[Elecraft] K3 RX AUDIO

[Joe Subich, W4TV]

 > The audio LPF that was added to the DSP board has a cutoff frequency
 > somewhere near 3.4 kHz if I recall.

The cutoff is 4.2 KHz - the same as the high limit of the DSP.

> The K3 does have a very flat passband with steep skirts out to the
> hi-cut value. I am guessing that the flat passband is what is
> bothering you.

I'm convinced of that ... the vast majority of rigs I've tested over
the years have a low-pass roll off characteristic to their audio -
generally in the 3 to 6dB per octave range from about 5OO Hz up.
This can be simulated in the K3 by setting 400 Hz at 0, 800 at -3,
1600 at -6, 2400 at -8 and 3200 at -9 (3 dB per octave - double
for -6 dB per octave).  If one couples the 6 dB/octave roll off
with a bandwidth of 2.6 KHz (200 - 2800 Hz) there is very little
difference in the audio "sound" between the K3 and other mainline
rigs.

I prefer to keep my RX EQ flat from 400-2400 Hz, set 3200 at -16
and bring the bandwidth in to 2.4-2.6 KHz.  The "flat" setting at
2400 effectively provides a little intelligibility boost compared
to the other rigs for those times I have to use SSB.

73,

    ... Joe, W4TV


On 7/21/2013 7:43 PM, Don Wilhelm wrote:
> Mike,
>
> If that 'hiss' is reduced when the bandwidth is reduced, then it is
> atmospheric noise that you are hearing, not any internally generated noise.
>
> The audio LPF that was added to the DSP board has a cutoff frequency
> somewhere near 3.4 kHz if I recall.  There is little falloff at
> frequencies lower than that.
> The K3 does have a very flat passband with steep skirts out to the
> hi-cut value.  I am guessing that the flat passband is what is bothering
> you.
>
> 73,
> Don W3FPR
>
> On 7/21/2013 7:18 PM, mikerodgerske5gbc at yahoo.com wrote:
>> I think the audio voice quality has been remedied long ago.
>> What lingers is the high end hiss that I and a few others hear.
>> Apparently this only bothers a minority.
>> On my 5047 it occurs with hi cut of about 2500 and gets worse to 3000.
>> If you run bandwidth 2.1 or below you will never hear it. 2.4 probably
>> hear it some.
>> It's most prevalent scanning a vacant band 6-20. Not as noticeable
>> when people are talking.
>> On the noisier bands I'm not sure you hear it at all. I was on 40 the
>> other night using NR and didn't hear it.
>>
>> This issue in general comes up frequently on other groups and is
>> negative press. It's usually called something like fatigue factor like
>> during a contest. I think some of this is holdover and bad press
>> before the dsp upgrade several years ago. I don't see anything wrong
>> with the audio itself, just the high end hiss. My top 3 eq bands at
>> -16 by the way.
>> Something that comes up also is how well the k handles lightning noise
>> spikes in agc and why can't others do it? That's positive press.
>>
>>
>
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