Basic questions about recording and mixing with Model 12

[Bambi]

Hello, I write to you in search for help with some basic proceedings with the Model 12. In addition to my limited practice with recording and mixing , I find the Model 12 very misterious and confusing sometimes. I'll explain you my starting point and what I'd like to achieve in case you can help me. I work completely dawless. I need to record 3 instruments, one after another, in 3 different channels, and then do the mixdown. I've read the manual, seen different videos, and revised your reference threads, but I'm still confused between basic usual proceedings and the ones in the Model 12;

1) I understand the difference between the analog and the digital world. However, does the Model 12 work any different when setting the best recording levels? Should I aim between -18 and -12 dB, as usual, or should I record as hot as possible without clipping?

2) When mixing, how can I know if my mix is distorting before reaching the Main bus? I don't know what to look at in the Meter Screen

3) Regarding faders, should I record the 2-track stereo mix using only the channels fader levels as a reference? And forget about the Main fader? How can I know then if I'm clipping?

4) Does the Main fader effecting only the external outputs mean that it will effect the 2-track stereo mix only if I press the Post Rec button? Where should I place the Main fader in this case: on top of it's way (+10 dB), on zero, or depending on the incoming level from the channels? (I don't need to do any fade ins or outs)

5) I'm not planning on doing any mastering, so I would like to get the loudest sounding mix possible directly

Please forgive such an extense post. I'm confused and a little bit lost with this question

 

[Mark Richards]

Welcome to the Forums, Bambi.

1) Should I aim between -18 and -12 dB, as usual

Yes​

4) Does the Main fader effecting only the external outputs mean that it will effect the 2-track stereo mix only if I press the Post Rec button?

From Post #13 in the Tips & Tricks sticky thread

POST REC switch
When this switch is on, signals from after the MAIN fader are recorded to the SD card​

5)...get the loudest sounding mix possible directly

Perhaps this DP-24/32 tip will help inform you.​

2) ...How can I know if mix is distorting before reaching the Main bus...
3) ...record the 2-track stereo mix...forget about the Main fader...How can I know then if I'm clipping?
4) ...Where should I place the Main fader...

I don't own a Model 12/16/24, so can't address anything specific to your mixer's operation.

These questions are really pretty generic to audio recording. If you haven't yet done so, you may want to purchase a book like Jeff Strong's "Home Recording", or something similar, available on Amazon and other sources, to help you advance as an audio engineer. ​

 

[-mjk-]

5) I'm not planning on doing any mastering, so I would like to get the loudest sounding mix possible directly

This is the Road To Disappointment. Mastering is essential to music production. You can make the loudest mix possible on a Model 12, but without a limiter, it's never going to sound loud how you want. You need to know that so you don't blame the equipment when your tune doesn't measure up to commercial music.

 

[Bambi]

Hello Mark and MJK, thank you for your messages. Mark, I've read your DP-24/32 tip and found it very interesting and informative. I think I'll go back to it from time to time to refresh different concepts and processes. And thank you for the book suggestion. Do you know any online resource too, in addition to the book, for basic home recording concepts and techniques?

MJK, thank you for the explanation. Don't worry, I won't blame my gear for lower volume results. I'm doing a great effort to learn audio, recording and mixing basics by myself. The main reason of most of my results being far from perfect is my inexperience in the field and my limited knowledge of recording gear and processes. I read and study all I can but I need time to understand the importance and reason of many of the practices and concepts in the field.

Regarding the Model 12, I'd like to precise one of my questions a little bit more. Mark perhaps won't be able to help me as he doesn't have that gear. My doubt is related to the input level adjustments. According to the manual, if I understood it well, I must only use the reference of the SIG lights and the Meter Screen bars, right? I mean that the channels' and Main faders don't effect the recording level, right?

Thank you both for your help

 

[Bambi]

I mean, if the channel and Main faders don't effect the incoming signal level, should I still set them to unity gain or is not necessary?

 

[-mjk-]

@Bambi said:

I'm doing a great effort to learn audio, recording and mixing basics by myself. The main reason of most of my results being far from perfect is my inexperience in the field and my limited knowledge of recording gear and processes. I read and study all I can but I need time to understand the importance and reason of many of the practices and concepts in the field.

You're doing the right thing. Keep at it and you'll eventually become an expert.

I mean, if the channel and Main faders don't effect the incoming signal level, should I still set them to unity gain or is not necessary?

Looking at the block diagram has gotten me dizzy, lol.

It looks like recording to the individual channels is indeed, pre-fader. In some respects the Model 12 is attempting to behave like an inline recording console whereas the signal path to the recorder is separate from the path to the Main L/R bus, which is the bus being monitored.

So, you can use the faders to mix monitors when recording to individual tracks. But the Main L/R faders should be set to unity unless there is a good reason not to. Just remember that the Main L/R bus is being recorded on the main mixdown channels in the recorder.

 

[Bambi]

Hello MJK, thank you very much for your answer. I'm sorry you had to struggle with the diagram to find a solution. I found a short "Note" on the manual that also explains the channel fader roll during recording. On page 40 of the Manual you have a subtitle named "Recording" on the right column. At the end of the column the "Note" says:
---- The channel PAN knobs and channel faders control the playback output signals of already recorded tracks or the monitoring volume of input signals. They do not control signals to be recorded ----

Regarding the Main L/R Bus there is something I don't understand well. I see the importance of having the Main fader at unity gain to get a good recording level on the Main Bus. However, I don't understand very well what this Main Bus recording serves for. First, if I record 2 individual tracks, one after another, I don't know if the Main Bus records the mix of the 2 or only the last one. Second, when I do the mix and balance of the 2 tracks later, the signal used for the mix is send from each channel, right? So, what is the function of the signals recorded on the Main Bus?

 

[Mark Richards]

I think you're getting overwhelmed. Let's take it back to basics for a moment (and trying to keep it as uncomplicated as possible).

This is my general understanding of the Model 12's basic functions:

The Model 12 is designed primarily to be a Front of House (FOH) mixer with multitrack recording and two track mixdown capability.

Your Model 12 has two digital recorders (the SD card):

• A digital 10 track multi-track recorder/reproducer on the SD card
• A digital 2-Track mastering recorder/reproducer on the SD card

The Multitrack Recorder (MTR) has 10 tracks corresponding to the Model 12's channels 1~10. Tracks 1 to 6 are mono; the remaing are paired stereo tracks (7/8 and 9/10). The stereo pair tracks are intended for stereo sources.

Individual Channels are hard-wired to the related specific Tracks (Channel 1/Track 1, etc.).

Mic placement, external gear input/output controls, and the Model 12's Gain controls for Channels 1~10 determine the level of the incoming audio signal to each Channel, and thus to each respective MTR track.

When the Record button is engaged, MTR tracks set to Record Ready will always record the current respective Channel audio signals on the respective MTR tracks on the SD card, whether or not the Channels have been assigned to the MAIN Bus.
​

The Master Recorder has 2 tracks (11&12 - L/R stereo) corresponding to the Model 12's MAIN Bus L/R.

When the Record button is engaged, the Master Recorder will always record the current L/R stereo audio signal present on the MAIN Bus.

If you have the most current Model 12, then your unit has a "Post Rec" button, that when activated, permits the MAIN Bus fader to control the signal going to the 2-Track Master Recorder (11&12). When the Post Rec button is disengaged (or absent, if an older unit) the MAIN Bus fader controls only the XLR output circuit.

On Playback, if the Post Rec button is engaged (or the SD Card button if an older unit), you hear the most current 2-Track stereo mix that's been recorded on the 2-Track master recorder (11&12 on the SD card).

Otherwise, you hear the signals that are on any Channels/MTR tracks assigned to the MAIN Bus.
​

Hope this helps a bit.

Those who own a Model 12/16/24, please offer corrections if I've misspoken so I can edit/correct the above.​

 

[Bambi]

Hello Mark, thank you very much for your explanation. It's a great summary. I think I understand most of it. There are a couple of things that I still doubt:

1) The signal recorded on the Main Bus when I record each individual track I think I won't use it while recording, only when I create the 2 track stereo master. In that case, is it still necessary to set the Main fader to unity gain when recording individual tracks? Because it seems that the fader doesn't effect the recording level at all

2) I'll describe you an example of how I've been recording, mixing and creating the 2 track stereo master until now, so you can tell me if I'm doing it right. I record 3 instruments, one after another: a keyboard line on a stereo track, a keyboard mono bass on a mono track, and a soft percussion set on another mono track (recorded with 1 microphone). I set each channel gain so that the signal stays between -18 and -12 dBFS (I check it on the Meter Screen), except for the percussion, which has some peaks around -6 dBFS. After recording the 3 tracks one after another, I proceed to do the mixing. So I set each channel fader to the level where I want it. I've been usually getting the balance I want by setting the percussion track above zero and the other 2 tracks below zero. I don't add any EQ, compression or effects. As I'm not mastering either, I want to get the loudest mix I can with this settings, so I set the Main fader to a level where the mix almost clips, but it doesn't, usually somewhere below the zero mark (the maximum is +10). I press the Post Rec button. Each channel has the Main send button active, and they are all in MTR Mode. Then, with all the Record Ready buttons inactive, I press the Record button next to the Play button and start the recording. When it's finished, I go to the menu and select the "Stereo Mix Export" option so I can later transfer the file to my computer

3) Next time I record I'll follow your unity gain recommendations for the different channels and Main fader. When MJK reads this he won't be surprised that I get such low volume final mixes, as I don't use any compression or processing at all. However I still feel that the final volume is way under the level it should be, even for being an unprocessed mix. That's why I asked you on the other thread about the Model 12 maximum recording level on the SD card, as the Diagram shows a 22 dB gap between the Main channel's maximum level and 0 dBFS. I can't show you any reference of my recordings yet but, if I have one in the following weeks, I'll post it so you can get an idea of how soft they sound

 

[Mark Richards]

I set each channel gain so that the signal stays between -18 and -12 dBFS (I check it on the Meter Screen), except for the percussion, which has some peaks around -6 dBFS.

You're doing it correctly.​

is it still necessary to set the Main fader to unity gain when recording individual tracks? Because it seems that the fader doesn't effect the recording level at all

Although the MAIN Bus fader doesn't affect the MTR tracks when you're tracking, the MAIN Bus fader is still active and affects any signal assigned to the MAIN Bus. If you don't use the MAIN Bus for anything while tracking, then you can bring the MAIN bus fader all the way down to infinity/off.​

I proceed to do the mixing. I've been usually getting the balance I want by setting the percussion track above zero and the other 2 tracks below zero.

Never go above unity gain. Set all your track faders to zero (unity gain) and adjust individual tracks downward from unity gain to get your balance. This is important for proper gain staging. (this article focuses on live sound systems, but the theory's equally applicable to recording.)

Combining multiple tracks raises the overall level of the combined signal going to the MAIN Bus, which reduces headroom or can overload the input stage of the MAIN Bus circuit, which means your mix is more susceptible to clipping distortion that may not register on your meters
​

I want to get the loudest mix I can, so I set the Main fader to a level where the mix almost clips, but it doesn't, usually somewhere below the zero mark

The MAIN Bus fader and its meter are your static reference points for gain staging in the mixdown process. The MAIN Bus fader should always be at unity gain and lowered or raised only for overall fade-out or fade-in of the stereo mix. Rebalance the track faders, never the MAIN Bus fader, to increase or decrease the overall audio level of your stereo track.
​

I get such low volume final mixes, as I don't use any compression or processing at all. However I still feel that the final volume is way under the level it should be,

There are only a few effective ways of maximizing the audio level of your finalized stereo mix while assuring you maintain good dynamic range and eliminate the risk of digital distortion:

1. Use judicious compression when tracking to help assure you have excellent peak to average signal ratios so you can raise the individual track levels by a few dB;
2. Normalizing the stereo mix; or
3. Run the stereo mix through a master stereo compressor/limiter.

#1 is an acquired skill learned through trial and error.
#2 and #3 require using a D.A.W.
​

Diagram shows a 22 dB gap between the Main channel's maximum level and 0 dBFS.

At the risk of causing yourself a world-class migraine, you may want to take a look at this.
​

 

[Bambi]

Hello Mark, thank you for your answer. I really appreciate you helping me with this. I'm starting to understand the importance and why's of some basic concepts like unity gain and others. I've read your link about gain staging. I always have it in mind in my process. However I was missing the unity gain factor when setting fader levels. I have a couple of doubts regarding this subject. First, as the faders musn't surpass the zero mark, why do the channels reach the +10 level? Second, how can I know if my mix is distorting before reaching the Main Bus? I guess that, if I set all the faders to unity gain and adjust them downwards, it's more difficult that the combined signal distorts. But I don't know if there is any visual reference on the Model 12 to check it. On the Meter Screen there is a screen that shows the signals as they were recorded on each track, but I don't know which screen shows each channel level during the mix, with the consequent decrease or increase as I move the faders.

Regarding the Post Rec button, as I'm not planning of doing any fade ins or outs in my songs, and as long as I set the Main fader to unity gain, it wouldn't make any difference for me to press it or not during the 2 track stereo recording, right?

Respecting the ways of increasing my final stereo mix levels I have to think about it. I want to do all the process again with all the corrections and see the results

 

[Mark Richards]

First, as the faders musn't surpass the zero mark, why do the channels reach the +10 level?

This section has been edited from the original and made better thanks to Ajarn's posts following​

The Block Diagram shows the faders are within the digital circuitry.

Since the Model 12 faders are a digital device and function within the digital domain, adjusting the track fader causes its digital value to change when moved from full off/infinity to full up.

On digital portastudios (DP-24/32/SD), when set to zero/unity gain on the Track fader scale, the Track fader converts a 0 dBu input signal to -6 dBFS going to the Master Stereo Bus. The Track fader set full up (+6 on the Track fader scale) converts the 0 dB input signal to -1 dBFS. So the Fader position and scale numbers can be thought of as a representation of the variance from Unity Gain.

When digitally tracking, mixing, and mastering, there's no digital equivalent on a dBFS meter to the analog "+6 VU". dBFS is only relevant in the digital world. It is the point beyond which there is nothing but distortion when the audio signal is converted from, and back to, analog. For A/D and D/A conversion purposes everything is 0 dBFS or less; there's no such thing as +6 dBFS, because in this context, anything above 0 dBFS is distortion.

However, within the digital processing circuit (i.e., after AD conversion and before DA conversion), signals may exceed 0 dBFS if the internal processing engine uses 32 bit or 64 bit floating-point math calculations. 32 bit or 64 bit floating-point math calculations permit this because essentially, they significantly increase headroom.

Something similar to the digital portastudios must be true also for the Model 12 faders. If so, the +10 fader position may actually be at or just under 0 dBFS when D/A conversion takes place, and if so it would be safe to raise the Channel faders and MAIN Bus fader above zero/unity gain in mixdown, provided doing so doesn't cause clipping. Senior moment, I guess! Hadn't considered that previously.

I recommend working at unity gain or less to assure adequate head room and minimizing the possibility of clipping when mixing down to stereo.​

Second, how can I know if my mix is distorting before reaching the Main Bus?

Keep the tracking at or below -12dBFS and the clip indicator from flashing when you track, and do the same for the stereo mix. If the signal entering the MAIN Bus is distorted you'll hear it.​

Regarding the Post Rec button, as I'm not planning of doing any fade ins or outs in my songs, and as long as I set the Main fader to unity gain, it wouldn't make any difference for me to press it or not during the 2 track stereo recording, right?

As I understand it, engaging the Post Rec button does two things: permits use of the MAIN Bus fader during stereo mixdown; and enables you to hear the completed stereo mix on the MAIN Bus when played back.​

 

[Arjan P]

They shouldn't. In digital recording, there's no such thing as +10 dBFS. Anything greater than 0 dBFS is distortion.

Mark, I think you're wrong here. Every digital mixer I know has (usually) 10 dB over the unity or 0 level on each fader. It has nothing to do with +10 dbFS (Full Scale). It simply gives you an extra 10 dB on the digital signal - and sometimes it is needed and you move the fader up. Will it cause distortion? No, for two reasons: 1. because you'll probably use it with low level signals, and 2. see below. If I have an acoustic guitar at -25 dB level and I move that fader to +10, the result is my guitar is now at -15 dB. No issues or distortion whatsoever.

Also, very important to know: Once a signal is digital and inside the mixer - there will be NO real distortion above 0 dB in the digital domain, no matter how high I turn EQ gains or slide faders up. Because the mixer uses math internally (usually floating point calculations) the calculations may result in a digital signal above 0 dB, but it will be calculated down (together with all other signals) before anyone can hear it as distortion. This works the same in a DAW.

 

[Mark Richards]

Hi Arjan.
While you were posting, I was editing my post b/c I realized I hadn't thought it through.

I recalled that measurements I had done previously on my DP-24 indicated that on that unit, the track fader's zero/unity gain position yielded a -6 dBFS level with a 0 dBu analog input signal (Edit: see the re-run of the test in my Post #20 following).

So in my previous (now edited) Post #12, I'm making a guess that's how it might be with the Model 12.

I think that ties in with your comment about a signal recorded at -25 dBFS being raised to -15 dBFS with no distortion after maxing the fader.

Also, thanks for the additional information on how the digital signal is processed internally.

 

[Arjan P]

Mark, I purposely did not speak of signals as xx dBFS because Full Scale has no relevance inside the digital domain. So yes, if your analog gain on a channel input is such that the digital signal is at 0 dB (so just no distortion) then everything you do digitally inside the mixer cannot distort your signal, until you go back to analog. So the extra 10 dB on the fader will get the signal at +10 dB (not from -10 to 0). No problem, since two faders at 0dB will also add up to a digital level of more than 0 dB. There's only math taking place inside, so 10 faders with a 0 dB constant signal (let's say wite noise) will result in a huge positive dB number, since we are simpy adding up. Now ofcourse what we do with the master fader is important, because here we bring the final mixed signal back below 0 dB. But I say, use the extra 10 dB if you need it, it is what the fader was designed for.

 

[Bambi]

Hello Mark and Arjan, thank you very much for your answers. I have to think about it all because I'm a little confused right now. The way I understood at first the functioning of faders in this mixer was the following: you could have for example the channel faders close to +10 and then lower the Main fader, or you could have the channel faders at zero or below while you compensated them later rising the Main fader. The idea was not to clip on the Main channel, no matter which of the two methods you chose. I've never known if one way is better than the other for questions like, for example, the signal to noise ratio. However, talking to Mark here he gave me the very reasonable recommendation of setting the channel faders at unity gain and adjusting them downwards. Here's where it comes my doubt of if, being a digital mixer, the combined signals sent to the Main Bus can still distort, or if they'll never distort as long as the original recorded signals are correct.

Besides, I read an interesting article about 2 extra reasons than the usuals for recording at -18 dBFS. I don't know how accurate are the different subjects treated in the article, but I found the 2 reasons very interesting. One has to do with plugins, what doesn't affect me as I don't use computer. And the other has to do with having the faders close to unity gain because of the slider having much more resolution near that value that way below it.
https://decibelpeak.com/recording-levels-digital-recording/#reasons

 

[-mjk-]

@Arjan P I can distort the crap out of anything in my X32. I'm really not sure what you mean when you say that the console won't distort anything.

 

[Arjan P]

@-mjk- I said, and I chose my words carefully, "everything you do digitally inside the mixer cannot distort your signal, until you go back to analog."

A digital mixer adds signals together (like any mixer) and therefor must accomodate - internally in the digital domain - for signals higher than 0 dB. Two or more individual channels of white noise, both at unity gain, will produce a signal higher than 0 dB, but this is an internal calculation result for a digital mixer, NOT distortion. The master fader, just before going back to analog is there to make sure the resulting signal stays below 0 dBFS - hence, no distortion.

 

[Arjan P]

The way I understood at first the functioning of faders in this mixer was the following: you could have for example the channel faders close to +10 and then lower the Main fader, or you could have the channel faders at zero or below while you compensated them later rising the Main fader. The idea was not to clip on the Main channel, no matter which of the two methods you chose. I've never known if one way is better than the other for questions like, for example, the signal to noise ratio. However, talking to Mark here he gave me the very reasonable recommendation of setting the channel faders at unity gain and adjusting them downwards. Here's where it comes my doubt of if, being a digital mixer, the combined signals sent to the Main Bus can still distort, or if they'll never distort as long as the original recorded signals are correct.

@Bambi You understand correctly, and there's nothing against working with all channel faders at or around unity gain (and it's good practice, certainy if you also work analog mixers). Also, you are right about the increased resolution the fader has around 0 dB. But my point was, there's nothing against going over 0 dB for a fader, if you need the extra dBs in the mix. I only came into the discussion when it was said that everything over 0 dB is a no-go area for digital mixers. That's only true when going from analog to digital or vice versa.

The combined signals internally in the digital mixer domain will not distort if: 1. the signal was well recorded and stays below 0dB at the AD stage and 2. going out of the mixer the master fader is used to stay below 0dB as well.

 

[Mark Richards]

Bambi, I can't speak to the Model 12, but the tests below demonstrate how signal levels and unity gain settings work on my DP-24. I think it's reasonable to consider the Model 12 may behave in a similar way.

These test results support what Arjan wrote above:

The combined signals internally in the digital mixer domain will not distort if: 1. the signal was well recorded and stays below 0dB at the AD stage and 2. going out of the mixer the master fader is used to stay below 0dB as well.​

On my DP-24:

• The Input Trim Knobs, Track faders, and Track meters reflect the incoming signal after A/D conversion.
• The Stereo Master fader and meter reflect the outgoing signal before D/A conversion.
• The Track faders control only the outgoing Track signal and have a fader scale range of infinity (full off) to +6 (full on), with unity gain at the zero position on the Track fader scale.
• The Master Stereo Bus fader has a fader scale range of infinity (full off) to zero/unity gain, with the zero/unity gain position on the fader scale coincident with the fader being set to full on.

In this test, the Master Stereo fader and meter are used as the reference point by setting the Stereo Master fader to full up (zero/unity gain on the Master Stereo Fader scale).

• A source 1kHz .775 volt (0 dBu) analog reference signal was sent to Line Input A.
• The digital Input A Trim Knob was set to unity gain (about the 1 o'clock position).
• The Track fader was set to zero/unity gain on the Track fader scale.

This was the result:

• The incoming analog reference signal when A/D converted produced -6 dBFS on the digital Track Meter.
• The Track Fader set to zero/unity gain on the Track fader scale in turn sent a -6 dBFS signal to the Stereo Master Bus.
• With the Stereo Master Bus fader set full on (zero/unity gain on the Stereo Bus Master fader scale), the Stereo Master Bus meter showed a -6 dBFS level.

Keeping the incoming analog signal at 0 dBu, and with the Stereo Master Bus Fader remaining set full up to zero/unity gain:

• Moving the Track Fader to full on (the +6 position on the fader scale) raises the outgoing Track signal to the Stereo Master Bus to -1 dBFS on the Stereo Master Bus meter.

Returning the Track fader to zero/unity gain on the fader scale:

• Lowering the incoming analog reference signal to 0.3162 volts (-7.8 dBu) results in a -12 dBFS signal on the Track Meter and on the Stereo Master Bus meter with the Stereo Master Bus fader set full on (zero/unity gain on the Stereo Bus fader scale).
• Raising the incoming analog signal above 1.23 volts (+4 dBu) results in clipping if the Input Trim Knob is not used to attenuate the source signal.