Posted by
Joe Subich, W4TV-4 on
Dec 19, 2009; 10:12pm
URL: http://elecraft.85.s1.nabble.com/Re-K3-receiver-noise-questionable-test-results-tp4192141p4192893.html
> I agree the 50Hz boost adds nothing useful, but I find to
> increase the 100, 200 and 400 values make the audio sound
> more balanced and easier on the ears. This is not boosting
> the bass so much as trying to compensate for the bass
> roll-off inherent in the K3.
My tests with an audio spectrum analyzer using both broadband
noise and internally generated receiver noise show that the
K3 is flat from 100 Hz to 4100 Hz when using the 6 or 13 KHz
roofing filters with FC=2.10 and BW=4.00 to either speakers
or Line Out. Headphone response is another issue that can be
addressed with the Rev C/Rev D DSP assemblies or replacing the
10 uF headphone coupling capacitors with 100 uF caps and/or
using high impedance headphones.
I find that boosting the bass results in a muddy and distorted
sound when using quality external speakers. The bass boost
makes the amplifier work too hard to overcome the issues at
the output and 9 dB of gain at 100 Hz is effectively pushing
the 100 mW headphone amplifier to over 750 mW - well beyond
its capabilities. If you absolutely must have more "low end"
the way to accomplish that is by further cutting the high end.
73,
... Joe, W4TV
> -----Original Message-----
> From:
[hidden email]
> [mailto:
[hidden email]] On Behalf Of Julian, G4ILO
> Sent: Saturday, December 19, 2009 3:02 PM
> To:
[hidden email]
> Subject: Re: [Elecraft] : K3 receiver noise questionable test results
>
>
>
>
>
> Joe Subich, W4TV-4 wrote:
> >
> >
> >
> > If one is going to attempt to mimic the "pink noise" behavior,
> > there is no need to bother with the low frequency boost. It
> > simply puts more strain on the audio amplifier, increasing the
> > amount of IMD products, with little or no aural benefit. A
> > better RX EQ configuration with essentially the same perceived
> > sound:
> >
> > 50: -16 dB (reduce sub-vocal noise and hum)
> > 100: 0 dB
> > 200: 0 dB
> > 400: 0 dB
> > 800: 0 dB
> > 1600: -3 dB
> > 2400: -5 dB
> > 3200: -6 dB
> >
> >
>
> I agree the 50Hz boost adds nothing useful, but I find to
> increase the 100, 200 and 400 values make the audio sound
> more balanced and easier on the ears. This is not boosting
> the bass so much as trying to compensate for the bass
> roll-off inherent in the K3.
>
> I will agree that low frequencies have no benefit when trying
> to copy weak signals but surely it is the role of the
> filtering to cut out those frequencies by manual adjustment
> when trying to receive a weak signal? The purpose of
> equalization is to achieve a pleasant and balanced audio
> response for general use.
>
> -----
> Julian, G4ILO. K2 #392 K3 #222.
> * G4ILO's Shack -
http://www.g4ilo.com> * KComm -
http://www.g4ilo.com/kcomm.html> * KTune -
http://www.g4ilo.com/ktune.html>
> --
> View this message in context:
>
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