I have a speakerphone with an 8 ohm speaker. I want to be able to redirect the signal to headphones instead of the speaker built into the phone. The headphones are 24 ohms.
I could just take the wires from the speakers and connect them to a Radio Shack headphones plug and plug my headphones into that. Would that be sufficient? Is it a problem that the phone is built to send the signal to an 8 ohm speaker but I’m sending it to 24 ohm headphones?
I actually did rewire it using the above method and it works sorta okay. Sometimes the sound can have a bit of a “pulsing”? quality to it and the first part of words get cut off. Not all the time, though. I’m guessing that the 8->24 ohm discrepancy is causing problems.
I think it should be OK. Your amplifier output has been generated by a circuit that makes its voltage follow some waveform, and if your speaker or headphone impedance was much lower than the amp was designed for, too much current would flow, damaging parts in the amp. But you are going the other way, and the amp will just see a surprisingly light load, no harm done.
In speakers it is also somewhat important to make the best use of energy, because energy is expensive at this point in the system. You want to match impedances somewhat closely to do this. But, hey, you’re using headphones - they aren’t supposed to transform much sound energy, not right into your ears. Your energy is a big surplus at this point. Still OK.
The weird pulsing cutoff problem you describe sounds to me like something else going wrong, and I would guess it’s in the amp or the system upstream of there, because I think it’d be hard for headphones to create that kind of effect. But I must admit I don’t know what the deal is with this, it’s just my impression.
I’m gonna WAG here that the cutting out is some kind of voice activation thing to keep the speaker from feeding back. I really can’t see the headphone playing a part in that but if you stick a 12 ohm resister in parallel with the headphones the amp will see 8 ohms.