Gain vs Faders in recorders

#1

Hi everyone,

I am Albert Guimerà, from Spain and, as always, I have another sound related question.

Lately I’ve been messing with the Sound Devices MixPre 6 which my film school has just purchased and while working with it I came across something that I don’t quite understand. I hope you can help me.

The Sound Devices MixPre 6 is a 6 channel audio recorder and mixer that allows you to record 6 independent tracks plus a stereo downmix (so that would be a total of 8 tracks but only 6 of them are “good to use in sound post production”).

The recorder has 4 knobs which in basic mode are used as gain controls for channels 1 through 4 (recorders such as the zoom h5 or h6 have similar controls for their gain settings). This I understand perfectly.

However, when you put the recorder in Advanced mode, the knobs stop acting as gain controls and become faders that, when turned up or down only affect the volume of that particular channel within your downmix, they do not affect the gain of the actual channel track which is recorded separately. If you want to change the gain setting for a particular channel, you must access a submenu and change it using a small selector knob. This is not only slow but it’s also quite annoying since the recorder does not display your channel’s levels while you are changing the gain.

I talked to a fellow student friend of mine who is now a senior (I am a junior) and he told me that this is because, apparently, in pro shoots, sound recordists like to keep the same gain setting. But this doesn’t make any sense to me because, what if you go from recording a really quiet, intimate moment to a really loud moment within the space of one scene? Shouldn’t you change your gain settings to record both moments at a good level?

Other pro mixer-recorders such as the Sound Devices 788T are usually used with a channel mixer such as the CL8. This sounds logical to me because you have 8 knobs to control your gain settings and 8 more knobs to control the level of each channel within your downmix.

Could someone clarify all this for me? As you can probably tell, I am quite confused.

Thanks in advanced,

Albert

#2

So your friend is actually pretty much right; you tend to not want to “ride the gain” too much during shoots, because that can make the editing process a lot more difficult, and in some cases it actually increases your risk of having bad sound. Ideally, you find an appropriate gain setting that works for the whole take, or split the signal into two channels, one with a higher gain for the soft moments, and one with a lower setting for the loud ones. The risk you run by riding the gain too much (changing level as you’re recording) is that you might be a little late on a level change, or make a bad adjustment, and you’ll create a weird volume spike or dip in the middle of a line that can be time-consuming (or sometimes even impossible) to try to fix in post. I’ll often do gain changes while recording if scenes have obvious moments where you can get away with it, but generally I actually try to minimize gain adjustments mid-take.

You seem to understand the concept for what the knobs are doing in Advanced mode, though! It’s allowing you to adjust monitoring volume without adjusting record volume, which is actually really useful - it lets you select and focus on which tracks you’re monitoring, and can really help isolate sound problems during a take. It does seem inconvenient that you have to dive to a sub-menu to change record level (I certainly don’t like the sound of that), but conceptually you seem to totally get what the device is doing on that setting. Presumably what you’d want to do is set your gain levels before rolling on normal mode, and then maybe switch to Advanced to monitor while recording?

#3

Thanks for your quick reply @Kevin_Senzaki. I’ll see if what you suggest is an option as soon as I get my hands on the machine again.

I understand why you’d never change gain settings mid-take, as a matter of fact I almost never do because the first and only time I did it it was a nightmare to deal with in post.

What I meant was (apologies for being unclear in the first place): You should never change your gain settings “mid-take”, I understand that, but should you change your gain settings from one “shot to the next” or should you always try to keep the same gain setting for the whole scene?

I generally change my gain settings with every shot because, since the microphone’s position usually changes, I like to set my levels again, but my friend’s explanation of why the MixPre 6 functions the way it does has me so confused that I don’t even know if what I’ve been doing up until this point is “okay” or not.

#4

Yes! It makes perfect sense to change gain levels between setups, for exactly the reasons that you describe. I’ll sometimes ask actors to speak at roughly the volume they think they’ll be speaking at during the shot (especially if their voices get loud), so I can try to find an appropriate gain setting. Also, sometimes if my tracks are clipping really badly during a take, I’ll lower the gain right away to try to at least save as much of the performance as I can.

#5

I’d be surprised @Guima793 if there is not a setting somewhere in the menu to change in Advanced Mode the knobs back over to controlling gain like they do in Basic Mode. So I’d have a good hard dig through the menu and manual to find the setting. (if the MixPre6 can NOT do this then I’d be a bit shocked at this weirdly random limitation! You have no such problems even on the cheap Zoom F4)

Note though that if you use timecode in your bag with the MixPre6 you lose channels 5/6 :frowning: One of the reasons I don’t like the MixPre6 :-/

So for me the MixPre6 is more like a “MixPre4”

A good tip is to ask them to deliver a few of their lines to you, this increases the odds they’ll talk at a similar level to the take itself than if you just ask them to say random conversation to you. (which could be at a completely different level to the how they are in the scene itself!)

If you’re reading the script itself before you approach the actor you can also often get a heads up as to if there are moments in the scene which are very quiet or loud just from knowing what is going to be happening in the next scene. (having a good chat with others too like the DoP, 1st AD, and director can also be informative about such things, if you can catch them when they’re free without intruding)