[Richard Crowley]

It is good to see videographers that have good sense for audio coverage. And especially “young-players” new to the game. Congratulations, you demonstrate excellent sense for audio.

Yes a Sennheiser G3 wireless system is probably the most common solution to the scenario you are presenting. It is a very good choice. Remember that you will need the proper cable/adapter to interconnect the receiver with the audio input on your camera.

You might want to think about recording the presenter on one channel of your camcorder, and an audience-reaction mic (perhaps the mic on your camera?) on the other channel. That would get more natural sound to sneak some of the room sound in with the direct channel from the presenter. Especially if they are doing things (telling jokes, etc.) that evoke audible reactions from the audience.

NO, clipping a wireless lav onto your subject will NOT create problems with the venue system. UNLESS the venue system is also wireless and you are using a channel that is incompatible. But the G3 systems are “frequency agile” which means that you can change the channel of your rental system to avoid interference with any wireless system in the venue.

The professional, local, equipment rental houses will typically offer “frequency coordination” services and help you select (and even configure) equipment for the locatoin (city and even venue) you are operating in.

I would say “good luck” but you don’t need luck with the kind of good sense you exhibit.

[Richard Crowley]

There are “auto-mixers” that sense who is speaking and turns on that microphone. For example Shure SCM810 or Rane AM2 or any of the products from Dan Dugan, including plug-in accessories for existing mixers.

https://www.shure.com/americas/products/mixers-dsp/scm810-8-channel-automatic-mixer
https://www.rane.com/am2.html
https://www.dandugan.com/

You need at least one microphone between each 2 people. If you try to do one mic per 3 or 4 people, the difference between the people (because of the different distance) will be too much. Some people will be very loud and others will be very difficult to hear.

With so many auditors/students, this method could get very expensive very quickly which is why it is rarely used. To get decent sound in that situation, people will hire 2 or 3 good boom microphone operators (depending on how many people you are trying to cover).

This really is one of the most difficult kinds of scenarios to get good sound from. There are no effective short-cuts that anybody has ever heard of.

We don’t know whether you are doing a single event or whether this is a series of sessions? There is also the option of renting equipment if you need it only a few times.

[Richard Crowley]

1) Put a wireless lav (or headset) microphone on the teacher. DO NOT attempt to “aim” a microphone of any kind at the teacher, especially if you have only one microphone person to cover the auditors.

2) If you cannot get a microphone within 3ft/1m of an auditor to hear what they say, then forget trying to pick up the auditors on a microphone, and have the instructor repeat the question or statement. In many cases, it is better to have the teacher repeat the question anyway in order to make better sense of it for the other students.

[Richard Crowley]

Wow, that is a BIG conference room. What are the acoustics like? Is it very reverberant (shiny wood paneling, or big glass windows, etc.)?

Shotgun mics in general are not useful because near reflections from ceiling, walls, even table top, “confuse” the microphone and render it not directional. Shotgun mics are also used where you have a dedicated and experienced person to keep the microphone aimed precisely at the subject. Or sometimes stationary in a seated interview situation where the subject never moves.

A microphone attached to the presenter is the most common way of dealing with an instructional setting (vs. a full-scale video production with a boom operator, etc.) At least a clip-on “lav” mic, or even a “headset” microphone with a nearly invisible wand that is very close to the subject’s mouth. And we often use wireless rigs for this to avoid tripping up the presenter with a trailing mic cable. Unless the presenter is absolutely hard-attached to the podium, etc, and never moves, using a fixed microphone is rarely effective.

How many in the audience (“auditors”)? What resources do you have to work with? What equipment? What crew? (Experienced boom operator?) What budget for rentals, etc? Is this only for recording, or do you also have to deal with reinforcement?

Are you only capturing audio for recording, or is there also sound reinforcement to deal with in this large room? What kind of quality do you need? Do you need full broadcast quality, or only casual documentation quality, or only “transcription quality”?

[Richard Crowley]

Auto-mixers continuously measure the TOTAL sound level (to establish a “baseline background level”, and they measure the level from EACH channel and compare it to the others, and to the “baseline ambient” level. It “enables” a channel when it “detects” that someone there is talking. Now “enable” may mean bringing it up from a lower level, or it may bean un-MUTING the channel, etc. however the sound operator has determined the proper operation is for the situation. And “detect” is also a rather complex thing with other parameters to configure by the operator.

One of those parameters to configure is how to handle concurrent channel activation. In some situations (such as a panel discussion or a congressional committee hearing, etc.) the chair or master of ceremonies or moderator, etc. has “priority” and over-rides any other channels. But in other situations (as with this TV show judges’ panel), they set it up so that any channel that is active has equal priority and is mixed with the others. Of course in a live TV talent show (etc.) they have a human mixer also sitting there who is performing the final mixing function with the automatic feature only as an aid.

Those lav mics are close enough to the judges’ mouths, and the judges are spaced far enough from each other that they exceed the 3:1 rule. The mouth of the adjacent judge is well over 3x farther from each microphone than the mouth of the judge the mic is attached to.

In the case of our “Table Talk” show, the guys are rather energetic. They are all runners and very physically fit, as well as “Type A” personalities and very frequently interrupt and talk over each other. And because of their personalities, they also frequently lean into the table and violate the 3:1 rule. In many cases the sound of a particular guy is almost louder on an adjacent mic than on their own microphone. Because the producer wanted no visible mics, we had to secure the lavs into the inside collars of their shirts. This is a pretty casual group, and they only wear suits and ties on very formal occasions or in very conservative venues.

Because the entire production is shot “iso” (each camera recorded to a separate media) and then “switched” during post-production, the audio is also recorded as each microphone on a separate channel and then the audio is “switched” in a similar manner to the video. Of course, for purposes of production design, the audio does not strictly “follow” the video switch becasuse there are lots of wide shots and over-the-shoulder shots and reaction shots and side-shots, so editing the audio is for all practical purposes another whole pass through the show after all the video shots have been selected.

We used five Sony EX1 cameras, each recording internally to their SxS cards. And on the most recent series, we used the producers new Zoom H6 recorder to grab the separate mic audio tracks. We also fed each mic to their respective camera both for sync purposes, and for a backup recording. I used my Panasonic AW-HS50 video switcher just as a “multi-view” so the director could see all five cameras.

I used a mic-spliter to send the mic channels to both the cameras and to the mixer/recorder.

[Richard Crowley]

That photo shows that the microphone placement is just outside the 3:1 rule. In addition, it seems rather likely that they are using an auto-mixer and ducking the mics when the subjects aren’t speaking.

[Richard Crowley]

Sorry can’t imagine hiring an audio pro and not letting them handle the audio.
But “handling the audio” often does NOT include DESIGN, but only EXECUTION (sometimes spelled “accommodation”). I have been arguing from day one for using headset mics, but I was limited to using lavs, and HIDDEN at that. The producer thinks it is OK to see the fifth camera on a circular track around the table, but he doesn’t want any visible microphones(!)

The programs are shot completely ISO, and he does the switching/editing completely in post production. And that includes recording all four microphones on separate tracks and manually mixing the audio to avoid the 3:1 problem. In many cases the sound from one of the OTHER guys is almost louder in the mic than the person who the mic is attached to!

Those “talent show” programs with the panel of judges have the people separated far enough to avoid the 3:1 rule. Or at least the ones that I have seen.

[Richard Crowley]

Is this a ballpark rule of thumb or is this based on some hard wave form analysis? Just curious. Obviously your source needs to be much closer to the mike other wise background noise dominates the audio. But I have not heard that it produces tinny or any other characteristic sound other than noisy

A simple Google search will reveal dozens of explanations and demonstrations of the 3:1 rule with. There can be very serious phasing problems when sounds are picked up by two microphones at different distances. And timing problems as well.

I am doing sound for several seasons of a TV show where four guys are sitting around a rather small (~1.3m) table, and we have endless problems with the 3:1 rule. But that is what the producer wants.

https://vimeo.com/70030114

[Richard Crowley]

What do you mean “mixed on stereo tracks”? Do you mean that BOTH microphones are equally audible on JUST he Left channel, and BOTH of the microphones are equally audible on JUST the right channel? Or do you mean the one microphone appears exclusively on the left channel and the other microphone appears exclusively on the right channel?

Are you listening to the playback from the DR-40 on proper stereo headphones?

Posting an audible sample is worth at least 1000 words.

[Richard Crowley]

You told us what microphones you are using. And what mixer you are using. Presumably you have connected the normal XLR output cables from the receivers into the XLR inputs of the mixer.
However, other details are not revealed. For example…
1) What does each microphone sound like when you “solo” that channel on the mixer? Is it OK there, or does it sound “tinny”?
2) Are you violating the 3:1 rule? Each microphone must be at least 3x farther from the other source as from its own source (the subject’s mouth)
3) How did you have the channels panned? Were you mixing them, or are you keeping each microphone exclusively on a separate channel?
4) What did you record this on? How was the recorder (camcorder?) connected to the mixer?
Without knowing at least those details, nobody can really help much.

Posting an audible sample is worth at least 1000 words.