Heil Proset & K3 Audio fixed, sort of.
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Heil Proset & K3 Audio fixed, sort of.
 
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In order to try and eliminate the objectionable "noise" (careful avoidance of distortion, harmonics etc deliberate) in my headset I've fitted an LC filter with a 4kHz cut off. This would still pass odd order harmonics for lower audio frequencies. This filter has totally eliminated the annoying "noise" I was hearing with the downside that I have to run more AF gain to compensate. This kind of backs up previous measurements made by others that the harmonics are well down, and not noticeable. It's a bit disappointing that I had to do this but the headphone audio is now very nice indeed.
73 Paul. |
Re: Heil Proset & K3 Audio fixed, sort of.
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It suggests that perhaps you were hearing the artifacts > 4 KHz, such
as the 12 KHz with modulation sidebands or the one at 3.9 KHz. Maybe you were not hearing the artifacts directly but beats amongst them? Jack K8ZOA Paul Fletcher wrote: > In order to try and eliminate the objectionable "noise" (careful avoidance of > distortion, harmonics etc deliberate) in my headset I've fitted an LC filter > with a 4kHz cut off. This would still pass odd order harmonics for lower > audio frequencies. This filter has totally eliminated the annoying "noise" I > was hearing with the downside that I have to run more AF gain to compensate. > This kind of backs up previous measurements made by others that the > harmonics are well down, and not noticeable. It's a bit disappointing that I > had to do this but the headphone audio is now very nice indeed. > > 73 Paul. > Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
Re: Heil Proset & K3 Audio fixed, sort of.
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It's difficult to know. It's definitely high in frequency because I couldn't hear it in my right ear which has some HF loss (sadly don't have a calibration curve  ) Any ideas as to how this could be tracked down?
This needs a better fix though because of the overall attenuation the filter introduces. 73 Paul. |
Re: Heil Proset & K3 Audio fixed, sort of.
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You could do an active filter w/ a BW limit....
On Mon, 2008-09-08 at 15:34 -0700, Paul Fletcher wrote: > > > Jack Smith-6 wrote: > > > > It suggests that perhaps you were hearing the artifacts > 4 KHz, such > > as the 12 KHz with modulation sidebands or the one at 3.9 KHz. Maybe you > > were not hearing the artifacts directly but beats amongst them? > > > > It's difficult to know. It's definitely high in frequency because I couldn't > hear it in my right ear which has some HF loss (sadly don't have a > calibration curve :-) ) Any ideas as to how this could be tracked down? > > This needs a better fix though because of the overall attenuation the filter > introduces. > > 73 > Paul. _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
Re: Heil Proset & K3 Audio fixed, sort of.
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In reply to this post by Paul Fletcher
Using Spectrum Lab with my "on motherboard" sound card shows a
persistent artefact at 12 KHz with sometimes one either side of it. This doesn't appear when listening to typical speech on SSB but tuning to CW shows it, the signals either side of the 12 KHz one are +/- the tone of the CW signal, i.e. typically +/- 700 Hz. Audibly, there is more hiss and high frequency "roughness" when listening to CW signals with the K3 than listening to the same signal on a parallel connected K2 with it's AF DSP filtering, I would have hoped the RX equaliser would cut the high frequency signals but it doesn't. Looking at the circuit tends to suggest the place for a low pass filter would be the output of the DAC prior to the audio amplfier at "LHPOUT/RHPOUT" on the K3 DSP IF: DAC Audio board. Looking at the audio spectrum from my K3 (without FM) shows nothing above 4 KHz, so a low pass filter to cut everything above perhaps 5 KHz would do no harm. I am reluctant to modify my K3 unless it's an official Elecraft modification, but there is certainly some high frequency audio present that could do with removing. 73 Dave, G4AON K3/100 #80 -------------------- It suggests that perhaps you were hearing the artifacts > 4 KHz, such as the 12 KHz with modulation sidebands or the one at 3.9 KHz. Maybe you were not hearing the artifacts directly but beats amongst them? Jack K8ZOA Paul Fletcher wrote: >/ In order to try and eliminate the objectionable "noise" (careful avoidance of />/ distortion, harmonics etc deliberate) in my headset I've fitted an LC filter />/ with a 4kHz cut off. This would still pass odd order harmonics for lower />/ audio frequencies. This filter has totally eliminated the annoying "noise" I />/ was hearing with the downside that I have to run more AF gain to compensate. />/ This kind of backs up previous measurements made by others that the />/ harmonics are well down, and not noticeable. It's a bit disappointing that I />/ had to do this but the headphone audio is now very nice indeed. />/ / _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
Re: Re: Heil Proset & K3 Audio fixed, sort of.
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I've been sharing my findings with M1PAF and we have now both put a RC
Low Pass Filter across the headphone transducer of our Heil headsets but only in the right headphone so that the left one can still hear the artifacts for comparison. I have chosen a LPF with values of R=260 Ohms & C=0.2uF This has a 3dB point at 3060KHz. The Impedance of the Heil Headset is 200 Ohms per transducer. There is no doubt that the RC filter works. I can hear a nice clean CW note in my right ear and artifacts in the left. This is almost true for SSB. I do have to adjust my volume to a higher level, if the volume knob was originally at 9 o'clock position for normal use with the RC filter fitted I turn it up to 10 o'clock position..... not a lot of difference. Although these tests are none scientific and don't involve expensive test gear, one is for sure I can't hear the artifacts anymore on CW and less so on SSB and my test set are my ears, which I'm afraid, won't give you any fancy dB signal levels or a spectrum analysis !! Perhaps someone out there with test equipment might like to look into a Low Pass Filter design which could be incorporated into the K3 as standard or an improvement over my simple RC LPF in a headset? All the best, Berni G0IDA Dave G4AON wrote: > Using Spectrum Lab with my "on motherboard" sound card shows a > persistent artefact at 12 KHz with sometimes one either side of it. > This doesn't appear when listening to typical speech on SSB but tuning > to CW shows it, the signals either side of the 12 KHz one are +/- the > tone of the CW signal, i.e. typically +/- 700 Hz. > > Audibly, there is more hiss and high frequency "roughness" when > listening to CW signals with the K3 than listening to the same signal > on a parallel connected K2 with it's AF DSP filtering, I would have > hoped the RX equaliser would cut the high frequency signals but it > doesn't. > > Looking at the circuit tends to suggest the place for a low pass > filter would be the output of the DAC prior to the audio amplfier at > "LHPOUT/RHPOUT" on the K3 DSP IF: DAC Audio board. Looking at the > audio spectrum from my K3 (without FM) shows nothing above 4 KHz, so a > low pass filter to cut everything above perhaps 5 KHz would do no > harm. I am reluctant to modify my K3 unless it's an official Elecraft > modification, but there is certainly some high frequency audio present > that could do with removing. > > 73 Dave, G4AON > K3/100 #80 > -------------------- > It suggests that perhaps you were hearing the artifacts > 4 KHz, such > as the 12 KHz with modulation sidebands or the one at 3.9 KHz. Maybe you > were not hearing the artifacts directly but beats amongst them? > > Jack K8ZOA > > Paul Fletcher wrote: > >/ In order to try and eliminate the objectionable "noise" (careful > avoidance of > />/ distortion, harmonics etc deliberate) in my headset I've fitted an > LC filter > />/ with a 4kHz cut off. This would still pass odd order harmonics for > lower > />/ audio frequencies. This filter has totally eliminated the annoying > "noise" I > />/ was hearing with the downside that I have to run more AF gain to > compensate. > />/ This kind of backs up previous measurements made by others that the > />/ harmonics are well down, and not noticeable. It's a bit > disappointing that I > />/ had to do this but the headphone audio is now very nice indeed. > />/ / > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com -- _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
Re: Re: Heil Proset & K3 Audio fixed, sort of.
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In reply to this post by Dave, G4AON
The 12 KHz artifact appears to be the audio output DAC clock, with the
demodulated audio forming upper and lower sidebands with it. It's down considerably, but still is apparently causing issues with those who have good high frequency hearing response. The K3's audio seems to have way too much high frequency response, with white noise visible up to 20 KHz and beyond in the headphone and speaker output ports. Most communications receivers roll off the audio response at a few KHz. A bit of roll off in the K3 would be beneficial, I think, either RC or LC. Jack K8ZOA Dave G4AON wrote: > Using Spectrum Lab with my "on motherboard" sound card shows a > persistent artefact at 12 KHz with sometimes one either side of it. > This doesn't appear when listening to typical speech on SSB but tuning > to CW shows it, the signals either side of the 12 KHz one are +/- the > tone of the CW signal, i.e. typically +/- 700 Hz. > > Audibly, there is more hiss and high frequency "roughness" when > listening to CW signals with the K3 than listening to the same signal > on a parallel connected K2 with it's AF DSP filtering, I would have > hoped the RX equaliser would cut the high frequency signals but it > doesn't. > > Looking at the circuit tends to suggest the place for a low pass > filter would be the output of the DAC prior to the audio amplfier at > "LHPOUT/RHPOUT" on the K3 DSP IF: DAC Audio board. Looking at the > audio spectrum from my K3 (without FM) shows nothing above 4 KHz, so a > low pass filter to cut everything above perhaps 5 KHz would do no > harm. I am reluctant to modify my K3 unless it's an official Elecraft > modification, but there is certainly some high frequency audio present > that could do with removing. > > 73 Dave, G4AON > K3/100 #80 > -------------------- > It suggests that perhaps you were hearing the artifacts > 4 KHz, such > as the 12 KHz with modulation sidebands or the one at 3.9 KHz. Maybe you > were not hearing the artifacts directly but beats amongst them? > > Jack K8ZOA > > Paul Fletcher wrote: > >/ In order to try and eliminate the objectionable "noise" (careful > avoidance of > />/ distortion, harmonics etc deliberate) in my headset I've fitted an > LC filter > />/ with a 4kHz cut off. This would still pass odd order harmonics for > lower > />/ audio frequencies. This filter has totally eliminated the annoying > "noise" I > />/ was hearing with the downside that I have to run more AF gain to > compensate. > />/ This kind of backs up previous measurements made by others that the > />/ harmonics are well down, and not noticeable. It's a bit > disappointing that I > />/ had to do this but the headphone audio is now very nice indeed. > />/ / > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com > Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
RE: Re: Heil Proset & K3 Audio fixed, sort of.
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> The 12 KHz artifact appears to be the audio output DAC clock, > with the demodulated audio forming upper and lower sidebands > with it. It's down considerably, but still is apparently > causing issues with those who have good high frequency hearing > response. I'm confused ... my measurements show the "12 KHz artifact" is more than 70 dB below a 1V peak signal. The artifact is not measurable when the headphone level is below -30 dBV. This level is comparable to the in band receiver noise floor with a -73 dBm RF signal and below the in band noise level with -100 dBM (1 uV) or -130 dBm sources. I do not understand why an out of band signal some 70 dB down should be an issue. The only reason the 12 KHz artifact can even be noticed with test equipment is that the K3's out of band noise floor (noise above the DSP and IF cut-off) is so exceptional. Even with AF gain, the audio noise outside the passband is no more than -100 to -110 dBV (I can't measure it). To complete the record, the 12 KHz artifact is also present on the Line Out DAC about 70 dB below the desired signal. 73, ... Joe, W4TV > -----Original Message----- > From: [hidden email] > [mailto:[hidden email]] On Behalf Of Jack Smith > Sent: Tuesday, September 09, 2008 6:09 AM > To: Dave G4AON > Cc: [hidden email] > Subject: Re: [Elecraft] Re: Heil Proset & K3 Audio fixed, sort of. > > > The 12 KHz artifact appears to be the audio output DAC clock, > with the > demodulated audio forming upper and lower sidebands with it. > It's down > considerably, but still is apparently causing issues with > those who have > good high frequency hearing response. > > The K3's audio seems to have way too much high frequency > response, with > white noise visible up to 20 KHz and beyond in the headphone > and speaker > output ports. Most communications receivers roll off the > audio response > at a few KHz. > > A bit of roll off in the K3 would be beneficial, I think, > either RC or LC. > > Jack K8ZOA > > > Dave G4AON wrote: > > Using Spectrum Lab with my "on motherboard" sound card shows a > > persistent artefact at 12 KHz with sometimes one either side of it. > > This doesn't appear when listening to typical speech on SSB > but tuning > > to CW shows it, the signals either side of the 12 KHz one > are +/- the > > tone of the CW signal, i.e. typically +/- 700 Hz. > > > > Audibly, there is more hiss and high frequency "roughness" when > > listening to CW signals with the K3 than listening to the > same signal > > on a parallel connected K2 with it's AF DSP filtering, I would have > > hoped the RX equaliser would cut the high frequency signals but it > > doesn't. > > > > Looking at the circuit tends to suggest the place for a low pass > > filter would be the output of the DAC prior to the audio > amplfier at > > "LHPOUT/RHPOUT" on the K3 DSP IF: DAC Audio board. Looking at the > > audio spectrum from my K3 (without FM) shows nothing above > 4 KHz, so a > > low pass filter to cut everything above perhaps 5 KHz would do no > > harm. I am reluctant to modify my K3 unless it's an > official Elecraft > > modification, but there is certainly some high frequency > audio present > > that could do with removing. > > > > 73 Dave, G4AON > > K3/100 #80 > > -------------------- > > It suggests that perhaps you were hearing the artifacts > 4 > KHz, such > > as the 12 KHz with modulation sidebands or the one at 3.9 > KHz. Maybe > > you were not hearing the artifacts directly but beats amongst them? > > > > Jack K8ZOA > > > > Paul Fletcher wrote: > > >/ In order to try and eliminate the objectionable "noise" (careful > > avoidance of > > />/ distortion, harmonics etc deliberate) in my headset > I've fitted an > > LC filter > > />/ with a 4kHz cut off. This would still pass odd order > harmonics for > > lower > > />/ audio frequencies. This filter has totally eliminated > the annoying > > "noise" I > > />/ was hearing with the downside that I have to run more > AF gain to > > compensate. > > />/ This kind of backs up previous measurements made by > others that the > > />/ harmonics are well down, and not noticeable. It's a bit > > disappointing that I > > />/ had to do this but the headphone audio is now very nice indeed. > > />/ / > > _______________________________________________ > > Elecraft mailing list > > Post to: [hidden email] > > You must be a subscriber to post to the list. > > Subscriber Info (Addr. Change, sub, unsub etc.): > > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > > Elecraft web page: http://www.elecraft.com > > > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
Re: Re: Heil Proset & K3 Audio fixed, sort of.
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I agree that it's around 70 dB below the normal signal level.
The original poster believes it is the source of his problem. My ears are not good enough to hear 12 KHz. Jack K8ZOA Joe Subich, W4TV wrote: >> The 12 KHz artifact appears to be the audio output DAC clock, >> with the demodulated audio forming upper and lower sidebands >> with it. It's down considerably, but still is apparently >> causing issues with those who have good high frequency hearing >> response. >> > > I'm confused ... my measurements show the "12 KHz artifact" is > more than 70 dB below a 1V peak signal. The artifact is not > measurable when the headphone level is below -30 dBV. This > level is comparable to the in band receiver noise floor with a > -73 dBm RF signal and below the in band noise level with -100 > dBM (1 uV) or -130 dBm sources. I do not understand why an > out of band signal some 70 dB down should be an issue. > > The only reason the 12 KHz artifact can even be noticed with > test equipment is that the K3's out of band noise floor (noise > above the DSP and IF cut-off) is so exceptional. Even with AF > gain, the audio noise outside the passband is no more than -100 > to -110 dBV (I can't measure it). > > To complete the record, the 12 KHz artifact is also present > on the Line Out DAC about 70 dB below the desired signal. > > 73, > > ... Joe, W4TV > > > > > > > > >> -----Original Message----- >> From: [hidden email] >> [mailto:[hidden email]] On Behalf Of Jack Smith >> Sent: Tuesday, September 09, 2008 6:09 AM >> To: Dave G4AON >> Cc: [hidden email] >> Subject: Re: [Elecraft] Re: Heil Proset & K3 Audio fixed, sort of. >> >> >> The 12 KHz artifact appears to be the audio output DAC clock, >> with the >> demodulated audio forming upper and lower sidebands with it. >> It's down >> considerably, but still is apparently causing issues with >> those who have >> good high frequency hearing response. >> >> The K3's audio seems to have way too much high frequency >> response, with >> white noise visible up to 20 KHz and beyond in the headphone >> and speaker >> output ports. Most communications receivers roll off the >> audio response >> at a few KHz. >> >> A bit of roll off in the K3 would be beneficial, I think, >> either RC or LC. >> >> Jack K8ZOA >> >> >> Dave G4AON wrote: >> >>> Using Spectrum Lab with my "on motherboard" sound card shows a >>> persistent artefact at 12 KHz with sometimes one either side of it. >>> This doesn't appear when listening to typical speech on SSB >>> >> but tuning >> >>> to CW shows it, the signals either side of the 12 KHz one >>> >> are +/- the >> >>> tone of the CW signal, i.e. typically +/- 700 Hz. >>> >>> Audibly, there is more hiss and high frequency "roughness" when >>> listening to CW signals with the K3 than listening to the >>> >> same signal >> >>> on a parallel connected K2 with it's AF DSP filtering, I would have >>> hoped the RX equaliser would cut the high frequency signals but it >>> doesn't. >>> >>> Looking at the circuit tends to suggest the place for a low pass >>> filter would be the output of the DAC prior to the audio >>> >> amplfier at >> >>> "LHPOUT/RHPOUT" on the K3 DSP IF: DAC Audio board. Looking at the >>> audio spectrum from my K3 (without FM) shows nothing above >>> >> 4 KHz, so a >> >>> low pass filter to cut everything above perhaps 5 KHz would do no >>> harm. I am reluctant to modify my K3 unless it's an >>> >> official Elecraft >> >>> modification, but there is certainly some high frequency >>> >> audio present >> >>> that could do with removing. >>> >>> 73 Dave, G4AON >>> K3/100 #80 >>> -------------------- >>> It suggests that perhaps you were hearing the artifacts > 4 >>> >> KHz, such >> >>> as the 12 KHz with modulation sidebands or the one at 3.9 >>> >> KHz. Maybe >> >>> you were not hearing the artifacts directly but beats amongst them? >>> >>> Jack K8ZOA >>> >>> Paul Fletcher wrote: >>> >>>> / In order to try and eliminate the objectionable "noise" (careful >>>> >>> avoidance of >>> />/ distortion, harmonics etc deliberate) in my headset >>> >> I've fitted an >> >>> LC filter >>> />/ with a 4kHz cut off. This would still pass odd order >>> >> harmonics for >> >>> lower >>> />/ audio frequencies. This filter has totally eliminated >>> >> the annoying >> >>> "noise" I >>> />/ was hearing with the downside that I have to run more >>> >> AF gain to >> >>> compensate. >>> />/ This kind of backs up previous measurements made by >>> >> others that the >> >>> />/ harmonics are well down, and not noticeable. It's a bit >>> disappointing that I >>> />/ had to do this but the headphone audio is now very nice indeed. >>> />/ / >>> _______________________________________________ >>> Elecraft mailing list >>> Post to: [hidden email] >>> You must be a subscriber to post to the list. >>> Subscriber Info (Addr. Change, sub, unsub etc.): >>> http://mailman.qth.net/mailman/listinfo/elecraft >>> Help: http://mailman.qth.net/subscribers.htm >>> Elecraft web page: http://www.elecraft.com >>> >>> >> _______________________________________________ >> Elecraft mailing list >> Post to: [hidden email] >> You must be a subscriber to post to the list. >> Subscriber Info (Addr. Change, sub, unsub etc.): >> http://mailman.qth.net/mailman/listinfo/elecraft >> >> Help: http://mailman.qth.net/subscribers.htm >> Elecraft web page: http://www.elecraft.com >> > > > Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
Re: Re: Heil Proset & K3 Audio fixed, sort of.
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My hearing is good to 18Khz and I don't hear it on my K3. I see it clearly on the spectrum analyzer, but I don't hear it. How about a WAV recording from someone who hears it? 73, Barry N1EU |
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In reply to this post by Paul Fletcher
I think this plot explains why.
capt0809091710.jpg It is a sequence from my GB3RAL 70MHz beacon sending JT65B. The high frequency alias is quite clear. It is inverted which might be why it sounds so strange. So for example 900Hz is aliasing to 11.1kHz. It is a long way down, >60 dB. You might not think it to be a problem but perhaps if the headphones are more sensitive at HF it could be. Here is another where I moved the VFO to show the effect of different frequencies over the passband. capt0809091717.jpg The amplitude appears fairly consistent. I think a simple low pass filter is all that is needed and a cut off of maybe 7 kHz would be appropriate. Maybe even lower as this 4kHz ESSB plot with the FM filter shows, the audio response is limited above 2.5kHz. capt0809091722.jpg Mike
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Re: Heil Proset & K3 Audio fixed, sort of.
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> The amplitude appears fairly consistent. I think a simple low pass filter
> is > all that is needed and a cut off of maybe 7 kHz would be appropriate. > Maybe > even lower as this 4kHz ESSB plot with the FM filter shows, the audio > response is limited above 2.5kHz. Mike: You may want to revisit that last measurement. My measured data closely mirrors that shown on N1EU's website with the 6 kHz filter engaged: http://n1eu.com/K3/K3_notes.htm See chart entitled " Elecraft K3 SSB Receive Passband..." Paul, W9AC _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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You are right, I had set the width as high as I could, which was 4kHz. I didn't move the centre frequency to 2kHz. I have just done it again but this time with the centre frequency set to 2kHz and I see 4kHz width. The highest I can get it up to is 300Hz-4.2kHz.
But, I found something else. I managed to have LO at 0 and HI not go above 3.4kHz. I found out that LO was actually negative, but read as zero as a result of switching mode from Shift/Width to Lo/Hi. It really was negative too, the other sideband came through. I don't understand the display logic here. Surely if LO is negative, which is quite legitimate, it should read so? These displays are not what I thought originally. E.g. AM mode, LO/HI 0-4kHz, Fc2.1 BW 8.2 kHz. I agreed the RF bandwidth as 8.2 kHz but not Fc, which I would think to be zero for AM. So Fc relates to the audio centre frequency and BW relates to the RF bandwidth, not the audio bandwidth. That was where I was going wrong. HI/LO only relate to audio. Mike
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Re: Re: Heil Proset & K3 Audio fixed, sort of.
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In reply to this post by Jack Smith-6
What I do believe is that there is an artifact or artifacts.... and I
can hear them. I put the LC filter as mentioned before on my headset and the so called "artifacts" are gone. It's very simple, I can't hear them with my ears if i have the LC filter in irrespective of expensive equipment dB levels and measurements and perhaps they are 70dB down but there is something there and I'm not the only one to hear it. My hearing is good up and beyond 12KHz, perhaps that is part of my problem. There is also no filtering on the circuit from the DAC to the audio amp as far as I can seeso everything coming out from the DAC is amplified. 73's Berni G0IDA Jack Smith wrote: > I agree that it's around 70 dB below the normal signal level. > > The original poster believes it is the source of his problem. > > My ears are not good enough to hear 12 KHz. > > Jack K8ZOA > > > Joe Subich, W4TV wrote: >>> The 12 KHz artifact appears to be the audio output DAC clock, with >>> the demodulated audio forming upper and lower sidebands with it. >>> It's down considerably, but still is apparently causing issues with >>> those who have good high frequency hearing response. >>> >> >> I'm confused ... my measurements show the "12 KHz artifact" is more >> than 70 dB below a 1V peak signal. The artifact is not measurable >> when the headphone level is below -30 dBV. This level is comparable >> to the in band receiver noise floor with a -73 dBm RF signal and >> below the in band noise level with -100 dBM (1 uV) or -130 dBm >> sources. I do not understand why an out of band signal some 70 dB >> down should be an issue. >> The only reason the 12 KHz artifact can even be noticed with test >> equipment is that the K3's out of band noise floor (noise above the >> DSP and IF cut-off) is so exceptional. Even with AF gain, the audio >> noise outside the passband is no more than -100 to -110 dBV (I can't >> measure it). >> To complete the record, the 12 KHz artifact is also present on the >> Line Out DAC about 70 dB below the desired signal. >> 73, >> ... Joe, W4TV >> >> >> >> >> >> >> >>> -----Original Message----- >>> From: [hidden email] >>> [mailto:[hidden email]] On Behalf Of Jack Smith >>> Sent: Tuesday, September 09, 2008 6:09 AM >>> To: Dave G4AON >>> Cc: [hidden email] >>> Subject: Re: [Elecraft] Re: Heil Proset & K3 Audio fixed, sort of. >>> >>> >>> The 12 KHz artifact appears to be the audio output DAC clock, with >>> the demodulated audio forming upper and lower sidebands with it. >>> It's down considerably, but still is apparently causing issues with >>> those who have good high frequency hearing response. >>> >>> The K3's audio seems to have way too much high frequency response, >>> with white noise visible up to 20 KHz and beyond in the headphone >>> and speaker output ports. Most communications receivers roll off the >>> audio response at a few KHz. >>> >>> A bit of roll off in the K3 would be beneficial, I think, either RC >>> or LC. >>> >>> Jack K8ZOA >>> >>> >>> Dave G4AON wrote: >>> >>>> Using Spectrum Lab with my "on motherboard" sound card shows a >>>> persistent artefact at 12 KHz with sometimes one either side of it. >>>> This doesn't appear when listening to typical speech on SSB >>> but tuning >>>> to CW shows it, the signals either side of the 12 KHz one >>> are +/- the >>>> tone of the CW signal, i.e. typically +/- 700 Hz. >>>> >>>> Audibly, there is more hiss and high frequency "roughness" when >>>> listening to CW signals with the K3 than listening to the >>> same signal >>>> on a parallel connected K2 with it's AF DSP filtering, I would have >>>> hoped the RX equaliser would cut the high frequency signals but it >>>> doesn't. >>>> >>>> Looking at the circuit tends to suggest the place for a low pass >>>> filter would be the output of the DAC prior to the audio >>> amplfier at >>>> "LHPOUT/RHPOUT" on the K3 DSP IF: DAC Audio board. Looking at the >>>> audio spectrum from my K3 (without FM) shows nothing above >>> 4 KHz, so a >>>> low pass filter to cut everything above perhaps 5 KHz would do no >>>> harm. I am reluctant to modify my K3 unless it's an >>> official Elecraft >>>> modification, but there is certainly some high frequency >>> audio present >>>> that could do with removing. >>>> >>>> 73 Dave, G4AON >>>> K3/100 #80 >>>> -------------------- >>>> It suggests that perhaps you were hearing the artifacts > 4 >>> KHz, such >>>> as the 12 KHz with modulation sidebands or the one at 3.9 >>> KHz. Maybe >>>> you were not hearing the artifacts directly but beats amongst them? >>>> >>>> Jack K8ZOA >>>> >>>> Paul Fletcher wrote: >>>> >>>>> / In order to try and eliminate the objectionable "noise" (careful >>>>> >>>> avoidance of >>>> />/ distortion, harmonics etc deliberate) in my headset >>> I've fitted an >>> >>>> LC filter >>>> />/ with a 4kHz cut off. This would still pass odd order >>> harmonics for >>>> lower >>>> />/ audio frequencies. This filter has totally eliminated >>> the annoying >>>> "noise" I >>>> />/ was hearing with the downside that I have to run more >>> AF gain to >>>> compensate. >>>> />/ This kind of backs up previous measurements made by >>> others that the >>> >>>> />/ harmonics are well down, and not noticeable. It's a bit >>>> disappointing that I >>>> />/ had to do this but the headphone audio is now very nice indeed. >>>> />/ / >>>> _______________________________________________ >>>> Elecraft mailing list >>>> Post to: [hidden email] >>>> You must be a subscriber to post to the list. >>>> Subscriber Info (Addr. Change, sub, unsub etc.): >>>> http://mailman.qth.net/mailman/listinfo/elecraft Help: >>>> http://mailman.qth.net/subscribers.htm >>>> Elecraft web page: http://www.elecraft.com >>>> >>>> >>> _______________________________________________ >>> Elecraft mailing list >>> Post to: [hidden email] >>> You must be a subscriber to post to the list. >>> Subscriber Info (Addr. Change, sub, unsub etc.): >>> http://mailman.qth.net/mailman/listinfo/elecraft >>> Help: http://mailman.qth.net/subscribers.htm >>> Elecraft web page: http://www.elecraft.com >>> >> >> >> > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com -- _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
Re: Re: Heil Proset & K3 Audio fixed, sort of.
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In reply to this post by Jack Smith-6
I fixed this in my headphones with an LC filter that takes the 12Khz
trash down an additional 12dB I can easily hear the 12Khz stuff on good headphones at normal operating levels, even though it's at 60 to 70dB down on the desired audio. Because it's non-harmonically related it's impact on the perceived audio quality is much greater than harmonically related distortion. I have very good hearing and worked for a few years as a professional sound engineer specialising in recording acoustic music. If you can't hear past 10Khz or your headphones have a restricted frequency range then this will be a non-issue. For me it was an irritant but by no means a show stopper, the K3 is a fine radio that sounds much nicer than my Icom's did However I am glad I invested the time to add LC filtering to my head set as the improvement is worthwhile. 73 Brendan EI6IZ On Tue, 2008-09-09 at 10:27 -0400, Jack Smith wrote: > I agree that it's around 70 dB below the normal signal level. > > The original poster believes it is the source of his problem. > > My ears are not good enough to hear 12 KHz. > > Jack K8ZOA > > > Joe Subich, W4TV wrote: > >> The 12 KHz artifact appears to be the audio output DAC clock, > >> with the demodulated audio forming upper and lower sidebands > >> with it. It's down considerably, but still is apparently > >> causing issues with those who have good high frequency hearing > >> response. > >> > > > > I'm confused ... my measurements show the "12 KHz artifact" is > > more than 70 dB below a 1V peak signal. The artifact is not > > measurable when the headphone level is below -30 dBV. This > > level is comparable to the in band receiver noise floor with a > > -73 dBm RF signal and below the in band noise level with -100 > > dBM (1 uV) or -130 dBm sources. I do not understand why an > > out of band signal some 70 dB down should be an issue. > > > > The only reason the 12 KHz artifact can even be noticed with > > test equipment is that the K3's out of band noise floor (noise > > above the DSP and IF cut-off) is so exceptional. Even with AF > > gain, the audio noise outside the passband is no more than -100 > > to -110 dBV (I can't measure it). > > > > To complete the record, the 12 KHz artifact is also present > > on the Line Out DAC about 70 dB below the desired signal. > > > > 73, > > > > ... Joe, W4TV > > > > > > > > > > > > > > > > > >> -----Original Message----- > >> From: [hidden email] > >> [mailto:[hidden email]] On Behalf Of Jack Smith > >> Sent: Tuesday, September 09, 2008 6:09 AM > >> To: Dave G4AON > >> Cc: [hidden email] > >> Subject: Re: [Elecraft] Re: Heil Proset & K3 Audio fixed, sort of. > >> > >> > >> The 12 KHz artifact appears to be the audio output DAC clock, > >> with the > >> demodulated audio forming upper and lower sidebands with it. > >> It's down > >> considerably, but still is apparently causing issues with > >> those who have > >> good high frequency hearing response. > >> > >> The K3's audio seems to have way too much high frequency > >> response, with > >> white noise visible up to 20 KHz and beyond in the headphone > >> and speaker > >> output ports. Most communications receivers roll off the > >> audio response > >> at a few KHz. > >> > >> A bit of roll off in the K3 would be beneficial, I think, > >> either RC or LC. > >> > >> Jack K8ZOA > >> > >> > >> Dave G4AON wrote: > >> > >>> Using Spectrum Lab with my "on motherboard" sound card shows a > >>> persistent artefact at 12 KHz with sometimes one either side of it. > >>> This doesn't appear when listening to typical speech on SSB > >>> > >> but tuning > >> > >>> to CW shows it, the signals either side of the 12 KHz one > >>> > >> are +/- the > >> > >>> tone of the CW signal, i.e. typically +/- 700 Hz. > >>> > >>> Audibly, there is more hiss and high frequency "roughness" when > >>> listening to CW signals with the K3 than listening to the > >>> > >> same signal > >> > >>> on a parallel connected K2 with it's AF DSP filtering, I would have > >>> hoped the RX equaliser would cut the high frequency signals but it > >>> doesn't. > >>> > >>> Looking at the circuit tends to suggest the place for a low pass > >>> filter would be the output of the DAC prior to the audio > >>> > >> amplfier at > >> > >>> "LHPOUT/RHPOUT" on the K3 DSP IF: DAC Audio board. Looking at the > >>> audio spectrum from my K3 (without FM) shows nothing above > >>> > >> 4 KHz, so a > >> > >>> low pass filter to cut everything above perhaps 5 KHz would do no > >>> harm. I am reluctant to modify my K3 unless it's an > >>> > >> official Elecraft > >> > >>> modification, but there is certainly some high frequency > >>> > >> audio present > >> > >>> that could do with removing. > >>> > >>> 73 Dave, G4AON > >>> K3/100 #80 > >>> -------------------- > >>> It suggests that perhaps you were hearing the artifacts > 4 > >>> > >> KHz, such > >> > >>> as the 12 KHz with modulation sidebands or the one at 3.9 > >>> > >> KHz. Maybe > >> > >>> you were not hearing the artifacts directly but beats amongst them? > >>> > >>> Jack K8ZOA > >>> > >>> Paul Fletcher wrote: > >>> > >>>> / In order to try and eliminate the objectionable "noise" (careful > >>>> > >>> avoidance of > >>> />/ distortion, harmonics etc deliberate) in my headset > >>> > >> I've fitted an > >> > >>> LC filter > >>> />/ with a 4kHz cut off. This would still pass odd order > >>> > >> harmonics for > >> > >>> lower > >>> />/ audio frequencies. This filter has totally eliminated > >>> > >> the annoying > >> > >>> "noise" I > >>> />/ was hearing with the downside that I have to run more > >>> > >> AF gain to > >> > >>> compensate. > >>> />/ This kind of backs up previous measurements made by > >>> > >> others that the > >> > >>> />/ harmonics are well down, and not noticeable. It's a bit > >>> disappointing that I > >>> />/ had to do this but the headphone audio is now very nice indeed. > >>> />/ / > >>> _______________________________________________ > >>> Elecraft mailing list > >>> Post to: [hidden email] > >>> You must be a subscriber to post to the list. > >>> Subscriber Info (Addr. Change, sub, unsub etc.): > >>> http://mailman.qth.net/mailman/listinfo/elecraft > >>> Help: http://mailman.qth.net/subscribers.htm > >>> Elecraft web page: http://www.elecraft.com > >>> > >>> > >> _______________________________________________ > >> Elecraft mailing list > >> Post to: [hidden email] > >> You must be a subscriber to post to the list. > >> Subscriber Info (Addr. Change, sub, unsub etc.): > >> http://mailman.qth.net/mailman/listinfo/elecraft > >> > >> Help: http://mailman.qth.net/subscribers.htm > >> Elecraft web page: http://www.elecraft.com > >> > > > > > > > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com Don‘t complain. Nobody will understand. Or care. And certainly don‘t try to fix the situation yourself. It‘s dangerous. Leave it to a highly untrained, unqualified, expendable professional. _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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