Wireless Microphones

[beefkabob]

I just bought the Fulaim X5M wireless mic system. I'll hang one mic above my students and put the other my lapel, trying to get better sound for the students on Zoom and for my recordings. If that doesn't please me enough, I'll buy a quality Lavalier mic for myself. There was an AnkerWork M650 on sale, which got me researching the devices. In the same price bracket, there's also the Hollyland Lark M1, but the Hollyland and the Lark reportedly both have lower quality sound and don't allow a Lavalier mic like the Fulaim does. I wanted a cheap option to experiment. The Rode mics are reportedly better but for 3-4x the price.

It makes me wonder if there's a good way to measure mic quality other than subjective impressions.

 

[No. 5]

I haven't looked at those microphones so I don't know how easy the mic's in question would be to mount, but a traditional way to measure a mic is by using the process for substitution calibration. It's a very similar process as measuring the free-field response of a loudspeaker, but some thought would need to go into interpretation of the results (i.e. flatter may not be better in this case).

 

[beefkabob]

I haven't looked at those microphones so I don't know how easy the mic's in question would be to mount, but a traditional way to measure a mic is by using the process for substitution calibration. It's a very similar process as measuring the free-field response of a loudspeaker, but some thought would need to go into interpretation of the results (i.e. flatter may not be better in this case).

I don't need flat. I need to pick up voices. Also, mic quality depends on where it's aimed, distance, and so on. I have two decent quality mics that are only usable up to three inches away. Then I have some lower quality mics but they can pick up voices better for conference calls. I want better voice quality without having to put my face in the mic. I did test the audio, and it's noticeably better than the one built into my laptop. I haven't compared it to my Logitech camera's mic, though.

 

[EERecordist]

I spent time looking at wireless microphones for location sound. Your variables are the quality of the microphone itself, the packaging - lavalier microphone on a wire or all in one microphone and transmitter, the wireless band - TV bands that vary by country or digital 900, 2.4Ghz digital, FM or digital, delay - digital compression for FM adds delay, and digital transmitters add delay, powering, durability, and of course price.

Getting the microphone close to your mouth with an earset/headset microphone is a big improvement for a wired system going to a beltpack transmitter.

Delay is up to you.

You can find used Sennheiser G3 & G4 inexpensively, the Sony UWP are similar.

You could also look at mid-price between the ones you mention and the Sennheiser and Sony FM systems. Those would be Deity, and Rode. Lectrosonics used are a very solid FM system above the Sennheiser and Sony. Countryman makes tiny and reasonably priced wired lavalier microphones.

Wired lavalier microphones need a powering voltage of about 3-6V akin to phantom power, and the wiring and voltage has to match the transmitter.

I would point a cardioid microphone at the audience, rather than hang a lavalier above them. Lavaliers are not very sensitive because they are inches from the speaker which can have a loud SPL. A wired small diaphragm condenser, needing phantom power, will be more sensitive. You can see it in the sensitivity spec.

On YouTube Curtis Judd reviews sound for video.

 

[No. 5]

It makes me wonder if there's a good way to measure mic quality other than subjective impressions.

I don't need flat. I need to pick up voices. Also, mic quality depends on where it's aimed, distance, and so on.

Agreed, that you don't need flat; you need a known reference if you want to quantitatively measure a mic's quality. Hence the suggestion of a technique that uses a known reference to quantify things like the mic's ability to pick up voice, polar response, sensitivity, and other measurable characteristics.

But if you're not looking to quantitatively measure a mic's sonic quality, but assess by other means, that's cool. I just misunderstood what you were looking for.

 

[beefkabob]

I don't think I was discarding what you said. I was just thinking that it was a complex problem. For instance, a Lavalier mic is pinned to a shirt, typically, and would have to be measured at an angle to the voice.

 

[No. 5]

No worries, mate. Measuring a microphone does have complexities that measuring a speaker doesn't, but as long as the microphone's being compared have their capsules in as close to the same point in space as possible, and are pointed in as close to the same direction as possible, useful results can be had.

Since your vocal source will be off axis, getting a polar response to 45 to 90 degrees off-axis is highly recommended, then you can have an idea of how the sound quality will change depending on where the lav is pinned or how the talker moves their head. If it's not possible to get a lavalier attached to a mic stand, you could do axial and polar response all from ground plane... in fact, ground plane is probably the easiest and simplest way to do something like this.

EDIT:
To add some data to that, a couple years back, there was an installation where one of their Electro-Voice N/D767a microphones sounded bad. Using the building's lobby floor as a ground plane and a computer speaker for a source, a significant bass roll-off was confirmed.

The source obviously wasn't flat, but I was only interested in the difference between the the mics. And speaking of differences, here is the normalized polar response of one of the good mic's from that installation:

You can clearly see how angle would affect what is picked up.

Anyway, the point is that it's doable if you have the space, tools, and inclination.