I can’t answer all these questions, @Kevin_Senzaki would be the best person to cover this but here are the answers I can give.
Do wireless transmitters add noise to your signal?
They can … depending on interference, the type of technology used, how cheaply they are made. But in good conditions with good transmitters there is no extra noise added.
Are all/most transmitters okay or do you have to buy high end ones?
Depends what you mean by high end. Saramonic has a low cost kit that is apparently pretty awesome, the next up is R0De and then you get into what I consider completely un-adffordable. Below the Saramonic kit is pretty much all garbage.
Saramonic SR-WM4C - 100$
Rode RodeLink - 400$
The two above systems are considered good “low cost” woireless systems.
Here is an example of a REALLY cheap wireless kit … TL:DR … its crap.
I did a terribly awkward review of it here … don’t judge me, I’m usually behind the camera for a reason … I feel I should redo that review. Stop watching 6:36 … I’m actually embarrased by the rest of the review … so bad.
Like I said, there is a reason I’m normally behind the camera.
Even compared to my crappy Audio Technica shotgun, it sounds like crap. Like I said, I think I should re test the mic system but I don;t expect it to be much better the second time around.
Why do people keep using XLR cables when this option is available to them?
LOTS OF REASONS!
400$ and up per person you need to mic.
It’s not that lavaliere mics sound bad but each type of microphone (long shotgun, short shotgun, large condenser, dynamic …) have unique sound properties and uses and a lav mic, with it’s tiny capture area won;t sound as rich and full a a large condenser for example.
Wireless mics are prone to interference.
Government regulation can also suddenly make your kits “illegal” to use. This happened recently in the US when the government decided to attribute certain bands to emergency rescue. It made older wireless kits illegal to use since the frequencies they operated on were now in the spectrum reserved for emergency services.
Actually, Amazon has THIS at the bottom of every wireless mic listing.
Consumer Alert: Most users do not need a license to operate this wireless microphone system. Nevertheless, operating this microphone system without a license is subject to certain restrictions: the system may not cause harmful interference; it must operate at a low power level (not in excess of 50 milliwatts); and it has no protection from interference received from any other device. Purchasers should also be aware that the FCC is currently evaluating use of wireless microphone systems, and these rules are subject to change. For more information, call the FCC at 1-888- CALL-FCC (TTY: 1-888-TELL-FCC) or visit the FCC’s wireless microphone website at http://www.fcc.gov/cgb/wirelessmicrophones.
Multiple kits == multiple frequencies
If you need to mic up more than one person, you need a system that can deal with multiple packs and multiple frequencies without interfering with each other. That can get expensive and complicated pretty quick.