Probably phono connectors if the speakers are a little old.
There's some pictures here:
I've got a pair of JBL L100T speakers I"m trying to get rid of. They were given to me, so I don't even know if they work. I'm trying to test them out before I sell them, but the input jacks are of a type I'm not sure I've seen.
They are circular and look almost like RCA ins, but I tried an RCA cable and no dice. They don't look like coaxial and they certainly aren't twisted wire. Does anyone know where I can find out about these inputs? I did a Google search but didn't come up with anything.
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I found a manual for the 'L' series, http://manuals.harman.com/
It says that the connectors are heavy-duty binding posts that will take banana plugs, spade connectors or bare wire. Doesn't sound like you described though.
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by: OnlyodinPosted on 2009-01-28 at 19:50:09ID: 23494170
They are probably RCA sockets, but you will need to connect them to the output of an amplifier in order to get any reasonable sound from them.