LEBEN CS 300F

With JAN 6197 (GE) tubes.

A tube-based stereo integrated amplifier designed according to a construction philosophy that combines traditional circuit design and carefully selected components with the use of distinctive vacuum tubes chosen for their linearity, reliability, and sonic characteristics. The output stage employs four GE JAN-6197 tubes, a power pentode originally developed in the 1950s for computer and military applications, designed to withstand frequent transitions between full conduction and cutoff. Leben repurposes this now-discontinued tube for audio applications and enhances its characteristics through a specially developed circuit. The company has also selected and stockpiled NOS JAN-6197 tubes from older production runs, preserved in their original condition, ensuring the availability of replacement tubes. The driver circuit uses two Hitachi 17EW8 tubes, specifically developed for Hi-Fi applications and also no longer in production, for which Leben uses selected NOS components.

The design employs a fully tube-based circuit with automatic biasing, allowing new tubes to be installed without manual bias adjustments while automatically compensating for variations in current draw and differences between individual tubes. The power supply and audio circuits use high-quality components, while the WBT-type speaker terminals allow the nominal load to be selected between 4, 6, and 8 ohms. Rated output power is 15 watts per channel, a relatively modest figure compared with higher-powered modern amplifiers, but consistent with the design philosophy of the CS-300F and particularly well suited to efficient loudspeakers. The configuration prioritizes control, linearity, and sound quality over the ability to reach extremely high listening levels, making it suitable for smaller rooms or systems based on efficient loudspeakers.

The Leben CS-300F features five line-level analog inputs, one of which is dedicated to a CD source, as well as a tape loop connection. The front panel also incorporates a bass boost control with two settings, +3 dB and +5 dB below 100 Hz, together with a 6.35 mm headphone jack. A selector allows the user to switch between loudspeaker and headphone listening, providing direct and intuitive access to the main functions. The layout therefore reflects a traditional approach to integrated amplifier design, with essential controls remaining directly accessible from the front panel.

From a sonic perspective, the use of JAN-6197 tubes contributes to a presentation characterized by speed, precision, and excellent linearity, while avoiding the excessively bright or analytical character sometimes associated with particularly fast-sounding electronics. The CS-300F combines the definition and immediacy typical of some solid-state designs with the greater fluidity and tonal density associated with tube technology. The midrange maintains a natural and articulate presentation, while the reproduction highlights the breathing quality of recordings, subtle dynamic variations, and the positioning of instruments within the acoustic space. The response retains a smooth and tactile character without compromising transient accuracy, allowing the system to convey both ambient information and the nuances of the performance with clarity.

The particular combination of linearity and naturalness allows the CS-300F to handle a wide range of musical genres, from jazz recordings to orchestral compositions, while maintaining a balance between definition, articulation, and involvement. Its ability to accurately follow the interaction between instruments and preserve the separation of individual sources contributes to an orderly and information-rich soundstage. The low-frequency section delivers a full and slightly rounded presentation through the upper-bass region, while at higher listening levels and when paired with particularly demanding loudspeakers, the available power can reveal its limitations in reproducing the deepest bass frequencies. This behavior is nevertheless consistent with the amplifier's rated power and intended application, as the CS-300F is designed to be used with suitably efficient loudspeakers.

The external construction also deliberately recalls the aesthetics of Hi-Fi equipment from the so-called Golden Age of stereo. The side panels are made from natural Canadian white ash, an exceptionally hard and dense wood traditionally used for baseball bats and oars. The finish of the side panels complements the front and rear panels, while gold-finished knobs and controls with green detailing complete a strongly distinctive aesthetic that recalls the design of audio equipment from the 1960s. The result maintains a classic character while preserving the functionality of the controls and the robust construction associated with Leben products.

Technical specifications:

• Tubes: 4 x JAN-6197 (GE); 2 x 17EW8 (Hi-Fi)
• Output power: 15 W x 2
• Frequency response: 15 Hz – 100 kHz (-2 dB)
• Distortion: 0.7% (10 W)
• Input sensitivity: 600 mV
• Input impedance: 100 kΩ
• Output impedance: 4/6/8 Ω, selectable
• Headphone output impedance: 300 Ω
• Power consumption: 82 W
• Accessories: 1 detachable AC power cable
• Dimensions (W x D x H): 360 x 270 x 140 mm
• Weight: 10.5 kg