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Racer X (Unregistered Guest)
Unregistered guest
| | Posted on Saturday, January 29, 2005 - 9:24 pm: | 
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I've seen quite a few questions and statements about which microphones work well with particular radios and I though I'd post some comments about microphones and their use.
There isn't any specific microphone that sounds good with a particular radio. Any microphone can sound good with any radio as long as two things are compatable - output level and impedance. Output level is the most critical factor, but impedance is important when the microphone is unamplified.
Output level is the actual voltage the microphone provides. Pretty much any microphone has enough output for newer radios. Even inexpensive stock dynamic microphones (notice I didn't use the word cheap?) have plenty of output for all newer radios when they are used properly. Older radios with high impedance microphone inputs generally don't work well with low impedance unamplified microphones because the output level is too low. Power microphones are really flexible because you can vary the level from nearly no output to very high output.
Impedance is a little more complicated. New radios are made to work with low impedance microphones (low-Z) at around 600 ohms. Older crystal, ceramic, and dynamic microphones that were made to be used with tube radios are high impedance (high-Z) at around 50,000 ohms. Generally speaking you can use a low impedance microphone with a high impedance radio as long as the output level is high enough, but not the other way around.
Probably the most common high impedance microphone still used is the unamplified D104. Even thought it's crystal element has plenty of output, there is a well known issue with impedance mismatch when using it with a radio that is made to work with a low impedance microphone. The low frequency output of the element is lost in the transfer and you get a "tinny" sound.
The impedance of power microphones vary greatly but isn't important because the element is loaded by the amplifer and not the radio. The amplifier acts as a buffer, and with the variable output level, a power microphone will work with nearly any radio.
So why do microphones sound different? It's the interaction of the microphone and your voice. Different microphones have different frequency responces, so your voice sounds different from microphone to microphone.
A manufacturer can design microphones to have specific responces regardless of the type of element used, but generally D104s and other crystal and ceramic microphones have a taylored high frequency emphasis, while electret condenser and dynamic microphones have a very flat responce.
Some folks prefer to hear the high cut responce of a D104 while others prefer the flat responce of a dynamic mic like a Turner Super Sidekick. I personally like a nice flat responce because the high cut of a D104 is difficult for me to listen to for long periods of time.
Using a microphone properly is also important. Because sound waves degrade with distance, to have your voice sound it's best on the air it's important to speak directly into your microphone at a close distance of about 2" with a slightly softer than normal speaking voice. This will allow the microphone to pick up all of the complexity of your voice, have a good output level, and low background noise level. Even stock dynamic microphones sound good when used this way.
When using a power microphone it's best to keep the microphone gain of the radio high and the microphone's output level as low as possible while still fully modulating the radio. Too high of an output from the microphone can introduce background noise and in extreme cases cause distortion and even oscillation or squeal. An added bonus is that the battery in the power microphone will last longer.
Did I miss anything? Comments or Questions? |
Patzerozero
Intermediate Member
Username: Patzerozero
Post Number: 384
Registered: 7-2004
| | Posted on Monday, January 31, 2005 - 12:24 am: |
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GOOD sounding POWER mic=louder then stock mic, still clear and intelligable, doesn't pick up excessive background noise.
grant xl for dx in mobile sounds GOOD with ANY power mic i put on it, though some pick up too much background noise-575 is good if i'm parked, road devil if i'm moving, but 99% of the time-STOCK MIC
delta force sounds best with stock mic, but 575 is louder
icom 735 with heil hm10 with hcx4 is the only thing that sounds any good on it
ar3500 is EXACTLY like grant, they all work, though i use shure 526t or 575 when not going stock
S9 also can use anything, but you do have to turn radio mic gain way down & mic almost to nothing, but it does make a difference.
not in any particular order, but for handhelds, 575, road devil, 104m6, OLD turner road king76, shure HH amplified, superstar dm461 amplified/noise cancelling have all served a useful purpose. now, not to knock 808's praise of the dm452, for $18 it is a very cost effective mic, i just find at any level, and that being with radio down quite a bit and 452 just cracked on a hair or less, it picks up the sound of the air molecules drying out in my shack! even down that low it provides significant amplification, but it amplifies noises i didn't even know were there! my 1st choice for my radio would be the road devil, but i recommend the superstar dm461 for customers on a budget-it seems to provide as much amplification as the 452 and it is noise cancelling, doing a decent job at keeping background noise down.(why doesn't copper carry that one?)
and yes, always, as you said, racer, radios mic gain up, mics level low, and as much as i hate to state this publicly, i do clip my limiters, but put them on a switch for when it's not needed, to use for dx and don't go crazy for a power mic, in fact talked dx today mobile on grant xl & S9, and base on 735, S9 & ar3500-and at no time today did any of my radios have a power mic on 'em! loud is good, compression scatchiness is fun but muffled is #$@%!!! |
Racer X (Unregistered Guest)
Unregistered guest
| | Posted on Monday, January 31, 2005 - 7:30 am: |
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I've got to disagree with you Patzerozero. I've never found that power microphones make you sound louder unless they have built in compression.
Stock mics have plenty of output and can easily fully modulate every radio I've ever used. My limiters are functioning and adjusted properly, so there may be a difference with a clipped limiter, but then turning up the gain makes the radio overmodulate and your voice peaks are lost as splatter on other channels.
The only reason I'd ever use a power microphone is to get a different sound from a different element or to add compression so I sound louder. |
Patzerozero
Intermediate Member
Username: Patzerozero
Post Number: 390
Registered: 7-2004
| | Posted on Monday, January 31, 2005 - 11:46 am: |
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i did say ' but 99% of the time-STOCK MIC' and 'at
no time today did any of my radios have a power mic on 'em!' and my limiters, though clipped, are on a switch so they do operate as intended for local communications, just as the magnum topgun radios sound better up close with the topgun off.
i probably should have been in bed, & not playing here when i typed last nite, but as you can see, i don't really use power mics all that often, though i have a lot of 'em. there is added punch, though, when talking locally thru lots of dx/noise when my son keys the S9 in the base using whatever power mic may be attached to the one side over the stock mic that's also always attached. a power mic is like an optical illusion-to the ears. i really never opened up a dm452 mic, don't know what's in it at all, but when my 12 year old switches between that & stock mic on S9, which is sufficient, his voice is changed from that of a little boy to a much deeper, fuller sound with more punch that makes a difference in ability to hear him thru noise at a distance. and that illusion appears-signal sounds louder to the ear.
hey, racer, youasked for comments, there they are-no problem! the only problem is, nobody knows how to use 'em! clip the limiter, mic gain all the way up and mic level all the way up and you can't understand a word they say, then they blame it on the radio... |
Racer X (Unregistered Guest)
Unregistered guest
| | Posted on Monday, January 31, 2005 - 9:10 pm: |
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On a radio like the S9 which has a speech compressor built in and enabled at all times, a power mic will increase the compression level if the microphone output level is higher than stock - and I would imagine yours is.
I understand from Lon's posts that the DM452 is an electret condenser microphone. Usually they have a fairly even frequency responce, but perhaps this microphone has some equalization built into it as your son's voice sounds deeper on it than than the stock microphone.
My opinion on clipping limiters is that it is always wrong to do so and I have good reasons. It allows the radio to overmodulate and splatter. Unfortunately the peaks of your voice that are lost as splatter to other frequencies happen to be the same portion which has the most detail and is most critical to communication. So in clipping the limiter you lose voice detail and cause splatter on other frequencies. It's a loss-loss.
Let the limiter do it's job and you sound good and don't cause splatter. That's a win-win. |
Patzerozero
Intermediate Member
Username: Patzerozero
Post Number: 395
Registered: 7-2004
| | Posted on Tuesday, February 01, 2005 - 7:12 pm: |
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ah, yes, just like those 5/8 base antenna wars on the other thread...but, that's ok! i have never had my grant xl on a 'scope, and with no power mic, as it operates 99% of the time, with the limiter in line, mic gain on radio fully clockwise, reports from as close as neighbor 200 feet away are crystal clear. with limiter switched out of line, mic gain needs to be backed down to about 2 oclock(from 5 oclock) and his report is that it is 'louder & deeper'. when my mobile is about 1 mile from my house, in clipped condition, to my ear, it appears to me as well,'louder & deeper' with no bleedover up or down 1 channel. dead silence today, no dx, wife in my truck, had son talk to me on xl while i listened on ic735, no power mic on xl, at a distance of approx 15 miles, amp off, clipper in, xl sounded fine, crystal clear, ts dx350 on, signal increased from 3-s units to better then 5 s-units, audio APPEARED to get louder as well, while remaining crystal clear. amp off, clipper out, voice showed more 'swing' on rcv meter, and son's voice sounded deeper, louder and yes, though absolutely understandable the extra deepness was tweaked by moving the notch & rit just a pinch. maybe not broadcast quality, but definitely not 'muffled' or unreadable by any stretch of the imagination. amp on produced the same approx 2 s-unit increase, but swing on rcv was increased even more. apparent loudness was increased, yet readability did not change whatsoever. i know when talking dx, with the limiter switched out, receiving stations have told me 'they hear me better'. nobody, local or dx has ever said my audio is muffled or unreadable in any way, AM or SSB. could it be the 'better' quality of the older uniden style radio, maybe. would the same results appear with a different xl, maybe, maybe not. for that matter, my grant lt, with same mods gets same types of reports, i just use xl-because. would these results appear on ANY other cb, again, maybe, maybe not. like i said, part of the problem is 'not knowing how to use it. sure, crank up the mic gain, crank up the dm452 or 575m6 level all the way, clip the limiter, turn up radio to 6 or 7 watts, amp on high-you ain't understanding a thing!!!
i understand your points-detail, critical and loss. and, like i've said, when it comes to amps, antennas, mics, radios, i don't have a scope, (except for my icom) never used any scope or other type of test equipt to test things, i just go out in the real world & try it. sure, not all responses are from knowledgable folks, but my true tests involve those who want to sound good-not just 'blow everybody off the air'. and another true test is to have my wife or son listen-she has NO desire to talk on radio, so when i make her do it, if there is the least bit of trouble in understanding or hearing what i'm asking her to listen to-she flat out won't do it! what better test could there be then that?
hey, i don't need trouble w/ tvi/rfi w/neighbors, so at base i use restraint, when it comes to mobile, dx & long local distance, i try whatever possible to gain an edge, and have found the clipped limiter to perform better then a power mic. laws of physics may say otherwise-they've used 'em to try to prove a pitcher can't make a curveball bend-but there are exceptions to everything!
ain't AMERICA great! |
Racer X (Unregistered Guest)
Unregistered guest
| | Posted on Wednesday, February 02, 2005 - 1:35 pm: |
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Some folks think that they can tell if someone is overmodulating by listening for a distorted signal. By the time you can hear distortion the level of overmodulation is very high. The fact that the audio pitch changes when you switch out the limiter means that you're overmodulating and that means splatter - whether you hear it or not. The amount varies with the level of overmodulation.
When your voice peaks go over 100% modulation that portion of your audio is lost as additional sidebands on other frequencies. That's why your voice sounds deeper when you switch out your limiter. The peaks of your voice are gone and what's left is bassier and yes - louder. The average modulation level has increased but at the expense of detail.
That's why speech processing is so cool. It compresses or clips your speech so that no detail is lost, but you still have a higher average modulation level. You sound basically the same but just louder. That's why TV commercials are so much louder than programs are. They want to be sure you hear what they say, so they compress the audio levels to the point where everything is the same volume.
Before I even talk on a radio, I put it on my station monitor, feed it a 2 tone signal, and adjust the AMC and ALC . Of the dozens of radios I've adjusted, I've never had one that was even close to 100% from the factory. If your radio has never been on an oscilloscope to have the limiter adjusted for 100% modulation then you are missing out on an an "edge" that you could have. You may even find that you don't bother switching out the limiter because you don't need to anymore. |
Patzerozero
Intermediate Member
Username: Patzerozero
Post Number: 408
Registered: 7-2004
| | Posted on Thursday, February 03, 2005 - 5:41 pm: |
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i'm not done with you yet, racer!
have discussed this with MY tech & am waiting for him to return from skiing, so we may continue this debate!!
:-)(-: |
Chad
Intermediate Member
Username: Chad
Post Number: 131
Registered: 11-2004
| | Posted on Thursday, February 03, 2005 - 9:52 pm: |
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100% is 100% Said and done, the game IS staying at 100% through the line as much as possible. If the radio and processing is up to the task, then it's up to the amp(s), can they handle the duty cycle? Power supply?
Don't go over 100% and you will be clean, sound good, and stay out of trouble.
Chad |
Racer X (Unregistered Guest)
Unregistered guest
| | Posted on Friday, February 11, 2005 - 8:19 pm: |
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Chad - What kind of equipment do you use to keep the modulation high in broadcast applications? From what I've read it's mostly multiband compression. For communications I use RF and AF speech processors and mostly clipping type processors rather than compression.
I like to use my TS450SAT to listen to AM broadcast. It's fun to watch the audio level function on the meter and see just how much the station's audio level is fluxuating. It really varies from station to station. |
Racer_x
Intermediate Member
Username: Racer_x
Post Number: 313
Registered: 2-2005
| | Posted on Wednesday, April 13, 2005 - 6:41 am: |
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Patzerozero - Did your tech ever return from Skiing? |
Patzerozero
Advanced Member
Username: Patzerozero
Post Number: 690
Registered: 7-2004
| | Posted on Saturday, April 16, 2005 - 12:19 pm: |
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uh, yea.
he was down here visiting his mom last weekend but neglected to bring his 'tech stuff' with him.
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Redwolf_145
Junior Member
Username: Redwolf_145
Post Number: 42
Registered: 4-2005
| | Posted on Tuesday, April 19, 2005 - 9:42 pm: |
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Well If it works good Then Don't Touch it... Some People think a radio is trash if it has been clipped... But that is not always the case... had a uniden pro 510xl That was clipped sounded like a Big high dollar radio.... no complaints.... you can overmodulate with out it being clipped... |
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