New Audio Board Evaluation

[James Brundige]

My audio credentials: Many years in audio and music. Taught audio recording at Berklee, and film sound at Film Video Arts NYC.

First shoot with new audio board was a classical music performance. A few short tests before hand, now in post.

Executive summary: The new audio board take the Red audio section from barely useable to slightly useable. Not ready for prime time. I hope and assume this will be fixed with Epic.

While the pro audio world functions at +4dB, the Red is another level, something around 0. Feeding it the audio you send to any other pro camera will distort. If you feed it conservatively, it will sound fine, but will need to be significantly boosted in post production. The low noise floor of digital recording makes this possible. It sounds ok, but is not an ideal workflow.

Metering: not enough segments, not very accurate

Phantom power: Does not power my Neumann mics. Anybody have luck with Schoeps or Sennheiser?

Sound quality: The D/A converters are acceptable, but not in the same league as the stunning image quality.

For features and big budgets, two system sound is the way to go. The EFP world will have to get by until a pro audio section, with pots, good meters, and a standardized level is available. Perhaps feeding mic level is a good work around because it can be adjusted: I have not yet tested that. I will continue to record important audio on a second system. (My $3K Sony stills sounds better)

I'm sure we all appreciate the free audio upgrade. It is a step in the right direction. Hopefully the Epic audio section will complete the journey.

 

[Stuart English]

Sound in RED ONE

Sound in RED ONE

No question an external mixer feeding line level, or an external audio recorder will deliver the highest sound quality.


However the other comments I'd ask you to clarify. Not picking on you, really interested in your opinion.

You say that professional audio is "+4dB" ? RED follows what Sound Devices calls "0dBu / -20dBFS"
But where is the issue there, and what exactly do you mean by +4dB.. +4dB what ?

You say that feeding it the same level you send to other camera it will distort. What would you normally send another camera?

You say that the meter does not have enough segments and its not accurate enough - what resolution and accuracy do you need?

You say you hope this will be fixed on EPIC, what do you expect to see in that case?

 

[Rob Gardner]

Audio concerns

Audio concerns

These are pretty severe comments on the audio quality of the new boards. I'd be interested in hearing from other audio guys on the subject. We have been going double system on everything we have done so far, but it would be good to hear another audio review from another source.

 

[Joel Kaye]

Here's my review. I've recorded almost all dialogue I've shot on RED for about a year (old board and new board). I've had zero complaints. More typically I get - "man that sounds great". I use a Sennhieser 416 which is a hot mic and seems to play really well with REDs 48v. I've had a RODE on that didn't work great once.

Anyway - if you're recording chamber music you're probably not taking that into RED, but dialogue and typical sound fx - RED's plenty good. Plus a little post processing goes a long ways.

I would like to see on camera pots and meters that are visible when you're adjusting levels.

 

[Jeff Kilgroe]

I get pretty good results with the onboard audio. There's no question that a good external mixer feeding line level to the camera and/or external recorder is superior, but that goes for any camera I've ever used.

I found the old board to be problematic since it couldn't properly supply phantom power. My RODE mics work great with the new board and phantom power. With the old board, the NTG-2 had to be externally powered even though it has internal battery power (1x AA). It just didn't put out enough juice.

The RODE NTG-3 is a great match with the RED One and so is the Sennheiser 416. The Schoeps CMIT5U shotgun is also a great one. Some mics I don't like are the Sennheiser ME66, AudioTechnica 40xx mics, and just about anything that says AZDEN on it.

I'm hoping that the upcoming DSMC cameras will have a "pro" audio module that includes pots and levels... I'd like to see a module which is essentially a pro audio mixer.

 

[James Brundige]

You say that professional audio is "+4dB" ? RED follows what Sound Devices calls "0dBu / -20dBFS"
But where is the issue there, and what exactly do you mean by +4dB.. +4dB what ?

You say that feeding it the same level you send to other camera it will distort. What would you normally send another camera?

You say that the meter does not have enough segments and its not accurate enough - what resolution and accuracy do you need?

You say you hope this will be fixed on EPIC, what do you expect to see in that case?

First, let me say I am a big fan of the Red camera. It is a game-changing device that produces stunning pictures. My comments are motivated by my conviction that it would not be difficult to record equally good audio. The Red audio section is usable as a sound recording medium, but not in remotely the same league as the images. It will suffice for ambience recording and simple dialogue.

Sorry if my terms are not clear. I use +4 dB as shorthand for +4dBu at 1.23 volts RMS , the pro audio standard, as opposed to -10dBv (-7dBu) that consumer devices send out RCA jacks.

When I send a tone at OdBu out of a pro mixer, it comes into the Red near the witness mark, but the headroom of the camera at that point is so much less than the mixer, it (the camera) has to be run below that level. If I record tone at that level, it comes into FCP at -28dBFS. So any safe recording runs between -50 dBFS and -30 dBFS. This is not an ideal signal to noise ratio.

Real world example: I just shot a stand up with Robert Redford for my latest film (broadcasting this September on PBS). I split the output of a Wendt mixer to the Red and a Sony EX1. The Sony audio was much stronger when imported to FCP. The Red audio, when boosted to match the Sony, was thinner with a lower S/N ratio, and so was discarded. I have sent the same signal levels to a variety of cameras and recorders over the years, and the post production flow produces the same results. But the Red audio comes out significantly lower, too close to the noise floor, IMHO.

Meters: The Red meter has a few segments in fairly large increments. As I watch the meters, it's hard to see the real flow of the audio. It's kind of blocky looking. Anything yellow is right next to crunchy distortion, so I run it in the middle of the green, which produces a useable, but low level, recording. It sounds fine, but it does not conform to industry standards as well as the many broadcast video cameras I have used for the last 30 years.

Is the Red witness mark supposed to be 0 dBu / -20 dBFS? If it is, then the camera starts distorting at about -12 dBFS, which is not enough headroom.

What I want in the Epic.
1. Pots, AKA potentiometers, AKA knobs. A clear and intuitive control of the preamp.
2. Better meters.
3. More headroom.
4. A recording level that moves into post more like other cameras and recorders. I suggest +4dBu as the standard.
5. Really good A/D converters.
6. In summary, it should be a really good 4 track digital audio recorder, so we don't have to handle audio and picture elements separately. In the digital age, there should be no need for a two system recording, unless you are into serious multi-track situation.

I join Rob Gardner in welcoming other inputs and opinions. The real point of this post is to provide feedback in the development of the Epic. I would also love to use the audio section of the R1 more than I do now, and would be happy to know any combination of gear and technique that produces good results. Perhaps I should just get a Senn 416, but I've alway thought of that as an ENG mic. I shoot a lot of classical music, and prefer the Neumann sound.

 

[Eki Halkka]

When I send a tone at OdBu out of a pro mixer, it comes into the Red near the witness mark, but the headroom of the camera at that point is so much less than the mixer, it (the camera) has to be run below that level. If I record tone at that level, it comes into FCP at -28dBFS. So any safe recording runs between -50 dBFS and -30 dBFS. This is not an ideal signal to noise ratio.

I haven't ever recorded anything to a Red One with the new audio board... but this doesn't sound right at all - to me this sounds like either you're doing something wrong, or your board is broken.

The reference manual says "A 0dB reference voltage level of 0.775V provides approximately 8dB of headroom above reference.", so you should be able to feed the camera "+4dB equpment" signal at decent levels.

The levels in FCP or any other editing software should be around -8dB for the in-camera 0dB reference signal, if i understand the specs correctly, and there shouldn't be audible distortion before digital zero.

 

[James Brundige]

I haven't ever recorded anything to a Red One with the new audio board... but this doesn't sound right at all - to me this sounds like either you're doing something wrong, or your board is broken.

The reference manual says "A 0dB reference voltage level of 0.775V provides approximately 8dB of headroom above reference.", so you should be able to feed the camera "+4dB equpment" signal at decent levels.

The levels in FCP or any other editing software should be around -8dB for the in-camera 0dB reference signal, if i understand the specs correctly, and there shouldn't be audible distortion before digital zero.

8dB of headroom is correct. So a normal audio program needs to be recorded BELOW that reference level to be safe. There are lots of invisible 12 dBu peaks in a normal recording. As I said, the same reference tone goes into FCP at -28 dBFS, when transcoded through Red Alert. Same result if I just drop in the proxy.

I do not believe my board is broken: it was just installed and tested. What I am doing is recording a normal audio program in the middle of the safe area, as indicated by the Red meters. The results are a recording that sounds fine, but comes into FCP at an unusually low level.

 

[Anson Fogel]

My tests Mirrors Jame's exactly

My tests Mirrors Jame's exactly

James/all -

My tests and experience, with new audio boards in our R1 serial number 4784, mirror James to the letter. We too are experienced audio folks. We tested with Sennheiser MKH30/60 combo for M/S stereo decoding, our normal field audio config. The EXACT same experience and conclusions, with the exception that our Senhheiser 30 and 60 worked fine with RED phantom power.

We are thus using a Sound Devices 702T, with the usual boom/blimp, and use a clapper for synch, as tethered timecode is not realistic in the field for doco run and gun. But this situation prevents us from using a 1 man crew, we need one on audio, one on sound, and we often do not have sound when we should have, due to run and gun challenges.

We are considering another Sennheiser 60 on the camera, but the usability/practicality of adjusting audio levels on the fly with red, combined with the low input levels/noisefloor in FCP, mean we are not really in the mood to spend the money and time to get another mic, and deal with the mounting and case changes...with EPIC on the way.

James is 100 percent on - world class images, mediocre to poor overall audio.

 

[Rocco Schult]

I am not that much of an audio pro, but always thought for those of us with an audio person using a digital mixer, an AES input might be handy, together with an exceptionally good analogue in of course.

 

[Stuart English]

Audio Input Levels

Audio Input Levels

The reference manual says "A 0dB reference voltage level of 0.775V provides approximately 8dB of headroom above reference.", so you should be able to feed the camera "+4dB equpment" signal at decent levels.

That's incorrect. if you check that again it should say 18dB of headroom...

i.e if reference is ay 0dBu = 0.775V RMS = - 20dBFS you have 20dB of headroom before digital clip, so in practice you should have about 18dB of analog headroom before distortion.

A 0dB tone recorded on the RED ONE should show at "-12" on FCP.

 

[Stuart English]

Audio Levels

Audio Levels

the same reference tone goes into FCP at -28 dBFS, when transcoded through Red Alert. Same result if I just drop in the proxy.

So as a matter of interest for a signal that shows up as "-28" in FCP, where on the RED audio meter does that signal appear -

i.e. how many segments to the left of the witness mark?

 

[Michael Romano]

Might like to check out this thread...
http://reduser.net/forum/showthread.php?t=32765&page=3

I did a pretty comprehensive audio test with the new board and build 20.1.3. As far as actual quality goes, I'm not super impressed with the D/A's on the RED. I can't speak for those that put mics directly into the camera, I've never even tried that as we always have a mixer feeding line level. How bout putting all the audio options in one place though? I would dig that!

Another possible issue:
If you're over modulating on the return from camera but not seeing clips on the RED meters, check the "Output" level setting. It can be overdriven even if the audio is just fine on disk.

 

[James Brundige]

So as a matter of interest for a signal that shows up as "-28" in FCP, where on the RED audio meter does that signal appear -

i.e. how many segments to the left of the witness mark?

A 0 dBu tone recorded right on the witness mark comes into FCP at -28 dBFS, which is -16 on the FCP meter, which has "0" at -12 dBFS.

There is not 18 dB of headroom above that point. Not even close.

 

[Hans von Sonntag]

We are thus using a Sound Devices 702T, with the usual boom/blimp, and use a clapper for synch, as tethered timecode is not realistic in the field for doco run and gun. But this situation prevents us from using a 1 man crew, we need one on audio, one on sound, and we often do not have sound when we should have, due to run and gun challenges.

Anson,

We do docs as well and I hate tethered teams for many reasons. I also don't want to scare people with a clapperboard. Hence working TC-sync of the Sound Device and the RedOne is vital for me. And it works flawlessly. You slave the RedOne's TC with the Sound Device, disconnect them and off you go. On set by eyball the TC does not appear in sync , you will se a difference of a second or so but on the media TC sync is spot on. The only downside is that you have to re-sync both devices after every reboot of the camera.

Stuart, any idea to keep the external TC after reboot?

Hans

 

[Karl Lohninger]

I'm with James here and have exactly the same problems. Stuart, a DVX100 follows the simple standards, why oh why can't RED? The 'meters' are unusable! What about actual db markers there?
I would never use audio on a RED as master the way it is. But even for backup/replay it's rather painful to set up. I'm on the latest 'audio board' btw. NO headroom!!!

Then the headphone output is so low, again, pretty useless......;-(
Jamming the camera (in this case TC 25) is an exercise that's.....well, let's call it 'involved'. I always have to do it twice to get it to sync exactly. The first time it's exactly one second off....?

Turning the camera off makes it 'forget' some settings (display i.e.) AND timecode. I have a hard time naming any other camera with this kind of un-noble behavior.

I'm not really a friend of those 'menu driven' cams and don't see the point....but, as it is now, running sound on a RED is 'annoying' to say the least. There need to be meters, there need to be markers, there need to be switches and pots that are accessible, there needs to be stable TC - I mean come on, one's supposed to tape a lockit box onto the beast? - and there needs to be a headphone output - with a pot even - that puts out usable levels.....simple things really that - as I said - a DVX or HVX or EX1/3 can do in it's sleep. Time to wake up ;-)

Karl

PS. audio standards are well known in the industry ....

PPS. even though lately the fan(s) inside the camera stops when recording - or are supposed to stop - the camera, used on a sound stage too noisy for close-ups. And to watch the camera department to tape ice-bags all around the cam body plus a dedicated fan just for the camera in a moderately hot sound stage is a view to behold ;-)

Anyway, aside from all the qualities the RED has, there's some serious short comings on the audio (TC) dept.

 

[Eki Halkka]

That's incorrect. if you check that again it should say 18dB of headroom...

I copy-pasted that...

...from what seems to be an old version of the manual. The one currently at Red site says 18 dB.

 

[James Brundige]

I copy-pasted that...

...from what seems to be an old version of the manual. The one currently at Red site says 18 dB.

This is critical information. If the witness mark is 0dBu, where is the yellow?

From my tests, it appears to be 6 dBu above the witness mark, or about two meter segments.

Stuart, do you know what the meter increments are?

 

[David Rasberry]

We use +4dBu as the maximum volume reference point, but standard VU meters are calibrated to 0 reference at .775v/0dBu. The extra 4dB is minimum VU headroom before clipping and is the red zone above 0 reference on a VU meter, with most modern line level circuits able to handle +18dBu-+20dBu analog peaks before clipping. Hence the -20dB FS digital correlation with 0dBu analog as 0dB FS is the digital clipping point.
I don't know about Red's audio circuits, but inadequate analog peak headroom in the preamps as been a problem with Sony ENG cameras for as long as I can remember.
If the outboard mixer uses LED level indicators they are usually calibrated to peak reference rather than RMS or VU these days, meaning they read about 6dB higher for the same signal level compared to a standard reference VU meter. Same could be true of Red's internal meters.

 

[James Brundige]

Post Script

Post Script

This thread was inspired by my first experience with the new audio board. It is a chamber music piece, where I was fed a great mix from house audio.

The show is now rough cut, and I have to add this note to the discussion:
The audio sounds fine, and was entirely useable. In post, I had to boost recorded levels from 8 - 12 dBu to get to the broadcast standard of -24 dBFS.

Bottom line is IMHO the audio could be much better implemented, but for those who need it, the Red audio can work.

Here's hoping the Epic hardware will be more user friendly, and provide an audio path in the same league as the amazing Red images. Now for a week at the beach.....w/o computer.