Takeaways:
- There are three major types of audio connection types used: XLR, TRS, and RCA.
- RCA is the smallest, with a single pin and a circular jacket around the outside of it. They are common in stereo and television equipment. It only transmits one channel per cable, so for stereo you will need two connections and for multichannel you will need six or more.
- TRS stands for tip-ring-sleve and has three circular ridges on the connector to indicate as such.
- This cable can either contain mono or stereo audio.
- mono cables with three ridges are "balanced." A balanced cable contains two copies of the signal, with one out of phase. The practical upshot of this is that it eliminates much of the electrical noise present in most systems. The purpose is to isolate the signal, reducing or eliminating interfeerance from other nearby devices.
- TRS comes in two configurations: eighth-inch (or 3.5MM) and quarter-inch. Quarter inch was the standard until the intrduction of eighth-inch for consumer devices such as cell phones, computers, and lower end headphones and speakers. Quarter inch is still used in studio equipment and instruments due to its higher construction quality.
- A variation on the TRS connector is the TRRS connector. these are commonly used with combo headphone/microphone jacks or analog video and audio output for camcorders. Unlike the traditional TRS connector however, it is only available as a 1/8 inch or 3.5mm connection.
- There are 3 standards for TRRS, OMTP, CTIA and CTIA style av21.
- OMTP is used by most older Nokia phones and certain types of chromebooks.
- CTIA standard is used in most apple products and newer android phones.
- CTIA style av21 is used with iPods and other mp3 players with microphone capability.
- XLR cables have three pins in a triangular formation though the plug itself is cylindrical. They have a clip to connect and disconnect them and they are heavier and longer, often with better shielding. They are used almost exclusively by professional microphones.
- Shielded cables are protected from random noise. Cables without shielding can cause ground loops, where the electrical signal is fed back into itself. Shielding can also cut down on bus noise, or other sounds that occur when electrical components are improperly isolated.
- you can convert between any of these connector formats, with adaptors, however you will not benifit from any advantages. For example, an RCA to stereo plug will not turn your mono signal into stereo without a second RCA connection. XLR to TRS connectors will not balance your signal. They , allow you to connect things together, but no more.
- S/PDIF is a digital format that is limitted, roughly, to CD/DVD quality audio. It uses either optical or coaxial cables. Coax s/PDIF uses a connector identical to RCA, however RCA connectors can be used though not recommended.
External resources
TRRS standards and devices.
discusses ground loops, and how to avoid them.
Audio/visual resources
a 50 hertz tone, similar to the sound of ground hum heard in the southern hemisphere.
a 60 hertz tone, similar to the sound of ground hum found in North America and other parts of the world that opperate on a similar electrical grid
An example of hiss. If you hear a lot of this in your recordings, it is due to low quality recording preamps.
An example of bus noise. If you are hearing this on a portable computer, the quickest way to eliminate it is often to simply remove AC power. If it is not on a portable computer, your audio hardware must be better isolated from other electrical components in your computer's case.
this is the sound of LTE data being sent and received by a cell phone or other data mobile provider.
this is an example of the noise generated by GSM data being sent or received nearby. These and similar noises can indicate poor quality cables, and/or a lack of shielding.
