Power mics

Well, after tiring of almost eating the standard mic that came with the McKinley, I decided to buy a power mic.
Chose the Cobra M75 due to its appearance and build quality, which upon receipt I can say is top notch. Solid ABS construction with a metal mesh. The power control is a horizontal rotating wheel on the top-reverse, easy to use but out of the way.
Ordered from Knights wired with a six pin for the McKinley and he included a battery (9v).
Chunky American style sized which is nice once you get used to it.
The only drawback so far is of course the loss of the freq. up & down buttons on top of the std President mic.
I’ll let you know how I get on with it.....

There is absolutely no need to use a power mic with the McKinley. I got one just over a month ago, all the contacts I've had have complimented me on the audio with the stock mike, one prevalent DXer being surprised to find it was the stock mic.

You don't say where you got the radio from but I suspect that if it wasn't Knights the problem is that the FM deviation and AM modulation just needs upping. Most manufacturers set the FM deviation to around 1.8kHz and AM modulation (which also affects SSB) to 80-90% to ensure they keep within CEPT limits - countries like Germany enforce them quite rigorously. The problem is that whilst the rest of the EU uses 2kHz FM deviation we use 2.5kHz in the UK so 1.8kHz would sound quite quiet on the UK 40 channels however on AM and SSB all that happens is you MAY put out a slightly weaker signal, not a quieter one.

On AM and SSB mine puts out maximum power at 2/3 mic gain with the stock mic. Once the mic gain is high enough you're reaching the peak power output anything more than that is just a waste as the ALC circuit will limit the input audio to try to prevent over-driving and all you do by feeding it a higher input from a power mike is guarantee distorted crap harder to understand audio. If DX is your aim you do not want to be sounding all loud and booming like they do on the Superbowl in the USA or the ESSB brigade do in the UK. You want quite tight articulate audio so you can be understood through the noise so you cut the bottom, cut the top, peak 2kHz, keep the mic gain as low as you can whilst still being able to reach peak power.

Hiya Rory,

Nice posting mate on your new acquisition, be good to hear how you get in with it.

Conor has made some good points, but I'd also like to add.......


The Cobra M75 mic circuitry does indeed cut the bass below 600Hz and rolls off above 1.2khz or so so good 'telephonic audio' can be achieved. The three window design also helps for those that don't hold the mic straight to the mouth. (The amount of times I've seen that mic upside-down, backhanded, "come-on rubber-ducky", Convoy style mic hold is unbelievable!)
The 'power' mic amplification is quite subtle compared to most and so long as you don't crank it all the way up it should be a good'un.


Be nice to see a simple buy & plug in approach to your problem that many others can follow suit. We don't all have the ability to rip open our rigs and hook up FM deviation meters


All the best,
Victor

I just prefer to hold the mic a little further away. But doing so with the standard mic some contacts said that my audio dropped away. Rubbing lips with it was better.
I got the McKinley from Knights in answer to NC above.

I’m on a regular net tonight, so I’m gonna see what people think with different gain and power settings.
As with all kit, there will be the correct balance.

It feels nice to hold the Cobra too and it has a nice classic look with the three section mesh grille.
Bit like a modern take on a news anchor mic.....

Nice one Rory, glad you found a net too mate

I had a similar looking mic years ago and pretty sure it was a 'Realistic'(?) It was a great mic.
I know I bought it from Tandy's....flipping 'eck, anyone else remember Tandy's? Popped in every month for my free battery

You'll have to let us know how you get on.


73s
Victor

Yep, I remember Tandy. Went there as a kid to buy a laser pointer when they first appeared.
Summary:
The power mic is no good. A mismatch to the McKinley.
No matter what I tried I was either not being heard, or told that it was all just bass.
Back to the standard mic and all of a sudden everyone said I was crashing in, no problem.
Some said to change the insert may help, but following tonight’s trial, I think I’ll consider that a failed experiment and shelf the M75 for now........

Next to antennas, microphones are a contentious subject on CB, (probably Ham too from what I've heard on air).

Bear with me now, the written word is often misconstrued due to it's lack of nuance...."You say tomato, I say tomato" doesn't work unless you know the phrase and put the American accent in your head when read. The following is a discussion.....not a dig


You say 'no matter what you tried' but we have no idea of what you tried'....
Did you adjust the 'mic gain' on the radio too along with the microphone setting?
What setting is the 'mic type' set to in the radio menu, 'EL' or 'dY'?
Was this just on FM, or did you try AM & SSB too?

When most people hear less treble or high frequency they often mistakingly say 'more bassy'.
(I've also heard, "muddy", "boomy-but not", and every other adjective that would put a 1980's wine testing session to shame! )

It's often difficult when someone else is giving a radio report too.....
I wouldn't trust a radio report from anyone with a 40 year old rig that's never seen a service or been 'twiddled', poked, prodded and generally more man-handled than a 40 year old street whore
Where they all on nice new shiny, factory set & adjusted radios?

Then to top it all you now say the stock mic is "crashing in, no problem" and yet the whole reason for buying a power mic was because you were unhappy with the stock unit(?!)


Hmmm, see my point?


I know, I know, sometimes life must be much simpler for ourselves. "I bought it, it didn't work, I flogged it on fleabay, end of....."
Not a problem for some, do whatever makes you happy, there is no right or wrong.

But you can see why it all becomes a bit contentious, confusing and I wouldn't say 'misinformed' but maybe under-informed.


We get the same with antennas - "Buy such-and-such antenna, it's the dogs b*ll*cks", followed by, "I bought one, it's cr*p". But the first guy bought it with new decent coax and connectors.....the second guy bought the antenna new and connected it to their 28 year old, half rotten, thin unidentifiable coax with bird-sh*t soldered el-cheapo PL259 connectors!
That little bit of extra information would help better judge the antenna


I can bet the next suggestion you get is the 'weird' stock microphone element placing......."it's nowhere near the hole-you-speak-through" sort of thing. Unless you're an acoustics engineer you probably will be baffled along with everyone else.
I mean, why else would a company manufacturing radios make it in such a way?



Anyway Rory, I hope you get to where you want, honestly I do
Just didn't want to see you chasing the proverbial dogs tail trying to get there or anyone else for that matter.


All the best, (and I do mean that with sincerity),
Victor

The idea with the power mic was to allow me to hold it a little further away. 
Holding the stock mic approx 1/2" away seems ok. Several stations (base and mobile in different directions) were happy with the stock mic, but no one liked my audio with the Cobra power mic.
I tried various combinations, radio mic gain low, Cobra high; vice versa and all in-between.

Even with both the radio and mic on their highest setting, I was told that my audio was quiet.
I switched back to the stock mic, and suddenly everyone was keying up to say how it sounded fine now.

Mic type was set to electret.

What I had hoped was that the Cobra mic would allow me to hold it a few inches away and still maintain a clear audio.

I'm not overly fussed, it was more an experiment.
I had assumed that because the mic was pre-amplified it would allow for a slightly more "casual" use  - as you mention above Victor, with the hold position being a little less disciplined. But even talking very directly into it I was told that the stock mic sounded better.
I don't dislike the stock mic, but wondered if the "power" type mic would be an advantage.......

All of what I say / assume may be full of holes (so to speak) as I am very new to this game (and have been very lucky with it all so far.....).

That's a crying shame Rory, I had hoped you'd get some better luck with the new mic.

I remember when I first started CB and I went through mics like crazy, everyone gave me completely different reports and I must've had half a dozen or more sat in a drawer. It was only one day being left befuddled with it all that I told a breaker to wait a moment whilst I changed mics.......I didn't change the mic, yet he gave me a completely different audio report (!?!?)
I didn't call him out on it but tried the same 'mic change trick' several more times over the years with the same results.....

Just didn't want to see anyone else go through that same rigmarole I did


Well, obviously you did try literally everything Rory so it's good of you to feed that back.
One for the list of non-compatible pairings I suppose.

Like I said, others will read this discussion maybe many months later and get some value from it


All the best,
Victor

I have emailed Knights, to see if they have any ideas. Both the rig and mic came from them.
I did try the “changed my mic” trick that you mentioned, but still got bad reports for the power mic.
Annoying, because I have seen videos with people using one on the Grant II with good results.
I’ll update when I get a reply from Knights......

The Doctor wrote:

The idea with the power mic was to allow me to hold it a little further away. 

The downside of that is that it picks up all the background noise. Using a power mike makes that worse.

Quote :

Holding the stock mic approx 1/2" away seems ok. Several stations (base and mobile in different directions) were happy with the stock mic, but no one liked my audio with the Cobra power mic.
I tried various combinations, radio mic gain low, Cobra high; vice versa and all in-between.

Even with both the radio and mic on their highest setting, I was told that my audio was quiet.
I switched back to the stock mic, and suddenly everyone was keying up to say how it sounded fine now.

Mic type was set to electret.

For the stock mike it wants to be electret because the stock mike uses an electret mike element that requires a supply voltage unlike a dynamic mike. For the Cobra I'd expect probably dynamic. That would have an effect on the volume of your transmit audio so give it a go with the Cobra and mike type set to dynamic.

You also want to be talking "across" the mike, not directly into it so you want to hold it at a bit of an angle to your mouth, not directly at it to reduce things like the "pop" you get when saying the letter P.

Thank you guys. I will try this tonight.

Right. All advice here was good advice, so thank you both for yours.
With mic type set to dynamic, gain up full on the rig (a little counter to what I had thought) and the mic up at around 2/3 it’s max, I now have it working just right.
Very happy with the look and feel of the Cobra, so I’m dead pleased with the result.

Cheers,
Rory

Hi Rory,

What can I say? Sorted!

There we were thinking everything had been tried, (I mentioned mic type setting too and Conor/Northern Crusader pointed specifically to it! ) Never mind, pleased that you got there.

Just goes to show how complicated something as simple as a mic change really can be

Honestly, bl**dy pleased for you and glad you're happy with a great looking mic.


Thanks for posting your result as well, it's sure to help someone else in the same or similar boat.

All the best,
Victor