Audacity Forum

I'm going to really have to study these pictures and stuff, but you rock. I think that this combined with the diagram is probably enough. You've done a buttload of work to help me out, thanks a lot!

So, I'd need one of those boxes (plus all the junk that goes inside, plus the batteries) for each headset, right?

Beyond that, to up the volume I need to pass the signal coming out of the mixer through an amplifier, does that style of amp matter so long as it amplifies noise?

<<<You've done a buttload of work to help me out, thanks a lot!>>>

Not as much as you think. I already have this stuff in boxes from other jobs. You hit something I do. Underneath the brown butcher paper is a Whirlpool washing machine.

<<<So, I'd need one of those boxes (plus all the junk that goes inside, plus the batteries) for each headset, right? >>>

I'm afraid so. In electronic phraseology, the system on the headset side is "wet" or has battery supply on it and the system on the mixer side is "dry" because it only has sound on the wires. No battery.

I once made a very much larger box with small flashlight AA batteries in it to do the same job. And it did do the same job, except I expect it to last a couple of years without turning it off.

<<<to up the volume I need to pass the signal coming out of the mixer through an amplifier>>>

Not quite that easy. The order in this list is not accidental.

-- Noise canceling microphone
-- Battery for the microphone
-- Microphone amplifier
-- Sound mixer
-- Connection to the computer for recording.

Your mixer has electrical sound noise associated with it. It says so in the instructions. The noise is not that much lower than the signal coming from the microphones, so with everything running, I expect you will have a ffffffffffff gentle rain on trees noise in the background of the show that you can't get rid of.

So boosting the microphone level (I can't emphasize how tiny and delicate it is -- 0.001 volts) in a special, quiet microphone amplifier almost always happens first. Then mixing. Books are written about how to make a MicPre, microphone preamplifier.

You can try it with one channel and see what happens. It may be enough for you to go with. You might be able to adapt the output of the mixer directly to the Mic-In of your PC. This is where it gets fuzzy. How much noise and how much amplification and the volume of the headsets all play a part.

It might work OK if everybody talks really loud.

Koz

Radio Shack used to make a cheap four channel microphone mixer. Part number 32-1106. They still offer the instruction book.

That's all it did. It didn't have meters and it had very minimal electronics inside. I believe it delivered the show at microphone level, so you had to follow it with a "real" Microphone Amplifier for it to be useful.

But it was designed to do that, and it wasn't noisy.

We used it for a cousin job to yours. The projection booth operator had to be able to hear comments by the people in the theater, so we had eight microphones (two mixers) spread around between the seats. It worked remarkably well. You were always close enough to one microphone to be picked up.

Koz

Ok, since I'm completely ignorant in all this junk, the circuits look like something I coud do but it seems like a potentially more effecient use of my time and money to just buy a mixer with a preamp built in, yes? Am I looking for phantom power to supply power to the headsets or is there something else I need to be aware of to get power to these things? Is this basically what the question started with before all your help? It looks like via http://www.epanorama.net/circuits/micamp.html that I'd be looking to spend about 60 bucks on just the preamp once I get everything together for multiple headsets assuming I attempted to build it myself, and that's not accounting the learning curve and some mistakes.

So confused, ovewhelmed and appreciative for your help...

edit- relooking at all this junk, I think I'm screwed, even with phantom power? I really don't understand what phantom power is... Basically, what I'm thinking is that the headsets aren't going to be an option?

double edit- Assuming phantom power is my major issue, would something like http://www.amazon.com/Behringer-1202FX- ... 302&sr=1-3 work for me, while I realize that it doesn't have enough mic inputs? Is splitting one or two of those inputs a bad idea, or does it not transfer the power to the mics?

<<<Phantom Power>>>

That's good. You're catching on. Commercial, Theatrical, Phantom Power is a remote cousin (on his father's side) to what you're doing. They have exactly the same problem you do. Some top end microphones have electronics inside and need power to run.

http://kozco.com/tech/audacity/wynonna2.jpg

There are a couple of differences. The grownups use a special three conductor microphone cable (the one on the left)...

http://kozco.com/tech/audacity/UnbalBalAdapter.jpg

... They can run that cable (carefully) hundreds of feet, and their phantom power is 48 volts, not 5. It's called Phantom Power because it runs on normal, every day studio microphone cables and it's difficult to detect how it works.


To recap, you have one good, well designed, computer communications headset designed to plug directly into one Windows PC, but you want to use six or eight of them at the same time into one computer. You have a noisy environment, so the communications headsets are completely correct in this application.

I don't know a simpler way to do that than the picture with the mixer I posted (they make larger ones) and with the homemade electronics. I'll find the larger one I built with the flashlight batteries and take a picture. That one is a lot easier to see what I did.

If you can find a dead quiet room, you can use a much simpler USB microphone in the middle of the table and go with that. Much easier. Most of this craziness is designed to overcome a crappy environment.

Your headsets are low-end, too, by the way. They make noise canceling headsets for the military and airplanes. They're a lot more expensive and hard to install.

I keep wanting someone to post and argue with me. "Oh, they make that in a simple $49 USD package from Sweetwater Sound. Nobody yet.

Koz

kozikowski wrote:I keep wanting someone to post and argue with me. "Oh, they make that in a simple $49 USD package from Sweetwater Sound. Nobody yet.

They make cheap dynamic (don't require phantom power) headset microphones: http://www.audiomate.co.uk/proddetail.php?prod=A090AH
Probably sound rubbish, but at that price could be worth buying one to see if it is good enough for the job in hand.

As they do not require power, it removes the need for the 8 little power supply boxes.

<<<Probably sound rubbish, but at that price could be worth buying one to see if it is good enough for the job in hand.>>>

And being a dynamic type of microphone, has to be larger and heavier to accommodate the magnets and diaphragm.

<<<As they do not require power, it removes the need for the 8 little power supply boxes.>>>

But not everything else. You still need the adapter to get the microphone into the mixer and the USB device to get the mixer into the computer -- assuming you didn't buy the mixer with the built-in USB, with which I have no experience.

Or plug the mixer directly -- as-is -- into a Mac or large deskside PC. It's the Windows laptop that kills you here. Did we ever establish whether your laptop has a High-Level, Stereo, Line-In? Some do. That's one adapter you don't have to buy.

Koz

I thought aighead said he already had a mixer and adaptors - though I don't know if it's suitable for microphones or requires a higher level signal.
If he can get the computer recording from the mixer that he has, using a dynamic microphone (any old dynamic microphone), then there's a very good chance that these dynamic headsets will work (though in this price range you certainly won't get anything like "studio quality").

The mixer is high-level only. It has a noise spec somewhere in the -80/-90 dB, which is nice for high level, but gives you a composite performance noise floor of-20 dB if you start with a microphone. Serious FFFFFFFFFF!

That's why I posted that a simple one channel of this should be tried just as it is. It may be good enough.

Koz

steve, I may have to look into those, I've already got the mixer and adapters like it's going out style. As far as the noise I don't think it's too bad with a dynamic mic, but I'll certainly try another test. I've never bought anything from outside the country, so we'll see how that goes... Thanks for the link!

I'm not sure what a "high-level" input is, but I'm certain I have the standard line-in and mic ins.

As far as the noise is concerned, I'm rocking a 7 dollar microphone for the room now, so fidelity isn't a huge concern to me. Ideally it wouldn't be terribly noisy, but I understand my budget doesn't allow for anything great (or even good).

Once I get my junk together I'll post some examples...

I'll also have to read over the past couple posts to learn and figure out what you guys are talking about.

Thanks some more!