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Author Topic: Ying outputs, was I really that wrong?  (Read 6393 times)

Erik Jerde

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Re: Ying outputs, was I really that wrong?
« Reply #20 on: January 04, 2016, 12:11:53 pm »

Read this:

Why not wye?
http://www.rane.com/note109.html
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Matthew Knischewsky

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Re: Ying outputs, was I really that wrong?
« Reply #21 on: January 04, 2016, 01:51:27 pm »

Read this:

Why not wye?
http://www.rane.com/note109.html

I carry several adapters built from this note in my work box for the times when summing just has to be done and the "correct" solution is not available. The first one I made was for a Mackie mixer that did everything I needed except mono out.
Matt
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Luke Geis

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Re: Ying outputs, was I really that wrong?
« Reply #22 on: January 21, 2016, 11:33:14 pm »

Perhaps this is fuel for the fire?

So if you have two balanced outs and you want to make a mono connection that sums them together, could you not use only pin 1 and 2 from the left send and then use only pin 3 from what would be the right side? The connections in the outputs would then never technically be in direct connection with each other. The balanced input at the speaker or amp would sum the signals together as normal right? The impedance would not harm the outputs either as it would just be like dropping a hot or cold pin. Or is this crazy talk? 

I only suggest this as a solution, not as a practice. I have never done this myself as it was my learning as well that coupling outputs into one source is bad juju.

My understanding of most music is that the sub content is almost always up the middle anyway. I suppose if your listening to an old Jimi Hendrix recording you could have drums and bass on one side of the stereo field, but I would solve that problem by just panning things up the middle anyway. In a distributed system where it is simply playback and background, mono and or summed music sources is usually ideal for simplicity in signal delineation and reduction of confusion in recordings where the sound could come from different speakers in a multitude of locations.
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John Roberts {JR}

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Re: Ying outputs, was I really that wrong?
« Reply #23 on: January 22, 2016, 12:00:16 am »

Perhaps this is fuel for the fire?
why;;;?
Quote
So if you have two balanced outs and you want to make a mono connection that sums them together, could you not use only pin 1 and 2 from the left send and then use only pin 3 from what would be the right side? The connections in the outputs would then never technically be in direct connection with each other.
Ummm Maybe... I think you mean 2 from the left to 2 (+) mono input, and 3 from right to 3 -(-) mono input. (1 is for shield).

The bad news is balanced/differential outputs deliver signal as 2 wrt 3, so if one or the other output line is floating and unterminated the output between them may be inaccurate.   
Quote
The balanced input at the speaker or amp would sum the signals together as normal right? The impedance would not harm the outputs either as it would just be like dropping a hot or cold pin. Or is this crazy talk? 
crazy like a.... (insert your own joke here....)
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I only suggest this as a solution, not as a practice. I have never done this myself as it was my learning as well that coupling outputs into one source is bad juju.
It will work for some outputs and not for others, so not a reliable approach.
Quote
My understanding of most music is that the sub content is almost always up the middle anyway.
an old affectation from the days when vinyl was king... Pure left or pure right LF peaks could push the needle out of the track.
Quote
I suppose if your listening to an old Jimi Hendrix recording you could have drums and bass on one side of the stereo field, but I would solve that problem by just panning things up the middle anyway. In a distributed system where it is simply playback and background, mono and or summed music sources is usually ideal for simplicity in signal delineation and reduction of confusion in recordings where the sound could come from different speakers in a multitude of locations.
SR is mostly mono...

JR
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Don't tune your drums half-ass. Listen to what a properly "cleared" drum sounds like.   http://circularscience.com/

Steve M Smith

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Re: Ying outputs, was I really that wrong?
« Reply #24 on: January 22, 2016, 02:54:14 am »

So if you have two balanced outs and you want to make a mono connection that sums them together, could you not use only pin 1 and 2 from the left send and then use only pin 3 from what would be the right side? The connections in the outputs would then never technically be in direct connection with each other. The balanced input at the speaker or amp would sum the signals together as normal right?

Definitely not.  Someone did this to me once.  They gave me an XLR lead to plug into the mixer which had a minidisc player on the other end.  They were using it for backing music to a laser show.

A quick test showed it to be working but when it came to show time, about half way through, it went very quiet with no bottom end.  Next track, it was o.k. again.

It turned out that what I thought was a summed input was actually left on pin 2 and right on pin 3 so the balanced input on the mixer was subtracting one from the other rather than adding.  This means that all you can hear is the difference between the two signals.

The surprising thing was how much difference there was between left and right on most tracks.

On closer investigation, I found that they had two adaptor leads.  Two RCA phonos into a male XLR and two RCA phonos into a female XLR.  They usuallr ran one each end of a mic lead so they could make up a long stereo RCA phono lead.  As they knew I needed an XLR input they just plugged their adaptor in at their end and presented me with their XLR end.


Steve.
« Last Edit: January 22, 2016, 02:57:44 am by Steve M Smith »
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Luke Geis

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Re: Ying outputs, was I really that wrong?
« Reply #25 on: January 22, 2016, 03:55:39 am »

I was being tongue in cheek so keep that in mind.

If the audio was not panned and the output could pass the signal without fail, then in theory you could make a two into one with the above idea, but there would be no point to do so. It was a rhetorical idea.

In the case of the OP's query, having the desired tracks cued would have been ideal actually. It would have given him two mono outputs instead. Most cue's sum the signal to mono and a control room output would follow that. The relative mix would be different if in PFL, but many mixers also have AFL cue options as well, so that may have worked better in this case.
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Ivan Beaver

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Re: Ying outputs, was I really that wrong?
« Reply #26 on: January 22, 2016, 11:57:55 am »


Definitely not.
It turned out that what I thought was a summed input was actually left on pin 2 and right on pin 3 so the balanced input on the mixer was subtracting one from the other rather than adding.  This means that all you can hear is the difference between the two signals.



EXACTLY

This also know as "common mode rejection ratio" or CMRR on a spec sheet.

It is EXACTLY what help keep noise out of a balanced line.
 
Whatever is COMMON to both pins 2 and 3 gets rejected by whatever the CMRR is.

DO NOT DO THIS!!!!!!!!!
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John Roberts {JR}

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Re: Ying outputs, was I really that wrong?
« Reply #27 on: January 22, 2016, 12:26:26 pm »

EXACTLY

This also know as "common mode rejection ratio" or CMRR on a spec sheet.

It is EXACTLY what help keep noise out of a balanced line.
 
Whatever is COMMON to both pins 2 and 3 gets rejected by whatever the CMRR is.

DO NOT DO THIS!!!!!!!!!
For a stereo feed it gives you Left minus Right... For panned stereo, signals panned dead center will completely drop out, for true stereo pair mic'd recordings coherent direct sounds will be diminished, and non-direct incoherent (ambience) sounds will not be diminished.

This L-R is a very old school technique to extract ambience sound from stereo recordings to feed rear speakers, since dominant mono signals cancel, what's left works to enhance ambience effects (generally some delay is added to rear speakers to keep sources localized in front speakers).

And this is while I grabbed pin 2 from one side feeding 2 and pin 3 from the other side to feed 3, to deliver L+R or summed mono... but as I already mentioned, unused outputs may need to be terminated to get a good result, and single legged outputs won't have a negative signal to grab yo get polarity right.

Several reasons why this isn't reliable enough to use. 

JR
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Don't tune your drums half-ass. Listen to what a properly "cleared" drum sounds like.   http://circularscience.com/

Steve M Smith

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Re: Ying outputs, was I really that wrong?
« Reply #28 on: January 22, 2016, 01:07:13 pm »

DO NOT DO THIS!!!!!!!!!

I did know not to do this.
However, at the time, I didn't realise I was doing this!
I worked it out quite quickly once it happened though.

This L-R is a very old school technique to extract ambience sound from stereo recordings to feed rear speakers

Many years ago I had a centre rear speaker connected to the left and right outputs of my amplifier to do this.  Known as the Hafler hook up if my memory is to be trusted.


Steve.
« Last Edit: January 22, 2016, 01:12:49 pm by Steve M Smith »
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Ivan Beaver

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Re: Ying outputs, was I really that wrong?
« Reply #29 on: January 22, 2016, 01:28:58 pm »



Many years ago I had a centre rear speaker connected to the left and right outputs of my amplifier to do this.  Known as the Hafler hook up if my memory is to be trusted.
 
Phase Linear suggest hooking up rear speakers between the + terminals (speaker + to L_+ and speaker - to right +) for an effect.

I remember another example was to use 2 rear speaker hooked in series-but of opposite polarity on 1 speaker (so you had the 2 neg hooked together) and the + of each speaker hooked to the + of the amp channels, R and L.

Yes you would get "something".

And that was pretty good back in the 70s-------------


Steve.
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A complex question is easily answered by a simple-easy to understand WRONG answer!

Ivan Beaver
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ProSoundWeb Community

Re: Ying outputs, was I really that wrong?
« Reply #29 on: January 22, 2016, 01:28:58 pm »


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