If you've been keeping up with my writings for a while, you know that I had the pleasure of recording a concert done by the Queensland Wind Orchestra a few weeks ago. Because orchestras are quite a large group to record, there is specific recording techniques that work best for this genre of music, especially when it comes to microphone placement among such a big ensemble; two that I will be discussing today are widely known as the AB technique and the OTRF technique.
AB Technique
This microphone placement technique is specifically designed to capture a wide stereo image, using distance between two microphones to give depth and space to a signal (Los Senderos Studio, 2018).
Two microphone are placed parallel to each other. The distance between the two microphones can be anywhere between 30cm to up to 4m - because in the case of the QWO recording we were working with such a large group, we had our two microphones placed quite far apart. The use of this microphone placement was also effective in picking up instruments of the ensemble that aren't often easily noticed - for example the cello and the the harp.
In this technique it is also effective to use a cardioid polar pattern, as that ensures that you are not picking up sounds from the audience and the pickup is only focused on the orchestra in front of you.
ORTF Technique
For this orchestra recording we also paired the AB pattern with another technique, named the ORTF technique (named after its developers, Office de Radiodiffusion Télévision Française). This method utilises two cardioid microphones, with their capsules spaced 110º apart
(DPA Microphones, 2018).
The placement of these two microphone emulates the distance and angle of human ears, resulting in a more authentic stereo recording. In the case of the QWO concert, this was our most important goal, as we wanted to recreate the live performance experience as much as possible in our finished product.
This microphone technique is usually placed a few feet above the conductor, to capture what his ears would. This pair of microphones is usually the most important in an orchestra recording, capturing the sound as the conductor directs and intends it.
And those are the basic microphone placements for an orchestra recording that I have learnt over the past few months! Keep in mind that the distance between microphones in each pair is important, as incorrect distancing can sometimes result in the proximity effect or phasing issues, causing the loss of some frequencies in the recording.
Works Cited
DPA Microphones. (2018). PRINCIPLES OF THE ORTF STEREO TECHNIQUE. Retrieved August 2018, from Mic University - DPA Microphones: https://www.dpamicrophones.com/mic-university/principles-of-the-ortf-stereo-technique
Los Senderos Studio. (2018). Stereo Microphone Techniques. Retrieved August 2018, from lossenderostudio.com: http://lossenderosstudio.com/article.php?subject=11
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