SD 633 set up. Does this seem reasonable?

[Jonathan Levin]

Hi all.

Getting to know my 633.

I'll be recording 24 bit 48k poly files to card. Scratch track will be from Nikon D800.

Is this set up correct to you:

Mixer out (line level) xlr to 1/8" mic in (also line I believe). Set unity using tone to set camera.

1/8" cable from headphone jack on camera to 1/8" RTN on ) 633 for monitoring audio going to camera.

Any suggestions? Does this sound reasonable?

Jonathan

[Rick Reineke]

You would need to attenuate line level to mic level; balanced to unbalanced as well if using the main XLR outs. I think the 633 also has an aux. 3/4 send via an unbalanced 3.5mm TRS jack, which maybe be easier than building (or buying) a custom XLR to 3.5mm TRS cable. I don't know what level it spits out either but most SD mixers offer some kind of attenuation depending on the output. There's also output connections and returns on the 10-pin Hirose connector as well. Wiring the cam's 3.5mm input plug is kind of up to you, depending on whether you want to feed both L&R channels, just one, or with a cam mounted mic on one channel, the mixer's output on the other.

[Jonathan Levin]

Rick thanks for that. I already have a custom xlr to 1/8" cable. I was using that with my shure fp33 out to D800 in and the audio was quite useable.

I'll have to play with the levels and settings on the 633 to see what works. Again the camera track is just going to help sync the mixer audio in post. I'll slate too.

As far as the RTN, is it correct to assume that that is now what they used to call monitor in?

No on camera mic will be used just a shot gun and lav, both on iso tracks and mixed in post.

[Rick Reineke]

"As far as the RTN, is it correct to assume that that is now what they used to call monitor in?"
- Yes.. that's what Shure called it as I recall.

[Jonathan Levin]

Great Rick! On the fp33 it is indeed called monitor in.

Now go bbq something and have a great rest of the weekend!

Cheers.

Jonathan

[Richard Crowley]

A "1/8" mic in" on a DSLR would be MIC LEVEL, It will NOT be "line level"!

Fortunately the SD 633 has switchable XLR outputs. So you can switch the 633 to MIC LEVEL output to accommodate the mic-level input of your DSLR.

[Jonathan Levin]

Richard, i overlooked that thanks. My fp33 had mic/line switchable outs too.

[Steven Digges]

Hey Johnathan,

Why record 24 bit 48 k audio files? Is that what you edit in? Most video codecs are 16 bit.

Steve

[Richard Crowley]

It is quite common to record and edit in 24-bit depth even through we are only releasing in 16-bit.
The big reason is HEADROOM. Especially if you are recording something unpredictable.
Or if you don't have an experienced, dedicated crew person monitoring the audio full-time.

I record in 24-bit all the time even for audio-only projects. It isn't a video thing.

[Jonathan Levin]

And I know I can convert from 24 bit to 16 bit or anything else. Can't go 16 to 24. More just to have a master file I guess just in case.

[Jim Michael]

Originally Posted by Richard Crowley

It is quite common to record and edit in 24-bit depth even through we are only releasing in 16-bit.
The big reason is HEADROOM. Especially if you are recording something unpredictable.
Or if you don't have an experienced, dedicated crew person monitoring the audio full-time.

I record in 24-bit all the time even for audio-only projects. It isn't a video thing.

What do you mean by headroom here? And how does that mitigate risk from something unpredictable, in the recording sense?

[Jonathan Levin]

I'm goiung to go out on a limb here but Richard and others really know the answer. I'm just exercising my still developing audio brain:

Isn't headroom the "sound" you get with everything turned down on a mixer, but you still hear audio in some fashion, like a hiss or hum, for lack of the correct term. Just the sound of the electronics?

I may be getting this mixed up with noise floor.

Again, someone who knows way more than I will add something I'm sure.

Jonathan

[Richard Crowley]

Originally Posted by Jim Michael

What do you mean by headroom here? And how does that mitigate risk from something unpredictable, in the recording sense?

Having 24 bits of dynamic range allows you to record at a LOWER average level while maintaining equivalent signal-to-noise ratio. That way you have more "headroom" which is the margin of safety between your predictable peaks and clipping.

Back in the bad old days of analog recording, tape was pretty forgiving of occasional peaks beyond the end of the VU meter. But in the digital world, 0 dB FS (Full Scale) is the ABSOLUTE HARD LIMIT of recording. If you go the slightest bit over that, the signal will be CLIPPED. And that means DISTORTED.

The major task of audio recording is setting the record levels. You need to keep your audio in the "Goldilocks Zone". If it is too low, you will be "down in the mud" of the noise floor of the gear. And if it is too "hot" you will hit the top of the range and CLIP the signal.

24-bit gives you a much more comfortable dynamic range to work within so that you can set your average levels low enough to avoid unexpected clipping while still having enough bits below you to stay well out of the "mud" of noise floor.

[Jonathan Levin]

Thanks Richard!

[Jim Michael]

Interesting. I always took bit depth to define the number of discrete steps between the minimum and maximum levels of whatever was being measured.