I was just interested and googled around and found nothing about *any* standard, so I took
the ruler around the building and measured some things. All older stuff ... 5 years plus,
but all 5/8"
My first experience with RCA plugs was at about age 10 when my father brought home a
Telectrosonic reel-reel tape recorder that had RCA ins and outs. The speaker jack was an RCA
with a switch that disconnected the internal speaker when you plugged in an external.
Well all of my stuff had 1/4", so I drilled the rivets out and put 1/4" jacks in the thing.
One of the issues then was the plastic bezel had a very small tunnel to the RCA jack
which was pretty small, maybe 7/16" and most of my fat phone plugs didn't fit in
there, so I cut the hole bigger. Never looked so good after that, but I recorded and
played many hours on that tape recorder, even added a toggle switch so I could record
and play on either track. It was mono, but with a 1/4 track head and preamp for the
other stereo channel.