If headphones are out-of-phase, can you hear it?

opc

Member
Paid Member
2004-10-15 10:57 pm
Ottawa, Ontario, Canada
Absolutely... and it's not a subtle effect.

You go from "in your head" imaging and soudstage, to a strange reverberant and completely unfocused image.

If you don't want to swap wires, you can make a sample file using Audacity and swapping the polarity of one of the channels. No need for hardware changes.

Cheers,
Owen
 
Is it worth adding a phase reverse switch to one side?

No. The bass will turn to crap, especially with open 'phones.

When I test headphone cables before we ship them out, I use Lenny Kravitz's Fly Away. The opening guitar part lets me know that left and right channels are correct, and the bass after that opening part tells me that polarity is correct. If one channel's polarity is reversed, the bass is significantly diminished.

se
 

xnor

Member
2010-10-06 8:55 pm
Think of it this way: the wavelength of low frequencies can be a few meters, yet the distance between our ears is just a couple of centimeters. Even if a low frequency sound source is completely to your left or right the other ear will receive pretty much the same with a tiny phase shift only.
For an inversion (or 180° phase shift) you'd have to have a huge head. In other words: it's completely unnatural. Think of the unnatural stereo separation in headphones only 10 times worse.
 
It's funny you are asking this question. I will throw my two cents in, but I think you have your question answered.

If you are listening to a modern mix, the upper freq are usually put out of phase slightly to give the illusion of soundstage. If you have the headphones out of phase, then you will undo and reverse the phase on one side and it wil be in phase for the upper freq, but BUT the bass will be out of phase and seem to cancel each other, but this is actually going on in your brain, not physically cancel each other in the air, as two subs might do. Weird huh?

Radio FM stereo is about 50% out of phase I believe, to add to this Illusion of stereo.

Remember that true (origonal) stereo is just guitar-drums on left with uppers out of phase 50% and vocals-bass with uppers out of phase.

All in all you should be able to easily detect it.
 
So studios deliberately destroy proper stereo imaging?

FM stereo radio takes this to the ultimate degree?

True stereo is pan-potted to left, right and (out of phase) centre?

To me this sounds like complete nonsense - could someone who actually knows about studios and broadcasting comment on this? Each statement is the exact opposite of what I have always believed.
 
Remember that true (origonal) stereo is just guitar-drums on left with uppers out of phase 50% and vocals-bass with uppers out of phase.
No, it's not. You are maybe talking about some screwy rock albums from the 60's where they were trying to cram 30 layers of overdubs onto 4 tracks, but REAL stereo recordings of the 50's and since have never had things like that done to it.

Only time I can think of any manipulation being done with true stereo recordings is when a shuffling box was used. But that's only to be used specifically with certain techniques using spaced omnidirectional mics with the intention of correcting low frequencies.

Regarding modern recordings: phase is sometimes manipulated at different frequencies to create a certain special effect during the mixdown. But, tasteful engineers can use this artistically to create something interesting to listen to. I hear it in experimental electronic stuff alot, in a good way. As far as I know, fake stereo widening is not the normal thing all mastering studios do just to make something pop out more. It does get used, but more often than not to try and repair and salvage a poor mix that's pretty much already mono. Most of the modern pop music you might here that being done to sounds like freakin' garbage anyway, so it really doesn't matter. Its not normal to do it to REAL recordings.
 
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I detect left/right relative phase problems on stereo material much more accurately by noticing the stereo soundstage. In correct phase, you can place instuments across the soundstage. Out of phase it sounds to me like the sound is coming from only the extreme far edges of the soundstage and nothing is right in front-center. This effect is immediately noticeable and identifiable with speakers or headphones; probably more easily detected with headphones.
 
So studios deliberately destroy proper stereo imaging?

FM stereo radio takes this to the ultimate degree?

Well, I don't know about studios, but radio stations definitely process the hell out of their signal. Especially compression, to try and widen their coverage area.

And at least once, I listened to a song on FM I had at hand. They were definitely "Extra-stereoizing" the mix for whatever reason.
 

Deafer

Member
2013-04-24 9:06 am
Modern studio and broadcast processing equipment allows all sorts of modifications to the basic sound signal(s) coming from the performer(s). If you look at a televised concert you will see a host of microphones in use - not just a simple stereo pair or decca tree. If you look at how studio recordings are made you will also see a host of microphones (8 mikes for a drumset?). Vocalists nowadays, apart from opera singers, all seem to need very heavy hammering from a rack of processing gear to get their trademark sound. Then comes the mixing stage where a lot more hammering goes on before the audio can crawl out of the CD and vibrate some speakers or headphones.
 
And the techies roadies and humheads are running around with phasing guns to send an asymmetric waveform and detect any mics or cables that are accidentally out of phase. There's enough comb-filter effects or flutter echoes on instruments picked up by multiple mics without phase cancellation! Unless you're taking about the dual-capsule mics the Grateful Dead used for a while for ultimate feedback resistance (they only sang into on capsule, but both faced the same direction)...which didn't sound very good anyway.

We used to have all kinds of phase 'guns' and various little boxes to send & detect an asymmetrical waveform to make sure mics & even devices were phased the same, but I haven't been able to find one for sale now for years.
 
Well, I don't know about studios, but radio stations definitely process the hell out of their signal. Especially compression, to try and widen their coverage area.

And at least once, I listened to a song on FM I had at hand. They were definitely "Extra-stereoizing" the mix for whatever reason.

[Emphasis mine]

Sorry to revive a long dead thread, but lots of us find old posts via google, when you need specific information the date doesn't matter. Anyway, in the interest of accuracy, I felt like I had to point this out..

Now I may be wrong--wouldn't be the first time--but the bolded sentence is misunderstood hooey, right? I can't imagine the content of a signal having jack to do with coverage area.
 

PRR

Member
Paid Member
2003-06-12 7:04 pm
Maine USA
>> compression, to try and widen their coverage area.
> hooey, right? I can't imagine the content of a signal having jack to do with coverage area.


Listeners tend to "like" the LOUDEST station.

The carrier strength (measured on a field strength meter) is not affected by signal, compressed or silent. Yes, the 50uV/M line is not moved.

Most radios, to a point, AVC all stations to about the same carrier strength at the detector. (FM does this indirectly by clipping to uniform level.)

The loudness at the speaker is strongly influenced by heavy modulation. These stations will attract more listeners. (You might think listeners would turn-up or turn-down as needed. But scanning the dial, the strong stations leap out at you.)

A flip side is interference. Even at the same carrier-to-noise ratio, the over-loud signal will "cut through" better.

As a range extension from 50 miles to 60 miles (just 1.6dB more over-compression) is potentially 44% more area and (if uniformly populated) 44% more listeners to claim to advertisers, over-compression is a fiscal imperative.

In a non-commercial field, amateur radio, speech is usually processed to raise level. Old rigs cut speech bass and then amplified into clippers followed by high-cut filters. Speech can be clipped horrendously and still be intelligible (though not flattering or pleasing). Fast compressors were added so clipping could be less. I understand that 20 years ago digital processors were developed to do all the tricks and more than even AM broadcasters use. Fairly inexpensive PCB you tucked behind your mike jack. Probably built-in now.