[Elecraft] External speaker recommendation.....

[Jim Brown]

On 1/6/2014 2:02 PM, EricJ wrote:
> The K2 speaker has been better for CW than anything else I have tried. 

Elecraft found a VERY good speaker for the K2.  Don's advice about 
looking for a 4 ohm speaker is also good -- virtually all loudspeaker 
amplifiers have a VERY low output Z, typically 0.1 Ohm or less, making 
them a constant voltage source. By simple Ohm's law, they will provide 
maximum power to the lowest impedance  which they are designed. Power is 
E squared divided by R, so you can use them with higher Z speakers, but 
you will lose 3 dB of level for 8 ohms, another 3dB for 16 ohms.

The second part of the equation is loudspeaker efficiency. In general, 
the smaller the loudspeaker, the less efficient it is. In other words, 
louder = bigger. The best 4 ohm loudspeaker I know of is the MR55, made 
by RCF, and Italian company. I've used them in some high profile 
projects. They're not cheap. Smaller speakers in their line are not 
nearly as nice.

73, Jim K9YC