Recently picked up headphones (marked 2000 ohms) with two wire leads only, phone plug is missing. Is there a way to determine which wire is ground in order to add a phone plug?

If they are speaker type phones use a small 9 volt battery and connect the neg terminal to one wire, and get access to one of the speakers...when you touch the wire to the battery +..if the speaker moves out that is your positive terminal, if it moves inward that is your neg terminal,

:Recently picked up headphones (marked 2000 ohms) with two wire leads only, phone plug is missing. Is there a way to determine which wire is ground in order to add a phone plug?
:

Presumably the two earpieces are still wired together and the "two wire leads" to which you refer are the ends of the single cord which would normally plug
into the radio. If this is the case you don't need to worry about individual earpiece phasing.

If this is the case, the polarity doesn't matter- there is no "ground" as such. Assuming that it works at all, it will work equally well connected either way. Phasing is not an issue.

A safety consideration is that if the headset backshells are metal, they could short to the driver and be at high DC potential. This is really only an issue if you plan to use them with an early radio that routes B+ battery power through the phones and then back to the audio output tube plate. Later sets that use a coupling transformer to isolate DC from audio AC are somewhat safer. ANYWAY, if you do have a metal backshell (as opposed to bakelite), ohm the leads to it. If you get a reading other than "open", be aware that a potential safety hazard exists.

::Recently picked up headphones (marked 2000 ohms) with two wire leads only, phone plug is missing. Is there a way to determine which wire is ground in order to add a phone plug?
::
:
:Presumably the two earpieces are still wired together and the "two wire leads" to which you refer are the ends of the single cord which would normally plug
:into the radio. If this is the case you don't need to worry about individual earpiece phasing.
:
:If this is the case, the polarity doesn't matter- there is no "ground" as such. Assuming that it works at all, it will work equally well connected either way. Phasing is not an issue.
:
:A safety consideration is that if the headset backshells are metal, they could short to the driver and be at high DC potential. This is really only an issue if you plan to use them with an early radio that routes B+ battery power through the phones and then back to the audio output tube plate. Later sets that use a coupling transformer to isolate DC from audio AC are somewhat safer. ANYWAY, if you do have a metal backshell (as opposed to bakelite), ohm the leads to it. If you get a reading other than "open", be aware that a potential safety hazard exists.

Also, the original idea of having polarity was so that when you ran plate current through the windings, you wanted to aid the permanant magnets rather than oppose them, so old phones have "plus" and "minus" symbols, so that they will be louder when hooked directly to the tube plate.
Lewis
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