Were stereo phone plugs/jacks once "keyed"?

[rjb]

Here's a trivial, inconsequential question:

I've got an old Switchcraft panel mount "stereo" (TRS) phone jack, pulled out of something or other, PN JJ-033.

No 1/4" phone plug I have (TS or TRS) fits in the jack; the plug's "head" is too big for the jack's "yoni"....

Were TRS plugs and jacks once built with a smaller diameter, to avoid accidental insertion of standard 1/4" phone plugs?

This question won't be keeping me up nights; I'll just toss the part before it accidently gets installed in a project.
But I am a bit curious.

Thanks,
-rb

[52 Bill]

Here's a trivial, inconsequential question:

I've got an old Switchcraft panel mount "stereo" (TRS) phone jack, pulled out of something or other, PN JJ-033.

No 1/4" phone plug I have (TS or TRS) fits in the jack; the plug's "head" is too big for the jack's "yoni"....

Were TRS plugs and jacks once built with a smaller diameter, to avoid accidental insertion of standard 1/4" phone plugs?

This question won't be keeping me up nights; I'll just toss the part before it accidently gets installed in a project.
But I am a bit curious.

Thanks,
-rb

It might have been pulled from an SWR combo head, they use those for 2-way speaker connectors. They are made smaller so you can't plug a standard 1/4" plug into them. Check the Switchcraft site, I'm sure that they still make them.

I think the first time I ever saw one was on some sort of aircraft radio.

[Enzo]

1/4" is just one standard size of connector. There are other standards. SOme telephone switchboard plugs come to mind.

They were not made smaller so you couldn't plug a 1/4" into them, they were just a different size standard. Like 20mm fuses versus 1-1/4" fuses.. They didnlt make them so you couldnlt use the other size, they are just two different standards.

The 1/4" plugs are 6.35mm, the TT series for example are 4.39mm.

[52 Bill]

They were not made smaller so you couldn't plug a 1/4" into them, they were just a different size standard. Like 20mm fuses versus 1-1/4" fuses.. They didnlt make them so you couldnlt use the other size, they are just two different standards.

Yes of course they are just a different type, but in the case that I mentioned SWR did use them to prevent someone from easily plugging in a different speaker cable into the stereo crossover output jack.

Oh, by the way they are .206" size and are available from Switchcraft.

[Enzo]

Sorry Bill, I wasn't disagreeing with you. If you use two types on one unit, sure, it is to prevent misconnections. I was speaking more towards why different sizes exist in the first place. I am familiar with the SWR situation you describe.

I have an old tape recorder - Webcor or similar - and it has 1/4" mic jacks. They are not as deep. The mic plug is considerably shorted than a regular 1/4" male. A regular plug works in the jack as long as you let the excess length hang out. But try to plug the mic into a guitar amp and the tip won;t reach.

[rjb]

1/4" is just one standard size of connector. There are other standards. SOme telephone switchboard plugs come to mind.

Well, I'll be darned. I always thought the 1/4" size was inherited from telephone switchboard plugs.

[g1]

First thing that came to mind was "Bantam". Now I see that is just another name for what Enzo mentioned, TT series connectors.
However, the JJ-033 mates to a PJ-068. These are used in aircraft headsets. Near the bottom of this page: TRS connector - Wikipedia, the free encyclopedia

[Enzo]

1/4" size was inherited from telephone switchboard plugs.

Sure, but like anything else, standards developed and changed over time. Remember when speakers all had 1/4" jacks. SOme 4x12 cabs added XLR jacks, which can't blow the plug out on loud peaks like a 1/4 can. SOme larger PA cabs had those four pin things, EPI maybe? Then along came Speakons.

Or microphones. Remember when mics had that threaded thingie you screwed on? Then low-Z and XLRs happened.