Topic: Sound Devices MixPre-3 and 6, Part 5

[rippleish20]

Thank you. All of this in line with what I've read but, in the end, it's not really clear exactly whats going on.

At the end it does not matter at all. The noise level of this unit is so low and the limiter so good that no matter how you set your gain: your recording will be usable ;-)

Johannes

I understand the concept. I prefer to do the minimum on my recordings post production so it does matter to me. More importantly, I am interested in knowing how it works! I do recognize that it probably makes zero difference noise wise.

[gewwang]

Thank you. All of this in line with what I've read but, in the end, it's not really clear exactly whats going on.

At the end it does not matter at all. The noise level of this unit is so low and the limiter so good that no matter how you set your gain: your recording will be usable ;-)

Johannes

I understand the concept. I prefer to do the minimum on my recordings post production so it does matter to me. More importantly, I am interested in knowing how it works! I do recognize that it probably makes zero difference noise wise.

How do you determine what level to set your gain to?

[spyder9]

^^^  Agreed. How do you determine what level to set your gain? 

Also, why is the Mix levels way-hotter than my Mic levels?  Is Gain, in Advanced mode, applied to the Mix recording or the Mic recording? 

[rippleish20]

^^^  Agreed. How do you determine what level to set your gain? 

Also, why is the Mix levels way-hotter than my Mic levels?  Is Gain, in Advanced mode, applied to the Mix recording or the Mic recording?

In advanced mode, you select a channel using the big channel/fader knob, use the touch screen to drill down to "gain" and use the knob on the side to adjust trim (gain at the the pre stage). The Channel knobs themselves control the second stage gain, the volume of the track going into the mix.

"How do you determine what level to set your gain?" I'm not sure exactly what is meant by this question. I use advanced mode and the above process to set the level. I shoot for +12 to +6 in the recording itself. If I am using microphones, I start  +18db gain wise. SBDs are more problematic as they vary enormously. Being in for soundchecks helps quite a but I typically start at +6 db but can end up from -2 to 30db gain wise (these numbers are relative to what the mixpre starts with, when in advanced mode, when setting a channel to "microphone" or "line".

[gewwang]

^^^  Agreed. How do you determine what level to set your gain? 

Also, why is the Mix levels way-hotter than my Mic levels?  Is Gain, in Advanced mode, applied to the Mix recording or the Mic recording?

In advanced mode, you select a channel using the big channel/fader knob, use the touch screen to drill down to "gain" and use the knob on the side to adjust trim (gain at the the pre stage). The Channel knobs themselves control the second stage gain, the volume of the track going into the mix.

"How do you determine what level to set your gain?" I'm not sure exactly what is meant by this question. I use advanced mode and the above process to set the level. I shoot for +12 to +6 in the recording itself. If I am using microphones, I start  +18db gain wise. SBDs are more problematic as they vary enormously. Being in for soundchecks helps quite a but I typically start at +6 db but can end up from -2 to 30db gain wise (these numbers are relative to what the mixpre starts with, when in advanced mode, when setting a channel to "microphone" or "line".

Well, if you have the knob on the side to adjust the trim and the channel knobs to control the second stage gain, then my question is how do you determine where to set these two settings?

I know that I never had a good answer when I ran V3 into a recorder. Do I run the V3 gain at +30 and the recorder gain at 5? or do I run the V3 gain at +10 and set the recorder gain to 10?

[dogmusic]

This is why I have previously suggested that there is actually no analog gain control but that setting levels is always post ADC.

They say it quite clear. The maximum analog gain is 75 dB. And indeed, with the gain control set to "advanced" you have access to the
analog preamplifier gain.

If you apply gain with the fader then you are applying digital gain. And you can achieve a maximum of 96 dB from microphone to recording.

My thinking is that the analog gain is always wide open. The analog input level is actually set by the source.

[rippleish20]

This is why I have previously suggested that there is actually no analog gain control but that setting levels is always post ADC.

They say it quite clear. The maximum analog gain is 75 dB. And indeed, with the gain control set to "advanced" you have access to the
analog preamplifier gain.

If you apply gain with the fader then you are applying digital gain. And you can achieve a maximum of 96 dB from microphone to recording.

"The maximum analog gain is 75 dB. And indeed, with the gain control set to "advanced" you have access to the analog preamplifier gain"

From my reading this is largely correct, or at least its the impression I've gotten.  This is why I sued advanced mode.

"If you apply gain with the fader then you are applying digital gain"

I think this is true in advanced mode but not in custom...

https://www.dvestore.com/blog/video-sound-devices-mixpre3-and-mixpre6-modes-and-signal-routing/

"If you want discrete, isolated tracks, then you need to be in Advanced or Custom Mode. When you record ISO tracks, the tracks will record the audio signal that is post-gain but pre-fader to the isolated track. This is what we call pre-fader or pre-fade recording. However, you can have the ISO tracks be post-fader. You need to be in Custom Mode and enable advanced settings for both "Channel" and "Record." This makes the ISO tracks post-fader. In Advanced Mode, the MixPres are configured...You also have separate control over the trim control which is the gain, as well as fader control.

The use of terms and the way something is said is important. In custom mode, the ISOs are post fader. Is this just a poor use of the term fader - and they really just mean big channel knobs used as fader controls in advanced mode - or does it mean it's a digital gain? Why say "post fader"?

I guess my conclusion that the pre-amp is a probably a digitally controlled, analog preamplifier. In other words, the knob are digital controls. In custom mode, the "fader" knobs also control the pre up to the maximum pre gain and then the purely digital gain kicks in?

[rippleish20]

^^^  Agreed. How do you determine what level to set your gain? 

Also, why is the Mix levels way-hotter than my Mic levels?  Is Gain, in Advanced mode, applied to the Mix recording or the Mic recording?

In advanced mode, you select a channel using the big channel/fader knob, use the touch screen to drill down to "gain" and use the knob on the side to adjust trim (gain at the the pre stage). The Channel knobs themselves control the second stage gain, the volume of the track going into the mix.

"How do you determine what level to set your gain?" I'm not sure exactly what is meant by this question. I use advanced mode and the above process to set the level. I shoot for +12 to +6 in the recording itself. If I am using microphones, I start  +18db gain wise. SBDs are more problematic as they vary enormously. Being in for soundchecks helps quite a but I typically start at +6 db but can end up from -2 to 30db gain wise (these numbers are relative to what the mixpre starts with, when in advanced mode, when setting a channel to "microphone" or "line".

Well, if you have the knob on the side to adjust the trim and the channel knobs to control the second stage gain, then my question is how do you determine where to set these two settings?

I know that I never had a good answer when I ran V3 into a recorder. Do I run the V3 gain at +30 and the recorder gain at 5? or do I run the V3 gain at +10 and set the recorder gain to 10?

I understand the question better now but I think its more applicable to a V3 than a Mixpre. I've never used a V3 before, but I would do what I do with a uglybox/M10 scenario. I would set the "gain" to the highest level I could for an "average" scenario. If after using it for a number of shows I found I could leave it at 30 and never clip and it left some headroom to fine tune the gain I would leave it there and use the "trim" knob to fine tune it. The Mixpre scenario is different, at least in advanced mode. There are two gain stages but they are not both controlling the final gain on the ISO tracks (which is what I care about). The first stage controls this. The second stage is controlling the volume of the tracks going into the L/R mix.

Lets say you record four tracks - two tracks from microphones and two from the soundboard - and you want to create a matrix later by importing the recorded tracks into a DAW. With the recorder, you set the gain according to what you want the levels on recordings to be. I want my recordings at -12 to -6 db. In the DAW, you adjust the levels of the two pairs according to what you want the mix to be. I typically drop my audience recording by -5 db in the mix, for example. In advanced mode on the mixpre, you are doing both of the processes on the fly. The first stage is controlling the volume of the recording and the second stage is setting the level of the tracks go into a L/R mix, which can be recorded separately.

[spyder9]

^^^  My question:  First stage is the "Gain" in the Advanced Menu option (which affects the ISO tracks loudness)  and 2nd stage is the Knobs (which affect the Mix loudness)?  Does that sound correct?

[Chuck]

Man, you guys got me all confused. I have mine in Custom > Basic ganged left and right.

When I turn the #1 knob it brings tracks 1 & 2 up or down together. The #2 knob controls the gain of track 2 separately and I use that to match channels. When I see the red bars where I want them I'm happy. Do the same for 3 & 4...

[rippleish20]

^^^  My question:  First stage is the "Gain" in the Advanced Menu option (which affects the ISO tracks loudness)  and 2nd stage is the Knobs (which affect the Mix loudness)?  Does that sound correct?

Yes

[jbell]

That's how I've run mine and it was one of the first units shipped!!  Never let me down.  It is the best piece of gear I've bought in a long time.  Super happy with my unit. 

Man, you guys got me all confused. I have mine in Custom > Basic ganged left and right.

When I turn the #1 knob it brings tracks 1 & 2 up or down together. The #2 knob controls the gain of track 2 separately and I use that to match channels. When I see the red bars where I want them I'm happy. Do the same for 3 & 4...

[Johannes]

I understand the concept. I prefer to do the minimum on my recordings post production so it does matter to me. More importantly, I am interested in knowing how it works! I do recognize that it probably makes zero difference noise wise.

The answer to how it really works can only be given by the maker of the unit. And I would very much like to see an official block diagram! As others have pointed out: it is finally a combination of analog and digital gain. I stopped worrying about the technical details, after having used the units a few times. I watch the meters, set the level a bit on the conservative side and enjoy the result.   

I frequently use two settings
1) Gain set to Basic => Faders control the gain stage
I use this, when I want easy control  (no fiddling with the mini knob on the side) and when I only need the ISO tracks. I aim for -12 to -20 dB on the meters.

2) Gain set to advance => Gain is set via trim and faders control the Mix
I use this, when I need the Mix (to feed a camera) or when I use the MixPre-6 as audio interface. In this case I use the trim to get -12 to -20 dB on the meters. The faders are set to whatever the mix requires.

Both scenarios work fine for me in various task.

Johannes

[noahbickart]

Why is SD not being forthcoming about analog vs. digital gain?

I’ve been using custom mode with everything set to advanced, except gain at basic. Then I gang 1/2, 3/4, and 5/6 and use the big knobs to set levels for the ISO tracks, and don’t record the L/R mix.

I’ve been very pleased with the results, but if all analog gain isn’t available in this mode, I’d be interested in trying it another way.

[justme]

The three channel knobs on my MixPre-3 does not have the same angle when set to 0 dB.
Non of them are pointing at 12 and no one is at the same angle as the others. All of them are a few different minutes early of 12.

Anyone else have noticed this or did I just have bad luck?