On Thu, 1 Apr 2010 19:06:14 -0400, Joe Subich, W4TV wrote: >In order to have reasonable articulation, the CM-500 >needs at least 3dB (closer to 6dB) per octave of boost >above 800 Hz and requires 6dB per octave of cut below >400 Hz in order to avoid being "boomy" or "muddy."
You and I must be listening to very different CM500s. Many members of our contest club bought them and have them on the air, and I own two. Every CM500 I've heard sounds great with only the two low octaves at full cut, and no other EQ. How do you listen to evaluate a transmitted signal? My standard method is with my K3 set for at least 2.7 kHz bandwidth (and wider is better, so that I'm not fooled by what the RX filtering is doing, and so that I don't miss distortion). Indeed, you can make any signal on the band sound very muddy or very thin and bright by using a narrow filter and shifting it high or low with respect to the signal. >It should never be necessary to use that much EQ to make >a microphone "sound good" and is a symptom of a poorly >designed capsule (or preamp). No, it's the sound of a mic with different EQ. Go to the Shure website and study the frequency response of their communications mics, like the 444. They have limited low end, and a BIG peak (about 8dB) around 3kHz. The reason for that peak is the rolloff built into the skirts of SSB TX filters -- it compensates for that rolloff! Heil mics do the same thing (but not very nicely, to my ear). Compare those communications mics with the Shure SM81, which is flat as a pancake up to 15 kHz. I own a lot of pro dynamic and condenser mics that are flat from 50 Hz to 12 kHz, and I've used a few of the dynamics with my ham gear when I didn't have a ham mic handy. RE16, RE20, RE27 are examples -- I've done a LOT of contesting with them, and I can easily make them sound very competitive, but also very clean. If I plugged them in with no TXEQ, they would sound VERY muddy. They need a LOT of low cut (full cut on at least the three lowest bands of the K3 equalizer) and that big peak around 3kHz. There's NOTHING wrong with the design of those mics or the preamp. They are simply designed for a different purpose -- high quality recording and broadcast of speech and music. 73, Jim Brown 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
