I believe this also means that the K3 headphone output circuit will deliver 10X power (with fixed V, P~1/R) into a 30-ohm headphone as a 300-ohm headphone, so at some point the amp might clip as you raise the headphone impedance?
Barry N1EU On Mon, Dec 28, 2015 at 12:57 PM, Jim Brown <j...@audiosystemsgroup.com> wrote: > 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:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to n1eu.ba...@gmail.com ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
