Amplifiers designed and engineered by the master himself, Mr. Taku Hyodo
Leben CS300 Integrated valve amplifier $POA
The Leben CS-300, an integrated amplifier with 12 watts of glorious tube power - through the stock 4x Russian Sovtek EL84 valves, well-known for high sound quality. The driver circuit utilises two matched GE 5751 valves (a premium version of the 12AX7A) which are stable and very reliable. Five line inputs with tape monitor, headphone output, speaker / headphone selector, variable output impedance (4 / 6 / 8 ohms) make the CS-300 a fully featured integrated amplifier of impeccable performance. Classic retro look but no difficulties matching SACD's or DVD-A's standards.
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Leben CS300XS Audiophile Grade Integrated valve amplifier $POA
The Leben CS-300X, a limited edition version of the CS-300 integrated amplifier with 15 watts of ultimate tube power - with improved Mullard EL84 valves. A whole range of other parts have been improved to make this a real collectors and audiophiles dream! With the same driver circuit utilising two matched GE 5751 valves (a premium version of the 12AX7A) which are stable and very reliable plus featuring five line inputs with tape monitor, headphone output, speaker / headphone selector, variable output impedance (4 / 6 / 8 ohms) make the CS-300X a fully featured integrated amplifier of the highest standard with a truly classic appearance.
The high input sensitivity of EL84 does not require a complicated circuit and accordingly it can create a low distortion output signal. EL84 valves are nowadays produced in several countries, however we used a premium EL84 from MULLARD (UK) which offers increased sound quality. For the driver circuit we used a Five-Star-Tube from General Electric: the 5751 (premium version of 12AX7A) which has passed the "JAN" (Joint Army & Navy) standard of U.S. Army and has very stable and reliable qualities.
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Leben CS600 Integrated valve amplifier $POA (special order)
Available by special order, the Leben CS-600 is a top-range intergated amplifer utilising the best components and workmanship. By switching two selectors inside of the cabinet, you can use either of 6L6GC or 6CA7 (EL34), and LED indicators on the front panel will show you which tube is applied. Pre-amp In terminals on the rear panel allow you to use CS-600 as a power amplifier by switching a selector on the front panel, you can by-pass all the functions except the volume control. A wide-range and flat frequency response up to 100kHz is capable enough for digital audio formats such as SACD and HDCD.
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Leben RS-28CX Pre-Amplifier with Phono Stage $POA (special order)
Available by special order, the RS-28CX pre-amplifier with phono stage is equipped with the CR type equaliser based on GE (General Electric / USA) 12AT7 authorised by "JAN" (Joint Army & Navy) standard from US Army and can reproduce a very high quality and clear sound without adding any NFB (Negative Feedback).
To avoid compromising on sound quality, one of the solutions we adapted to totally protect the sensitive CR type equaliser from negative effects was to develop a separate power supply unit. Likewise, some of the finest available high-end audio components were selected for the RS28C to keep the deflection of the RIAA curve below ±0.3%. Of course, the phono equalizer is only one of the strengths of the RS28C. Another notable feature is a very strong output voltage created by the dual-triode tube 6CG7 from General Electric (USA) used for the line stage.
Leben further selected the best quality tubes out of these and constructed a powerful SRPP type amplification which can supply power amplifiers with a maximum 80V of clean output signal. In considering the fact that output voltage of a standard preamplifier is more or less 40V, the RS-28C can output about two times as much voltage which will drive power amplifiers with very low input sensitivity. Likewise, when using the RS-28C with a high sensitivity power amplifier, a 5-step attenuator is present in order to eliminate residual noise from speakers. Leben also included two outputs (one fixed and one variable) in order to cope with requirements for adding a subwoofer.
There are two major types of RIAA phono equalisation systems, one is NFB (Negative Feedback) type and the other is the CR type. A representative pre-amplifier equipped with NFB type equalizer is the MARANTZ Model 7. This is a 3-step amplification NF equaliser based on 12AX7, which applies NFB from the 3rd stage cathode to the 1st stage cathode, (so-called "K-K type"). The advantage of the NFB type is that it does not require a high gain level and is not very sensitive to tube quality. However, the impedance of NFB at high frequency range becomes very low and results in a negative effect - the sound becomes hard and dry. The NFB type is usually used as it is an easier way to attain a good signal-to-noise ratio.
As for the CR type, a masterpiece preamplifier equipped with the CR type equaliser is the vintage Harman-Kardon Model "Citation IV". CR type equalisation requires a high gain level and is much more sensitive to tube quality. Since tube quality will be directly amplified, the finest possible quality tubes are needed for this type of equaliser. Moreover, proper implementation is more difficult. However, the CR type is much more superior sonically to the NFB type, being very stable in the high frequency range and is able to reproduce a very high quality sound especially when high quality valves are used.
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Leben CS-250 Power Amplifier $POA (special order)
Available by special order, the Leben CS-250 pentode power amp is equipped with French-made tubes 6K6GT produced by "Visseaux" (France), which were produced in 1959 under licence from Sylvania (USA). 6K6GT have been loved and used for all kinds of audio products for many years due to their sweet sound even without any bias tuning.
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Leben CS-660P Power Amplifier $POA (special order)
Available by special order. One of Mr. Hyodo's favourite KT66 based power amplifiers is the QUAD II, (The QUAD II has recently been re-launched due to the demand from audiophiles). Mr Hyodo has now decided to design a new power amplifier using the same KT66 tubes but incorporating high-end audio grade components, far superior to those used in the original QUAD design.
A special feature is the choice of two output valves: KT-66 and optional 6CA7 (EL34). By switching two selectors inside the cabinet, you can use either KT-66 or 6CA7 (EL34) KT-66 or 6CA7 (EL34) KT-66 or 6CA7 (EL34) KT-66 or 6CA7 (EL34) valves. A LED indicator at the foot of each tube will change its colour and show you which tube is in use. You also can use several other tubes of different sound characteristics. (Refer to the tube list at the bottom.)
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