Recently I have been reviewing what field mixers are available to use in conjunction with DV cameras, and more importantly the need for signal calibration between devices. The Sound Devices 302 has a bar graph display peaking at +20dBu (approx. 7.75Vrms) thus allowing for the monitoring of extremely high signal levels. One would assume that during line up, the inputs on the DV camera would be adjusted so that the standard 1kHz tone @ 0dB (= 0dBu and not the more common +4dBu) caused a reading of 0dBFS on the DV camera's meter. However, this obviously allows for absolutely zero headroom on the camera for any sudden peaks which exceed 0dB on the field mixer. Therefore, the 302 user's manual recommends setting the input levels on the DV camera so that the meter registers -20dBFS for the 0dB line up tone thus allowing for the 20dB headroom to be accommodated by the camera.
The bar graph meter on the 302 turns orange at 0dB (i.e. -20dBFS on the camera) and then turns red at +8dB (i.e -12dBFS on the camera).
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