Novice has question about microphone.

[Alex Ethridge]

Although I have soldered some very basic circuits together in the past, I am not an electronics hobbyist and know just some about the subject.

I have a digital video camera and want to rig some kind or wireless FM microphone that will be received by a pocket FM radio patched into the digital video camera's mic input. I am concerned about the qualities of the mic element.

Most of the little ready-built circuits (Example Here) use an electret mic.

Should I change the mic to get better sound pick-up? The mic may be up to three or four feet from the subject(s) at times.

Also, do these mics produce reasonably good sound quality? I don't want my subjects to sound tinny.

Side Note: I realize the receiver sensitivity and discretion is very important so I did a little (internet) research. I ordered the Sony SRF-S84 receiver as it is touted to be about the best receiver available in its size.

 

[audioguru2]

Alex,
If the receiver doesn't have a mic-level output, then it will need an attenuator, unless your camera has a line-level input.
The Sony receiver is probably digital, so it will probably be very fussy about receiving a signal that must be EXACTLY on-frequency, like a radio station. That, and other reasons below, are why I recommend using a Sony-matching transmitter. Use a uni-directional cardioid microphone element to reduce background noise and echos.

Cheap Transmitters:
1) Although a cheap electret mic element is quite good, it is usually omni-directional and picks-up background noise and echos.
2) An analog transmitter is difficult to tune to an exact frequency, such as 99.9MHz. It might actually be tuned to 99.85 or drift to there (that would be very low drift), then a digital receiver may mute. One moment it works, the next it doesn't.
3) The circuit may cause a tinny sound because it cuts low-frequencies so that customers don't complain about air-conditioning rumble pick-up.
4) The circuit probably does not have high-frequency pre-emphasis, as required for radio stations. So its received sound will be muffled.
5) The circuit probably has high distortion, which is masked by its narrow bandwidth.
You get what you pay for.

 

[audioguru2]

Most of my comments about cheap transmitters apply to all of the FM transmitters in our Projects Section.
I will say no more.

 

[Alex Ethridge]

Thanks for your comments; for someone on my level of understanding, they are very educational.

Thinking out loud:

What I am trying to do is solve the problem of being sometimes 10 feet (more or less) away from my subject in an area with ambient noise of a party of family gathering and my subjects sounding like the background instead of the subjects they are. Since all this stuff is already here or on the way, I will test its performance.

It is difficult for me to understand fully what you write; but, I do get the broader parts of the meaning. I know I do get what I pay for; but, the problem I have run into has been that the remote mics I have been able to find that are intended for this purpose have been offered to me locally for between 500- and $650. This is outside my budget totally. When I started this project, I thought I would surely be able to find an out-of-the-box solution for about $150.

The mic I referenced in my example above is analog, as you know, and the receiver is a Sony SRF-S83, also analog. I chose this receiver because it is known for its sensitivity and selectivity. I also got an SRF-59 as a backup. I just couldn't afford another S83 at $65 and the 59 was only $25 and the tuner is almost as good.

I do have an attenuator cable I got from Radio Shack.

I will look into changing the mic element and I will test what I have here for sound quality. If it puts my subjects into the (sound) foreground, that will at least be one accomplishment.

Just a thought: I wonder whether the built in mic on my $700 Panasonic DV camera is any better?

 

[audioguru2]

Alex,
For long-range pickup that reduces background noise, consider a "shotgun" microphone. It is longer than a conventional mic and must be aimed at your subject, but may solve your problem very well.
A not too expensive but high quality brand is Audio-Technica. They specialize in mics and wireless-mic systems. Their ATR55 shotgun mic is recommended, and even has a "normal" or "long-range" switch. The Audio-Technica web-site has a wealth of information for you and is here:
http://www.audio-technica.com/index2.html
Perhaps a local dealer will give you a tryout.

If you use your camera's mic then it may pick-up zoom-motor sound and handling noises. With a short cord to a tripod-mounted shotgun mic, then maybe the wireless can be eliminated.

 

[Alex Ethridge]

Wireless is a must.

There are too many people moving around at these family gatherings, including the photographer (usually me). One rather important event, my parents' 50th wedding anniversary (June 19), there will be upwards of 100 people, a dance floor, a band and too much excitement for any wires.

I looked at the Audio-Technica site and searched all over for prices. I guess its one of those places that if you're the kind of person who needs to know the price, there's no need for you to ask.

I guess I've seen so much cheap junk labeled "shotgun" that I am rather cynical about the capabilities. It's hard to imagine anything in my budget that could fit on top of a DV cam and really squelch the indiscreet loudmouth standing at my shoulder.

However, if I could get one that truly had that capability, it would be even more desirable than a wireless mic. It would put the sound pick-up whereever the camera was pointed.

 

[audioguru2]

Alex,
I did a quick search on Google and found a link that sells the quality ATR55 shotgun mic for only US$46. The link is here:
http://www.atr55.com/
That is only the first link on Google. Also try a Froogle search. A local dealer probably won't come close.
It certainly will pickup in the direction that the camera is pointing, but I haven't tried one with a loudmouth beside it. Will you try it?

 

[Alex Ethridge]

You don't know how much I appreciate your help. I am in an area here where I have absolutely no idea what is good and what is not and how much good 'stuff' ought to cost. At $46, this is certainly within my price range. (Now, if I can only get back the money I spent playing around with things I didn't know enough about.)

It isn't really as bad as I made it sound about the loudmouth. It is just that at my family gatherings, people tend to enjoy themselves and each other. They certainly aren't boring, sedate gatherings.

I'm going to do some more research on that mic. I certainly want it mounted on top of the camera and I wonder what its physical lenght is. I also wonder if the one that Panasonic makes is just as good. It is actually made for mounting on top of my camera and is only about two-and-a-half inches long.

It would be nice if a mic two-and-a-half inches long would do as well.

Anyway, you've given me some good things to think about and research.

 

[audioguru2]

Alex,
Due to quite long audio wavelengths, the longer a shotgun mic is, the better it is. I don't think that a 2 1/2 inch mic is any good. The Audio-Technica shotgun mics are 6 to 14 inches long. Good-luck with its mounting to your camera.

 

[Alex Ethridge]

I have been browsing and found this mic . It has a definite advantage in that it fits nicely atop a DVCam. On the down side, it is twice the price of the ATR55, and it might not be quite as directional.

The ATR, however, has a bad point, too: A mic that long is obtrusive.

If I get the ATR, I will save money on the front end and will probably have a better-performing directional mic. If I get the Sony, it will fit atop the DVCam nicely; but, its directional performance is unknown at this time.

I can't find anything as yet where mics like these are evaluated. At present, I am leaning toward the ATR. I think I will make an inquiry as to its actual physical length.

Reasoning out loud:
ATR is in the mic business and is likely to have a better-performing microphone. Sony, on the other hand, although they do produce good products, will cut costs by using cheaper electronic components than their designers intend. Case in point here where it is apparent the designers intended larger capacitors in this radio circuit and Sony cut the size, probably to save money.

 

[audioguru2]

Alex,
1) Thanks for the great link about modifying radios. I like to modify and improve electronic items too.
In your voice application, the music modifications won't apply.
They talked about changing the de-emphasis capacitors: European radio stations use a different de-emphasis than North American stations (its a long story that I'll tell in another post). When you buy a radio then it won't sound right if it was made for the other market. But how can you tell? By listening to it. The high frequencies will sound too bright or dull if it is wrong. I'm still using a 14-year old SRF-29 at the beach, and I haven't even looked inside.
2) The Sony mic is only 1 1/2 inches long. Maybe they use a folded waveguide inside to make its acousical length longer. I dunno about it. Its mounting method would be a real convenience for you.

 

[Alex Ethridge]

I found this 900-MHz wireless mic last night. I don't know why it didn't come up in earlier searches.

Here's another link on modifying radios. This is the SRF-59. It is currently available and is under 20 USD. The S83 is now out of production and the replacement, the S84, is $60. The author of these articles says these radios are very close in sound quality, espacially after mods. This is nice since one can be had for so much less.

The purpose for choosing one of these radios was for their supposed duscreet and sensitive tuners.

 

[audioguru2]

Alex,
Be wary of 900MHz since it might pickup interference from all your neighbours' cordless phones, unless they've gone to 2.4GHZ and beyond.
I don't like lavalier mics because they make it sound like the user (or TV announcer/reporter) is talking through a heavy blanket (or actually a turtle-neck sweater). Have you ever heard an underwater throat mic? Vowels only, that they somehow say is speech. A lavalier is similar.

 

[Alex Ethridge]

The 900-MHz Sony Wireless (WCS-999) has three channels and an earphone that allows the user to hear what is actually being received. So, interference from neighbors' phones is something they have prepared for.

After reading this evaluation from a real user like myself, I have decided that a shotgun mic might be effective is situations where there are no reflective walls floors and ceilings--like outdoors, for instance. (See the section headed "Mic Testing by Stefan G. Berg ".) However, my usage will be mostly indoors.

At this point, it looks like I will need more than one mic, one shotgun for doing outdoor events like my grandkids playing soccer and baseball, the outdoor event of my parent's 50th and then another wireless for when I want the subject to sound like he/she is in intimate presence of the mic.

I'm still liable to vascillate at this point; but, it looks like I may get both the Sony WCS-999 wireless and the ATR55 you suggested.

You may be thinking I am not going strictly as you have attempted to move me; but, if you are thinking that, you certainly don't know how much help you have been. You have enlightened me issues I had absolutely no awareness of before. For someone who didn't know any more than I did when I started this thread, I sure have gotten an education from you.

 

[Alex Ethridge]

Just Musing:

Considering the fact that video cameras make pictures of only what is in front of them, I wonder what the logic is for an omnidirectional mic, especially in this day of advanced technology.