To work on audio electronics, you need some test equipment. In this article I discuss what you need and how much you need to spend on it.
Old electronic test equipment can now be bought at a very sharp price. Gear which would have cost thousands 15 years ago, is now available for often less than 100€. This is a real bargain – the quality of equipment made by companies like Hewlett Packard and Tektronix back in the 70s and 80s was very high indeed, and it can be more robust than almost anything made today. When you buy it in good condition, it often works as well as it did when new.
This is a very simple project that takes only a few hours to make. It is a pair of 8 ohm resistive loads which can be used to test a mono or stereo power amplifier.
If you are working on an audio amp, you often need to see how it will behave when it is delivering power to a load. Using real loudspeakers is not practical, especially if you want to test at high levels and with sine waves. The noise would be unbearable, also you might damage a speaker. So you need a load to use instead of a loudspeaker.