Proposing a $2K "Fix" to Boss for Distance-Learning Solution

[Cornelius Allen]

Hi guys,

I work for a small startup that provides adult education services for professionals seeking financial certifications via in-residence *and* distance-learning formats (a hybrid, essentially). My job is primarily as a videographer, webcasting the 4-hour lectures to a rather small group of learning-distance participants through a CDN that also allows the content to be played on-demand.

Our video delivery is good. It's clear, lit well, the equipment we use is decent. However, the audio is quite bad. This is a symptom of not having the largest budget but also my prior inexperience in audio. We use a rather crude http://www.bhphotovideo.com/c/product/758972-REG/Acoustic_Magic_201_The_Voice_Tracker_II.html and the ambient noise level has annoyed me (and our online participants) so much that I don't use it anymore. Until this issue is resolved, I will resort to close-miking the lecturer with a lavalier mic and have him repeat the questions that our (adult) students have in class so that our online students will hear.

The problem is that we want to produce a clean, near-studio quality pickup of students of the class asking questions/making comments so that our online participants will have a better, more interactive experience.

Here's what I'm going to propose to my boss (the owner of this startup): I want to mike our 12-15 students in class with boundary microphones connected to an automatic mixer like the http://www.bhphotovideo.com/c/product/188356-REG/Shure_SCM410_SCM410_4_Channel_Automatic.html. This audio will be feed via XLR to a http://www.bhphotovideo.com/c/product/672719-REG/Beachtek_DXA_2T_DXA_2T_Universal_Compact_Camcorder.html and my a/v HDMI line from the camera is fed to my laptop and streamed through my CDN to our online participants.

Will this work, you think?

Here's my "to buy" list that I've developed through an east coast retailer. The microphone splitter that you see is to use one channel on the mixer with two mics so I can use the last channel for the new lavalier system that I will purchase.

Thoughts? Suggestions?

[Richard Crowley]

I have significant doubts whether four barrier mics will adequately pick up "12-15" students. Especially since we don't know anything about how you have the students situated, nor the acoustics of your classroom/studio. Your stated number of students vs. your apparent number of mics/mix channels implies that you think you can pick up 3 or 4 students per microphone. This seems overly optimistic even under ideal conditions, and I suspect you don't have ideal conditions.

IF all your students are seated at solid tables with hard surfaces and facing towards the instructor.
IF there aren't things that can block the sound (like open laptop computers or binders)
IF the students are careful not to talk over each other and speak up (vs. mumbling or whispering)
IF they are also careful to not have or do things on the table that will generate noise.
IF you use at least one barrier mic for each TWO people (i.e. 6-8 mics)
IF you have a nice quiet classroom/studio with decent control of acoustic reflections.
IF you have someone on the crew whose priority responsibility is to monitor the audio

THEN maybe you have a chance of using your auto-mixing barrier mic scheme.

ELSE, you may be better off with the instructor repeating the question. That scheme has the benefit that the instructor can state the question succinctly and in a manner that will make sense to the online students.

[Josh Bass]

If anyone has an answer that could work for a one man band or two person crew (neither of which is a pro sound guy) i would love to know. I frequently encounter these shooting situations (trying to pick up an entire audience possibly asking questions at any time) with a regular corporate client on two man shoots and occasionally solo with other clients.

Best solution weve found? You guessed it...stick a shotgun on the camera and pray. The me66 seems to work particularly well at picking up fairly quiet folks from silly distances. It aint pretty/clean, but its intelligible. Usually. This is in a smaller room with similar crowd size as the OP's. in a hotel ballroom? You got me.

[Cornelius Allen]

Thanks Richard for your reply. I should clarify a couple of things:

1. I went over the numbers and we typically have 8-12 students.
2. The students are 35-50 year old adults who are financial professionals. They typically don't move around in uncontrolled, agitated manners like children.
3. The classroom that we lecture in/webcast from is a typical college lecture room. Not acoustically-designed. About 50-60 feet tall, 30-35 feet in width. There are two banks of tables, each side having four tables. Two students typically occupy each table. All are facing forward.
4. Noise factor: there is an internal projector fan and two older A/C units that are quite discernible. However, I can have us moved to another lecture hall where there are more modern (and quieter) a/c vents piping the classroom.

I *thought* that if we placed a boundary pic at each table of *two* students, it could work, but your critique raises concerns of my own.

If the boundary mics wouldn't be feasible, what about suspended microphones? Perhaps two http://www.bhphotovideo.com/c/product/68459-REG/Shure_SM57_LC_SM57_LC_Microphone.html pointing downward from a http://www.bhphotovideo.com/c/product/331888-REG/Samson_SABL3_BL3_Ultra_Light_Boom_Stand.html?

[Greg Miller]

Cornelius,

I'm a bit confused about numbers. You say you typically have 8 to 12 students. You say "one mic per two students." That would be 6 boundary mics, worst case, and maybe more if a given session has more than the "typical" number of students. But your wish list shows only 4 boundary mics, and the automatic mic mixer has only 4 inputs. I see a problem here.

Using low-cut filtering on the boundary mics would reduce pickup of the A/C noise. It would not have any adverse effect on intellibility of the voice pickup. However, the projector fan noise is probably higher in spectral content, so a low-cut filter probably would not help much with that.

Even if they're adults, I tend to agree with Richard about picking up other noise. I guess my biggest concern would be someone typing on a laptop. That might generate a lot of "thumping" noise on the table, which would be transferred to the mic.

[Richard Crowley]

My biggest concern is trying to use a boundary mic for more than two people. You will never get decent "even" pickup with a wide disparity in pickup distances. My second concern is "signal-to-noise" ratio, where "noise" includes poor room acoustics. You are doing yourself no favors (at least acoustically) with such a small number of people in such a cavernous and reverberant space. You would be better off in a small conference room.

Shure SM57/58 is not noted to excel in distance pickup applications as you propose. OTOH, I have seen a similar TV program that uses SM58-style mics just lying on the table, and if a student speaks, they pick up the mic and use it close (6~9 inches). Pop filters (foam balls) are an absolute requirement for amateur users like this situation.

IME, boundary microphones are dramatically over-sold as solutions in applications where they don't belong. An application as you describe, especially with no sound person, does not have a high expectation of success IMHO.

[Rick Reineke]

I concur w/ Richard and Greg, having the instructor repeat the questions/comments, and would be the cheapest and easiest option. Otherwise a centrally mic on a stand or a pass-around wireless H/H are other options. I also highly doubt the auto-mixer would do any good in your scenario.
I did many (hundreds) of continuing educational seminars in hotel ballrooms and picking up audience questions was usually an issue, and I always had a few room mics to pick up what I could and to eliminate 'dead-air'. My situation was not a OMB operation and I was the dedicated audio eng./mixer, I also had to split the house mics or 'integrate' the two systems. (my preferred method)
Much of this has previously been discussed, so you may want to search this and the DVX audio forums for more info as well.

[Cornelius Allen]

Thanks guys, I really appreciate the well-thought-out and critical feedback.

So, the notion of using boundary mics (according to you all) does not seem to have a hint of promise.

What would you all do if you had a higher budget?

Here's my last and final thought: What if I close-miked all the students instead, using a multiple receiver unit like 2-3 of these http://www.bhphotovideo.com/c/product/847959-REG/Nady_U_41_QUAD_LT_O_U_41_QUAD_LT_Wireless.html or a handheld setup like a couple of http://www.bhphotovideo.com/c/product/850300-REG/Nady_U_81_OCTAVO_HT_U_81_Octavo_HT_Wireless.html (with a http://www.bhphotovideo.com/c/product/285063-REG/QuikLok_A_188_A_188_Desktop_Microphone_Stand.html)?

[Rick Reineke]

"What would you all do if you had a higher budget?"

The Nady H/H multi mic system would 'probably' work, but you would not want the mics 'open' when not being used, so an experienced mixer would be wanted'

otherwise.
- a boom system with a (experienced) operator
- five or more cardioids hung for the ceiling (and a experienced sound mixer)
- kind of ridiculous, but a desk stand/mic could also be put on each desk.. this too would require an experienced mixer.

[Richard Crowley]

First rule of wireless microphones: A $5 cable is ALWAYS MUCH BETTER than even a $5000 wireless mic. NEVER use a wireless microphone where you could use a wired mic. This is one of those exceptions where use of the words "always" and "never" are well-justified.

If you really have your heart set on auto-mixing, I would look at using a Shure SCM820-DB25. It has 8 auto-inputs for your students, plus an auxillary input for your presenter's wireless receiver. ($1900) http://www.bhphotovideo.com/c/product/943513-REG/shure_scm820_db25_digital_intellimix_automatic.html
And for microphones, I would consider using something like On-Stage DJM-618 18" Gooseneck DJ Microphone with XLR. ($25 each) On-Stage DJM618| B&H Photo Video
And mount them on On-Stage DS7100B Basic Fixed-Height Desktop Stand with Black Shaft ($9 each) desk stand| B&H Photo Video

One mic between each TWO students.

That is a bit over your original proposed budget, but IMHO, it has a MUCH better chance of success. It gets the microphones MUCH closer to the students' mouths which you will REALLY need in such a hostile acoustic environment. Yes, those are rather cheap gooseneck mics, but they are only for occasional random speech pickup. You don't need expensive microphones for such brief, intermittent and casual use.

[Greg Miller]

I did not say that boundary mics are absolutely useless in this situation. I certainly do agree that they are not the best solution.

Given that you are not expecting "feature film" or even "network TV" quality audio from the students, you do have some leeway. You do not need a dedicated boom operator for each pair of students, plus a dedicated mix-operator for the feed.

If your heart is set on boundary mics, I'd say give them a try, provided that:

1.) everyone agrees in advance that the students won't sound as good as the instructor (who is personally miced);

2.) you have each mic serving a maximum of two people, who are seated at the same table where the mic is located, no more than arm's length away from the mic;

3.) you acknowledge that if people are typing on computers that will most likely cause a lot of "thumping" by way of resonance in the table, and the mics will pick that up loud and clear;

4.) because of the noise described above, the gated mixer might go crazy, and not work at all the way you hope.

Given the above, if you really want to try boundary mics, and if you have an option to borrow or rent some, then try them. The result will probably be better than what you have now; it certainly will not be the best possible option.

In general, the closer you can get the mic to the student's mouth, the better off you will be in the long run. And by all means, don't waste any money on wireless... there is absolutely no reason you need wireless in this scenario, and running 4, 5, 6, etc. transmitters and receivers simultaneously will just give you a huge potential for problems.

And of course if you close-mic all the students, and have an operator riding gain, then you have the possibility of really good "broadcast quality" audio. You just need to find the level of compromise that satisfies you and your client.

[Cornelius Allen]

Thanks everyone for this AWESOME feedback. I think I'll be moving in this direction:

1. I'm going to abandon the idea of boundary microphones. It's just too many concerns. Instead, I'll try Richard's suggestion of using the inexpensive Onstage gooseneck microphones for no more than *two* students at each table. This is the best thing I've seen recommended here that strays away from my initial thoughts on wireless handhelds and/or lavalier microphones.

2. Because the budget doesn't call for it, I'll be going with my initial though of using the less expensive four-channel Shure automatic mixer.

In all, based on the feedback here, I'll have a setup that can stand up against my "hostile acoustic environment," and present our online participants a substantially improved audio experience with the type of interaction that can be afforded with hearing (in great clarity) the questions, comments and other feedback of their in-class classmates.

[Rick Reineke]

If you can instruct (or put an official looking note on the table) to remind the participants to "get close to the mic when speaking", that could help as well.
Good luck Cornelius

[Greg Miller]

Originally Posted by Cornelius Allen

I'll be going with my initial though of using the less expensive four-channel Shure automatic mixer.

I think you're making a wise choice. Richard's suggestion seems to be a good one: a $25 mic in the right place will sound much better than a $250 mic in the wrong place.

Note that the suggested gooseneck mic has an XLR connector mounted on the bottom end of the gooseneck. That means the mic does not screw onto the stand... it plugs into the stand! So you can't use a simple stand with a 5/8"x27 thread. You need a stand (or "base") that has an integral XLR connector. That will narrow your options, and raise the price. By the way, consider stands or mic mounts with a shock mount built in. Otherwise, keyboard typing "thumps" will still be transmitted through the table to the stand, through the stand to the mic, and through the mic into your audio track. Or, at the very least, put one or two thick mouse pads under each stand.

I am still confused about your 4-channel mic mixer. Originally you talked about 12-15 students. Later you revised that downward to 8-12 students. OK, we've agreed to use one mic for every two students. You're talking about a 4-channel mixer. That means a maximum of four mics, which translates to a maximum of eight students. Add any more students, and that mixer will be inadequate; you'll need to get a bigger mixer. You apparently think a 4-ch mixer is a good choice; I don't understand the logic behind that unless you are deciding to limit the class size to eight students as an absolute maximum. Care to clarify this point?

[Richard Crowley]

Originally Posted by Greg Miller

... you can't use a simple stand with a 5/8"x27 thread. You need a stand (or "base") that has an integral XLR connector.

Or you could simply put the bottom part of the mic into a conventional mic clip which threads on to any standard 5/8-27 stand. Simple and inexpensive.

We must have missed something about the 4-channel mixer though. If you have one mic per two students, you appear to be limiting yourself to 8 students in the classroom audience.