Cinema Camera 6K sound problems

I have seen similar posts about this before with other BMD cameras and am waiting to see any responses that address the issue with specific examples. At the very least I would like to hear from Blackmagic camera owners that this is what they are experiencing or no, that sounds broken. To me it seems broken. I’ll start with the general with specifics below.

Checking these forums I have found what seems like the same problem and the responses they have received are vague, at best:

Responses stating that you should always be shooting dual system sound so it doesn’t matter whether or not the inputs are any good.

Responses stating that the mic they used was too weak so they should use a mic with a battery.

Responses stating that the 3.5mm jack preamps are “notoriously bad” and they should use the phantom powered mini-xlr jacks instead.

Responses stating that there is a repeatable known issue where the audio cuts out when the gain is raised too high. (From 2019 but erupted in 2023)

I have tried all of these and are having the same problem with every “solution.”

Here is what I am experiencing:

When I received the camera I immediately charged a battery, put in a card, put on a lens and shot some test shots of my sons sawing wood for their pinewood derby cars. I checked that it was set to camera audio left and right for the inputs. I left the gain at the default. I just wanted to see what I would gety right out of the box.

I was no more than 4 feet away due to space limitations. They were talking at a normal speaking volume for 8 and 11 year old boys and, as I said, sawing wood. I also would talk to them over the sound of the sawing from right behind the handheld camera.

When I reviewed the footage at first I thought there was no sound at all but, with headphones on I can barely hear it. I then tried a few things in my house while my family was watching TV. I noticed that the meters never went above around -40dB. With headphones plugged into the camera, I could barely hear anything either. Yes, I was plugged into the headphone jack, not the microphone jack. With the gain turned all the way up (+6dB for the on camera setting) I get levels of around -30ish to -25dB.

I then tried a microphone in the 3.5mm jack - the RodeVideoMicro and set the inputs to 3.5mm - mic left and right. I got the same results. If I increase the gain to get the levels into the -6dB range I got significant background noise.

I have made several calls to Blackmagic customer service with various results:

The first person I talked to suggested I update to the latest firmware - no change

The second person kept insisting that there is no “normal” sound level and of course I would have to adjust input levels depending on the should level of my subject. Not addressing the issue that I could not hear my subject at all unless I “adjusted” my input levels all the way up.


Since all of this was just quick “living room” tests I decided to do more controlled tests.
I tested the following:
RodeVideoMicro - into 3.5mm
RodeVideoMic NTG (mic built in gain set at manufacturer rec’d 10)- into 3.5mm
Rode NTG-2 - into mini-xlr using a battery in the mic
Rode NTG-2 - into mini-xlr using +48v phantom power
Sennheiser MKE400 - into 3.5mm
Zoom H4n - using it only as a microphone into 3.5mm
Zoom H4n - using it as an audio interface between microphone and camera into 3.5mm
RodeVideoMic NTG into Zoom
Sennheiser e200 GW wireless into Zoom

I tested all of these mics in the following way:

1. Record at the default input level on the camera, noting what the audio meters were reading.
2. Record at whatever gain increase I needed to get the audio meters to land around -6dB (or as close as I could get. Some never got there.)

I then took those files into DaVinci Resolve. I raised the low audio level files to see what it would take to bring them up to around -6dB and hear what noise it added.

This is already an enormously long post so I’ll just sum up my findings. What I discovered is that ALL microphone levels regardless of input method were so low that their input levels needed to be raised to the maximum and for the on-board microphone, even that wasn’t enough.

The only setup that resulted in “normal” expected audio levels was when I either used the Zoom H4n as a microphone or routed the microphones through the Zoom H4n. My assumption is that this method utilizes the Zoom’s preamps rather than every other method using the Blackmagic preamps.

If that’s what people mean by saying that the onboard preamps are “notoriously bad” it seems a little out of spec from what any other camera manufacturer considers normal. I have never, in my years of using audio/video equipment run into this kind of audio issue.

I will render and post my tests if anyone is interested and, hopefully we can quantify the problems I and others are having and maybe we can finally get an apples-to-apples conversation.

Sounds like you have a problem with the preamps. I have a 6k G2 but haven't tested the onboard (built in) mics yet. I generally use the built in mic on my fx3 for scratch audio, but it's usable in a pinch...

If you had the levels set to Line for the mics, I could understand your recording would be near inaudible, but you have assured us that you are using mic levels.

What happens when you have no mics plugged in to the 3.5mm jack or the XLR? Just set the first page of the Audio tab to camera-left and camera-right and talk. Do you see higher levels of audio on the screen than when you had mics connected to the camera audio ports?

As for you expectations that your recording should be much higher, I find you don’t need to get the levels into the yellow zone to have good results in post.

Since I don’t have your camera, please tell me if you have a High setting you can select to boost your audio. I use that setting on one of my cameras.

If you need to boost audio in DaVinci Resolve, there are many ways to do that. I use the dropdown menu selection so that my clip audio in the timeline conforms to one of the industry standards such as EBU. If you still have a lot of noise, there are many effects that can deal with that. Some of the recent effects that Resolve now offers are Voice Isolation and Dialogue Leveler; you can select them at the track level in the Mixer in the Fairlight tab.

To illustrate one approach, say Track A1 has the voice and the saw recorded. Duplicate that track as A2 and then use Voice Isolation and Dialogue Leveler in the Fairlight mixer to enhance the spoken audio and remove the sound of the saw. When you playback A1 and the new A2 tracks, your spoken words will be better.

If my previous post doesn’t help, it may be your camera’s at fault. But it might be working properly according to your settings. We can’t really know how all settings interact. BMD Support may request that you send the camera in to have it diagnosed.

We do seem to know the mics are not at fault though as they work well with your external recorder.

Understand this is very frustrating. Appreciate that you are trying various options to get your desired results.

Rick,

Thank you for the detailed response. For your questions:

What happens when you have no mics plugged in to the 3.5mm jack or the XLR? Just set the first page of the Audio tab to camera-left and camera-right and talk. Do you see higher levels of audio on the screen than when you had mics connected to the camera audio ports?

I know my post was huge and easy to get lost in it. The first tests were without microphones. My sons talking and sawing wood was with just the camera microphones (set to camera left and right.) The levels when I am about 3-4 feet away from the camera are around -40dB.

Since I don’t have your camera, please tell me if you have a High setting you can select to boost your audio. I use that setting on one of my cameras.

I have looked pretty extensively at the menus and read the manual from beginning to end (literally) and haven't seen any indication of a "High" setting.

I do know how to boost the audio but I feel like I shouldn't have to boost everything I ever record and then perform noise reduction on everything because.

If my previous post doesn’t help, it may be your camera’s at fault. But it might be working properly according to your settings. We can’t really know how all settings interact. BMD Support may request that you send the camera in to have it diagnosed.

I believe this is the case. Yes, I have called BMD support - it was in my original post (not being snarky, I know it was a loooong post):

I have made several calls to Blackmagic customer service with various results:

The first person I talked to suggested I update to the latest firmware - no change

The second person kept insisting that there is no “normal” sound level and of course I would have to adjust input levels depending on the should level of my subject. Not addressing the issue that I could not hear my subject at all unless I “adjusted” my input levels all the way up.

Those were only the first two calls. Another suggested my microphones were the problem and looked up the RodeVideoMicro stating that it's sensitivity rating was -33dB so it "was not strong enough to be heard by the camera." He also said I should use a Shure SM57/58 because it was a condenser microphone. For those who don't know that's a "Man on the street" kind of handheld mic, or one that you'd see on a mic stand for a singer. Not a microphone used in film production He also said that the onboard microphones aren't meant to be used.

As I said earlier in this follow up, I believe it can't be operating as expected so I sent it back to B & H for exchange. I only had a 30 day window so I had to act. The replacement should be on its way tomorrow. I am hopeful that that will provide all the answers I need (and work as expected.)

I put all of my tests (minus the initial video where i discovered the problem) up on YouTube - link below. It is processing as I write this so hopefully it will be available before anyone sees this post.

I appreciate the help. I'm glad active forums like this exist.

Cheers!
Daniel

Here is what I am experiencing:

When I received the camera ...

I don't understand the situation given that you experienced the audio problem right after you received the camera.

If this is a new camera, Blackmagic’s reseller should either tell you what you’re doing wrong or replace the camera.

You did the right thing, sending it back to B&H. If I remember correctly, the BMPCC 4K had a similar (if not so extreme) issue, which a firmware update improved (a bit), although in that case the onboard mics were substantially better than the 3.5mm jack from the outset.

The levels you describe are not within the realm of "reasonable variation" between units. If the replacement is the same, you obviously have to decide whether you can live without onboard sound without external amplification.

Rob, Thank you for checking it out.

What I'm trying to get to the bottom of is whether this is normal or if I have a broken camera. As I stated at the beginning, as soon as I noticed what I think is a problem I looked at forums and talked to both the vendor and BMD support and was told that this is normal. Even forum responses when anyone says they are having sound problems were told things like "don't use the onboard mics, the preamps are terrible, use a battery powered mic, only use the xlr inputs, etc,...

If this is normal then something is very wrong with the design of the camera. Before I just sent it back and got a replacement with the same problem I wanted to get an understanding of what I'm dealing with. So I posted as clear of a description of what I am experiencing. If everyone responded with "Yup, that's what mine is like also." Then I would look for a different camera. If everyone said that that was not what they experience then I would try to exchange it for a properly working camera.

But, as I said, I sent it back for exchange. We'll see in the next week whether the issue is resolved or not.

Cheers!
Daniel

Daniel, looking forward to your experience with the replacement camera.

As for that High audio setting, I use High on my URSA Mini 4.6K but I see it’s not available on my BMPCC4K.

I record audio externally when shooting with the BMPCC4K but I do record in the UM4.6K camera using Sennheiser 416 MKH with 48V phantom power as a backup in case the MixPre-6 II ever fails (which seems like it will never fail). Admittedly I don’t have young children or a cat running a saw to see how the Pocket handles the sound levels.

Another suggested my microphones were the problem and looked up the RodeVideoMicro stating that it's sensitivity rating was -33dB so it "was not strong enough to be heard by the camera." He also said I should use a Shure SM57/58 because it was a condenser microphone. For those who don't know that's a "Man on the street" kind of handheld mic, or one that you'd see on a mic stand for a singer.

I do know, the SM57 and SM58 are classic dynamic cartioid (not condenser) mics. These are both capable of extremely high SPL and as such are not very sensitive and not super useful at 4' unless you're using them for drum overheads or some other high SPL source.

I'm curious to see the difference between the waveforms for the Zoom recorder and the camera. The camera "should" land somewhere between notoriously bad and -6db. I don't know of any mic that's going to reproduce a conversation from 4' away (without gain) at -6db so that's not entirely unexpected. With normal conversation at a distance of 4' I think -20db to -30db is probably a reasonable expectation.

If you want to get scientific, download some pink noise to get an accurate A/B.

https://www.audiocheck.net/testtones_pinknoise.php

Good Luck

I’ve watched part of your video six posts above.

The video below was made by Jessops. Jessops isn’t some guy on YouTube. It’s a major UK photography chain. Its video shows the pickup performance of your Røde VideoMicro at 1m, 2m and 3m. It is possible that there are videos on YouTube that do the same kind of thing for your Røde VideoMic NTG.

How Far Can you Use your Rode Microphone?

If your VideoMicro isn’t itself defective (unlikely given that it isn’t the only mike you had this problem with), you have the mike plugged in right, and you’ve followed the Røde instructions on setting level, I would regard the performance of the camera that you sent back as simply unacceptable.

I would suggest that you re-read the Blackmagic user guide section on audio, and Røde’s user guide on the mike, before you try out the replacement camera. Also, there are YouTube videos on setting up the VideoMicro for recording that might be worth a look.

Note what the Jessops video says at 1:33. I’d suggest that you also watch the follow-up video referred to.