AHh lots of fun to respond to....

First off the topic of wireless mics.  The microphones used on the TED Talks is likely the DPA 4088.

Second on the topic of them being wired or wireless if they connect to a belt pack.  You will not be able to get the power and quality required out of a headset unless you have something the size of a beltpack near it.  Mind you there are some small beltpacks and it isn't unheard of for me to hide them in wigs on stage, see the Lectrosonics SM series for example.  But they are all many times larger than the mics themselves to provide both quality, predictable and minimum latency, as well as required power.

I have put mics and beltpacks on dancers doing all sorts of manuvers.  It takes some time to get right, but if you take your time, and think about things before hand you can secure them to instructors doing martial arts just as well.  The catch is, depending on what exactly they are teaching, where you position the pack has to be carefully thought about, as one on the small of the back or waist won't work very well if they will be demonstrating basic breakfall techniques, etc.  You would likely want to look at the inside of the thigh, placed there using a mic belt.

In as far as restriction of movement, this is one of many things that set a good A2 apart on broadway, they will take time to ensure that the cable is secured close to the body where it needs to be, with appropriate strain relief (On broadway this is likely tape, but you can use clips etc. as well in places where hiding it is not as essential) where needs to happen so that there is no restriction of movement.

In the end if an A2 has done their job right, the talent can forget they are even wearing a microphone.  But also this requires a fair amount of prep work, and time with the talent.  This may be something your instructors are unwilling to do.  In which case your best option may be to use a shotgun or hyper cardioid, and follow the talent around.  This may itself be a distraction however, so a choice is going to have to be made at where ever you are located and explained to the talent you have coming in to teach.

If you do use an area micing technique, understand in order for it to be effective you are going to have to actually mix the microphones.  Area mics do not get around physics, so if you want nice clear vocals, first they need to be as close to the source as possible(Inverse Square Law) and second you will need to only use a single microphone at a time(3:1 rule).

Now in as far as hanging choir mics and when to use them, and why they get placed like they do...

Any area mic is going to tend to have a lot of gain applied to pick up a wide area, thus the name.  This does in fact mean that if you aren't very careful about placement and speaker location, you will not get nearly enough acoustic gain before feedback.  If placed correctly however, they can do a very effective job on picking up larger sources, ie. choirs, ensembles, etc.  Again you have to keep in mind the rules I mentioned above, which means you can't put two mics closer together just for more volume, especially if using a mono system(Stereo you can cheat a little).

Why would you put mics above the orchestra when the sound is point out?  Because not all the sound is focused out.  Think about the vast majority of instruments in an orchestra, most of them radiate sound in many directions.  And in fact the pickup from above the orchestra can be nearly as good in many cases.  If it was simply a matter of the sound 'moving forward' only, then you would never see an orchestra in a pit, ever, because most of the time the sound would only bounce around in the pit.  But obviously it doesn't do that.  Sound is emitted not only by the bell of many wind instruments, but also by the keys.  String instruments radiate sounds not only from the strings themselves, but thankfully from the resonant bodies, otherwise we wouldn't hear a lot of sound at all.

So picking up the sound from above can be very effective, you wouldn't want to be behind the orchestra because there are a few instruments that are more directional in their sound, and the balance wouldn't be the same, not to mention you would have human bodies for high frequency to get absorbed by in the way, but slightly in front and a little above works well.  Especially true when micing a live performance where people are coming to see the orchestra play, and not paying to see the microphones blocking their view of the orchestra:)

Finally why use BT or not..  Well short version is, if talking about for live reinforcement at all, it wouldn't be suitable.  Latency requirements for live reinforcement are FAR more restrictive than they are when your listener can hear you 50-100mS offset and not have a clue because they aren't seeing your mouth move, or hearing your natural acoustic sound for phasing to occur.  Live however this becomes a huge issue, and latencies of that much would be completely unacceptable.  Not to mention limited bendwidth of many bluetooth headsets mean you don't get good quality at all.  If however these are acceptable limitations to you, sure try it out.  You may want to run tests on battery life, maintaining connection, etc. as well though.

And of course for any solution, have a backup.

       Seablade


On Wed, Apr 24, 2013 at 1:39 AM, david <gnome@hawaii.rr.com> wrote:
On 04/23/2013 07:16 PM, Gene Heskett wrote:
On Wednesday 24 April 2013 01:15:04 david did opine:

On 04/23/2013 03:26 AM, Gene Heskett wrote:
Another possibility might be a clip-on blue tooth device like the cell
phones use, but those are _not_ long range, with 6 feet about the
maximum practical range.  I tried to make a dongle work over about a
15 foot path here but could only keep it working for 2 or 3 minutes
at a time.

Then there's my silly JABRA EasyGo phone headset that works and connects
just fine up to 100ft. I know that from personal experience, since our
parking space is about 100ft from our house. I've sometimes left my
phone there, and had my headset start beeping about losing connection
about the time I get in the house.

Similar experience at my office when I left my phone on my desk and
walked out into the courtyard.

That amount of power in a BT headset is probably sick bird, but if it
works, what the hey?

I don't know, it's my first ever BT headset. Supposed to be able to connect to 2 devices and work for listening to audio, but I don't have any other BT devices to try with and don't listen to music through my phone.


--
David
gnome@hawaii.rr.com
authenticity, honesty, community
http://clanjones.org/david/
http://dancing-treefrog.deviantart.com/
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