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I need an inexpensive microphone capable of clearly picking up speech etc from several metres away. Have tried various makes and models without success

You need a condensor mike, I've seen them as low as $99

Thanks but little help have tried several including one recommended by shure specialist everything further than about 1 foot is muffled and the gain needed causes terrible feed back

If it's for one specific speaker, you can get a shot gun mic, of which there are several manufaturers, off the top of my head Sennhieser makes a couple of them....if it's for a room full of people, say a conference table with a bunch of people, either an omni condenser in the middle or individual mics in and array around the table.....

Rob

Ooops! None of those options are cheap!

[This message has been edited by RJC (edited 11-27-2006).]

Thanks. it is for a small stage with several people speaking.I have tried specialised mics eg shure easiflex and boundary mics but these expensive babies are almost useless an sm58 does the same job at a fraction of the price. the mics are hung from ceiling above the actors but can be several feet away as actors move around. Cannot afford individual radio lapels or cheek-mics etc. someone suggested adapting an old fashioned crystal mic of the type used for very old tape recorders any comments...

You may have to use two Mics with a mixer. If possible you could make your own collectors from construction paper and make cones that collect the sound and place them around the mics pointed in the direction of the actors. Dynamic mics such as the Shure SM 58 should work fine. Some testing may be required. If the stage is not too large one mic may do it.

Thanks again The system you suggest is what I use at the moment. The cone suggestion is interesting though will give it a go

Condenser shotgun mic. They are made for the application you describe. Don't look at music stores. Go to web sites that sell video and film equipment.

Thanks Just one question how can this type of mic be amplified through PA system?

Shotgun mics are just condenser mics with elongaged bodies and notches on them to reduce sounds coming in from the side. Audio Technica makes a whole series of them.

They use regular xlr mic cables that plug into a PA system. You will most likely need phantom power on the mixing board - which is pretty common nowdays.



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Larry
www.audibleresponse.com

Thanks a lot. I have tried such mics but with little success they all claim to do the job but don't. This silly little am dram thing is starting to nip my brain there does not seem to be a decent inexpensive mic designed to pick up general noise at anything further than a couple feet end of story. Just as a PS AND TALKING POINT for live band work I prefer Audia Technica to Shure but that is just my personal preference I have several in my mic case and have coverted the band to using them. I also carry one SM58 just in case the (stubborn)guitarist loses or breaks his he prefers shure but that is guitarists for you.

I'm not sure I understand what is going on. I've been mulling this over for a bit, when I happen to think about it. There is no reason a condenser mic won't do what you need it to do, as I understand your needs. You may be overdriving the input gain and it seems as though you need to "ring out" the system.
An omni would certainly funtion well in picking up all the cast members/speakers from where ever they are on the stage. Obvioulsy you'll need the FOH loudspeakers out front, not beside or behind the stage.
My large diaphragm mics will pick up vocalizations from anywhere in the room, an upper floor loft, and even downstairs in my living room. Those mics are Uni directional mics, not omnis.
It seems to me you have other issues than microphones that need to be cleared up first.

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Miltenberger Homes

"That ol' dog's so mean, he ain't done nothin' but eat nails and [naughty word removed] nickels ever since he was born"

Big Jim,

I don't mean to be a wet blanket, but there is a great deal of misinformation in the advice and comments that you have received.

Not to discourage the use of good microphones, but even the best microphones, as you have found, will fail if the whole system design is not considered.

Your problem is that you need more acoustic gain from your sound system, than is available given relative distances between microphone, source, audience, and loudspeaker.

Assuming that there are no major malfunctions in your sound system, like blown high frequency drivers, you are running into the brick wall of the "laws of physics".

A great tutorial on what is happening, and how to conquer it is at the following web page:

http://hyperphysics.phy-astr.gsu.edu/hbase/audio/pag.html

Your choices are:

1) Move the microphone(s) close to the source (wireless lavs are a great help)
2) while keeping the number of open (utilized) microphones to an absolute minimum. (live mixing)
3) Move the speakers further from the microphones
4) Move the audience closer to the speakers

Welcome to sound system design 101. Even the very best microphone
will fail, if your sound system isn't properly configured.

Careful equalization will help you optimize a well configured system, but won't let you cheat the physics. Use the web link I provided to get a grip on the problem. It will provide a graphic explantion of the problem and help you find a solution.

Post back here to let us know if it helps.

JP

Noiseboy,

Specifically what was the "great deal of misinformation"? Can you quote it? Your tone is very condescending for someone with seven posts. You don't know your audience here.

I seen no misinformation. The best solution may not have been found yet, and all the factors may not have been considered, but that's a different story from misinformation.

I don't agree that the problem is is simply a lack of acoustic gain. You can't make the actors scream to improve the acoustic gain. The problem is gain-to-feedback; isolating the performer's voices while providing enough system gain before you get the squeals and resonances. I do see your other points as well - especially points 2-4. Those certainly should be checked.

The ideal solution would be for the performers to wear wireless lav mics. That would end it for the most part. However, he said he can't afford that. Alternatively, shotgun mics give the best front-to-side noise cancellation and the best gain-to-feedback ratio.

One thing that hasn't been mentioned is the proper use of EQ and the placement of the speakers themselves. I hope Big Jim has considered these basic solutions. Most "house" speaker systems are designed to have a very wide dispersion angle which can make it difficult to get enough gain before feedback. Simply angling the speakers a little differently, or throwing up some acoustic dampening material in specific spots can help a lot as well.

If the system is EQ'ed properly, you'll also be able to get a lot more gain before feedback. If you can, see if you can borrow an RTA (Real Time Analyzer) to get a feel for the frequency response of the room in different spots.

Are there always specific frequencies that feedback before others? With a decent parametric EQ, you can minimize them even if you don't have access to an RTA.

I didn't intend to come off as condescending, I apologize if I did. In re-reading the thread, Big Jim did not really define the parameters of the problem until fourth message.

With regard to specific misinformation:

"You need a condensor mic". -Jim tried a few condensor mics. They didn't solve his problem.

"... make your own collectors from construction paper and make cones that collect the sound and place them around the mics"- This would have modified the frequency and polar response of the microphone in a destructive, rather than constructive manner.

" There is no reason a condenser mic won't do what you need it to do, as I understand your needs. You may be overdriving the input gain and it seems as though you need to "ring out" the system...It seems to me you have other issues than microphones that need to be cleared up first."

-Nothing in Big Jim's thread indicated that he was overdriving the input. The idea of "ringing out" the system is more on track, assuming that Big Jim is familiar with the term, and the practise of forcing a system into feedback for the purpose of identifying points of instability so that they can be addressed with an equalizer. I believe that Dark Lander was spot on at the end, as this is not specifically a "microphone only" problem.

Larry, you wrote:

" I don't agree that the problem is is simply a lack of acoustic gain. .. The problem is gain-to-feedback; isolating the performer's voices while providing enough system gain before you get the squeals and resonances."

This is a textbook example of the lack of acoustic gain. Here's why:

Acoustic gain describes the difference in sound level, at the listeners ears, with the system "on" compared to 'off".

Potential Acoustic Gain (PAG) is the practical maximum of acoustic gain that is achievable given the relative distances between the source and last row of seats, source and microphone, microphone and speaker, speaker and furthest audence member. It doesn't account for highly directional microphones or loudspeakers, or the number of open microphones (NOM) greater than 1. Worst case is an omni directional speaker and microphone.

I am sure that we agree that Big Jim's goal is to ensure that every every audience member can hear the actors, as if they were sitting close to the performance. So one (very important) goal of the for sound system is to supply the audience with sound level that relates to what they would hear if they were sitting at "X" distance from the stage.

If the room is quiet (and note that we are assuming this is an absorptive room with little reverberation then probably don't need too close to the source, assuming that they are speaking at a reasonable level. If the room is noisy, then we need to sit close to source so that we can hear them above the ambient noise.

The reference distance that we want to mimic for the furthest audience member is defined as Equivalent Acoustic Distance (EAD). It is a log function of source level at a reference distance, to the ambient noise level + 25dB. In a noisy room, EAD could be 2'. In a quiet room it could be 8' or 12'.

Once we know the EAD, we can determine the gain the required to provide this level at the listener, with the Needed Acoustic Gain (NAG) equation. This takes into account the distance to the furthest listener divided by the EAD, and converts this to a decibel reference with a log function. The higher the number, the greater the needed acoustic gain. If you want your sound system to function without worrying about feedback, your PAG needs to be greated than NAG, and most people calculate with an extra margin for stability, so that PAG-6dB => NAG.

With regard to the role of equalization, yes it is can be helpful in taming the frequency of a system. It can't fix a system that is dysfunctional where PAG < NAG.

RTA's are useful devices for ear training, and locating feedback. They are marginally useful for system equalization.

Larry, I realize that I have a limited posting history. My intent was to help Big Jim get to the root of his problem, and avoid throwing time or money into equipment that won't get him any closer to solving his problem.

Here are a few more useful links to some background on this issue:

http://proav.pubdyn.com/2006September/2006SeptemberSoundInsight.htm

http://shure.custhelp.com/cgi-bin/shure.cfg/php/enduser/std_adp.php?p_faqid=71

http://preview.tinyurl.com/yc4nj9 (to a Shure PDF on calculating acoustic gain)

Hi again, Noiseboy,

Well...we probably just got off to a rocky start. Written words don't convey the subtleties of speech, and I probably over-reacted a bit myself...my apologies as well.

There is certainly a lot of useful information in the links you provide above. They're well worth reading.

I believe we're really on the same page, but sometimes technical people will disagree on a term's usage within the context and that can throw things off. The main definition that wasn't clear is that of "acoustic gain". I was using the term as simply the output of the source (how loud are they talking); whereas you are using it not only as the source output level, but include the destination output level (speaker output) as well.

The toughest part of any of these recommendations is that there is a very limited budget for Big Jim to resolve these. Obviously, sinking some serious money into an acoustic analysis of the room and/or replacing some or all of the equipment, adding acoustical treatment, etc. would get the best result.

Let's see if we can agree on the following low-cost options:

1. In lieu of lav or headset mics, a directional (condenser) mic will do the job better than any other type of mic.
2. Adjust the speaker cabinet to point more directly at the audience and away from the mics - or just move them further from the mics.
3. Adjusting the frequency response via EQ will improve intelligibility (and sound more natural) and result in less gain required.
4. Finding the most prominent frequencies either by ringing the system out or by using an RTA and reducing them with narrowband EQ will increase the gain before feedback.
5. If there are inexpensive ways, such as adding curtains to the stage area, to reduce reflections there, that will also allow higher gain and improve intelligibility.
6. Anything that can be done to the room itself that would reduce reflectivity would also help, although this would probably not be an inexpensive solution (adding bass traps or broadband absorbers, for instance). I have seen improvements to houses of worship acoustics where beautiful quilts have been donated and hung on the walls. It's not ideal, but it's better than nothing.

There are always more expensive options; one of which would be to distribute the sound more with additional speaker cabinets (getting the speakers closer to the audience). Each cabinet would then have to produce less output to provide full coverage. In inexpensive systems, I've seen this done without delay lines, but it is preferable to add delays to successive speaker cabinets as they get further from the stage. There are calculations to determine the delay, but I don't think we need to get into the math here.

If there are additional no or low-cost options that I've omitted, please let me know.

Actually it would modify the response of the mic in a non-manufacturer-intended way, and is, as you stated in an earlier post, a simple matter of the "laws of physics" - or more directly to the point, audio physics. Ever been to a football game? Or seen one on TV? Maybe you've seen the funny looking guy with headphones and a quarter-domed sheet of plastic pointing it at the field. That's a highly directional cannon mic setup. Used to gather sound from the players on the field - but in a larger area than say a highly directional shotgun mic.

So this would achieve a similar concept in theory. Would it be practical in this situation? One wouldn't know until they tried it in this setup.



Noiseboy, now it's become a post of who can spew schooling better. Part of the problem here is that the original post didn't do a good job of explaining the issue - I think we can all agree on that. The second problem is that they're attempting to get broadway quality of sound with a backyard setup. We can also agree it isn't going to happen without some thought and possibly some money being put into the equation.

There have been numerous examples throughout audio history where a product was not used as designed and intended - yet yielded pleasing results. So while we can appreciate the schooled answer, that's not always real world reality. One must learn to operate on their feet in a live situation - without the rulebook sometimes. Larry's response that you quoted is very valid. Something in the construction of the room could toss your school information out the window if there is a feedback-causing frequency in that room, and thus gain to feedback threshold becomes useful knowledge based on the setup being used.

As for Big Jim's needs, well, we don't know the room, stage, mixer, speakers, mic(s), size, composition, number of actors, number of audience members, etc... So it's not an easy to answer question based on lack of needed information. With that said, I'm overly surprized that no one here has mentioned one of the oldest and cheapest mic's to use, the radio shack PZM. Those big flat square mics that you plant on a wall to pick up sound in a room. Not overly expensive, and can take a ton of gain before they feedback. The only thing is that you'd likely need two, one on each side of the stage about mouth level. And the fact that you'd pick up stuff you didn't intend, though there's no way around that without money and a top notch setup.

To be fair, Larry is a knowledgable producer, and a forum moderator here.

Jody

What I mean by overdriving the input gain is that channel's gain control on the mixer that's being used may well be turned to 11, understanding that with the exact same sound level going into the mic, that gain control can and will often be turned up to a point of feedback.
To me it made perfect sense.
I also mentioned, in my next sentence, loudspeaker placement, which very often, as you well know, is a prime enabler of feedback, as is mic placement in relation to said loudspeakers.


Very simply and....
In keeping with Big Jim's needs to keep spending to a minimum I would suggest that "ringing out" the system is the key as offending frequencies could well be cut and enable him to gain the volume he needs while not spending prodigeous amounts of money having the venue tuned. Too often one must do with what one has, run what you brung, so to speak. Cutting those offending frequencies is the most economical means of attain his goals, as I understood them.

In any given venue, not designed with acoustics and live sound in mind, the key is to tune what gear you have to suit the room and get the best gain before feedback that can be attained so one can get the best sound they can with the existing equipment and room.

That's my story and I'm sticking to it.

Hi Larry,

Thanks for the thoughtful response. I am glad that you found the links informative.

Though much of what we do with sound has an artistic bent to it, it is important that the casual practitioners understand that there are rules to the game.

I agree that we have to use common terminology, which is why I try to stick with the text book definitions.

This exercise should be fairly straightforward if Big Jim can fill in the blanks with some additional information, like room dimensions, speaker type(s) and location(s), and working distances.





I don't take any great exception to anything on your list, however no single item will solve this unless PAG is very close to NAG.

Using high pass filter(s) will help if the system is on the edge of stability, because the low end will often trigger feedback first, due to the lack of low frequency directivity in many speaker configuraions.



If headworn mics are absolutely out of the question, then I agree that this is the next best option, assuming he has access to additional speakers. I also agree that additional zones of speakers should be delayed.

Regards,

JP

You have described a parabolic microphone. A useful device on a football field, or for recording the sounds of nature, but impractical for theatrical sound reinforcement. Placing a microphone in a construction paper cone, of indeterminate size and shape, does not create a parabolic microphone.



Jody, this isn't about "who can spew schooling better", but about explaining the root cause of the problem, and describing potential remedies.



We can leave the rulebook at home, as long as we accept that it doesn't invalidate the rules.



The "school theory" describes the limitations in the real world. Could there be an even worse case scenario? Sure, put stage or the audience in a round, reflective room, covered by a reflective dome, but acoustic gain would be the least of your problems.



I am very familiar with the PZM. It wasn't on my list of recommendations for sound reinforcement because of its wide pickup pattern. In my experience, it would be more likely worsen the gain situation, than to improve it.



I am not questioning Larry's credentials, and appreciate his willingness to continue a dialogue. I aprreciate yours as well.

JP

Dak, the term "overdriving" is commonly used to describe waveform clipping as the result of overload of an input stage. Your usage didn't make any sense to me. Thanks for explaining what you meant.



And I believe that I agreed with that mention.



The problem is that cutting the offending frequencies doesn't fix poor speaker or microphone placement, inadequate coverage, or bad acoustics.



Sometimes what you have will get you there, and sometimes it just wont cut the mustard. The trick is to recognize when it won't, so that you can find a a way to acquire what you really need to pull the job off.

Regards,

JP

Yup, I'm not disputing things, merely entertaining options. Whereas your responses tend to suggest that you're not. I can appreciate that. Just be open to suggestions.

The reality is, there's no way to give apropriate advice in the situation without knowing the things I mentioned before.

I prefer paying for the necessary gear for a situation. I'm betting you do to. However, there are lots of people out there who don't or won't.

Jody

Too true but when you have no other alternative because you can do nothing with the acoustics you have to do something, and using EQ to help control things does get you by, at times.
Is it the perfect solution?
Of course not but then, the real world is not perfect either.

Don't forget the original premise, at least the way I understand it, little to no money to spend.