Friday, January 3, 2003

[QA] Record a long event

Somebody asked me about recording a long event with several classes and making available the recordings to all participants for reviewing or transcribing; I figured it may be helpful for others if I post the answer here.

(I lost the date of the original email but the date here shouldn't be too off.)

Subject: Record a long event

Somebody asked me about recording a long event with several classes and making available the recordings to all participants for reviewing or transcribing; I figured it may be helpful for others if I post the answer here.

The class is led by a speaker with an interpreter who is constantly interacting with the speaker. The audience size is about 10-20 people. Short questions may be asked during the lecture but there is a question session at the end of each lecture for longer ones.

Here's my answer:

You may also want to read my answer to another person's question since both applications are quite similar. The answer is after this one.

It really depends on how much budget you have and what quality youare pursuing. And the purpose/use of the recording would be the mainfactor when weighting your budget.

I'll use the case of a budget-tight local 3-day workshop which I help with the recording as an example. They mainly record for later transcription work but many participants would also ask for a copy of the recording.


It does not make too much sense to do a multi-track recording for this application, so a 2-track (stereo) recorder is enough.

I highly suggest using a mid to high digital MP3 recorder for three reasons: operational convenience, the ease of post-editing, and the feasibility of releasing the recording.

A nice MP3 recorder enables you to do long hours of recording without worrying about switching tape, batteries (please use an AC adaptor), etc. It saves the need of a dedicated person for recording; it also avoids annoying interruption during the class. In the case of this local workshop, they just leave the recorder there and collect 12-14 hours of recording at the end of the day.

If the sound is pre-compressed (into mp3 format by the recorder), it saves huge amount of time transferring the data into the computer.

After post-editing, the recordings are also released in mp3 filesburned on either a CD or DVD data disc. It takes too much time andresources to make them available in CD audio. For example, a 3-dayworkshop is usually 24 hours long and that would require 24 CDs foreach participant. In mp3 format, each data CD can contain up to 2-3workshops' recordings with good quality.

A lower priced Archos 20G MP3 recorder ($130 on sale; $300 otherwise) would serve your purpose perfectly (but don't use the built-in mic preamp; it's only good if you record it via its line-level input). If very high quality is needed (for example, the recording is to be published as lecture CDs, etc.), Marantz or Denon ($700-$1000 plus a high volume memory card) mp3 recorder is recommended (quieter console noise being the main reason).

Alternatively, you may record with a laptop computer. If you are going with this option, we can discuss more.


In your case (the speaker moves around and writes on the blackboard), a wireless lavalier microphone clipped on each speak would be optimal. You may get one multi-band receiver for all microphones or multiple receivers for each of them.

If the budget permits, I'd suggest unidirectional (cardioid, hyper-cardioid, or super-cardioid) lavalier mics. It makes it easier for the trascribers.

For the audience, you may use a wired or wireless hand-heldmicrophone and pass it around for questions (please see my answer toanother person in similar situation below). However, in the nature ofyour workshop, if the audience isn't too big, I'd place one or twoomni-directional mics among the audience instead of passing the micaround. Some people are inexperience with a mic and cause unnecessarynoises; some just don't feel too comfortable speaking in front of amic; besides, a hand-held mic is a bit inconvenient for people to askquick questions during the lecture. There are too many kinds ofmicrophone to choose from: boundary microphones, hanging microphones,one-point stereo microphones, binaural microphones shall all be OK foryour application.


Since you'll buy wireless mic receivers, a 4-track or 6-track mixershould be OK (they should have good quality line level signals). If youare connecting wired microphones to the mixer, you should take thequality of the on-board mic preamp into account. Some onboard micpreamp is really bad.

Low priced ($80-$150) Behringer mixers are good enough for your purpose.

Miscellaneous equipments

If you are not getting a ground-loop eliminator/breaker (around $200-$300), please try to plug all your recorder, mixer, receivers, preamps into the same surge protector, to minimize ground-loop noise.

If the event needs a PA system, please read my answer to another question below for feedback control.

I omit the cables since they should be easy to figure out. A reminder: if the signal is not line level, please choose the shortest cable possible.

No comments:

Post a Comment