Re: [Elecraft] Re: Heil Proset K3 Audio fixed, sort of.
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: Elecraft@mailman.qth.net 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: Elecraft@mailman.qth.net 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: [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: Elecraft@mailman.qth.net 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: Elecraft@mailman.qth.net 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: [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. 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: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jack Smith Sent: Tuesday, September 09, 2008 6:09 AM To: Dave G4AON Cc: elecraft@mailman.qth.net 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: Elecraft@mailman.qth.net 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: Elecraft@mailman.qth.net 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: Elecraft@mailman.qth.net You must
Re: [Elecraft] Re: Heil Proset K3 Audio fixed, sort of.
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: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jack Smith Sent: Tuesday, September 09, 2008 6:09 AM To: Dave G4AON Cc: elecraft@mailman.qth.net 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: Elecraft@mailman.qth.net 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: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub
Re: [Elecraft] Re: Heil Proset K3 Audio fixed, sort of.
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: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jack Smith Sent: Tuesday, September 09, 2008 6:09 AM To: Dave G4AON Cc: elecraft@mailman.qth.net 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
Re: [Elecraft] Re: Heil Proset K3 Audio fixed, sort of.
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: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jack Smith Sent: Tuesday, September 09, 2008 6:09 AM To: Dave G4AON Cc: elecraft@mailman.qth.net 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
