JUST THE FACTS: I’ve done quite a bit over 35 years of Electronics Repair and Service, now retired. always loved TV & VCR Repairs, 2-way radio for Motorola, Pro-Audio Sound, Music, Keyboards, Even had a Yamaha, and Roland Franchise for the In-Warranty repairs. Taught Guitar, play the guitar today, my Hearing is excellent for Audio Sound articulation and intonation.
Tested and experimented with many a microphone, the HM-12? Well, I use the ICOM 7600 now with a Heil Goldline Studio cartridge and an HC-5 Cartridge switchable. A condenser MIC is nice, but picks up too much background noise. I always heard the big raves and reviews about the HM-12 Genesis Mic. Just had to give it a spin.
The Audio Curve for the Heil Goldline Studio is like 60 Hz-to-16 Khz right? The HM-12 is advertised as 80 Hz-to-14Khz. Who can tell the difference between the two with the 2 Khz difference on either end? I did!
The Settings on the 7600 ICOM BASS a –3 and TREBLE a +3 with the Goldline. Perfect Audio on Transmit, maybe a 3db Compression Boost for Emphasis overall. (Not Needed really) plenty of Articulation.
With those settings, I plugged the HM-12 in, thinking is should be not quite a sharp, same amount of Gain to drive the transmitter. Boy was I surprised, Muffled, Bassey Audio galore. Hardly any Highs, had to turn the TREBLE to +5 & the BASS all the way down to Minus 5. Now it sounds pretty good, actually like a Muddy sounding Goldline. Articulation in a separate receiver just wasn’t there with the advertised 4db Boost at 2000 hz, like the Goldine. Somethings wrong with this Mic? Needs a $300.00 Equalizer! That’s what everybody does, EQ it!
Okay- I returned the Audio Settings back to where we started. Unscrewed the ball, what have we got here? Cupped my hand over the Cartridge, Talking and monitoring the Audio, wow, there it is, the advertised Frequency Response in my cupped hand! But it’s covered up with the Foam Rubber crap on the Cartridge! I removed it all and the Drive went up 10 db, High Frequency went up significantly, even noticed a slight Bass boost! So my question is, If the Mic Element produces that Audio with a Cupped Hand, then why cover it up!!? it exists, use it….
So I throttled the BASS back down to -5, YEP- MINUS 5, Set the TREBLE at a +1, Plugged the Goldline back in, Identical Microphone, I mean, IDENTICAL. Switched them back & Forth many times, identical, now I have another duplicate Goldline Mic…Just looks different is all..
Here’s the FIX to make it work right: Just Unscrew the Big Ball, and grab the little Black FOAM square Stuck on the Dust cover, gently tear it off, and replace the dust cover. Don’t glue it in; it’ll stay put by itself. Or, you can take all that garbage off there, and put a little piece of Black Nylon Stocking or cheese cloth for dust, then you’ll have a real microphone! You can hear the Punch and the Sparkle now like you’re supposed to. The Articulation is there, wasn’t there before.
So, that’s why you can’t hear the audio loss on both ends of the Audio Curve of that HM-12, out of the box; it’s covered up with too much foam rubber! One Thin Layer, second Square layer, then inside the Metal ball, another foam rubber layer, then they even include a Foam “p” Pop Filter to put over the metal ball, 4 Layers of FOAM RUBBER?!! Over Kill, not for me.
My wife said, what are you always doing with those microphones? I said, I’m making them better. She commented after I explained all the above to her, She said, you wanna know something? I said what..?
You could make 10 different Microphones, Same Cartridge installed, just do what you just did, install different layers of Foam, plug Holes, Open Holes, change the sound of that same Cartridge 10 or more different ways, and nobody would know the difference! WHOA……. then resell it..
So what you are saying is, you could sell the $400.00 cartridge with less Foam rubber, and put the same Cartridge in a low end Mic, cover it up with Foam Rubber to change the Frequency Response, Label it differently, paint it a different color and sell it for under a $100.00, nobody would know any better!. Do you suppose…naw, that’s not happening, they wouldn’t…..let’s leave that one alone.
So what do you do with a 28 hz –to –18 Khz PR-40 Mic, when your Transmit Power is dropped by 30% on the Lower Frequency range that no one will hear anyhow?
Most Ham receivers are usually set to 2.4 or 2.5 KHZ all the time, they won’t hear anymore than 300-to-3000 hz with a Wide Range Studio Mic., their receivers are all too narrow, or their speakers are too tiny and non-resonant!
Course if your hearing is no good, or you use a hearing aid; none of the above review is for you anyway. Wanna buy a HM-12 cheap? Maybe I’ll keep it, use it on my Guitar.
Suggestion, Stick with your Hand Mic that came with the radio, it’s all you really ever need. You’re only impressing yourself. Got it?
73 WB0OAF
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