VAC Renaissance 140 - Manual (Page 5)

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INTRODUCTION
The Renaissance One-Forty is a completely unique power amplifier. It allies purist amplifying
devices with the power and solidity required to control modern audiophile loudspeakers.
The most noticeable feature of this amplifier is the 300B filamentary triode output tube.
Originally designed by Western Electric in 1935 (Footnote 1), it has several extremely desirable
features that have kept it in continuous production since that time. An examination of its
dynamic curves (Figure 1) reveals it to be a naturally linear device, more so than triode
connected pentodes or beam power tubes (ex: KT88, EL34), let alone any transistor device. It
gives this superb performance with voltages on the order of 450 VDC, not the 1000-1500 VDC
required by other output triodes like the 211 or 845. This lower voltage and lower output
impedance allows superior output transformer design, control of the loudspeaker, and safety.
Each 300B tube has its own separate heater power supply and independent cathode self-bias
network. This has several major advantages. No user adjustment of any kind is necessary to
maintain proper balance of the amplifier. The stabilizing action of this technique upon the idle
current (bias point) of each tube is exceptionally strong, and self corrects for large mismatches
among tubes or drift with age. This circuit also results in real-world output capability much
greater than the test-bench rating would indicate (Footnotes 2,3,4).
A total of eight 300B are used to reach 130 watts per channel in Class A.
The input circuitry of the Renaissance One-Forty is derivative of the unique Williamson
circuit, which provides pure, direct coupled, inherently balanced input amplification and
phase splitting. Type 6SN7/5692 octal twin triodes do the honors.
The superb VAC output transformer provides superb voltage/current translation, allowing
impedances from eight ohms to as low as one ohm to be driven.
The 35 pound chassis is machined from quarter inch thick aluminum plate. This strong,
resonance-resistant structure houses a total of eight transformers, from which sixteen power
supplies are derived.
The units is completely hand wired in three dimensional space for the shortest possible lead
lengths, allowing passive components to perform much nearer to the theoretical ideal.
The Renaissance One-Forty is designed not to the latest fad but to substance, for the highest
possible sound quality. Time spent familiarizing yourself with this manual will be well
rewarded.