[Elecraft] [K3] Rx/Tx equalization band selection

[Jim Brown]

On Sat, 23 Aug 2008 16:03:40 -0700, Mike Scott wrote:

>band centers of: 150, 250, 416, 693, 1154, 1921 and 3200 wit

The centers of audio filters in octave, half-octave, one-third 
octave, and one-sixth octave increments were standardized many 
years ago by scientists and engineers working in audio and 
acoustics. Unlike the communications standard for the audio 
bandwidth of communications systems, these are excellent standards 
that take into account how humans HEAR sound. We tamper with these 
standards at our own risk. 

>It would appear that the bottom equalizer band is beyond useful. 
>Even with maximum equalization gain the 50 Hz spectrum is still 
>way down. This tells me that we don't really have an 8-band 
>equalizer as only 7 bands have utility. The 100 Hz band is 
>questionable but barely within the zone.

50 Hz and 100 Hz octave bands are VERY important -- they allow 
equalization to correct for proximity effect in directional 
microphones, and to reduce the effects of breath pop. The octave 
bands below 500 Hz contribute little to communications. If allowed 
to modulate our transmitters, they waste transmitter power. The 
best designers of sound systems for reverberant spaces know this 
well -- we carefully roll off the low end of speech systems for 
big churches beginning somewhere between 200 Hz and 300 Hz. 

73,

Jim Brown K9YC