# B Dual mono versus stereo

1. Nov 14, 2016

### houlahound

stereo jack from a computer to a set of computer speakers and driven by a constant tone on a single track in Audacity do both speakers get the same signal in phase?

should I copy and paste the signal into two separate tracks and send them left and right to get two identical phase signals left and right?

I basically want to make stereo to mono equal in both speakers.

2. Nov 14, 2016

### Simon Bridge

Depends on the details of the amp output and the length of the cables. To be sure you will have to measure ... suggest interference method using a monotone.
The output is in-phase if the highest intensity sound is found along the line half way between the speakers.

A detailed answer will depend on why it matters.

3. Nov 14, 2016

### houlahound

the monotone is the question, a single tone sent through a stereo jack comes out as dual mono right but are they in phase or out of phase. just wondering how the stereo jack works really when splitting a single recorded track into two speakers.

4. Nov 15, 2016

### syhprum1

The length of cables is completely irelevent as the speed of electrical data in the cables is vastly greater than the speed of sound

5. Nov 15, 2016

### houlahound

Yeah I wasn't sure where phase loss came in over short distance to computer speakers.

6. Nov 15, 2016

### rootone

I'm not too clear what your aim is here.
However if it is to achieve an identical (mono) output from both speakers, you can simply just mix the two channels into one.
It doesn't matter what the source of the originally separate channels is, you just physically connect the left and right channels with piece of wire or similar.
Then from this connector you take a separate lead to each of the speakers.

7. Nov 15, 2016

### cjl

They should be in phase, if you have your speakers wired correctly.

8. Nov 15, 2016

### houlahound

Anyone have a circuit diagram of a stereo jack construction?

9. Nov 15, 2016

### houlahound

On a side note anyone know the reasoning behind sending a track left or right in a multitrack recording.

there must be some methodology behind sending say drums this way and vocals that way or however it is arranged.

is there a standard protocol for argument sake in pop music.

10. Nov 15, 2016

### DrGreg

It's got nothing to do with the jack. The split from mono to stereo occurs within the software. I'm sure no one would design software to split the channels 180° out of phase. (Assuming, of course, that the speakers are wired up correctly and the plug is fully inserted into the socket.)

11. Nov 15, 2016

### houlahound

the jack must receive separate signals it transports left and right, so it must have a ground, left and right. just want to know which is which.

12. Nov 15, 2016

### DrGreg

13. Nov 16, 2016

### Tom.G

Stereo Jack:
Ring = Right Channel (this makes it easy to remember!)
Tip = Left Channel
Shell = Ground (Common)

14. Nov 16, 2016

### houlahound

Cheers.

15. Nov 16, 2016

### sophiecentaur

If the two channels are in antiphase and exactly the same amplitude you will get a null along the line at right angles to the line of the speakers. BUT the room must not have any reflections off walls and furniture or the null will be filled in. The pattern will be a figure of eight and the setup can sound odd as your ears try to make sense of what they hear.
Look at articles of multiple radio antenna arrays. The same maths applies.