[Elecraft] SSB filter + Spectrograph recommendation?

[Don Wilhelm]

Ed and all,

The normal human voice will lose a lot of intelligibility and sound very
tinny if the low frequency content is substantially reduced.  The generally
accepted range for effective voice communications begins at 300 Hz.  The
high frequencies can be cut with little loss of intelligibility, and this
makes the use of narrower than normal filters useful in high QRM conditions.
My narrowest SSB filter on the K2 is 1600 Hz and is set for an audio range
of 300 to 1900 Hz.  Yes, set the stock OP1 filter passband between 300 and
2300 Hz with more attention at the 300 Hz marker than for the 2300 Hz
marker.

There have been several studies about the audio frequencies that are most
important for speach intelligibility and some have been reported in QST many
years back.  I believe the most authoritative information comes from
research done at Bell Labs back when Ma Bell started channelizing voice
transmissions on a single line.

If you need information on how to set up the filters and BFOs, refer to my
webpage www.qsl.net/w3fpr in my article on Dial Calibration - Step 3 deals
with the CAL FIL part.

73 and Happy Holidays,
Don W3FPR

----- Original Message -----

> Howdy, I've been playing with the K2 SSB OP1 and bfo filter setting and
need
> a recommendation-- my SSB board is stock and I'm using the Heil hand mic
> sold by Elecraft.
>
> Using the Spectrograph program should I be setting the bandpass freqs at
500
> and 2400 hz then tuning the bfo so that at the 500hz point the filter
> response begins to rapidly drop off? I see one fellow recommending using
> 300hz and 2300hz settings when adjusting the bfo - is this better for tx
> audio quality?
>