VAC Renaissance 30/70 - Manual (Page 4)

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INTRODUCTION
The Renaissance Thirty/Seventy 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.
The 300B tubes are operated using cathode bias. This circuit results in real-world output capability
much greater than the test-bench rating would indicate (Footnotes 2,3,4).
A total of two 300B are used in each channel to produce 70 watts in Class A.
The input circuitry of the Renaissance 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 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 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.