Some Audio Testing Results

[Kevin Halverson]

One additional question. When you were using the 302 mixer, was there a high pass filter (low cut) engaged? There is a noticeable shift in LF portion of the noise spectrum compared to the NGSX2 mixer.

[Elizabeth Lowrey]

JFirestone, thanks so much for posting this clip. I'm hungry to hear any new audio sample from the camera since there've been so few up to now.

My observations are that, while the noise with RED preamping is improved over what it was in the sound clip that predated the hiss fix in Build 13, there is still an unacceptable level of noise, way more than I expect with a piece of pro gear. I didn't hear this level of noise in Tonaci's clips but then don't recall whether he was using an outboard mixer. If this is indeed the inherent noise floor of the camera's audio subsystem when providing preamplification and phantom power, it is, in my judgment, unuseable. Very, very disappointing, although I will certainly give the dedicated and brilliant folks at RED ample opportunity to address the cause of this noise and implement necessary improvements, be they firmware or hardware.

The good news is that the audio sounded fine in line mode with the outboard mixers handling the mic chores. I concur that there was a very different tonal fingerprint between the two mixer samples with the 302 giving a pronounced boost to higher frequencies (and a louder output overall). I presume that was due to differences in gain settings and in the mixers themselves?

A very low level of noise is evident at the beginning of each mixer clip but is so low as to be totally lost once the speaker started. Was that noise the noise from the camera fans or from something else in the environment?

[JFirestone]

I am checking with Jeff, my sound guy, and one of us will post more details shortly. I know when I did a test with my ME66 I had to crank the levels almost all the way up to get proper levels. We used a MKH416 in these tests though, and I know it is a much hotter mic than the ME66, and the levels were significantly lower than what they were with my ME66. Jeff will be able to answer more definitively. I just checked my camera, and I don't think the settings have been changed since the test. It is currently set at 37dB.

[JFirestone]

A very low level of noise is evident at the beginning of each mixer clip but is so low as to be totally lost once the speaker started. Was that noise the noise from the camera fans or from something else in the environment?

I do believe that the noise you are hearing on each of the mixer clips is the camera fan. Jeff was sitting less than 3 feet away from the camera when doing the recordings, and while the microphone is very directional, he was close enough to pick up the fan noise.

[Fergus Meiklejohn]

I do believe that the noise you are hearing on each of the mixer clips is the camera fan. Jeff was sitting less than 3 feet away from the camera when doing the recordings, and while the microphone is very directional, he was close enough to pick up the fan noise.

I don't suppose you can remember what the fan setting was can you?
That noise isn't what I'd describe as "silent"..:pinch:

As far as the hiss goes, I'd agree with you all that this amount of hiss makes the RED mic level inputs pretty unusable.. I'm sure RED will sort it out as usual..

[S. Um]

JFirestone, thank you for posting the audio clip. I agree with the others here that the noise level from the Red preamps are unacceptable, especially from pro level gear. I'm surprised we haven't heard more complaints about this. Anyway, I hope Red is looking into this problem and can come up with a fix soon.

[Chris Parker]

Wow. Just read this whole post today for the first time. I can't believe someone from RED has yet to respond.

One person I would be very interested in hearing from on this is Gibby. He seems like 'the man' when it comes to RED as an EFP solution. Gibby, you put it through it's paces with audio on an ENG type shoot yet? What are your thoughts?

And folks at RED, what are you saying about all this? I am assuming things are not as bad as this thread leads us to think. Although it is scary. I just know that REDs have been in many situations shooting sound, and as of yet (until this thread) I haven't heard any alarm bells going off.

Very interested to hear from Gibby AND RED on the topic though.

[Kenn Michael]

The preamps are unbelievably noisy. I have my preamps set at 20db and the hiss is still very much there. Audio is clean with the line inputs as eclaire has pointed out.

It'll be interesting to see if they can get rid of the hiss as another software fix instead of swapping out the hardware.

I'm a post audio mixer as well, and I'd call this amount of hiss disastrous on a mix stage.

[Kenn Michael]

ALSO, there is a huge DC offset in the recorded audio. I'll be calling RED tomorrow about the audio issues.

[Greg M]

ALSO, there is a huge DC offset in the recorded audio. I'll be calling RED tomorrow about the audio issues.

I reported the DC offset to Red last week, the hiss is gone on my camera w/ Build 13 if I only enable CH1 and CH2.
Do you have all 4 channels enabled? Try enabling only the channels you are recording to and you should lose the hiss.

The DC off set is another issue, I was told they are working on it.