Audio Changes with Firmware 1.8 on Blackmagic Cameras
Finally, the Blackmagic Design firmware 1.8 has restored the normal audio input levels on their Cinema and 4K cameras. They have removed the digital attenuation which was causing very low audio recording levels. They have also restored the frequency response to what it was on version 1.2 which was not great, but better than all the releases that came after this. It is now down 3dB at 350Hz when in MIC level input mode and a very good 3 dB down at 35Hz when in LINE level mode.
Our DXA-BMD passive adapter can once again be used to record very clean audio into this camera. You can now achieve a 76dB of signal-to-noise ratio which is excellent for any DSLR camera. The camera gain should be set to 30% which is the “sweet spot”.
It looks like there was only a minor change to the audio performance on the Pocket camera. The “sweet spot” is now at 50% instead of 100%. The signal to noise ratio in not quite as good as its big brother but still a respectable 71dB at 50% gain. The frequency response is still the same relatively flat 45Hz to 18kHz with a weird bump around 70Hz.
The Very Bad News
Blackmagic has also seen fit to restore the same issue they had on version 1.2 of the Cinema and 4K cameras which switched the input to line level whenever the input signal became too hot. This will obviously cause you to lose your audio. The only way to reset this is to cycle the camera off and on. This will no doubt frustrate many users. It is advisable to carefully watch the levels on the VU meter of the DXA-BMD adapter to avoid this problem. The Pocket did not exhibit this problem.
After looking at all the measurements we took at various firmware versions since the release of this Cinema camera, it seems that Blackmagic has simply reverted back to the same performance as the old version 1.2, along with the same old bugs. Ironically, this was the best performing version so I suppose that is a good thing. Too bad they could not have resolved the original problems at the same time. This will at least now allow you to record clean audio into the camera without the digital attenuation issue which was causing all those low level problems.