From my formal training in audio tech, a 10 dB gain is needed to get a perceived doubling of audio. With an audio sampler device listening for volume levels recording on a level meter, try doubling the output level on your output device according to your sampling device and at the same time listening to what you think doubling actually appears to you, then compare mentally the difference to what you perceive is real. Totally different in my experience. I could never figure out what was double while looking at the actual controls and what was factually happening and what my hearing and brain perceived without measuring and metering 73, Bill K9YEQ
https://wrj-tech.com/ -----Original Message----- From: elecraft-boun...@mailman.qth.net <elecraft-boun...@mailman.qth.net> On Behalf Of Jim Brown Sent: Saturday, March 16, 2019 6:30 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] KPA1500 PA Current On 3/16/2019 2:31 PM, Edward R Cole wrote: > In the same vein: I recently tried out my new 2m 1500w sspa at 750w > in SSB and stations on my net only stated a slight increase in signal > 100 miles away vs running 130w. That should have indicated more than > one s-unit stronger (10Log (750/130)=7.6 dB). > > Definitely a "knee" in signal strength where change is most > significant and where change above is not so much. HF that should > even be more compressed. What you're calling a "knee" is better described as a combination of receiver AGC, perception of loudness and signal to noise by our ear/brain function, and how various signal characteristics combine to provide speech intelligibility. A change in OVERALL loudness of 6-10 dB is perceived as twice (or half) as loud when the signal is well above the noise, and 1 dB is about the smallest change IN OVERALL loudness that untrained listeners can perceive. But when the signal is close to the noise, a few dB change in the signal to noise ratio often makes a big difference in speech intelligibility. And what I learned in my professional life and have been teaching the ham community for more than ten years is that speech intelligibility is most strongly dependent on components in the 800 Hz to 3 kHz range, with higher frequencies making a small additional contribution. Roughly half of the ENERGY in speech is below 500 Hz, but this sound makes almost no contribution to speech intelligibility. SO -- using TXEQ to remove that sound is the equivalent of doubling the effective talk power (3dB)! This is why I've always recommended setting TXEQ for max cut in the three lowest bands, 6 dB cut in the 4th band (400 Hz), and a small boost (3-6 dB) in the top two bands. Careful use of good speech compression can add another 10dB of talk power, so the combination of EQ and compression can improve signal to noise by 13 dB, which is equivalent to multiplying transmitter power by 20! > Raising antenna ten feet above tree top is worth at least 10-dB in > signal improvement at VHF (and way more as freq is increased into > UHF+). I can lower my 2m array to 4-foot AGL by use of a winch. Going > from there to about 40-feet (tree top) is worth maybe 5-dB. Yes, and height above ground can matter a LOT on the HF bands. http://k9yc.com/AntennaPlanning.pdf 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 ______________________________________________________________ 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
