SSB Audio Oddity

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  • Updated 4 months ago
Newbie with a 6400, playing the audio through my PC speakers over the LAN.  The SSB audio quality has a peculiarity that I find difficult to describe, and what makes it worse is that I don't notice it on all signals.  But the effect I will try to describe is this:  I tune in a transmission to where I believe I have the speaker's natural voice, but it sounds almost as if he is "double tracking" or harmonizing with himself.  I have never noticed this on any of my old dial radios, in fact when I carefully tune in an SSB signal with the bandwidth relatively wide, it can sound almost as "hi-fi" as a good AM signal.

I suspect what I am describing is the result of settings I have not yet mastered, so I'm hoping that someone a) understands my feeble description of the effect; and b) can point me in the right direction to minimize this effect.  Again, it sounds like the person transmitting has an audio oscillator tracking the frequency of his voice and has superimposed it on his transmission.  That's maybe the best I can describe it. It doesn't seem to matter which bandwidth preset I have selected....

73, Brad K9BM
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k9bm .

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Posted 4 months ago

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Martin Ewing AA6E

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I'm not sure if I follow your description, but a few points:


Check your tuning step size. I usually use 50 Hz, but if you are being super critical, you might do better with 10 or even 1 Hz.


Check your RX equalization. Too much low freq response can be a problem. Use a reasonable "IF" bandpass setting, maybe 150 - 3000 Hz.


Also check your AGC threshold. Generally it wants to be as low as possible without cutting back the baseline noise very much. My opinion.


My received audio is quite good IMO, but there are a lot of bad signals out there. When comparing radios you need to be sure you're comparing apples to apples.


73 Martin AA6E
(Edited)
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Ted VE3TRQ

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This is a real shot in the dark, but could this be a problem with your sound card and clocking, with some issue between the sample rate of the incoming digital audio and your PC turning it into analogue audio? (I think that is more usually a sampling issue when going frrm analogue to digital.) What happens when you either use an external (USB) sound card or bluetooth headset?
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Bill -VA3WTB

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Is your RIT RX on and not on 0
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Ken - NM9P, Elmer

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I have experienced this occasionally when listening to stations running “hyper-bass” and if I have lo RX filter low-cut set at 50 or below.
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David Decoons wo2x, Elmer

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Another thing to check. Try going to settings/radio settings/rx and do the calibration against WWV. Could be you are slightly off frequency?

Dave wo2x
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k9bm .

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This is most definitely not a matter of being off frequency or not being tuned correctly.  I noticed after I posted that it seems to be more pronounced on stronger signals.  Yes, there is a lot of variation in the audio quality that folks transmit, and there are a lot of marginal signals out there.

I am going to install a T-connector and run the receive antenna to my 756PRO for an A-B comparison.  If the difference is significant I'll upload the recording.  Thanks to all....

Brad K9BM
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Paul

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Hi Brad, I think Ted may be on the right lines. I have experienced a similar 'ringing' effect albeit on another SDR. I cured the symptoms by changing the speaker sound card setting (bit depth and sample rate) in windows.
(Edited)
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Martin Ewing AA6E

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Brad, I assume the problem is not there if you use the Flex amplified speaker output?  Then it may be Windows.  Be sure you've turned off all the "effects" options for your Windows audio output channel.

Happy hunting.
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N8SDR

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Question, are you using the PC settings and possible also have the  speaker output of the flex plugged in to your computer as well? 
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Mark - WS7M

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I don't think I've ever heard this on 4 different flex radios: 6300, 6500, 6600 and now a refurb 6300.  All sound good.

I do tend to use the powered speaker output and not windows sound unless I'm remote.

Keep in mind that flex radio filters are digital.  If, in SSDR, you look in Settings -> Radio setup -> Filters there are controls to set the sharpness and latency of voice, CW and digital filtering.

I primarily work CW so I have noticed with some stations kind of a "thrush" type hiss associated with their CW signal.  I was suspecting a flex audio problem until I stumbled on other stations that did not "thrush" as they sent.

In this particular case the thrush sound that accompanies the CW is related to some of the DSP settings as well as the filter latency.   

So I would check your DSP settings as well.
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Luis del MOlino

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I have suffered something similar. When keying the electronic keyer, The monitorized sound I was hearing was doubled and made the keying impossible. At first I thougth the keyer chip has been damaged.

But after some careful investigation, I discovered the culprit was our dear Windows 10 that has unexpectly activated some "listening to this device" on other record evices on a some DAX reseved audio channel or something like that.

So my suggestion is that you check very carefully all sound devices in Windows 10 and unmark "listening to this device" on record devices. Perhamps you will find the culprit there of this unusual double reproduction of the receiving sound.

73 Luis EA3OG

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k9bm .

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I discovered the audio issue, and I feel a little foolish.  It's the subwoofer on my computer speaker system!  It almost sounds like it has a processing delay because it beats the low frequencies with the main speakers.  Curious I've never heard any anomalies with music, which sounds OK through these speakers (it's an old Boston Acoustic system).  Anyway, I turned the subwoofer control ll the way down and the Flex audio is perfect.  Sorry....

Brad K9BM
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Ken - NM9P, Elmer

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No need for embarrassment.  You did good detective work.

This is the first time I have ever heard of that one....Thanks for sharing.

Ken - NM9P
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k9bm .

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Well it also explains why I noticed it most on strong signals that apparently had wider frequency response microphones (more "hi-fi" transmitted audio).  Anyway, no need to change speaker system, it's very easy to simply turn the subwoofer control on the speaker all the way down when using the Flex.  Thanks for everyone's ideas!