What is the headphone impedance
If you simply use an ohmeter you would find that the DC resistance is about 100 ohms. A proper measurement using a HP 204C Signal Generator and a HP 3400A Voltmeter showed an impedance of 123 ohms from 300 Hz to 4 kHz. This makes sense since the Working Instructions for the Telephones,
Loudspeaking No. 2 (Canadian) states:
"On Telephones Loudspeaking No 2 (Canadian) loudspeakers are two binding posts marked No. 19 Set.
They are connected to loudspeaker through a winding of 30 ohms (approx.) impedance. This impedance
approximately matches the output impedance of I/C amplifier of No. 19 Set."
The I/C amplifier would have to be cable of driving multiple headphones without significant loading effects.
How and from where I can get accessories for my WS-19
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Check the QM Stores area of The Wireless Set No. 19 Group website. Accessories are often advertised there, for sale or trade, and you also have the option of posting a "Want" for a specific item.
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