[Elecraft] How loud it is!

[Ron D'Eau Claire]

      At 1 foot above the speaker I read 88 dba.  I read .306 volts
across the speaker.  I was surprised at this so I read it with an ac
millivolt meter to verify it.  I switched the audio filter out of the
circuit and it made no change.  - James
  
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A voltage measurement would be the way to compare rigs without exotic
sound gadgets. In the first place, sound level measurements are highly
imprecise unless the tests can be run under identical test conditions
including acoustic environments. I brought up the sound level
measurement only to point out that I really did have enough audio to
hurt my ears. 

A voltage measurement is best done across a resistor, not a sound
transducer like a speaker or headphone. The moving coil in the speaker
can cause peaks in the voltage depending upon whether it is moving
exactly in phase with the applied audio or not. There is some phase
shift caused by the mass of the cone. The current causes the voice coil
to move, and the moving voice coil induces a current in the wire. And
resonances where the speaker suddenly moves far more easily at one
frequency can produce differing voltages. It's a little bit like the
problem of trying to measure r-f power in an feed line with lots of
reactances present. 

Dummy loads like resistors are more predictable.

Ron AC7AC
K2 # 1289