Vacuum Tube Technology Overview

The basic purpose of the audio amplifier is to increase the current, voltage or power of a signal and deliver the signal to the speakers. The three basic types of amplifiers are solid state, hybrid (utilizes tube and solid state) and vacuum tube. Each technology has its positives and negatives. Although the general operational characteristics of the three audio amplifier types are similar, there is a differential in the sound.

There are two basic designs of tube amplifiers. One design is the triode amplifier (also referred to as single ended or Class A) in which one vacuum tube (300B, 2A3) is used per channel to amplify the audio signal. Within the tube, a small signal is placed on the grid which causes a large fluctuation of voltage. Thus, the small amount of signal controls the larger power so that the signal is replicated at a larger level of energy. Another design is the push pull amplifier (Class AB). Rather than using one tube, the push pull amplifier uses more than one tube per channel. One tube will amplify the positive portion of the signal and the other tube will amplify the negative portion. The push pull design provides greater wattage than the single ended amplifier. This is a very simplified rendition of how a tube amplifier works. For the detailed technical operations of audio amplifiers, we recommend engineering web sites.

In the past ten years, there have been four major technical developments that encourage the use of tube performance equipment. These developments are:

• The Compact Disc player. The CD player delivers a superior audio signal compared to the inexpensive turntable of the previous decade.
• The improvement of audio recording. Given that the CD player revealed the defects of poor recording, studios began to improve their techniques and equipment.
• The improvement of cable components. The components of any musical system are attached with cable that allows the audio signal to pass from one component to another. In the past, cheap-high-resistance cable was used, and even with good components the sound was limited.
• The dramatic improvement in speaker technology. The advent of computer assisted design and advanced materials has resulted in significant sound quality at reasonable prices.

These improvements have made it possible to put together an audio system with a vacuum tube amplifier at a reasonable price. The result is what some people refer to as “audio magic”. We encourage any person looking for a new audio or audio/video system to spend time listening to different technologies to find the equipment that is right for them. The reward is listening pleasure for years to come.