You know, those cables with the red and white round ends that plug into your stereo.
Why are they called RCA cables/connectors? Did the company RCA invent them?
When were they first used? What did they replace?
Is it correct to refer to video and coaxial SPDIF cables (which have the same connector) as RCA cables?
Yes
Dunno exactly when they came out, but they replaced hard-soldered connections and binding posts.
No. The connectors are “RCA” The cables are properly named for their use - ie: audio (red and white), SPDIF (orange), composite video (yellow), component video (red, green and blue), etc.
Generically, they are called “phono” connectors (though “RCA” is also commonly used, especially because “phono” sounds so much like “phone”, referring to 1/4-inch phone connectors, a different connector also in common use on audio equipment).
And it is called a “phono” connector because it was originally used to connect phonograph record players. Playing big, flat, round disks at 78 rpm – remember those?
I’ve been playing around with 1/4 inch, 1/8 inch, RCA, BNC, CoAx, Hi-Z, Lo-Z----- all kinds of different connectors and plugs for most of my life.
And yet… I always thought RCA plugs AND 1/4 and 1/8 plugs were all called Phono plugs. I guess only the RCAs are. The others are Phone plugs. Thanks t-bonham.
I guess they’re called phone plugs because they were originally used in telephone patch bays?!?!?
Yes, indeed.
In fact, they were used way back when the telephone ‘system’ worked by having the central operator use one of these connectors to physically connect the wire running from your house to the wire going to the house you were calling. Remember those old pictures of operators sitting in front of banks of jacks? Those were 1/4 inch phone plugs on the end of the cables that they were using.
Maybe it’s a UK/US thing, but any 1/4 inch plugs I’ve ever come into contact with (as a guitarist/home-recordist) have been called ‘jack plugs’. In fact I’ve heard (though admittedly it’s not that common) patch-bays called ‘jackfields’. FWIW.
Jackplugs? You Brits are wierd. 
Another historical tidbit on phone plugs - the “tip” and “ring” terminology regarding a phone line’s polarity goes all the way back to these plugs and the tip and ring contacts on them. Perhaps not used in phones, but the largest portion of a phone plug (the contact area closest to where you’d grip it) is called the sleeve.
Right. The RCA plugs with the ring of petals are phono. The 1/4" and 1/8" phone plugs are just that. Regular and mini.
There’s also a submini phone plug that measures something like 3/32" or so. I’ve seen them on things like cheap transistor readio earplugs. I’ve also run across a “bantam” phone plug in audio patch panels that’s just shy enough of 1/4" to cause erratic connections if plugged into a 1/4" jack. Conversely, a 1/4" plug in a bantam jack can damage the jack. Not hugely hard to tell apart, actually, the end of the bantam is shaped a bit differently than a 1/4" plug.