Re: Lav mics?
I will start out by saying I have very little experience with lavalier mics. I recently got a Line 6 LM4T lav mic to use with my G55 belt pac for a specific gig I have coming up and I am very dissappointed with it. It seems you have to talk almost directly into it to get any usable signal. Is this the nature of the beast or are there better choices I should consider for use with my existing system(TA4F connector). My choices are limited to dynamic mics(?) unless someone makes a lav mic with a battery that uses the TA4F connector. Is there such a creature?
Chuck,
Your Line 6 LM4T lav mic is a condenser mic, using phantom power from the beltpack. It is also cardioid, often not an improvement over an omni if the mic is chest worn.
Lav mics have small diaphragms, so are inversely proportionally less sensitive (less output) than larger diaphragms.
Dynamic mics are generally less sensitive than condenser mics, but all mics adhere to the inverse distance law: double the distance, loose 6 dB.
Talking "directly into it", say .5 inch,= "0" dBM, at 1 inch -6dBM, 2 inch -12 dBM, 4 inch -18 dBM, 8 inch -24 dBM, 16 inch -32 dBM.
If there are gain (or attenuation) controls in the belt pack, they have to be set to a much higher (or less attenuation) gain setting to work for a chest mounted lav than a headset lav or hand held mic, or the signal to noise ratio will be very poor.
Also, be aware the inverse distance law directly relates to gain before feedback and signal to noise ratio, at 16 inches the mic has 32 dB less gain before feedback, and will pick up room (and electrical interference) noise 32 dB more than if held at 1/2 inch. 24-32 dB less output is a huge difference, it only takes a 10 dB drop to sound half as loud.
The first time I had to use lav mics outside with adjacent stages, I quickly found the only way to get the (weak voiced) presenters audible was to make a "headset" out of a piece of wire and tape the mic on..
I did not find the sensitivity specifications of the Line 6 LM4T, but if you find microphones with better sensitivity specs (and smoother response curves) you might eek a bit more gain, but best insert a 1/3 octave EQ or parametric on the channel if your board does not have extensive channel EQ for whatever lav you use.
Chest resonances and feedback are not pretty..
Art