UHF wireless lav noise floor

[Richard Crowley]

The only “K&F Concept wireless lav system” I can find is the M8 with one transmitter and one receiver for $130
https://www.kentfaith.com/USKF10.002_m8-uhf-wireless-lavalier-microphone-for-dslr-camera

IME, you can’t expect good signal-to-noise ratio (SNR) or low noise-floor from any $130 wireless microphone of any brand or model. Here in the 21st century, you may get better performance from a more modern design like one of the digital wireless mic kits that shares the 2.4 GHz band with WiFi and Bluetooth, etc.

I would expect even a very budget kit like the “Azden PRO-XD 2.4 GHz Digital Wireless Lavalier System” ($200) would have a better SNR than any budget UHF system.

If you are in the United States, note very carefully that all wireless microphones in the 617-652 MHz or 663-698 MHz frequency bands will become illegal to operate after July 13, 2020 And in some cases even before that date as the 600 MHz band is auctioned off to mobile wireless users (i.e. cell phones, etc.) I wouldn’t buy any 600 MHz wireless mic at this late date.

It is pretty easy to discover how much of your noise floor is from the transmitter-receiver link vs. how much is from the microphone. Simple listen to the system in a noise-free environment. Perhaps an interior closet with the microphone burred inside a mound of pillows and blankets. You get the idea. Then simply unplug the microphone and compare the noise floor. That will demonstrate how much of the noise floor was from the microphone.

You are correct that selecting a low-self-noise microphone is very important in achieving low-noise wireless performance.

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Recording audio without metering and monitoring is exactly like framing and focusing without looking at the viewfinder.

[Clyde Villegas]

Thanks Richard!

Below is the link to the exact model that I bought. It’s more expensive than the one at the K&F website. The case is all metal so it’s heavy. I wonder why it’s not in the K&F website. The seller in Amazon is K&F Concept.

https://www.amazon.com/Concept-Wireless-Microphone-Transmitter-100-channel/dp/B07D326LWS

I followed your advise for the test. I placed the transmitter and mic inside several layers of clothes in my closet. I listened to my headphones and the noise was the same as when I did the test in my bedroom. Now, when I unplugged the microphone like you suggested, there’s absolutely no sound. I mean it’s like you turned off the transmitter. I’m not sure if this means that the transmitter has extremely low noise or if the system shuts off when mic is removed. I tried plugging a 1/8 plug and it’s still very quiet. What do you think?

ut in omnibus glorificetur Deus

[Richard Crowley]

Yes, I agree that the transmitter may be muting when it senses there is no mic plugged in.
Does the receiver have any indication of the signal strength of the radio signal?
Does the RF signal shut off (and “squelch” the receiver) when you unplug the microphone?
Else perhaps it is an indication that the Transmitter->Receiver link is actually quiet, but the mic is noisy.
Is there an way of testing the microphone in some other device? Camcorder?, cell phone?, recorder?

———————————————————————————
Recording audio without metering and monitoring is exactly like framing and focusing without looking at the viewfinder.

[Clyde Villegas]

Thanks Richard!

[Richard Crowley] “Does the receiver have any indication of the signal strength of the radio signal?”

The receiver indicates only if it’s either receiving or not receiving a signal. There are no levels of signal.

[Richard Crowley] “Does the RF signal shut off (and “squelch” the receiver) when you unplug the microphone?”

The RF signal in the receiver remains on even when I unplug the microphone from the transmitter. But it goes off when I turn off the transmitter.

Is it possible that the receiver has a noise gate that’s why it’s so silent when mic is unplugged? Though I think this is impossible for this mic system at this price point. What do you think?

Will try to connect the lav mic directly to my GH5 and Zoom H5 and see what happens.

ut in omnibus glorificetur Deus

[Richard Crowley]

[clyde villegas] “The RF signal in the receiver remains on even when I unplug the microphone from the transmitter. But it goes off when I turn off the transmitter.”
OK. That would suggest to me that the microphone is more likely to the the source than the transmitter/receiver.
[clyde villegas] “Is it possible that the receiver has a noise gate that’s why it’s so silent when mic is unplugged? Though I think this is impossible for this mic system at this price point. What do you think?”
Yes “squelch” (where the audio signal is muted or gated when the radio signal drops) is quite common. I would expect that even this gear would have proper squelch function.
[clyde villegas] “Will try to connect the lav mic directly to my GH5 and Zoom H5 and see what happens.”
Yes, it is always good to try different combinations to discover where a problem is coming from.

Even expensive wireless kits come with a microphone that isn’t very good. It is very common for professional users to buy a better microphone for their wireless kits. So, for such an inexpensive kit, it wouldn’t be very surprising to discover that the microphone was the weak link.

———————————————————————————
Recording audio without metering and monitoring is exactly like framing and focusing without looking at the viewfinder.

[Clyde Villegas]

Thanks Richard!

I plugged the mic directly to my Zoom H5. No audio signal at all. Then I plugged it to my GH5 and was only able to record left channel. I spoke to the mic for a few seconds then stopped talking so I can record the noise.

I brought it to Premiere Pro and used the loudness meter. I adjusted the overall volume level so that my voice would be in the “sweet spot.” When I stopped talking, you can see the loudness level of the noise (in red circle). I have no other mic on hand to compare it to except for another cheap one (Boya).

I think it’s noisy because the level is higher (but by just a bit) than the cheap Boya which is supposed to be noisy due to it’s cheap price.

ut in omnibus glorificetur Deus