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Author Topic: Stereo FOH Mix Pushed to Mono -> Pull How Much dB From Master?  (Read 6106 times)

Ken Nelson

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I read somewhere on here that if you take a stereo master mix (maybe it was any track) and push it to mono, pull whatever the master fader level is 6dB down to compensate for the extra heat of that stereo mixing going all down one channel. Is that right? There's got to be a standardized correlative value. TIA.
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Brad Weber

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Re: Stereo FOH Mix Pushed to Mono -> Pull How Much dB From Master?
« Reply #1 on: May 21, 2011, 06:24:39 pm »

I read somewhere on here that if you take a stereo master mix (maybe it was any track) and push it to mono, pull whatever the master fader level is 6dB down to compensate for the extra heat of that stereo mixing going all down one channel. Is that right? There's got to be a standardized correlative value.
If there is content common to both channels and it is in relative phase in both channels, then the resulting sum would be 6dB greater than a single channel.  If both channels have the same level and random correlation then the resulting overall summed mono signal level would be 3dB greater.  If the content is in only one channel then the resulting mono sum would be the same as the signal level of that channel.  If there is content common to both channels and the two signal are 180 degrees out of phase from one another then the resulting sum would 0.  So 6dB may be more compensation than is needed for many situations but should represent compensating for the maximum potential summation.
 
A related point is that pulling down the master may reduce the level but only after the master, the higher level still exists between where the signals are summed and the fader.  Thus it may be better to reduce the signal levels before summing rather than trying to attenuate them after summing.
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Tracy Garner

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Re: Stereo FOH Mix Pushed to Mono -> Pull How Much dB From Master?
« Reply #2 on: May 21, 2011, 06:34:43 pm »

If there is content common to both channels and it is in relative phase in both channels, then the resulting sum would be 6dB greater than a single channel.  If both channels have the same level and random correlation then the resulting overall summed mono signal level would be 3dB greater.  If the content is in only one channel then the resulting mono sum would be the same as the signal level of that channel.  If there is content common to both channels and the two signal are 180 degrees out of phase from one another then the resulting sum would 0.  So 6dB may be more compensation than is needed for many situations but should represent compensating for the maximum potential summation.
 
A related point is that pulling down the master may reduce the level but only after the master, the higher level still exists between where the signals are summed and the fader.  Thus it may be better to reduce the signal levels before summing rather than trying to attenuate them after summing.

Interesting. I wonder if this is why I never hard pan because it didn't seem like the appropriate reference point. I always pan -3  (or like 9 oclock/3oclock LR) and not full pan. I run my DJ mixer to PA console like this all the time.
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Mac Kerr

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Re: Stereo FOH Mix Pushed to Mono -> Pull How Much dB From Master?
« Reply #3 on: May 21, 2011, 07:18:21 pm »

Interesting. I wonder if this is why I never hard pan because it didn't seem like the appropriate reference point. I always pan -3  (or like 9 oclock/3oclock LR) and not full pan. I run my DJ mixer to PA console like this all the time.

Huh? By doing that you are just starting the mono sum before the stereo bus. If you are playing back tracks, what is the motivation for making them partially mono? If it is a mono PA that cannot cover the audience in stereo maybe you should fully mono the source, if it is a stereo system that can cover the audience in stereo maybe you should make the source fully stereo. I don't see much point to only sort of mono.

To the OP's question, pull back the stereo master till the level is right. If making everything mono makes it sound louder, pull the level back till it sounds the same level. Since only a dual mono track will likely sum to +6dB I would think that would be too much reduction.

Mac
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Gordon Brinton

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Re: Stereo FOH Mix Pushed to Mono -> Pull How Much dB From Master?
« Reply #4 on: May 21, 2011, 08:01:30 pm »

I am not sure I understand what problem needs solving here. Is the OP's two-track playback too loud?
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Ken Nelson

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Re: Stereo FOH Mix Pushed to Mono -> Pull How Much dB From Master?
« Reply #5 on: May 23, 2011, 07:12:00 pm »

I am not sure I understand what problem needs solving here. Is the OP's two-track playback too loud?

We mix our own sound in full stereo, and sometimes use house sound reinforcement, sometimes rent, sometime use our own PA. If a system requires mono to get adequate coverage, wanted to know how much heat to pull back. Was hoping could literally put a sticker on the board that says "0 for stereo, -6 for mono" or similar.
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Mac Kerr

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Re: Stereo FOH Mix Pushed to Mono -> Pull How Much dB From Master?
« Reply #6 on: May 23, 2011, 07:30:46 pm »

We mix our own sound in full stereo, and sometimes use house sound reinforcement, sometimes rent, sometime use our own PA. If a system requires mono to get adequate coverage, wanted to know how much heat to pull back. Was hoping could literally put a sticker on the board that says "0 for stereo, -6 for mono" or similar.

In reference to what? If you are feeding someone else's PA they are going to set the input level to what they feel is right. They will already be correcting for any difference that comes from your signal being stereo of mono.

Mac
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Ken Nelson

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Re: Stereo FOH Mix Pushed to Mono -> Pull How Much dB From Master?
« Reply #7 on: May 23, 2011, 07:58:55 pm »

Brad's post looks to be what I was looking for.
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Mac Kerr

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Re: Stereo FOH Mix Pushed to Mono -> Pull How Much dB From Master?
« Reply #8 on: May 23, 2011, 08:04:52 pm »

Brad's post looks to be what I was looking for.

What did it tell you about your situation? How much of your mix is coherent in both channels (same signal, same phase, same level) and how much is actual stereo, where the left and right signals are not exactly the same? Non coherent signals will sum to a maximum +3dB, the smallest level change that is easily heard by most people. They may even sum to a lower level than they started at depending on the phase angles of the various parts of the signal. It is not a simple number. How much dynamic range does your performance have? More than 3dB? This level difference is a complete non issue in a live sound environment.

Mac
« Last Edit: May 23, 2011, 08:47:08 pm by Mac Kerr »
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Tracy Garner

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Re: Stereo FOH Mix Pushed to Mono -> Pull How Much dB From Master?
« Reply #9 on: May 23, 2011, 08:14:34 pm »

Huh? By doing that you are just starting the mono sum before the stereo bus. If you are playing back tracks, what is the motivation for making them partially mono? If it is a mono PA that cannot cover the audience in stereo maybe you should fully mono the source, if it is a stereo system that can cover the audience in stereo maybe you should make the source fully stereo. I don't see much point to only sort of mono.

To the OP's question, pull back the stereo master till the level is right. If making everything mono makes it sound louder, pull the level back till it sounds the same level. Since only a dual mono track will likely sum to +6dB I would think that would be too much reduction.

Mac


Good question about why not hard pan...interesting enough, there are times when complete stereo separation is too much because there may be content in one channel that wouldn't be heard on the other side of the room if I hard panned. I usually don't have a center channel and even more often the speakers aren't in a place where I would get a good stereo image anyway.

Also, I'm not sure what it is - maybe phase related...hard pan doesn't give me the same relative volume. Straight mono is definitely not what I tend to go for when djing. Just a little bit less than hard pan seems to be the sweet spot. The majority of the time, I DJ with 320kbps MP3 files of dance-related music.
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Mac Kerr

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Re: Stereo FOH Mix Pushed to Mono -> Pull How Much dB From Master?
« Reply #10 on: May 23, 2011, 08:55:13 pm »

interesting enough, there are times when complete stereo separation is too much because there may be content in one channel that wouldn't be heard on the other side of the room if I hard panned.

If you turn off one of your speakers can you not hear the other one over the whole dance floor, or audience area? Reducing the width of the stereo signal for playback rarely has any advantage in my experience, even if you don't have good coverage.

Orchestral recordings are about a stereo soundstage, not many pop recordings are. If the system coverage demands mono, semi-panned stereo is not the answer. If the system has stereo coverage, semi-panned stereo is not the answer.

Mac
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Tracy Garner

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Re: Stereo FOH Mix Pushed to Mono -> Pull How Much dB From Master?
« Reply #11 on: May 23, 2011, 09:18:30 pm »

If you turn off one of your speakers can you not hear the other one over the whole dance floor, or audience area? Reducing the width of the stereo signal for playback rarely has any advantage in my experience, even if you don't have good coverage.

Orchestral recordings are about a stereo soundstage, not many pop recordings are. If the system coverage demands mono, semi-panned stereo is not the answer. If the system has stereo coverage, semi-panned stereo is not the answer.

Mac

recent example where I played a 1 hour DJ set before a comedy show. Did intro/outro music in between 4 comedy acts...

room was 120 feet wide x 40 deep with comedians set up where they had a 10 foot stage.

I had one monitor in front of the stage

2 JBL 725 elevated 30 inches from the floor. I pointed the speakers outward from the stage facing the far corners of the room. If I had done a hard stereo, each side of the room would have been missing something. At the same time, a hard mono for the music was less than desirable for the content. That Pop/dance music does have some cool stereo effects built in these days. I could have just set my DJ software (Serato Scratchlive) to mono. The majority of the room could hear stereo but the people at the most distant corners of the room would have been missing that content from the other speaker on hard pan.

It is likely nobody probably noticed but me so next time I'm in that room, I do an A/B with the different pan settings take a closer listen.



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Patrick Tracy

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Re: Stereo FOH Mix Pushed to Mono -> Pull How Much dB From Master?
« Reply #12 on: May 24, 2011, 01:59:47 pm »

I read somewhere on here that if you take a stereo master mix (maybe it was any track) and push it to mono, pull whatever the master fader level is 6dB down to compensate for the extra heat of that stereo mixing going all down one channel. Is that right? There's got to be a standardized correlative value. TIA.

There isn't a standard because stereo will sum with differing amounts of gain depending on how much information is common and how much is different.

If left and right were identical there would be 6.02dB of gain, but then that wouldn't really be a stereo signal. You could just use one channel and not have to compensate for any summing.

If left and right had nothing in common, say guitar on left and vocal on right, then summing would be approximately 3dB. You could put each into its own channel, pan center and let pan law compensate for you.

A real stereo signal will sum with gain between about 3dB and 6.02dB. In that case you just have to use your ears.

Tim McCulloch

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Re: Stereo FOH Mix Pushed to Mono -> Pull How Much dB From Master?
« Reply #13 on: May 24, 2011, 02:16:24 pm »

A real stereo signal will sum with gain between about 3dB and 6.02dB. In that case you just have to use your ears.

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Re: Stereo FOH Mix Pushed to Mono -> Pull How Much dB From Master?
« Reply #13 on: May 24, 2011, 02:16:24 pm »


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