Bob, The DSP code isn't quite settled yet. I can help you further optimize the K4 settings, including AGC and NR.
(Note that the NR settings are completely different between the two. We're also working on a much more advanced NR algorithm the doesn't have the "hollow" LMS sound of the current K3 and K4 NR.) Also, the K4 has better LF audio response, which may account for the wider-sounding passband. Wayne N6KR > On Jun 24, 2020, at 7:24 PM, Bob Wilson, N6TV <n...@arrl.net> wrote: > > This afternoon I made a 3-1/2 minute audio recording of two stations in QSO > with each other on 40 CW, using both a K3 and K4D, and switching back and > forth. Download here (2.3 MB): > > https://www.kkn.net/~n6tv/K3_vs_K4D_CW_Audio_by_N6TV_20200625.mp3 > > Recorded off rear headphone jack using an MK2R+ USB Sound Card. > > In sum, I think the K4D audio sounds quite a bit better, but the "500 Hz" > passband of the K4 seems wider than the K3 (wider skirts?). The AGC attack > time seems slower in the K4 (similar to Icom IC-7851 fast AGC, IMHO). So > the "leading edge" of each dot or dash is louder, which may improve copy a > bit. > > The loud station (about 599 + 10 dB) is AC2K in AZ, and the weaker one > (about S-6 to S-7) is NZ0T in MO. > > Timestamp What you're hearing > ------------ ------------------- > 00:00 - 00:16 K3 > 00:19 - 01:00 K4 > 01:01 - 01:21 K4 with NR engaged and adjusted for best copy ("Level 3") > (Tuned range 0 to 10, the complete range) > 01:22 - 01:25 K3 > 01:26 - 01:58 K3 with NR F1-2 (didn't adjust) > 02:00 - 02:35 K4 NR off I think > 02:37 - 03:10 K3 NR off > 03:13 - 03:20 K4 > > K3 is S/N 1495 with KSYN3A upgrade but original DSP board and Inrad 500 Hz > 8-pole CW crystal filter, with W9AC Audio Mod > <http://web.archive.org/web/20091011115528/http://n1eu.com/K3/k3audiomod.htm>. > (capacitors changed in headphone circuit to increase low end audio response) > K4D Field Test Unit S/N 0008 > > K3 and K4 were set with identical parameters where possible: > > AGC-F, ATT OFF, PRE OFF > RF Gain about 3 O'Clock on K3. > RF Gain 0 (max) on K4 > CW mode, 500 Hz bandwidth > Pitch 480 Hz / center of passband IF shift > AGC Attack: 210 (K4 only) > AGC DCY Soft (K3 only) > AGC HLD 0.05 (K3 only) > AGC PLS NOR/ON > AGC SLP 008 (K3) > AGC Slope 15 (K4 -- units are different) > AGC THR 010 (K3) > AGC Threshold 4 (K4 -- units are different) > AGC-F / AGC Decay, Fast:120 > AGC-S / AGC Decay, Slow: 20 > > 73, > Bob, N6TV > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to n...@elecraft.com ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
