I can't say that I was ever completely happy with the audio output of the K3. My father was an audiophile and the K3 reminds me a bit of some of the high-end audio stuff that he used to demonstrate to me. It had remarkable detail and clarity but it also revealed things that perhaps were best hidden and made it, to me, a bit tiring to listen to compared to my own budget stereo system.
On the K3 CW and data signals sound remarkably pure and distortion free and SSB sounds very clean and open. But on headphones particularly and on some speakers other than the internal speaker I do find the K3 tiring to listen to. This may be due to high frequency "artifacts" that some have mentioned, but I have come to the conclusion that it has more to do with the excessive low frequency roll-off in the K3 audio circuits particularly the headphone circuit. Today, I performed the RF gain calibration procedure, recalibrated the S meter, then experimented with the AGC threshold and slope settings along the lines suggested in this thread. I didn't find it made much difference to the sound of the radio, or even the ability of signals to "pop out" of the noise has been described. I then made some A/B comparisons between the K3 and my FT-817ND, since that was connected up and available. Listening on headphones, the FT-817ND was definitely the most pleasant of the two radios to listen to, and signals seemed to stand clear of the noise better. I then attempted to record this to make some demo MP3 files via the line audio from both radios. The difference, though still noticeable, was less marked than when listening on headphones. As my K3 is connected to its own dedicated sound card, I downloaded Spectran and used this to experiment with the effect of filtering on the received audio. You can play the K3 audio into one sound card and play back the output (optionally filtered by Spectran) to the regular one and listen with headphones plugged into the computer. This convinced me that the K3 is certainly capable of producing very high quality audio. I didn't see any sign of high frequency "artifacts" on the display. A low pass filter coming in anywhere from 2.7KHz or higher didn't make much difference to the sound at all. But changing the position of the high pass filter to allow more bass through made a big subjective difference to the sound. More bass made the audio less tiring and more pleasant to listen to. I have done the KIO3 mod to improve the bass through the line output and the mod on the main board for the speaker output. I still have the original DSP board. Recently I plugged a pair of cheap computer speakers into the rear speaker socket of the K3. Being computer speakers they were powered with a high impedance input so there is less attenuation of low frequencies than when using non-powered 8 ohm speakers. The audio quality was quite pleasant considering the price of the speakers. The audio through headphones plugged into the socket of one of the speakers was also much better than the audio from the same headphones plugged directly into the K3. I agree with others who have said that more information is needed than just "my K3 is noisy". We need to know what they are listening with, what impedance it is, what audio-related mods have been done. I personally think that the excessive attenuation of low frequencies in the K3's audio circuits particularly the headphone output is the major factor in many of the complaints that the K3 sounds tiring. I am not convinced that an add-in LPF will have any effect. What I am concerned about - especially in view of the cost of exchanging the DSP board for those outside the US - is whether the improvements in low frequency output are enough. A lower-cost workaround might be to try some powered computer speakers and use the headphone output on those. Most people will have computer speakers already they can hook up as an experiment, so it would not be difficult to try it. ----- Julian, G4ILO. K2 #392 K3 #222. * G4ILO's Shack - http://www.g4ilo.com * KComm - http://www.g4ilo.com/kcomm.html * KTune - http://www.g4ilo.com/ktune.html -- View this message in context: http://n2.nabble.com/Noisy-K3-receiver-tp4184529p4191926.html Sent from the [K3] mailing list archive at Nabble.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
