Lyra Connoisseur 4-2P-SE

Resolution of detail and ambience is also improved, so that imaging is more precise and three-dimensional, and soundstaging is considerably larger in terms of width, depth and height. The measured signal-noise ratio is not very different if you put your ear to the speaker and listen to the residual noise (without any music playing), but in practice, due to the superior resolution of the 4-2, when you play music, the noise and music are more easily separated, allowing you to ignore the noise better. As a result, the perceived signal-noise ratio when you listen to music is better with the 4-2.

History

Lyra-Connoisseur was founded in 1987 in California, and is a young brand, free of the burdens of legacy technology. From its inception, it has been able to focus on the application of advanced concepts and technology to music reproduction.

With our debut product, the 1.0 phono preamplifier, we introduced one of our core technologies - "3-dimensional air-dielectric construction", a labor-intensive technology designed to eliminate the problems caused by conventional 2-dimensional circuit boards. By building our circuits 3-dimensionally in the air rather than relying only on a 2-dimensional circuit board, we were able to increase component density and greatly shrink the overall size of the circuits, as well as reduce parasitic induction, stray capacitance and leakage currents. At the same time, as most circuit nodes are insulated by air (the best dielectric of all) rather than conventional printed circuit board materials such as Glass-Epoxy or Teflon, dielectric distortions are practically non-existant. With this innovation, the circuit bandwidth and stability could be raised substantially, with marked improvements to the measured and sonic performance.

With the 2.0 phono preamplifier of 1992, we upgraded the parts quality to the finest commercially available, converted the entire design into full dual-monaural construction - including separate L/R power transformers, designed new voltage regulators, and improved the performance and stability of the amplifier circuits. As with the 1.0, the 2.0 was available with stepped attenators and was designed to drive power amplifiers directly, enabling music-lovers to hear their LP collection at its best.

With the Lyra-Connoisseur 3.0 full-function preamp (development began in 1994), however, we wanted to accomplish considerably more. Rather than be satisfied with what was commonly accepted or available, we
wanted to push the limits of what was possible. We therefore rethought every aspect of how a preamp should be engineered, and developed our own technical solutions and custom parts where traditional concepts or existing commercial components didn't measure up to our requirements.

Separate power supply chassies for each channel, amorphous-core transformers, high-voltage film capacitor power supplies, and current-mode series/shunt hybrid voltage regulators were combined with high-speed amplifier topologies, custom capacitors, resistors, active devices and exotic ceramic-based circuit-board materials were just some of the technologies that we developed for the Lyra-Connoisseur 3.0. Unlike the 1.0 and 2.0, the 3.0 was designed to serve as a line preamp as well as a phono preamp, bringing the benefits of our technologies to CD reproduction as well as phono.

But while the 3.0 was very favorably received, it was extremely large, heavy, hot and expensive.

The present Lyra-Connoisseur 4-2 (based on the earlier 4.0 which development began in autumn 1999) is a preamp "system", consisting of a Line Amplifier and a separate Phono  Amplifier. It is intended to allow audiophiles to listen to both phono and digital/line-level sources with a similarly high level of sound quality, including the latest wide-band SACD and DVD software.

But while the 3.0 was very favorably received, it was extremely large, heavy, hot and expensive.

The present Lyra-Connoisseur 4-2 (based on the earlier 4.0 which development began in autumn 1999) is a preamp "system", consisting of a Line Amplifier and a separate Phono  Amplifier. It is intended to allow audiophiles to listen to both
phono and digital/line-level sources with a similarly high level of sound quality, including the latest wide-band SACD and DVD software.

TECHNICAL DESIGN

Without doubt, the 4-2 is designed to be a more manageable product than the 3.0. But rather than being in effect a reduced-cost version of the 3.0, the 4-2 is an attempt to advance the state-of-the-art in its own right, and introduces many innovations that the 3.0 did not have.

As has been the case with all Lyra-Connoisseurs to date, the power supply is housed in a separate chassis, as this avoids the negative effects of rectifier current spikes as well as transformer fields on sensitive amplification circuits. Each channel has its own 190VA R-core power transformer (designed to minimize capacitive coupling between the primary and secondary windings, thereby reducing the effects of conducted noise on the AC powerline), with the rectification performed by a double bank of low-loss Schottky diodes.
The AC is filtered into DC by custom-made "audiophile-grade"
electrolytic capacitors.

The filtered DC is sent by an umbellical cable and high-grade Fischer connector to the main chassis, where it feeds a system of stacked, multiple voltage regulators. At the input is a primary regulator which acts as an active filter and "shock absorber" against AC line voltage fluctuations, and provides the secondary reguators with constant, low-noise operating conditions. Multiple secondary regulators are used to avoid unwanted intermodulation effects between the individual circuit sections through the shared impedance of the voltage rails. In other words, each individual part of the amplifier circuit has its own regulator, for a total of 12 regulators per amplifier circuit. Therefore, the Lyra-Connoisseur 4-2 Line Preamp uses 24 regulators, while the 4-2 Phono Stage uses 48.

The amplification circuits are based on those used in the 3.0,
consisting of DC amps with servo correction. The amp circuits combine current-mode internal operation with global voltage feedback, and were designed to minimize the number of dominant frequency poles, simplifying the overall circuit operation without sacrificing linearity. The output stage is a JFET-based Class-A distortion-cancelling hybrid design that also incorporates BJTs and MOSFETs. The DC servo corrects offset errors and eliminates the need to use sonically degrading output coupling capacitors, but since the
servo operates outside of the signal path, it avoids adding its own signature to the sound.

We paid great care to the construction techniques and component quality. We developed a new "4th generation" computer-designed air-dielectric construction, that offers higher rigidity to reduce the effect of mechanical resonances on the circuit and greater precision to allow more consistent circuit operation. At the same time, we were also able to reduce the physical size of the circuits, making them more resistant to radiated noise. We also use a combination of tantalum-film and metal-foil resistors, with teflon capacitors for RIAA equalization. The critical components are made to a tolerance of better than 1% (capacitors) or 0.1% (resistors), ensuring that the RIAA accuracy and frequency characteristics are within 0.1dB across the entire audible range, and well beyond.

The 4-2 uses a very comprehensive approach to grounding. The double rectifier bank makes it possible to create a true one-point ground, free of shared impedances, unlike a conventional single rectifier bridge. At the same time, the main circuit boards were devised to reduce ground currents and noise, employing low-impedance power ground planes augmented with a separate star signal ground. And to
minimize the drop in voltage regulator performance caused by long wires and circuit traces, we invented a "circuit sandwich"
construction for the regulator and amplifier PCBs. In other words, the regulator board fits directly underneath the main amplifier circuit board, with each individual regulator positioned right below the part of the amplifier circuit that it services, less than 1 cm
away.

The overall result is a low-noise, wide-bandwith amplifier that is fully capable of stable operation without requiring any sort of phase compensation, ensuring that the phase characteristics within the audible range and the transient characteristics are both excellent. The phono section will pass a 500kHz square wave with only a slight amount of rounding, which converts to a frequency response of 3 - 4MHz. The line section doesn't start rounding off square waves until the frequency is about 1MHz, so its -3dB frequency response would be around 7MHz.

The controls of the 4-2 Line Amplifier are both unique and easy to use. With the goal of minimizing total input wiring lengths, we
designed a custom switch that combines dual-mono input selectors with dual-mono switched attenuators in a single structure. Both the selector and attenuator control knobs are mounted on a single coaxial shaft in a fore-and-aft arrangement, with the input source controlled by the front knob, and the signal attenuation controlled by the rear. This method is simple and much more mechanically reliable than belts or gears.

The 6-position silver-contact input selectors switch both the
positive and negative sides of the input signal at the same time. This isolates the preamp from any source component that isn't being used, and minimizes interference due to differing chassis voltage potentials coupling through the interconnects. The result is less ground current and a better s/n ratio.

The dual-mono 24-position level attenuators avoid the channel
separation problems that a conventional balance control would
introduce, while non-inductive leadless, custom-made metal foil resistors ensure the lowest-loss, most sonically transparent operation possible.

All internal wiring consists of 6N high-purity solid-core copper with either teflon or foam insulation for peak electrical and sonic performance.

Rhodium-plated RCA jacks are scratch-resistant and durable, assuring good electrical contact performance for far longer than with conventional gold-plated jacks. The main chassis is a rigid yet simple structure utilizing 6mm thick aluminum plates, providing a mechanically and thermally stable environment for the circuits, and protects them from air-borne acoustic energy. Mechanical damping of the main chassis is provided by its cabinet, which is hand-crafted from furniture-grade wood, and gives the 4-2 a high-quality appearance that is in keeping with its sound.