6600/Maestro distorted/scratchy cw audio using headphone from Maestro.

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  • Updated 6 days ago
  • (Edited)
Distorted/scratchy cw audio on 6600/Maestro (link local) only when using headphones. Note that this is actual on air audio not the side tone (although that is poor). When audio is from the Maestro speaker it is OK. All WNB/TNF/NB/APF are disabled. I have tried both my Radiosport RS20S and other phones with no difference. New radio with latest software. Have tried changing 10MHz Reference from TXCO to external as described elsewhere to no avail. I figure this is maybe a Maestro audio problem?
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Paul Rollin G4AFU

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Posted 4 weeks ago

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DK9DK

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I can confirm the same for 6300 / Maestro,especially with small bandwidth.The same effect occurs when operating with 6300 / Notebook and remote Control operation (Operation in LAN or Maestro /Notebook directly connected to 6300).Also the sidetone sounds distorted.Sorry FlexRadio,but for cw Maestro is very limited.
(Edited)
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Paul Rollin G4AFU

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I was going to put a fault ticket into Flex as I have had no official response regarding this problem. What do you think DK9DK?
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Michael Walker, Employee

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I would recommend a support ticket to diagnose.  You may also want to test with the Maestro directly plugged into the radio with a LAN cable and no other network or network switch involved.  If the audio is clear, then you have a network issue to diagnose.  
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Paul Rollin G4AFU

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Thanks Michael....my Maestro is connected with the LAN cable  directly into the 6600. No network involved. I have only had the radio about a month or more and have not even connected to a pc yet. It is more pronounced with headphones as I am "nearer" to the audio. 
I have plugged headphones into the Flex 6600 directly and directed Main Audio Out from the Maestro Audio menu to Radio and it is still distorted. I`m beginning to suspect a faulty audio output on the 6600 as I can turn the volume up to 100% (Maestro slice A audio control) and it still does not output full volume into headphone. I would have thought at 100% full audio on a S9 signal I would be deafened by the audio but I am not. 

Possible fault on the pre-amp stage hence the distortion?
(Edited)
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Michael Walker, Employee

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Hi Paul

If you have not, please open a support case so we can address this correctly.

Thanks
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Paul Rollin G4AFU

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Michael, #27805 opened yesterday. 
Thanks for the prompt action. Paul 
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Paul Christensen, W9AC, Elmer

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Two issues here:

 1) The OPUS CODEC used by Maestro is a lossy coding format.  As such, critical listening to CW when using headphones plugged into Maestro will result in "fuzzy" audio.  Noise is correlated to the CW note.  The noise is masked quite well in voice modes, but not CW.  There's no easy way around it until Flex implements a linear coding format (e.g., 12-bit linear, 4 kHz).  A linear format consumes more data than typical lossy formats, but it would be most welcome to have a menu-driven choice.  It's possible to mitigate the fuzziness effect somewhat with different CW pitch.  Hopefully, the next-generation Maestro will allow for a range of CODECs and sampling rates much like RemoteRig does.   

2) Maestro's CW sidetone is derived by the square-wave output from Winkey.  As I recall, FFT or some form of filtering is used to suppress some of the odd harmonics from Winkey's output, but the result is still rich in harmonic content that makes the CW side-tone sound like a square-wave.  The next-generation Maestro should produce a CW side-tone as a pure sinewave just as SmartSDR does.

Paul, W9AC
(Edited)
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Paul Rollin G4AFU

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Thanks Paul. One question....I have plugged phones into the 6600 directly and from the Maestro Audio menu changed Main Audio out to Radio. Still the same fuzzy audio. So I take it that the Maestro is routing audio to the 6600 and I am not listening to audio from the Flex radio directly?
If I dump the Maestro and use my PC/LAN/6600 is the cw not distorted?