CONVERGENT SL-1 ULTIMATE

Pre owned. In good condition. Shows signs of wear. Comes with original packaging and manual.

The SL1 Ultimate is the relentless evolution of the original SL1 from 1985, now presented as a preamplifier designed to unleash the full potential of the most refined audio systems. Every trace of electronic artifact is eliminated, while the external power supply completely isolates the transformer’s magnetic field, keeping any possible hum at bay. Rectification and initial regulation take place within the power supply unit, delivering pure, silent DC to the main chassis and avoiding the fine grain and dryness caused by noise intermodulation. Three independent, fully regulated filament supplies prevent dynamic compression caused by crosstalk and are further filtered for noise, while slow filament startup significantly extends tube life. The cascaded multi-stage audio power supply uses an extensive array of zero-feedback regulators and energy storage capacitors to provide exceptional dynamic range, precise soundstage imaging, and a natural musicality that remains intact even in complex passages. An isolation transformer further blocks RF noise from the AC line, achieving superior results compared to conventional and expensive power conditioners, without introducing their typical sonic coloration.

The fully tube-based circuitry produces a vibrant, natural sound, while the optional high-gain phono stage remains surprisingly quiet with any cartridge, whether high or low output. The preamplifier’s speed reaches exceptional levels, free from the artificial edginess that often affects high-frequency forced circuits, and maintains this rapid response even over long cable runs. Extremely low open-loop distortion provides detail and resolution without exaggeration, while the low feedback preserves naturalness and focus, avoiding the harshness common in high-feedback designs. Perfectly controlled output impedance quickly eliminates reflections in interconnects, delivering exceptionally clean and smooth mids and highs.

The chassis, made of robust steel with anti-RFI plating, ensures an environment free from noise and interference, while internal damping elements align the two chassis to prevent mechanical resonances from affecting the electrical fields. High-loss viscoelastic feet effectively isolate from floor vibrations. Low-loss circuit boards combine the transparency of rigid wiring with a controlled, musically balanced signature. Volume and balance controls follow the same philosophy, featuring military-grade rotary switches with solid silver contacts and precision resistors. Proprietary RIAA capacitors use an exceptionally pure dielectric with losses far lower than conventional materials, while purpose-designed coupling capacitors exceed the performance of standard audiophile components. Internal wiring uses ultra-pure annealed copper with minimal-loss insulation; connections are made via rhodium- and gold-plated jacks, silver soldering, and sealed switches to ensure maximum reliability and signal quality.

Everyday operation is simplified with a front-panel mute switch and automatic mute on power-up and shutdown. The Record/Normal selector prevents an inactive tape deck from loading the signal and ensures flawless recording quality when engaged. An additional set of main outputs expands configuration options, while the LOAD jack allows real-time optimization of the MC cartridge load, providing control typically reserved for the most exclusive systems.

Technical specifications:

• Gain (@1kHz): Line 26 dB; Phono 47 dB; IHF phono sensitivity 0.12 mV
• Gain Tracking: Line 0.05 dB; Phono 0.05 dB
• Frequency Response: Line 0.1 Hz–600 kHz +0/–3 dB (rise time 0.6 μs); Phono RIAA 20 Hz–20 kHz ±0.1 dB
• Harmonic Distortion (@1 volt): Line <0.0005%; Phono <0.001%
• Slew Rate: Line 15 V/μs; Phono 10 V/μs
• Maximum Output (@1kHz): Line 50 V rms; Phono 50 V rms
• Input Overload: Line 100 V rms; Phono 250 mV rms @1 kHz
• Noise: Line 112 dBA below 2 V output; Phono 96 dBA below 10 mV input
• Separation: Line >90 dB; Phono >90 dB
• Input Impedance: Line 50 kΩ, 20 pF; Phono 47.5 kΩ, 180 pF (user adjustable)
• Output Impedance: 100 Ω
• Maximum Load: Line <4000 pF and >5000 Ω; Phono <4000 pF and >10,000 Ω
• Dimensions: Main Chassis 48.26 × 13.31 × 30.99 cm; Power Supply 30.99 × 10.16 × 15.24 cm
• Weight: Net 29.0 kg