[Elecraft] [K3] need help with hiss on ssb receive

[Adrian]

The original post;

¨[Elecraft] K3 RX audio on voice modes <oh no here we go again>
paul bijpost p.s.bijpost at gmail.com 
Fri Apr 24 16:48:19 EDT 2009


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________________________________________________________________________

Hi fellow Elecrafters,


The K3 is the best & pleasant radio I ever had, but it also is one of the
most ear fatiguing I've ever listened to on voice.

I'm very surprised about this because Wayne's brilliant design should be
able to sound like the very finest sound equipment. The DACs and audio
stages are all top-notch.


I did a couple of tests in my audio studio and came up with the following
(ridiculous?) idea:

-The white atmospheric bandnoise (we all love her) should somewhere down the
line be converted to (near) pink audio noise before it hits our ears. In the
K3 and maybe many other receivers this doesn't happen, white RF noise is
linearly translated to white audio noise, sounding "high emphasized" to the
human ear.

I have a feeling in older receivers this was "mildened" by the electronics
that somehow gave a natural roll-off up the spectrum.


Too simple,right?  I thought so too.


So I built an accurate 3db/octave downsloping filter (in software) and fed
it with the K3's RX audio.

A -3dB/octave downslope converts white noise (equal energy per Hz) to pink
noise (equal energy per octaveband)

For our ears pink noise sounds "flat" since we listen to frequencies in a
logarithmic manner.


How did it sound with or without ?To me, like night and day.

-K3 in "pink mode" sounds round,smooth and balanced out. RX EQ now works
correctly and is able to really shape the sound to many different
"flavours".

-K3 in "white mode" to me sounds mean,agressive and sharp.RX EQ can hardly
correct this.


Could anyone else give this a try? There are quite a lot of software EQ's
able to make a -3dB/octave slope. Or milder slopes if you wish as long as
it's quite precise in dB/oct.

I wouldn't like a new discussion about different tastes of
audio/speakers/headphones/etc but I would be very interested in other people
able to copy this experiment and comment on it.


I have a feeling the K3 can do way(ne) better then it does in the audio
department.


Please excuse my english

73'

Paul

PD0PSB¨


-----Original Message-----
From: Adrian <vk4tux at bigpond.com>
Reply-to: vk4tux at bigpond.com
To: elecraft <elecraft at mailman.qth.net>
Subject: Re: [Elecraft] [K3] need help with hiss on ssb receive
Date: Sat, 24 Nov 2012 23:41:11 +1000


´We started shipping  DSP Assembly Rev D DSPs on new K3s about November
4th, 2009. That corresponds to K3-F Serial number 3626 

It's a two year old k3 #5047´

Snippets of information above exclude this possibility.

Just dropping the highs down isn't enough. The pink noise rolloff effect
is very good using the whole range spaced properly.

thankyou N1EU

Adrian ... vk4tux


-----Original Message-----
From: Mike Harris <mike.harris at cwimail.fk>
To: elecraft at mailman.qth.net
Subject: Re: [Elecraft] [K3] need help with hiss on ssb receive
Date: Sat, 24 Nov 2012 09:47:27 -0300


Hi,

This was a common complaint in the past.  Elecraft engineered a retrofit 
low pass filter for the RX DSP board which cuts off above 4kHz.  Or you 
can swap out for a replacement DSP board to revision D status where the 
LPF is fully integrated.  You might like to investigate what the status 
of you K3 is.

Details can be accessed via the Elecraft ordering page.

Regards,

Mike VP8NO

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