STM Mixer Stereo vs Mono

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djmicron
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Re: STM Mixer Stereo vs Mono

Post by djmicron »

Music Manic wrote: Sat Nov 05, 2022 4:00 pm Hi guys

I've just tested a few things and it's not a phase problem. It's the architecture of how mixers are built. the Ableton mixer shows the same problem.
If you phase one side of a stereo channel. Scope mixers or DAW ones it shows that there is just a 180 degree correlation between Left and Right nut funnily no phase cancellation when sent to the master out unless you mono it.

I find this structure weird but am getting my head around out. Please look at my pics if I'm not making myself clear.

Thanks
This is not weird, you are missing how the stereo path works, to better understand it, try to work with dual mono instead of stereo channels and you will see that even with two mono channels you can't NULL without a mono signal path (matching pan).

To subtract one signal from another one, they must be together, it can't be done if each signal is sent to a dedicated channel such as when one is sent to the left and one to the right.
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Re: STM Mixer Stereo vs Mono

Post by fra77x2 »

it can't be done if each signal is sent to a dedicated channel such as when one is sent to the left and one to the right

this is right. if you don't sum there is no sum.

But they add physically/ interfere in our ears and in correlation meters...

I have to admit for a moment i forgot that a stereo channel is just two mono channels that do not combine down the path.
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Re: STM Mixer Stereo vs Mono

Post by Music Manic »

djmicron wrote: Sat Nov 05, 2022 3:28 am
valis wrote: Sat Nov 05, 2022 2:03 am I think my point is that 'panning' implies a stereo bus, even if the source is a mono channel/signal.

I've followed this thread and it's still unclear how/where the sum is being done as a mono (master bus) chain.
when the source is mono and the signal is sent to a stereo bus, if the pan is centered then it's sent half on left channel and half on right channel, this is why when sending two separate mono sources to the master stereo bus and one of them is phase inverted and each of the mono source is pan centered, they will null, but if we change the pan setting on one of the two mono sources the null test will fail, because the signal on the stereo bus will not match.
On the other side, when using a stereo channel on the STM mixer, we have two mono sources linked to the same volume fader and hard panned left/right and the pan control on a stereo mixer channel on the STM is a crossfader like in a Dj mixer, it excludes the left channel when moved to the right side and the right channel when moved to the left side and to have individual pan control on a STM stereo channel, we have to use an insert effect such as the Stereo Pan located under the mastering folder and it allows to individually set the pan for each of the two mono signals.
It's a different story if we want to phase cancel against two stereo mixer channels, in that case if we invert the phase on both left and right channel on one of the two, the NULL test will work.
This is not specific to Scope mixers, this is what happens even when you have a stereo source on your DAW of choice.
Also it has to be noted that when in Scope there is a sync issue between different DSPs, it's a matter of a couple of samples and a NULL test will produce anyway a big amount of cancellation.
Yes it is definitely the architecture of any mixer channel that changes the behaviour of the source.especially the pan law part. Stereo doesn’t necessarily mean Left and Right per se. Different pan settings and laws will treat each side differently.

I naturally thought left and right were independent of which they obviously aren’t, when it comes to mixing architecture.
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garyb
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Re: STM Mixer Stereo vs Mono

Post by garyb »

there is reason for this. it's about music which before the present digital era was made by real people using real things. that's what ultimately excites the ears. the music, not the technicalities. of course, technicalities are important. but something that sounds cool to the ear always trumps "correctness".
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Re: STM Mixer Stereo vs Mono

Post by Bud Weiser »

garyb wrote: Sun Nov 06, 2022 9:41 am there is reason for this. it's about music which before the present digital era was made by real people using real things. that's what ultimately excites the ears. the music, not the technicalities. of course, technicalities are important. but something that sounds cool to the ear always trumps "correctness".
^^^^
Yeah ... THIS !

8)

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Re: STM Mixer Stereo vs Mono

Post by Music Manic »

garyb wrote: Sun Nov 06, 2022 9:41 am there is reason for this. it's about music which before the present digital era was made by real people using real things. that's what ultimately excites the ears. the music, not the technicalities. of course, technicalities are important. but something that sounds cool to the ear always trumps "correctness".
Sure but understanding architecture will help you create the stereo field and impression you require. I bet many don't know what panning does to different types of stereo files. You can mess things up and lose hope, especially of your a musician that loves sounds.
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Bud Weiser
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Re: STM Mixer Stereo vs Mono

Post by Bud Weiser »

Music Manic wrote: Sun Nov 06, 2022 11:10 am You can mess things up and lose hope, especially of your a musician that loves sounds.
Don´t wanna hijack your post,-

but I´m a musician and love cash more instead endless elaborating audio theory.
This rules for music theory too,- at least for me.

For sure it´s a plus when you know the basics (or even more).
But doesn´t replace the ear, expression and emotions.

Priority of theory is for teachers,- and I´m a bad one.
I know because I was one in the past until I decided to leave it for the other just because I wanted touring and live-performance after I had enough from studio artist work where everything was repeatable until it fitted best.
No risk, no fun, you know.

And the best studio recording-, mixing- and FOH engineers I worked with were self educated persons without exception.
Doesn´t mean they didn´t know some theory.

:wink:

Bud
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garyb
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Re: STM Mixer Stereo vs Mono

Post by garyb »

Music Manic wrote: Sun Nov 06, 2022 11:10 am
garyb wrote: Sun Nov 06, 2022 9:41 am there is reason for this. it's about music which before the present digital era was made by real people using real things. that's what ultimately excites the ears. the music, not the technicalities. of course, technicalities are important. but something that sounds cool to the ear always trumps "correctness".
Sure but understanding architecture will help you create the stereo field and impression you require. I bet many don't know what panning does to different types of stereo files. You can mess things up and lose hope, especially of your a musician that loves sounds.
here is one of those basics that is forgotten. any high quality engineer minimizes the number of stereo files used. just because a track sounds great in stereo doesn't mean that it will be great in a mix. most great recordings are made from mono files, not stereo files. stereo files should be used as a special circumstance, not as a general policy. it is the same as another problem created by computer systems. more plugins do NOT make better mixes. only the most necessary plugins should be used, not everything possible just because you can.

not trying to make a law or anything...

where did i say that knowing the architecture wasn't helpful?

i know what panning does to a stereo field when mixing a lot of stereo files, it creates shit. that was an early lesson that nobody wants me to speak of.
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Re: STM Mixer Stereo vs Mono

Post by Music Manic »

garyb wrote: Sun Nov 06, 2022 2:48 pm
i know what panning does to a stereo field when mixing a lot of stereo files, it creates shit. that was an early lesson that nobody wants me to speak of.
This is my exact point and what I’ve just found out for myself. Thanks for the confirmation
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Re: STM Mixer Stereo vs Mono

Post by valis »

In summary, the stereo channels and master in the mixer function exactly as one would expect coming from the analog realm, minus the crosstalk and noise from the mixer itself. Stereo channels in our DAW implement 'pan law' rather differently, hence (I think?) the confusion.
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Re: STM Mixer Stereo vs Mono

Post by fra77x2 »

exactly as one would expect coming from the analog realm
whatever...

:lol:
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garyb
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Re: STM Mixer Stereo vs Mono

Post by garyb »

t's not so much that stereo files are bad, it's that panning is already done in a stereo file, probably the needed ambience to hear a stereo field is also already done in a stereo file. so, stereo files should be special effect files, like a whole drum kit or a solo piano, if the piano isn't part of a bigger assembledge of instruments. otherwise, when you pan, half the music will be enhanced or diminished by the pan. there are also more chances for phase anomolies.

i know that i am not expressing anything especially well, but generally, mono files are preferrable, especially in a big mix of instruments. then ther stereo field can be made that makes sense for all instruments and/or sounds.
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Re: STM Mixer Stereo vs Mono

Post by fra77x2 »

I think what Gary is talking about are standard techniques. A track should translate well all its elements in mono. The stereo information is generally regarded that carries "effects". (ambience, polishing tonal color etc). This happens for many reasons but mainly because someone likes the song to have a great amount of its energy be carried by both speakers. This is somewhat of a rule for the whole track and strict for the low frequencies. Also mixing is all about contrasts and if everything in a mix is stereo then nothing really is. A sound can create the sense of space by positioning in contrast to another sound that is positioned differently. And the greatest extend of this arc is the contrast between a mono sound and a stereo one and this is what is mainly used because at the same time it fulfils all other neccecities of mono playback like radio mono compatibility, more constant loudness curve, better articulation of audio images etc...

From another point of view:
pan is just a tool on a mixer channel. It allows to route and crossfade a sound to 2 destinations

In my way of working i use custom mixers that are simple adders. They do not have pan control.

If I want to pan something I will feed part of the signal to another empty channel. But I won't stop there. I can feed some filtered part of a sound to the right lets say and then I can take a filtered version of the sum and feed it reversed the left to the right.

If I want to make a drum sound I can mix different samples to the left and the right and then send part of the sounds to the opposite channels... In general the possibilities are many... but in general someone should have enough experience with audio so to have a mental picture of what is mono and what is stereo in a mix. I have programmed a phase analyzer that displays lissagous curves and I have spend a lot of time with it. The process involves if I remeber correctly by heart taking the sine of the L-R and the sine of the L+R and displaying it as x-y coordinates... Now I don't have to use it anymore but I use it often because I like to watch the damn graphics. Also m-s techniques are powerful but not nessecary, also just a tool. Anything can be done with filters and basic effects/dynamics. Strict digital ITB is harder but possible for some genres with a lot of experience. The main problem with only digital is that it is complete abstract and you can paint just nonsense. Poor DACS replicate with accuracy this nonsense... sounds bad. Hybrid systems are better than what people used at the old days because beside analog processing there is also digital which is powerful. Also analog offers a repair service for nonsense created by digital means, they take them back to reality by forcing electrons to take the strange path. Its a magical eraser of ugliness.
Strict analog is great for personal fun and "wow even fck noise sounds interesting", or "i can't make it sound bad" moments.
But you can't sell this experiense it is kind of personal and gets a bit aphasic in moments...

But I still remember the day that I soldered my first sine oscillator, a pathetic diode lowpass self resonating, with uncontrollable distortion because of feedback instability and I hit it with a cute 555 D-envelope triggered by a simple RC binary counter and connected straigth to one of my old 5 inch monitors... this sounded good... and yes it was real. The whole circuit cost around 3euro... anyway we are in the digital era and kind of digital zealots. But how much difficult...

https://en.m.wikipedia.org/wiki/Lissajous_curve
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valis
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Re: STM Mixer Stereo vs Mono

Post by valis »

I will also add that the way people are wanting to use "pan" on a "stereo channel" or a source that begins as stereo, try using a plugin that gives you control via Mid/Side (M/S) and I think you'll get the effect you want.

Gary and others are correct in that 'panning' a 'stereo' source simply attenuates one side (and depending on pan law, might increase the side panned to to some degree, since most pan laws attenuate BOTH in the center position).

If you want to 'steer' the 'stereo placement' then mid/side is the right method which used to be a 'mode'. Why a "mode"? Well the 'mid' signal would wind up on channel 1 (ostensibly "left" if in a stereo channel) and the 'side' information on the second channel ("right" if stereo channel again), and then you would do your processing after said conversion (typically with a plugin to change 'modes'). After your chain of processing, you would then have to 'convert back' to stereo with a subsequent plugin, and here is where you could position the 'panning' and then also increase or decrease the 'side' information. Most modern plugins--at least in the software realm--simply you a M/S control and sometimes a 'low end cut' for the side channel within a plugin that remains stereo, and integrate the entire workflow or process into a single plugin.

I'll defer to others for Scope plugins that can do a similar process within our mixers, for I don't tend to work that way in Scope.
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Re: STM Mixer Stereo vs Mono

Post by valis »

Also, here is a somewhat related subject, how to ensure or check for mono compatibility, which covers things related to this topic we have been discussing: https://www.pro-tools-expert.com/produc ... patibility
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Re: STM Mixer Stereo vs Mono

Post by Music Manic »

garyb wrote: Mon Nov 07, 2022 7:15 am t's not so much that stereo files are bad, it's that panning is already done in a stereo file, probably the needed ambience to hear a stereo field is also already done in a stereo file. so, stereo files should be special effect files, like a whole drum kit or a solo piano, if the piano isn't part of a bigger assembledge of instruments. otherwise, when you pan, half the music will be enhanced or diminished by the pan. there are also more chances for phase anomolies.

i know that i am not expressing anything especially well, but generally, mono files are preferrable, especially in a big mix of instruments. then ther stereo field can be made that makes sense for all instruments and/or sounds.
You’re saying the stereo file should be the master file. I get this now

Do you know how scope streams the stereo file? Is it dual mono, split stereo etc?
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Re: STM Mixer Stereo vs Mono

Post by Music Manic »

valis wrote: Mon Nov 07, 2022 5:54 pm I will also add that the way people are wanting to use "pan" on a "stereo channel" or a source that begins as stereo, try using a plugin that gives you control via Mid/Side (M/S) and I think you'll get the effect you want.

This.
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Re: STM Mixer Stereo vs Mono

Post by valis »

Music Manic wrote: Mon Nov 07, 2022 7:40 pm Do you know how scope streams the stereo file? Is it dual mono, split stereo etc?
Those terms really are most relevant to feeding file(s) from disk. Scope is using pan law (-3dB iirc? I would have to search our old discussions) and otherwise the channels are discreet as sent into the mixer. Keeping in mind that there are many forms of pan law, as indicated from the linked article on the first page. Logic (my old friend) for instance has been set to "-3dBf compensated" for some time now, rather than just -3dB. The difference between between -3dB compensated and non compensated is not nearly as obvious as between -3dB and -6dB, and I don't think Scope's mixer compensates (unless it's been updated?) so I would guess that -3dB is correct in our environment.

The primary point GaryB made, is that we tend to make our judgements based on how the tool is set when doing an overall mix. So if you were to switch a mix that's already in progress from -3dB to -6dB, or vice versa, then there would be a subsequent change that would cause the engineer to need to 'remake' those decisions and choices to 'fix the mix'. However once you're already working in a given mode, our perception is our perception. The debate around this was somewhat related to the loudness wars, in that some modes kept more 'power' than others, and the compensated mode again keeps 'power' during pan (compensates a bit for the pan by applying more of a curve to the transfer function as you pan, just like with fades), to keep the 'power' of elements that need to stay forward in the mix.

This is of course just a summary from what I recall in discussions on hydrogenaudio and gearslutz a decade ago or so, and not meant to be definitive in any way.
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