I would not use any speaker less than 8 Ohms with the K3. The audio amplifier draws more current and distortion increases as the load impedance decreases. Best case THD+N vs. frequency for the audio amplifier is three times WORSE with 4 Ohm loads compared with 8 Ohm loads.
2 Ohm loads are not even spec'd. 73, ... Joe, W4TV > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of Tom Hammond > Sent: Tuesday, May 12, 2009 7:23 AM > To: Brendan Minish; [email protected] > Subject: Re: [Elecraft] External speakers for K3? > > > Brendan: > > >For general communications use I am very fond indeed of the speakers > >Motorola made for their various mobile rigs over the years, They are > >very cheap, efficient and sound great for good quality > communications > >audio. These are not Hifi speakers but for speech / CW they > do a superb > >job. > > > >Mostly they seem to be a pretty close match in size and > colour for the > >K3 too. > > I agree completely. > > >Some of them are 2 Ohm though, The ones I use with My K3 at > the moment > >are 2 Ohm ones, Since I do not know for sure if the AF amp > in the K3 is > >happy driving an impedance this low I stuck a 2Ohm 2W resistor in > >series with each speaker and still have more than enough audio in my > >shack. > > > >I have seen these available in 4-Ohm and amplified variants > too. Pretty > >much every radio in the shack is connected to a Moto speaker and I > >still buy them at rallies, collecting stuff I might need > someday must > >be habit > > > >Anyone know if the can K3 drive a 2Ohm speaker without bad stuff > >happening ? > > In a recent e-mail from Lyle Johnson, KK7P, he stated that, > while not 'designed' to drive 2-Ohm loads, the K3s AF amp > should "probably" work OK BUT that if one attempted to drive > the speakers too hard, and the AF amp attempted to draw > excessive current (and starts to overheat), the amp would go > into a protective shut-down mode, rather than risk damaging itself. > > For what it's worth, MOST (possibly all nowadays) of the > newer, plastic-cased, Motorola NON-amplified speakers are now > 8-Ohms... there may be some 4-Ohm speakers in the newer-style > plastic ('fitted back') cases, but I suspect that almost all > have now been switched to 8-Ohm speakers. > > I'm using a pair of 8-Ohm Motorola speakers on my K3 and it > sounds just fine. > > Cheers, > > Tom Hammond N0SS > > ______________________________________________________________ > 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 ______________________________________________________________ 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
