Hi Jim, Yes, reducing the low frequencies can make a difference. That was emphasized in "Single-Sideband Systems and Circuits" by SabinSchoenike of the Collins Radio Company back in the 80s. They found that the more compression, the more reduction of the lows is required.
However, even 10-12 dB of clipping causes a fair amount of distortion. CESSB, on the other hand, is virtually distortion-free based on our tests and those of users. Equally important, CESSB gets rid of transient peaks that throttle the gain back when ALC is used, thus eliminating splatter. We took this a step further in our own implementation -- there is _zero_ overshoot in the K4 even with CMP = 30. The proof is in the punch, if not in the pudding: we've had *many* unsolicited comments about the K4's CESSB of the form "...then I set CMP to max and got through on one call! Even my [spouse/friend/pet] was impressed." 73, Wayne N6KR On Thu, Jul 17, 2025 at 3:21 PM Jim Brown via Elecraft < elecraft@mailman.qth.net> wrote: > FWIW, the benefits of CESSB can easily be approached by a combination of > judicious use of TXEQ to kill the low audio frequencies below about 500 > Hz, and adjustment of COMP for an indicated 10-12 dB of gain reduction > on voice peaks. That combination provides an increase of "talk power" of > about 13 dB -- 3 dB for killing that wasted low end that makes no > contribution to speech intelligibility, and 10 dB for COMP. This is more > than two S-units, making 5W as effective as 100W! > > I've been doing this and recommending it since my first K3 in 2008. Last > summer, I had a long ragchew of 40M with neighbor W6GJB, who was at his > cabin in the mountains with his KX3 and a compromise antenna. When we > started, he was tough to copy, but when I talked him through those > adjustments, he was armchair copy for nearly an hour until it got later > and the band went long. > > 73, Jim K9YC > ______________________________________________________________ > 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, Inc. ______________________________________________________________ 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
