music enthusiasts are coming to understand that no music system can be any better than the performance of its preamplifier. There is growing sophistication in regards to absolute performance and price. At a time when ultra high price preamplifiers are routinely introduced at several times the cost of Spectral, the thoughtful music enthusiast is left to wonder exactly what benefits these lofty prices buy? We believe the sophisticated customer will find the answer in the uncompromising DMC-30SV. Few preamplifiers at any price can boast the designer credentials and unrivaled component quality of the DMC-30SV. Edge-of-the-art amplifier technology and advanced custom component design are utilized throughout the DMC-30SV to a degree rarely seen in stratospheric components. This is because Spectral engineers have identified those key components that most determine instrument stability and sonic transparency and have invested aggressively. When careful investment in superior circuit performance and signal path components becomes the design priority over elaborate metalwork sculpture, state-of-the-art clarity and signal resolution can be achieved affordably. Compare our new DMC-30SV reference preamplifier against the most costly and ambitious high-end preamps in the industry. We are confident you will discover the important musical difference superior engineering experience and design innovation make.