Many makers and engineers got into engineering through audio. Whether it be building a guitar pedal or modding the power amp in your home theater, working with audio components is a fun way to use your engineering skills.
This wishlist presents some of the tools and parts you need for working with audio. Audio is a broad topic, so this wishlist is a general overview of analog audio components. We'll get specific in later articles.
For audio related building, here are some handy tools to have on your bench!
An oscilloscope is your best friend for audio work. They can be used to check frequency response, distortion characteristics, and everything other specification that is important to an audio signal.
Audio work is all about frequencies. A function generator sends different kinds of waves at different frequencies so you know if your build is responding the way you want it to.
Multimeters are essential for every kind of electronics work; audio is no different.
Speaker Dummy Load
Since we can't use speakers for our testing, all that power needs someplace to go. A dummy load simulates a speaker in your circuit without blowing your head off with volume. A dummy load can be built with a high wattage resistor at the desired resistance, usually 4, 8, or 16 ohms for speakers.
If you're repairing equipment that has scratchy pots, many times, a bottle of contact cleaner is all you need. Drip a little bit into the pot and exercise it; your noise issues will often disappear.
You've probably already got a nice soldering station, so we won't get into soldering equipment, but with any soldering project, because we don't have six arms ourselves, a set of helping hands is very valuable.
Audio circuits use a wide variety of analog components to keep that audio sounding good.
Transistors are typically used to amplify audio signals, and sometimes distort. Different types of transistors have different characteristics, whether they are BJT, MOSFET, JFET, or even silicon or germanium.
If you're putting any kind of analog controls on your new creation, you'll likely need pots or faders.
Opamps (operational amplifier) designed to amplify signals and there's a wide range, from large and discrete, like the vintage API 2520 (and its descendants), to surface mount. Opamp design has come a long way and newer opamps, like the AD797, boast near zero distortion and noise, although classic opamps like the TL072 and 5532 still offer great sounds in the right circuit.
Transformers do a whole lot of things in an audio circuit; impedance matching, balancing, stepping up or down, etc. Because they only transmit audio signals, transformers also provide an important benefit: isolation.
Your opamps and transistors need to be powered, so chances are you'll need a good DC power supply. Op amps typically take somewhere in the range of +/-16V, while a discrete transistor based circuit might require a 24V supply. If you're making a microphone preamp that supplies phantom power, you'll need to supply 48V.
To get your audio signal in and out of your circuit, you'll need connectors.
Speakers, Headphones, and Mic
Now the fun part! The most important tools for testing audio devices are your ears. Speakers, speaker drivers, and headphones are the most important tools once you're ready to test your design. Fingers crossed that you don't get a blast of loud feedback when you flip the switch!
There are several different types of microphones – large diaphragm condensers, small diaphragm condensers, dynamics, ribbons, and more, all designed for specific purposes. We’ve selected a lavalier because it’s a tiny inexpensive mic that is convenient for testing on the bench.