VAC Renaissance 30-30 User Manual

RENAISSANCE THIRTY/THIRTY

Zero Feedback Triode

Power Amplifier

by

Valve Amplification Company

Operation & Maintenance

IMPORTANT UPDATE

PLEASE READ CAREFULLY

Your Renaissance Thirty/Thirty has been fitted with the “300B Sentry” thermal sensor
circuit. It works in conjunction with the indicator lights located between the output tubes,
and has two functions:

1)If the idle current in a 300B output tube should drop well below acceptable limits, the
light adjacent to that tube will light green. The tube should be replaced.

These lights will also be green when the amplifier is first switched on, and will
extinguish when the bias resistors have reached normal operating temperature after
several minutes. Note: a strong cool air current could cause the lights to remain green
even in normal operation.

2)Should any output tube draw excessive idle current (run away or internal short)
the light adjacent to that tube will glow red and the high voltage supply within
the amplifier will be shut down. The red light will stay on until the power switch
is turned off. This tube must be replaced.

The lights for the other three tubes will show green after a few minutes...this should
be disregarded.

This protection feature normally will operate with much greater speed than the AC
line fuse, and provides a high degree of protection against elevated temperature or fire
due to a major failure in an output tube. However, completely failsafe methods are not
possible. As with any high power electrical device, never leave the amplifier run
unattended. Turn the amplifier off immediately if you smell any strong odor, or if you
see any parts glowing orange through the gold vent grille.

To minimize difficulties, always source the highest quality tubes, avoiding inexpensive or
generic 300B tubes. For best sound we recommend obtaining replacement tubes from VAC,
stating that they are for use in the Renaissance Thirty/Thirty.

CAUTION

THESE UNITS CONTAIN NO USER SERVICEABLE PARTS. DO NOT REMOVE THE BOTTOM
PLATES OR TOP COVERS. LETHAL VOLTAGES ARE PRESENT WITHIN THE CHASSIS. DO
NOT OPERATE THE UNITS IF THEY ARE WET.

VACUUM TUBES BECOME HOT ENOUGH TO CAUSE SERIOUS BURNS. NEVER TOUCH A
TUBE WHEN THE UNIT IS ON. IT MAY TAKE SEVERAL MINUTES FOR THE TUBES TO
COOL DOWN AFTER THE UNIT IS SWITCHED OFF.

THIS AMPLIFIER IS VERY HEAVY. IT MAY BE ADVISABLE TO HAVE ASSISTANCE IN
UNPACKING, MOVING, AND SETTING UP. BE SURE TO USE PROPER LIFTING
TECHNIQUES TO AVOID BACK STRAIN AND INJURY.

INDEX

Introduction
Unpacking
Installation
Operation
Installing New Output Tubes
Replacement of Low Level Tubes
Care Of Chassis
Tips and Advice

A Word About Tubes in General
A Word About Output Tubes
A Word About Low Level Tubes
A Word About Impedance Matching
A Word About Feedback
A Word About Grounding

Tuning Your System
Specifications
Footnotes
Figures
Warranty & Registration Form

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INTRODUCTION

The Renaissance Thirty/Thirty 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 exceed 30 watts per channel 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.

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