Positive left With positive right into one speaker?

I somehow accidentally took positive left and positive right and put it into one speaker creating what I can only define as a passive mono background layer /channel,, leaving it VOID of vocals (but NOT vocal affects like reverb) and other sounds.

What is this called technically - it cannot be simply “out of phase” that’s a reverse polarity issue with one channel from what research reveals .

My best guess is that there are dominant frequencies of left and right that cancel each other out (symphonically?), in additions if you try this, you will notice the sound volume is nearly cut by half it seems. I can only assumed this is how the channels work through the signal combined into one speaker.

(Funny, I actually was using TWO speakers, connecting positive to positive and bridging the speakers using the negative)

I can only assume that dominant positive + dominant positive cancels out, leaving a diluted mono Channel..

Someone please enlighten me, and I’ll ship you a box of oatmeal cookies.

NO GOOGLE search has rendered successful -

I imagine this to be quite a fun topic, being a music mastering musician, this adds a completely new way of understanding signals, channels, and mixing /layering

... but WHY are certain signals literally void?

It is almost as if I am passively creating the “rear” channel in a surround system, which would be opposed to the “center” which typically i music or movies consists of the singing or dialog.

Thank you all in advance for giving this threat a shot, I’m confident on some historic musical mixing / mastering site THIS is in class session lol.
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If you do what you did that with a mono recording and set the gain of each channel to be the same then ideally you would hear nothing as the signal at both positive terminals would be identical and hence no voltage difference would exist between them... result, no audio in the speaker.

Any other material (stereo track) will produce voltage differences between the two terminals due to the two channels having differing content.

Vocals seem to cancel because they are often centre in the mix and so have similar content left vs right channels. Any instrument recorded centrally will also cancel.

I don't know if there is a proper name for the effect but if you think about it both phase and amplitude comes into it, in other words any difference in the left vs right will produce an audible output.
Many years ago, Mr. Sugar was taken to task as his company produced what was called an 'embryo-phonic' amplifier. It used a stereo amplifier with the rear channel wired as you described. The issue was not what was done but how it cheated on the name 'amplifier'. Amstrad improved a bit after that and called it 'system'.
It did enhance the independent signals from each but not both channels making a spacial effect, sometimes.
Quadraphonic or SQ recorded LP vinyl records, circa 1980, used a +30º and -30º phase shift encoder/decoder for the rear left and rear right channels, a much improved system that later became Dolby Pro Logic as we now know it to be.
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I imagine this to be quite a fun topic, being a music mastering musician, this adds a completely new way of understanding signals, channels, and mixing /layering

... but WHY are certain signals literally void?

Here goes.

When you connect a speaker across the two positive terminals, it will only respond when there's a difference in the voltage (signal) at those terminals.

ie, a vocal panned centre will have the same level in both channels, which means there's no potential difference (aka voltage, aka signal) between the terminals, and the speaker is silent.

An E-GTR panned hard left will have signal at the left + terminal, and the right + terminal will sit at zero volts. Therefore, the signal plays through the speaker.

What you've done is made it a mid-side system, and you're listening to the "side".

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Speakers wired plus-to-plus from a stereo amp with a stereo signal will produce the "difference" signal.
It's old news, goes way back to the Dynaco/Hafler system.

I've wired a small hidden speaker on top of the china cabinet in the dining room that way from the system out in the living room.
During any dinner parties, the "background ambience" sonics are pleasing to the diners.
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It's the same as connecting a stereo jack headphone out to a mixer balanced jack in.
You'll hear the channel difference, as bass is contained on both channels, it is somewhat cancelled. I believe a similar technique is also used on karaoke systems for cutting the voice.
As wiseoldtech says, this mode of connection forms the basis of an ambience adaptor.


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