V1/FX7 Audio levels part deux

[Steve Mullen]

Originally Posted by Tim Ducharme

2. As mentioned in another thread, the included Sony shotgun mic seems to record very low audio levels - it doesn't get close to reaching what would be considered peak signal strength.

Remember that HDV has a Reference level of -20dB not -12dB. So, the meter SHOULD look lower than you may be use if you have shot DV. Of course, with digital audio you NEVER want to get to near 0VU. -6dB peaks are fine because you can't see really brief peaks.

[Douglas Spotted Eagle]

HDV has the same reference level of all digital camera formats as has been discussed before.
If you acquire audio at an average of -20dB, you're hosed, especially with compressed audio formats. Do *not* acquire at an average of -20dB, even if your particular camcorder has a meter marking at -20 amongst other levels, if you want proper audio for post.
If anything, you need greater levels for HDV, simply because it's compressed, and won't be as forgiving in post as PCM. HDV is mpeg1/layer II audio whereas DV is PCM. However, metering is identical.
-20dB is the ATSC standard for all digital formats on reference tone to broadcast. This bears little resemblance to recording levels.

[Piotr Wozniacki]

Douglas,

Is this to say the V1's supplied microphone is a no-no?

[Steve Mullen]

Unfortunately, someone who posted doesn't understand the difference between REFERENCE level and AVERAGE level. So they post warnings that will only confuse you.

They also waste words repeating what's well known -- HDV uses -20. Nothing new here.

My point, obviously missed by the poster, was that someone used to recording DV -- will see a lower "average" levels when they shoot HDV. They could feel something wrong with the V1's mic when it is working fine. I doubt Sony used the wrong mic on the V1.

PS: Sony and Apple have long used -12dB for the REFERENCE level for DV. JVC has for years supported the option to use either -12 or -20 for DV.

[Bob Grant]

Originally Posted by Steve Mullen

Remember that HDV has a Reference level of -20dB not -12dB. So, the meter SHOULD look lower than you may be use if you have shot DV. Of course, with digital audio you NEVER want to get to near 0VU. -6dB peaks are fine because you can't see really brief peaks.

That's funny the meters on our DV and HDV cameras read whatever the incoming level is, as adjusted by the recording gain control. The DV tape in front of me, straight out of a Sony camera has tone and bars with the reference tone at -18dBFS but one could switch it to -12dB on many of the Sony cameras. This affects the knee of the AGC but if that's causing your HDV camera to record at an average program level of -20dB then you're not doing yourself any favours, switching the AGC off and going into manual is the best solution.

All that aside, a hotter mic does give better recording levels, even with AGC on from our experience.

And yes you can see brief peaks on the Sony cameras' meter at least, little red dot at 0dBFS, don't know if JVC have this feature or not.

[Douglas Spotted Eagle]

Originally Posted by Piotr Wozniacki

Douglas,

Is this to say the V1's supplied microphone is a no-no?

Not at all is this to say the V1 mic is a "no-no." It's an acceptable mic, despite what you're reading in this thread. It's not an optimal mic, an optimal mike is going to cost 10% of the cost of the cam while a great mic will cost a quarter of the cost of the cam.
Reference tones are for delivery to mixed format houses, and bear little relevance to acquisition. In an all-digital environment, reference tones are fairly meaningless.
Steve, you keep bringing up "reference tone" as relates to recording levels. Could you please explain why? It would seem to me the only reason you'd do so is to suggest average or peak levels. I'm clearly missing the reason you keep posting anything about HDV having -20dB reference tones as a feature.

Apologies to anyone confused; the constant referrals to reference tone in discussions of acquisition level has me confused too. Contrary to what's been posted earlier, you *won't* see lower average levels when shooting HDV vs DV vs any other digital format. I realize we all don't have your PhD as you've often pointed out, so please enlighten us. Better still, could you point us to some of your recordings? Here are a few of mine.

Note as Bob Grant pointed out, on older cameras the reference tone is switchable. This is because until the ATSC generated a standard, there was no standard. -10, -12, -14, -16, -18, -20, and even -22 dB were all used as reference points to 0dBVU over the past 12 years. Anyone who has worked with various DAT recorders can verify this for you. All of them used to be different. DV hasn't had a standard of -12dB.

[Craig Irving]

I hope no one objects to my newbie question posed in this thread but... when exactly should I use the input trim? I've been switching between 0db, -6db and -12db during a few loud shoots and yet I still can't seem to notice what exactly it's doing. I'm usually still adjusting my levels so that the VU meters reach 3/4rds full (approx).

As Steve has indicated, does it just depend on the microphone you're using it with and making the levels match, or does it also depend on the environment you'll be in?

For instance, if I'm using the same mic will my input trim setting be the same for a small quiet drama film that it would be for a loud concert environment? I read Steve's book but I'm still a little confused. Does the Vasst DVD get into this a little more?

[Piotr Wozniacki]

Thanks Douglas for clarification. Yes, it's true - my expertise laying somewhere completely else, I got quite confused with a couple of last posts on this subject. Still, I only am using the supllied short shotgun when I'm shooting hand-held and want my setup really like and easy for handling. Also, when I need an XLR input for my wireless, I use the other channel with this mic. And here is my problem: the Sennheiser kit I have is so much hotter than the mic in question, it's virtually impossible to get the channels balanced.

[Douglas Spotted Eagle]

yes, unfortunately Sennheiser has a knack for being a bit hot on most of their products, and many require a pad. You can trim it down in the menus. There are varying schools of thought on this, some folks really like hot mics while others hate them. I'm not a fan of super-hot mics in most scenarios, but that's my opinion. I also tend to be an AT guy, simply because I've got many thousands of $$ tied up in their mics. Their mics are "middle of the road" overall in terms output/sensitivity. They're not quite Sanken, but are far better than what ships with the camera, either. No camera in history, has ever shipped with a quality mic, IMO.

[Seth Bloombaum]

Originally Posted by Piotr Wozniacki

...Still, I only am using the supllied short shotgun when I'm shooting hand-held and want my setup really like and easy for handling. Also, when I need an XLR input for my wireless, I use the other channel with this mic. And here is my problem: the Sennheiser kit I have is so much hotter than the mic in question, it's virtually impossible to get the channels balanced.

I just finished several days of interview shooting. The interviewer's audio will not appear in the final project. Ch. 1 - Supplied short shotgun, camera mounted, for backup and reference only. ch. 2 - Sony ECM-77 wired lavalier, or, Sennheiser EW100G2 with bodypack transmitter and stock ME2 mic.

I don't intend on getting the channels balanced, I'll be using the ch. 2 audio only. If I needed to it is easy enough in editing, doesn't every NLE have this capability?

Yes, the Senn. is HOT. No problem - go into the camera menus and pad the channel down by -16db, or, go to the receiver menu and pad down there. There was no pad needed for the Sony ECM77, so, I was doing a bit of menu fishing when switching between the mics. Takes 20 seconds... and if you're monitoring with headphones (ALWAYS!!!) you know instantly whether your gain structure is set up correctly.

I would add my opinion to Mr. Spotted Eagle's - reference levels aren't usually relevant in digital acquisition.

When we set up a reference between a mixer and a digital recording device (camcorder, minidisk, dat, flash recorder, whatever) we have our choice whether to reference 0db analog to -20, -18, -12, -6... or even 0db digital. The convention is -20 or -12db, but that's no more than a working figure and is totally arbitrary. The only thing we care about is that the recording does not peak to 0db digital - how we get there doesn't matter. If audio engineer "A" says 0db on my mixer is -12db on the camcorder and engineer "B" says she works it at 0=-6db, great. Both approaches are valid.

[Alex Raskin]

So... how do you set V1's audio levels independently per channel when using one mic only?

Z1 used to have this feature, but not V1.

I'm thinking of making a Y-splitter for my XLR mic, feeding Ch2 camera Input from the same mic and therefore making the V1 believe there are 2 different mics connected.

But I'm afraid this simple split will completely throw the impedance.

(The reason for the independent level control, of course, is to have one channel lower to safely record louder sounds like shouting that may overwhelm the "normally" set volume level.)

Ideas?

[Douglas Spotted Eagle]

There is no way to independently control levels with only one mic. The Z1 offers the ability to make a safety channel, but not the V1. I'm assuming they used this as a bullet point difference between the two models.
If you *do* create a Y cable, you'll want to be careful to not switch on phantom. You could bleed off the return, but without digging into some books, I'm reluctant to provide instructions. Since the V1 is rarely my master audio source, I've not needed to be concerned with a safety. Given that a few people have asked, it's probably something I might dig into.

[Steve Mullen]

Originally Posted by Craig Irving

I hope no one objects to my newbie question posed in this thread but... when exactly should I use the input trim? I've been switching between 0db, -6db and -12db during a few loud shoots and yet I still can't seem to notice what exactly it's doing.

In the Chapters on the V1, I cover TRIM -- which is matching the camcorder to your mic's output level. With the Sony mic, one assumes Sony made sure the mic and camera matched. Therefore, you should not need to alter TRIM from the factory default setting which, if I remember, was 0dB. Moreover, you do NOT need to change TRIM to match the loudness of the sound. (There's a section at the end of Chapter 1 that covers the topic of audio Reference Levels, if you want to learn more.)

We've been talking about recording levels, not trim levels. I would re-read the section on setting levels in the Chapters on the V1.