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Recording high quality audio

bsellman's picture
Last seen: 2 years 5 months ago
Joined: 07/16/2012 - 7:33pm

I have beenproducing high quality 2 mic audio recordings for many years, including recordings of mainly classical and choral concerts. A number of years ago I was asked to also make a video of some of these concerts. Most camcorders do not have audio that is good for music concerts because even if they record using 48kHz/16 bit sampling, they have AGC circuits (automaic gain control) which basically eliminate almost all of the dynamics, which are especially important for music. While I have tried using the audio I record on a separate recorder as the audio for the video, getting everything in sync was frequently difficult.
For the last 2 or so years I have been using a Canon Vixia camcorder that has proven to be the solution for gettingCD quality audio with the video without the hassles and problems of attempting to sync aseparate audio source file. TheCanon Vixia line of camcorders (I think all of them)enable you to set the audio level manually (thereby turning off the AGC circuits) and alsoallow you to turn an input attenuator on, permitting you to input a line level signat to the mic inputs of the camcorder. This means that you can take the line level output of an external recorder (or mixing board if you need to go that route) and record it with the video, eliminating any potential sync problems.

The equipment I have been using is a Tascam HDP2 recorder (that includes mic preamps), a matched pair of Earthworks QTC40 mics, and I connect the line out from the Tascam to the mic input of the Canon Vixia camcorder, making sure that the audio recording level on the Vixia is set to avoid overloading (i.e., it matches or reads a bit lower than the meters on the Tascam).

If you'd like to see some of the results, look at my videos on YouTube, posted under the name bsellman2. Concert videos of Dolce Suono were recorded using the equipment listed above. There are also a few informal videos posted that I made using just the camcorder's mics; however, I'm not sure which ones had the AGC turned off. Here's a link to one of the Dolce Suono videos:

http://www.youtube.com/watch?v=fCY_AiazQoQ&feature=plcp

For comparison you can hear samples of the CDs I released, many recorded with the same audio equipment, by visiting my website www.dtrmusic.com

The article in a recent Videomaker talked about using small portable recorders, but syncing up during the editing process. The same process I mention above could work with a Canon Vixia and one of the very small portable recorders for work where you need to be able to move around. And just turning off the AGC can greatly improve the audio even when you use the camcorder's mics. With recording at CD quality you can do a lot of audio level adjustments in your editor without getting excessive added noise (if you have to raise the levels a lot at some points).



vid-e-o-man's picture
Last seen: 9 months 1 week ago
Joined: 02/06/2010 - 4:20am
Plus Member

Bob, awesome recording!!! I couldn't stoplistening. Was that one of your microphones on the pole in front of the stage? Where was the other placed? Now I know what 2/$1K mikes sound like. Keep shooting and recording such fine stuff.


ophelia's picture
Last seen: 2 months 17 hours ago
Joined: 10/03/2009 - 9:35pm

Awesome post Bob - great information.

I have been researching / learning abouthigh quality audio equipment and you have provided excellent examples. It is so helpful to have someone - other than a salesperson - demonstrate what can be done with a particular product. I also scrolled through your 'Tube videos, and I must say, the Ravel & Debussy were to die for...*sigh*. Working with that caliber of musicianship must make your work very pleasant. Thanks again!


paulears's picture
Last seen: 2 weeks 21 hours ago
Joined: 11/05/2006 - 8:36am

Nice recording - The key ingredients are good musicians, nice acoustics and apart from the equipment - the mist critical element - decent ears! What I hear so much are people using good equipment badly. You mustn't assume that it's the Earthworks mics that are soley responsible for the sound. In recordings in controlled environments then having some specialist microphones makes a difference - but swapping the earthworks for other quality microphones would have produced a different tonal result, but a very subtle one. The critical factor is knowing where to put them. The earthworks microphones are very specialist - and being omnis, need to be spaced, and with a sound source like this one, that is naturally balanced produce a much bigger sound because the space is pleasantly reflective and coloured. However, with spaced microphones time delays can be destructive, so he used his ears and experience to find the optimum location for them. This is not beginners technique at all. Using these mics can often result in really horrible sound if you don't do it properly. If you want to read about mic technique for this kind of thing - look here

http://www.dpamicrophones.com/en/Mic-University/StereoTechniques.aspx

Simple it is not. For audio recordings of amplified instruments it all goes out of the window - totally different techniques. For my stereo natural acoustic recordings I love an old style dual head microphone. It has two capsules, each with omni, figure-8 and cardioid sitting one on top of each other, and they can swivel - so it's essentially an X/Y format microphones, but with the other patterns can do other stereo techniques too. However, it's a problem for video because it is big and heavy and pretty ugly. It has to be in the middle so gets in the way and looks horrible.

Video people get very intense with their talk about the visual elements, or the ins and outs of the video formats, but often they just assume the sound will work. I totally agree with the comments on AGC, and it's the sound version of auto iris and focus. It can often produce something that works - but manual control is always better!