Is there such a thing as wireless drum mics?

[yoohoo]

Any help constitutes thanks!

 

[dgatwood]

Well, if you mic entirely with dynamics, you can pretty much turn any of them into wireless by adding a transmitter. IIRC, there are various such devices ranging from 1/4" jack versions for guitars and stuff to an XLR "tube extender" type that snaps on to the end of the mic.

Note, however, that it won't work with condensers unless your condensers have a built-in battery power option. (In other words, they can't provide phantom power, for obvious reasons.)

Why?

 

[kid klash]

I'm guessing that the answer is no. A drum produces a HUGE dynamic spike at the front of the envelope, and I can't imagine a wireless transmitter running on a 9v battery being capable of capturing that type of signal real time without adding lots of compression or distortion (or both).

Nifty idea though...

 

[dgatwood]

I'm guessing that the answer is no. A drum produces a HUGE dynamic spike at the front of the envelope, and I can't imagine a wireless transmitter running on a 9v battery being capable of capturing that type of signal real time without adding lots of compression or distortion (or both).

Don't know why not. Analog electronics only care about the peak-to-peak voltage, not the through-the-air dynamics. Standard mic calibration is 1V = 0dB at 1 Pa. Most mics won't come even remotely close to 0dB sensitivity without massive distortion (as in the mic no longer functions afterwards). Most dynamic mics are in fractions of a millivolt (mV). An SM58, for example, has an open circuit voltage rating of 0.19mV.

If a wireless transmitter running with a 9V supply voltage can't broadcast a 0.19mVpp input signal, either the circuit wasn't designed properly or it has way too high a gain setting in some built-in preamp (which can probably be fixed by cracking the transmitter or receiver open and trimming a pot). Either way, smack the design engineer with a clue bat.

About the only thing problematic might be that you'd want the transmitted level to be as hot as possible to maximize the SNR. That's where you could get bitten pretty hard. If the transmitter's input amplifier is cranked up for good SNR for vocals, all of a sudden you have to pad it before the transmitter because otherwise your transmission bandwidth will exceed the bandwidth of the receiver (and possibly the transmitter, if it is designed correctly, but I wouldn't count on it...) and you'll either be breaking all sorts of FCC regulations or the receiver will have a hard time finding the center frequency (or simply start losing the signal as the frequency range goes beyond the limits) and all hell breaks loose.

I am, of course, assuming FM here. AM is a different ball of wax, and you can get away with a lot more, really, assuming there's enough headroom in the analog electronics.... And digital (PCM) fm, CDMA/TDMA, other such tricks... that changes everything entirely.

That said, regardless of the modulation/encoding, the worst case is that you have to put in a pad between the mic and the transmitter to work around some overzealous engineer setting too high a gain on the transmitter's input stage.

 

[PhilGood]

I can't remember the last time I strapped my drums on and ran around the stage like Eddie Van Halen! Oh, wait!! There was that unexplained reason for that hernia operation...

 

[DJL]

Any help constitutes thanks!

I'm guessing you're miking up live drums on stage... maybe you're even a soundman who has too mike up two or three drum kits per show?

Anyway... not really, or at least not that I know of... but I like dgatwood's idea... although channel freq's might or could be a problem for a live soundman unless they were switchable.

 

[xstatic]

Sounds like a disater waiting to happen to me, but there is no reason you couldn't do it

 

[boingoman]

Totally possible, but more of a PITA than it's worth, I bet. I just read about some theater show where part of the show was a street-style drumkit made of plastic buckets, and they went wireless with it.

As far as level, goes, no problem. Like dgatwood said, proper set-up should take care of that. Clip-on horn mics are regularly subjected to very high levels, with some pretty hot spikes.

It would be very expensive, though. A rack of say six acceptable wireless is gonna be spendy.

And a couple things about wireless. They like, as much as possible, to "see" their receivers. And they are very sensitive to reflections off flat metal surfaces (like cymbals). These reflections can drastically reduce signal strength. I would think a bunch of wireless tucked into a drumkit would be pretty hard to manage.
I've been in places where a heating duct many feet above the stage has made a singer's wireless drop out.
There are powered antennas available, but again, that will get expensive and hard to set up very quickly.

You are thinking, though. That's always good.

 

[dgatwood]

And a couple things about wireless. They like, as much as possible, to "see" their receivers. And they are very sensitive to reflections off flat metal surfaces (like cymbals). These reflections can drastically reduce signal strength. I would think a bunch of wireless tucked into a drumkit would be pretty hard to manage.

Ooh, shiny!

The nice thing is the drums aren't likely to move much, so once you've gotten the mics placed, you can move your antennas (you do have a diversity receiver, right?) around until things work, but you're right, at the signal levels the wireless mics use, it might really suck to be the engineer trying to get things up and running....

What I'd kill for would be something operating in a band where power levels were a little less restricted... and throw... say a 5W linear on the transmitter, with a small fuel cell battery to power it....

By the way, whatever happened to the promise of decent digital spread spectrum in wireless mics with a working multipath compensation mechanism?

*sigh*

 

[boingoman]

Ooh, shiny!

The nice thing is the drums aren't likely to move much, so once you've gotten the mics placed, you can move your antennas (you do have a diversity receiver, right?) around until things work, but you're right, at the signal levels the wireless mics use, it might really suck to be the engineer trying to get things up and running....

I just imagine asking some lady in the front row to "please hold my kick drum receiver, just for the first set".

What I'd kill for would be something operating in a band where power levels were a little less restricted... and throw... say a 5W linear on the transmitter, with a small fuel cell battery to power it....

By the way, whatever happened to the promise of decent digital spread spectrum in wireless mics with a working multipath compensation mechanism?

*sigh*

What ever you are talking about is wayyyy out of my league.

I wonder about the future of quality wireless in general, as a lot of bandwidth is being offered up for sale. The audio industry is lobbying pretty hard to keep this from happening, but money talks.

 

[dgatwood]

What ever you are talking about is wayyyy out of my league.

I wonder about the future of quality wireless in general, as a lot of bandwidth is being offered up for sale. The audio industry is lobbying pretty hard to keep this from happening, but money talks.

Well, spread spectrum means either rapid frequency hopping or transmitting simultaneously at a broad spread of frequencies (this is "direct sequence" spread spectrum) simultaneously and using that to reduce interference. Kind of like using a balanced mic cable, only over the air. Your cell phone may do this (if it's CDMA).

Multipath reduction... there are a bunch of methods.... I remember reading about some of them back in the early 90s.... Given that, I'm amazed that we still have to put up with the crap that we do....

So far, the only multipath reduction I've seen is using multiple antennas and/or a couple of frequencies. That helps, but it doesn't do anything compared to tricks like (coded) orthogonal frequency division multiplexing, a.k.a. COFDM.

(Actually, COFDM was what I was thinking of when I was talking about spread spectrum before. For some reason, I had that confused with direct sequence spread spectrum... but I guess either one would probably help....)