Sound Devices MM1 - questions

IndiePaul · Jul 10, 2013

Hi

Will be filming my first movie shortly.

Film will be shot mostly inside (small apartment).

Audio will be captured using a boomed Audio-Technica AT4053B Hypercardioid Condenser mic linked to a Sound Devices MM1. The MM1 will be linked to a Tascam DR40.

I'm confused by 3 switches on the MM1.

High pass filter: 80, 160, off
User Guide says it is used to 'remove excess low frequency energy'. I'm not an audio pro so not sure what that means and when I should use it. If say there is some low background noise would I use say the 80 high pass filter then?

Peak Limiter: On, off
User Guide says ON 'Activates the peak limiter. Limits to +17db output'. I presume it's okay to always have this on?

Preamp Gain Switch vs Monitor In Gain switch
I understand what the 'Preamp Gain Switch' does (guide says ''selects the amount of gain from input to output, adjustable in 11 increments") but the 'Monitor In Gain' confuses me (guide says "Controls the level of Monitor Input signal"). If I adjust the 'Monitor In Gain' does that adjust the level of the output signal too? If so why are there two switches that basically do the same thing.

I will do lots of testing but wanted to clarify the above prior to doing so. Just a tad nervous since brand new gear and this is my first production.

Any advice would be hugely appreciated.

CraigL · Jul 10, 2013

IndiePaul said:
High pass filter: 80, 160, off
User Guide says it is used to 'remove excess low frequency energy'. I'm not an audio pro so not sure what that means and when I should use it. If say there is some low background noise would I use say the 80 high pass filter then?

What that is indicating, is at what frequency it will let the signal pass. If you select 80, it will block anything below 80Hz, 160 is 160Hz. Generally, if there's some ambient rumble you can't control (a/c for example) you can use this to try and reduce the background noise. Obviously, it's preferable to actual shut the machine down that's making the noise, but if you can't, this is a decent option.

Personally, I've always struggled with which is better, doing it at recording time or doing it in post, hopefully one of the audio pros here can offer some advice on that point.

IndiePaul said:
Preamp Gain Switch vs Monitor In Gain switch
I understand what the 'Preamp Gain Switch' does (guide says ''selects the amount of gain from input to output, adjustable in 11 increments") but the 'Monitor In Gain' confuses me (guide says "Controls the level of Monitor Input signal"). If I adjust the 'Monitor In Gain' does that adjust the level of the output signal too? If so why are there two switches that basically do the same thing.

I would expect this to adjust the gain on the monitor input signal only, there's separate jacks for it on the back. If you have some other signal you need to monitor (from a mixer perhaps) you could feed that mixer's output into the MM-1 so you can still hear it, even though it's not part of the signal that the mic input, or output I would imagine. The gain on that lets you set it's level individually to be comfortable independent of the input gain and headphone level which would be set when you gain staged everything.

The Peak Limiter, I think would heavily depend on the situation. Limiting it to +17dB might be too low, but I think that would depend on what gain the DR40 was set to? Be interested what the pro's think here also.

CraigL

LirvA · Jul 11, 2013

IndiePaul said:
High pass filter: 80, 160, off
User Guide says it is used to 'remove excess low frequency energy'. I'm not an audio pro so not sure what that means and when I should use it. If say there is some low background noise would I use say the 80 high pass filter then?

If you are getting really boomy and woofy bass. Like if you record a truck with a V-8 and loud exhaust passing by, or if you are recording thunder, and the bass is overloading the signal, cut it to try to get rid of the boominess, and tighten up the bass.

Here is an example of bass overloading the signal and producing distortion. I recorded this with the level set too high.

https://www.youtube.com/watch?v=3i8gPKF0rMw

You can hear parts where the bass is sustaining, and everything is distorted, you can't make out the guitars, and the bass quits playing and then you can make things out. This is the bass overloading the input. Turning down the level on my recorder solved the problem, and it's something you can do in conjunction with a low pass filter.

IndiePaul said:
Peak Limiter: On, off
User Guide says ON 'Activates the peak limiter. Limits to +17db output'. I presume it's okay to always have this on?

Ideally you would use this with a compressor if you are doing a scene where someone is talking quietly, and then grows to shouting/screaming. Watch your meters when you set the limiter level and don't let it get into the red.

IndiePaul said:
Preamp Gain Switch vs Monitor In Gain switch
I understand what the 'Preamp Gain Switch' does (guide says ''selects the amount of gain from input to output, adjustable in 11 increments") but the 'Monitor In Gain' confuses me (guide says "Controls the level of Monitor Input signal"). If I adjust the 'Monitor In Gain' does that adjust the level of the output signal too? If so why are there two switches that basically do the same thing.

IndiePaul said:
I will do lots of testing but wanted to clarify the above prior to doing so. Just a tad nervous since brand new gear and this is my first production.

Any advice would be hugely appreciated.

Is monitor in gain the volume control for your headphones/monitor? It shouldn't effect the output.

Alcove Audio · Jul 11, 2013

IndiePaul said:
High pass filter: 80, 160, off

A High Pass Filter rolls off low frequencies at the frequency selected (80Hz or 160Hz with a 6dB roll-off per octave, in this case). Wind and traffic rumble are frequent culprits. CraigL mentioned air conditioners - a HPF will reduce the rumble, but not the hum.

I personally avoid any modification to whatever I am recording; if you take something away it's often extremely difficult to add it back in later. That being said, however, there are times that you will have no choice. An 80Hz roll-off will not affect dialog, but a 160Hz roll-off can affect very deep male voices (James Earl Jones, for example). It's a judgement call.

IndiePaul said:
Peak Limiter: On, off
User Guide says ON 'Activates the peak limiter. Limits to +17db output'. I presume it's okay to always have this on?

This is a tough call. The way the MM-1 is set up the limiter works on both the input and output; you cannot select to limit just the input or just the output. So when you engage the limiter there is a reduction of the signal to the mic pre of the MM-1 and the output level going to the recorder. (My preference would be to limit just one or the other.) So, if you decide to engage the limiter what you will have to do is readjust your gain-staging for optimum levels at the recorder. As I mentioned, I personally prefer to avoid any modification to the signal if I can avoid it. But, as I also mentioned, there are times when you have no choice, such as when you have actors going from a whisper to a scream in the same scene. It's a judgement call that gets easier as you garner more experience.

IndiePaul said:
Preamp Gain Switch vs Monitor In Gain switch
I understand what the 'Preamp Gain Switch' does (guide says ''selects the amount of gain from input to output, adjustable in 11 increments") but the 'Monitor In Gain' confuses me (guide says "Controls the level of Monitor Input signal"). If I adjust the 'Monitor In Gain' does that adjust the level of the output signal too? If so why are there two switches that basically do the same thing.

Two different controls.

The Preamp Gain Switch controls the signal level of the mic.

Look on the rear panel, you'll see "Balanced Monitor Input;" a signal from the audio recorder can be sent to this input so the person using the MM-1 can hear what is being recorded as opposed to hearing what is coming into the MM-1. The Monitor In Gain controls the volume of that external signal coming in to the MM-1, and will have no affect on the output signal; it's for monitoring purposes only. On the bottom of the MM-1 is a DIP switch that will allow you to monitor the signal coming in to the MM-1 only, the external signal only, or both simultaneously (one in each ear).

IndiePaul · Jul 12, 2013

Thanks CraigL, LirvA and Alcove Audio.

Thanks for taking the time to reply.

Your advice is hugely appreciated.

Information received and understood.

All queries fully answered - I just need to get testing and shooting now!