Testing Guitar Amplifier Vacuum Tubes with a Computer Controlled Data Acquisition System

While vacuum tubes have been almost completely replaced by solid state electronic devices, there are still a few applications where vacuum tubes are used. One of these is in guitar amplifiers. As there are few companies still producing new vacuum tubes, most of the tubes used in amplifiers are old. The electric guitar was invented in the early twentieth century after the advent of the vacuum tube. Tube technology allowed a relatively small electrical signal from the guitar to be amplified and then converted to sound by a speaker. Electric guitars didn’t become really popular until the beginnings of rock and roll. It was the electric guitar that drove rock and roll, and rock and roll made the electric guitar known to everybody. With the advent of solid state electronics, transistors replaced tubes almost everywhere. However, there were and are many people who contend that tube amps still sound better than solid state amps. That is an interesting discussion itself, but it is not within the scope of this project. As vacuum tubes dropped out of favor, companies stopped making them. Small niche markets, like guitar players who didn’t like the sound of the new amps, weren’t enough to keep vacuum tubes in widespread production. There are still companies who make new tubes, but they are generally not of the same quality as the old tubes. This has created a market for vintage tubes where buyers are willing to spend quite a bit of money to acquire just the right tube for their amp. There are many opinions as to which tubes perform better, but there has been little quantitative study of the audio properties of these tubes. In the days before computers, studies of tubes would be done by painstakingly collecting hundreds of data points from hundreds of different tubes individually. The data generally would generally be current as a function of applied voltage. The curves created by this method would be published in a handbook and everybody would use this same data. In order to study the various new and vintage tubes being used today, it is desirable to have the ability to test them in a more efficient manner.