diy project actual good canon 5d audio


Posted on Feb 6, 2014

Improving the Canon 5D Mark II audio so that it can produce usable production audio. The first part of any engineering effort is data gathering, so I set about to measure the input frequency response of the 5D. My end goal was to use the Marantz PMD661 field recorderas a mic pre-amp and primary production audiorecorder, however I also wanted to take the audio line output from the field recorder and feed it into the 5D to


diy project actual good canon 5d audio
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capture "good enough" production audio. To start off I created a stepped audiofile in Adobe Audition (20-200Hz: 20Hz steps, 200-1KHz: 100Hz steps, 1kHz-20kHz: 1kHz steps) andupload it to the Marantz field recorder SD card. Then it was simply a matter of playing back the audio into the camera with a simple resistor dividercircuit to compensate for the level difference between a line out and a mic input. The stepped audio waveform you see below is the audio extracted from the 5D video file. The top (left channel) waveform is simple resistor divider that also represents the defaultfrequency response of the 5D audio mic input. The bottom(right channel) waveform is the effect of the resistor divider, pluscustom designedpre-emphasis circuit. I also plotted thenormalizedresults in Excel to make the data a little easier to see. The bottom line:The 5D has a highpass filter at about 120Hz. Thecompensation circuit has a high pass around60Hz. The default Canon filter makes people sound like Gilbert Gottfried with a cold. Like any design there were some trade-offs. The first, and foremost, is that I had to use whatever components I had sitting around the test bench, sort of like the cook in the kitchen with a bunch of semi-random ingredients. No, my filter components aren`t necessarily optimal but they`re good enough to get the job done with respectable engineering designmargin. Second, I had to accept some input loss for the...




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