Audio Levels Technique

[tirapell]

Nothing wrong with the 702 reading -18 dBFS when presented with a 0dBu tone, I'd leave the 302 at the default tone output level rather than mucking around with it. In fact 0dBu = -18dBFS is the EBU alignment standard and works just fine. All we're really concerned with is when you look at the mixer meter and see something registered there, you know what it implies is going on in the recorder. What it tells you is that when the mixer's 0dBVU light is on you have 18 db of wiggle room before the recorder will clip. Set your mixers output limiters to kick in at, say, +16dBu and you don't have to worry about clipping as any signal excursion trying to pass -2dBFS on the recorder will get limited

Steve, I understand what you're saying. I have to apologzie though. I wasn't looking at the unit right now and got turned around. Here's what I meant to say -- similar just the other direction.

Correct. It is. As displayed on the 302 meters. However, on the 702 meters, it shows-22dBFS (which is likely somewhere between -22 and -20 since there is no -21).

I should be fine then as the mixers output limiters will kick in long before I get to -2dBFS on the recorder with 22dBu of wiggle room, correct?

 

[Steve House]

Steve, I understand what you're saying. I have to apologzie though. I wasn't looking at the unit right now and got turned around. Here's what I meant to say -- similar just the other direction.

"Correct. It is. As displayed on the 302 meters. However, on the 702 meters, it shows-22dBFS (which is likely somewhere between -22 and -20 since there is no -21)."

I should be fine then as the mixers output limiters will kick in long before I get to -2dBFS on the recorder with 22dBu of wiggle room, correct?

Yep. see my previous post that I just edited. The 0dBu output of the 302 reading -22dBFS is pretty darned close to the SMPTE standard. If you want a little hotter level, go ahead and turn up the recorder input a couple of notches to get 0dBu from the mixer to read -20 or -18 on the recorder. But leave the mixer tone output level itself at the default rather than kicking it up.

 

[tirapell]

Yep. see my previous post that I just edited. The 0dBu output of the 302 reading -22dBFS is pretty darned close to the SMPTE standard. If you want a little hotter level, go ahead and turn up the recorder input a couple of notches to get 0dBu from the mixer to read -20 or -18 on the recorder. But leave the mixer tone output level itself at the default rather than kicking it up.

So it was apparently just a tiny bit off. Since the 702 adds gain in line level input to the tenth of a decibel, it only took +0.2dBu of gain to get the light to hit -20dBFS.

Thanks for all the help! Plan to give a thorough testing tonight at an event.

 

[Steve House]

So it was apparently just a tiny bit off. Since the 702 adds gain in line level input to the tenth of a decibel, it only took +0.2dBu of gain to get the light to hit -20dBFS.

Thanks for all the help! Plan to give a thorough testing tonight at an event.

Be sure to get back to us with the results of your field testing

 

[John Willett]

Nothing wrong with the 702 reading -18 dBFS when presented with a 0dBu tone, I'd leave the 302 at the default tone output level rather than mucking around with it. In fact 0dBu = -18dBFS is the EBU alignment standard and works just fine.

Correct :thumbsup: - 0VU on an analogue meter should be set to -18dBFS on the digital device (EBU standard), or -20dBFS if you are in the US (SMPTE standard).

This allows the correct headroom.

 

[davefisk]

I know I'm probably in the minority on this, but I usually run as hot as I can, numbers be damned. I guess this comes from my days recording drums to 2" analog tape. I'll send tone at -20 to calibrate machines, but after that, I'm usually running pretty hot. I've never had an issue with this. I will say that I don't just set levels and sit there. I have to be very aware of the script, and stay on the faders accordingly.

 

[tirapell]

Thanks guys!

Thanks guys!

Just a quick report:

Shot on Thursday evening and Saturday morning with the double system audio and the set-up described in this thread (boom into 302 mixer to 702 audio recorder). I have to say, the results were VERY good, limited only by my inexperienced audio guy(s) who I'm having to train on the fly. I try to get everything set-up and ready to go and he is only responsible for:

1. Pressing record on the 702
2. Getting the boom in position
3. Operating the fader (only 1st channel)
4. Monitoring on headphones

I'm teaching him on a "need to know" basis, but with limited responsibility he can focus on boom position and audio levels/monitoring.

For a first (and second) run, really it came out pretty well. It's difficult in some ways to have 2 separate recording devices (video & audio) but easier to get better shots in other ways. Definitely a bit of give and take, but a vast quality improvement.

Thanks for all the help getting this set up. The safety track works as intended (-6dBu from main track) and should be perfect for unexpected loud spikes, plus it allows the main channel to run a little hotter by design.

 

[tirapell]

Here's a quick excerpt, just to give you an idea of how the audio turned out. Ignore the video editing. This was done in about 2 minutes.

Password: audio

 

[Greg Smith]

Take this with a grain of salt -- I have old ears, and my monitoring setup is not the very best -- but I think I hear a tiny bit of delay in the right channel relative to the left. When I monitor only one side at a time, everything sounds fine. Both together has a slightly reverberant or "flanged" effect on my system. I can't imagine this could happen in production using the audio setup you described, but I wonder if one channel got shifted a little bit in post.

- Greg

 

[tirapell]

Tehe this with a grain of salt -- I have old ears, and my monitoring setup is not the very best -- but I think I hear a tiny bit of delay in the right channel relative to the left. When I monitor only one side at a time, everything sounds fine. Both together has a slightly reverberant or "flanged" effect on my system. I can't imagine this could happen in production using the audio setup you described, but I wonder if one channel got shifted a little bit in post.

- Greg

Could it be because I left BOTH channels on the video (I did it quick and didn't edit out the 'safety track' which was -6dBu from the main track)? Nothing else changed so I am positive it didn't shift after recording. I don't hear it, but I'm not saying it's not there. I know I don't have the most discerning ears when it comes to perfect audio.

 

[tirapell]

Take this with a grain of salt -- I have old ears, and my monitoring setup is not the very best -- but I think I hear a tiny bit of delay in the right channel relative to the left. When I monitor only one side at a time, everything sounds fine. Both together has a slightly reverberant or "flanged" effect on my system. I can't imagine this could happen in production using the audio setup you described, but I wonder if one channel got shifted a little bit in post.

- Greg

Try this one with only the main audio track. Let me know if the delay is gone.

Password: audio

 

[Greg Smith]

The new version sounds excellent to me. My only minor concern about the audio is the low-frequency traffic rumble in the background. You might see if you could roll off the low end a little without hurting the voice too much. Even that can be acceptable in a field shoot as long as there are plenty of other clues that you are interviewing real people in real environments, so it's not actually a great big deal. A lot of my work has similar issues, and I've never had anybody complain about it.

What microphone were you using?

- Greg

 

[tirapell]

The new version sounds excellent to me. My only minor concern about the audio is the low-frequency traffic rumble in the background. You might see if you could roll off the low end a little without hurting the voice too much. Even that can be acceptable in a field shoot as long as there are plenty of other clues that you are interviewing real people in real environments, so it's not actually a great big deal. A lot of my work has similar issues, and I've never had anybody complain about it.

What microphone were you using?

- Greg

Thanks for the response. I'm glad you pointed that out as I'll need to remember to turn off the safety track if I'm not using it for a finished product. You're right about the traffic. I stupidly did another interview right in front of a big refrigerator humming away. It came out ok for what I'm doing and due to the set-up I'm using (shotgun on boom close to talent, high quality preamps, mixer, recorder, etc), but live and learn for sure. Wish I had that one to do over. I see why experience is so important. When you're doing things for the 1st, 2nd, or maybe even 10th time, everything seems to be in about 10x speed. It's hard to remember all the things you know to do and have heard from others without the practice in the field.

Mic was always the Sanken CS3e. I only use it with a Rycote Softie now. Next step is the Rode Blip system, but that may be a while. Most of my stuff will be indoors.

 

[Steve House]

Good job!