On Mon,12/28/2015 5:10 AM, Barry N1EU wrote:
I've got some 300-ohm headphones and wondering if the impedance alone makes them a poor choice for my K3s?
As others have told you, it's not an issue. For at least 50 years, audio equipment has low impedance outputs that are designed to work into relatively high impedances. In audio, we don't "match" impedances like we would in RF. Power amplifiers, of which headphone amplifiers are a special set, are typically designed to provide 1V or so into any Z greater than about 100 ohms.
Think of it this way. High Z phones are designed to require more voltage but less current, while low Z phones require less voltage but draw more current. The IR drop in the output stage will reduce the voltage to low-Z phones, but they don't need as much voltage to be loud enough. And there will be little or no IR drop to higher Z phones, so they see the full 1V output.
Bottom line -- nearly all modern headphones are designed to work with a 1V source.
There's discussion of these issues in http://k9yc.com/GroundingAndAudio.pdf 73, Jim K9YC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
