Ever been confused / disoriented by phase shifting?

[bob p]

Just wondering if anyone else out there has ever experienced confusion / disorientation as the result of phase shifted stereo musical signals. I've experienced this a few times, when running two different phase shifted signals out to separate amps. If you get caught between them and if the signals are shifted just right, the result can be very disorienting.

The first time that it happened to me was back in the late 70s. I was onstage playing bass, and our guitarist turned on his brand new mutron biphase while he was playing Grant Geissman's guitar solo from "Feels So Good." The experience is hard to explain ... He had evidently spent a lot of time experimenting with the BiPhase, as he brought two amps that night... just to mess with the rest of us on stage.

I couldn't explain what happened, but I found myself standing still on the stage between those two amps, barely able to play, and barely able to remain standing. That wash of sound out of the stereo phasors just crippled me. It was as if I was brain-dead. It took me a little while to collect myself.

Has anyone else had an experience like this? When its done properly, shifted signals like this really screw with your senses. I'm surprised that you don't hear signals like this more often in recordings, just for their dramatic effect.

[guitarmike2107]

I have made myself "sea sick" with a chorus effect... I think positioning in the room had a major infuelnce though aa I struggled to re-create it.. thought it was the new brown sound

[Steve Conner]

I'm surprised that you don't hear signals like this more often in recordings, just for their dramatic effect.

To cut a long story short, you do.

It's called "negative phase", and the idea is to apply a wavefront to your ears that couldn't have come from any conceivable sound source. Your brain can't localize it.

Adding a smidgin of it to a stereo recording will widen the image and make it appear to come from beyond the speakers, or even behind you, filling the room. This is heavily used in more modern music, from dub onwards.

But you have to watch for mono compatibility. For maximum disorientation you want the left and right channels 180 degrees out of phase, but then the signal will disappear altogether in mono, so you couldn't do it in a mix intended for TV or radio.

You also need a good stereo system to appreciate it in recordings, and maybe some of the stuff Bob was smoking back in the 70s there. :-)

[Mark Hammer]

I think the only time I have ever been standing in front of a mic, having no idea what words were supposed to be coming out of my mouth, was a gig over 30 years ago, where I had split my signal to two amps. One was a Valco set to slow tremolo, and the other was a Fender feeding a Vibratone cabinet, also set for slow speed. The two were on opposite sides of me. Talk about distracting!!

Personally, I think one of the reasons why the semi-legendary Ibanez Flying Pan never caught on was because the panning was so extreme (no adjustable depth, I'm afraid), that between the phasing and panning, it was impossible to use stereo in a live situation. On paper, brilliant; in practice, appallingly unusable.

[bob p]

You also need a good stereo system to appreciate it in recordings, and maybe some of the stuff Bob was smoking back in the 70s there. :-)

By "Bob", you mean Bob Carver, right? After all the recording effect that you were talking about sounded like what sonic holography was intended to do. As it turns out I have one of those sonic holography preamps. With the right recordings the effect can be astounding.

My experience with the whole Sonic Holography concept has been that the effect is generally "orienting" rather than "disorienting". I think that this comes from the fact that the time delays that the circuit imposes are deliberately made small enough to account for the interaural distance between your ears. So the effect is subtle, and allows/facilitates object localization, rather than imparting huge delays that mess with your head the way that BiPhase did with mine.

[bob p]

I think the only time I have ever been standing in front of a mic, having no idea what words were supposed to be coming out of my mouth, was a gig over 30 years ago, where I had split my signal to two amps. One was a Valco set to slow tremolo, and the other was a Fender feeding a Vibratone cabinet, also set for slow speed. The two were on opposite sides of me. Talk about distracting!!

So YOU were playing the trem signals when you got confused?
Were those two trems set at similar, but subtly different speeds?

Mark, I think you've encountered the same phenomenon I was describing. I was caught between a wash of pulsed sounds coming from two different directions and the frequency of the pulses was just right to screw with my mental ability to process the incoming sound. When that happens, its sort of a magical effect that really screws with your head.

I can certainly understand how stereo tremolos could really be disorienting if they were set properly. I've experienced the tremolo effect, but my personal experience with the phasors was that they took the level of confusion up to a higher level. My personal experience is that similarly employed phasors present an even more confusing signal for the brain (my brain at least) to process. If anyone is reading this thread and hasn't experienced what we're talking about, a stereo phasing experiment is definitely worthy of your time.

I've tried to re-create the experience a number of times, but I've never been able to duplicate as impressive an effect as I had on stage that night with the Bi Phase. I'm not sure which factors might be necessary to make it happen. We were playing on a full size theatrical stage. That was a huge platform that allowed us plenty of room to spread out our gear, so the guitarist's two amps were located far away from me on each side of the stage. We were playing in a huge gymnasium, which was a large, highly reverberant room with balconies on both sides, so there were many different large, highly reflective walls to generate complex reverberation patterns. I haven't played in a venue that large in decades. I'm wondering if the room played a large part in screwing with my head. Maybe it was the depth of the stage, and the size of the room that contributed a lot of natural / complex reverberation to the sound. Of course, part of it could have been that I wasn't playing the sounds that were confusing me. Maybe a large part of it was due to the fact that I was trying to do something entirely different on the bass, while I wasn't focused on making those phase shifted guitar sounds. Maybe it has a lot to do with concentration on what you're doing, and trying to block out confusing extraneous inputs. I remember the guitar player wasn't at all confused, but I was so overwhelmed by the distraction that my mind was turned to mush until he stomped on the off switch at the end of his solo.

I seem to remember R.G. mentioning something like this happening to him once upon a time. It would be interesting to see if he joins the discussion.

[Jag]

I was way into psychoacoustics when I was in college. I did one experiment in EML lab with stereo delayed signals and phase shifting that would cause most listeners to almost fall off their chair. It was very dependent upon the listener being centered, almost perfectly, in relation to the speakers and really only worked if the listener was using phones. If you were not positioned perfectly, it just sounded like an out of phase signal.

I remember reading about one study, done in Germany, involving very low frequencies and phase shifting. They actually made some of the test subjects lose control of their bowels!

[bob p]

To cut a long story short, you do.

It's called "negative phase", and the idea is to apply a wavefront to your ears that couldn't have come from any conceivable sound source. Your brain can't localize it.

Steve, I wouldn't mind if you made a long story long. This experience was something that's always been at the top of my list of memorable experiences while playing out. If you've experienced the effect, and if you can elaborate on how to replicate it in a small room, I'd really love to hear more. So far I've tried using dual phasers and a stereo amp setup, but I just haven't been able to duplicate the intensity of the effect I described earlier. So I'm wondering if I really need that huge spread out soundstage, or a huge highly reverberant room, or a BiPhase. Perhaps I need to have someone else play the signal. Perhaps its a combination of all of these factors.

Just for reference, the only mind-altering substance involved in the experience was the MuTron BiPhase.

[bob p]

I was way into psychoacoustics when I was in college. I did one experiment in EML lab with stereo delayed signals and phase shifting that would cause most listeners to almost fall off their chair. It was very dependent upon the listener being centered, almost perfectly, in relation to the speakers and really only worked if the listener was using phones. If you were not positioned perfectly, it just sounded like an out of phase signal.

Wow. This sounds a lot like what I was talking about -- the effect presented an aural signal that was so difficult to process that I immediately became light headed and had trouble standing up. I must have been standing in the sweet spot.

Do you remember what kind of signals you used in the experiments?

[Jag]

It was a long, I mean, a while ago!

Here's what I recall,

I first noticed a minor effect when I was playing with a stereo delay (TC2290 I think). I was using VH Eruption as a source. At that point I wasn't really experimenting , I was working with delay parmeters and wanted to focus on settings rather than playing. I had phones on and, right at the end, where he does that long trem drop I accidentally brought up a fader that brought in the return from a digital modulation unit (probably a Digitech DSP 128). When that happened, I noticed that I got slightly dizzy so I started experimenting.

First I patched in a signal generator in place of VH (sorry Eddie) and started sweeping through frequencies. Not much really seemed to happen in the low frequency ranges but higher frequencies (8k-ish and above) the effect got really pronounced. Varying the frequency, manually, in the 8k - 10k range seemed to have the most effect.

Next I started messing with the delay times. IIRC 40-80ms hard to one side and half the delay time hard to the other side (20-40ms) and a tiny bit of dry right up the middle would really get things swimming.

Lastly I played around with the modulation. I can't remember if it was chorusing or flange (probably flanging). That was where I could really disorient myself.

I had a good week freaking people out with it in the EML lab.

I ended up using this effect in part of a recorded piece I did in quad for one of my assignments. I called it "Peaceful Uneasy Feeling" and it was played in a 400 seat theatre as part of an overall entertainment night at the college. Almost everyone sitting closest the centre of the theatre noticed the effect ( we didn't tell them ahead of time about the effect). The further away from centre people were, the less they noticed. The people sitting around the edges of the theatre thought the people in the centre were nuts, they didn't notice anything. No one fell out of their chair at the theater but, of course, they were listening in an open space as opposed to phones. The effect was noticed though.

I've still got the multi-track masters of that piece but don't really have any way to recreate the environment anymore.

About 10 years ago, before I got rid of my analog multi-track tape machines, I tried doing a mix-down, to stereo, of the tracks. Even on phones the effect was much less evident. I wish I would have transferred the multi-tracks to digital before I sold my decks! Maybe I'll see if I can get my hands on a 1" deck and bounce the tracks to Logic. I bet it would be fun to mess with in surround!

I don't recall playing with the environmental aspects at the time. I bet that a very dry environment would work better than a live/reverby space. It would be really cool to try it in an anechoic chamber. I think that's why phones enhanced the effect so much.

[Jag]

Now that I think of it, I probably don't need to dump the tracks to Logic. I should be able to do pretty much the same thing with Logic and the Waves suite!

HMMMMM, starting a new album in August. I think I've got an effect to use!

[Steve Conner]

Steve, I wouldn't mind if you made a long story long.

OK, here's everything I know about this kind of effect.

Normally when making stereo multitrack recordings, we try to keep all of the signals emanating from a given sound source in phase with each other. Stereo imaging is only supposed to be achieved by changing the relative amplitudes of the signals, like the balance control on your hi-fi amp or the panpots on a mixer do.

Of course more adventurous producers will mess with the phase too, doing things like Jag describes. The upside is that you can get incredible spatial effects, the downside is that they may sound terrible in mono, and may not work if you're outside of a sweet spot. (The standard amplitude-only kind of stereo gives a more predictable image that's still usable off-centre.) Generally, the main instruments in a mix should be properly phased, and this kind of thing should be used only as a special effect.

So that's what it does, but how to do it? The simplest phasing effect is, when introducing a mono signal into your stereo mix, flip the phase of one of the channels. This is so-called "negative phase", and Pro Tools, Logic and so on should let you do it.

If you don't do the DAW stuff, try hooking one of your stereo speakers up backwards for a taste of it. If you're used to listening in stereo, it can be quite unpleasant and disorientating, because as I mentioned earlier, the part of your brain that localizes sounds can't cope with it. The stereo image is destroyed, and you can't tell where any of it is coming from.

More advanced and subtle effects can be had by inserting a delay or phaser in one of the channels only, or two different delays or phasers in the left and right channels. Delays and phasers produce a phase shift that depends on frequency, and at any frequencies where the phase shift between channels adds up to an odd number of half-cycles, you get the negative phase effect.

In this context, a phaser acts similarly to a short delay whose delay time is controlled by the LFO. So you can see that once you start messing with that kind of thing, the stereo image could get seriously out of hand.

My old Yamaha sampler offered stereo dephase and detune: it could delay one channel of a stereo sample, and/or play it at a fractionally different speed to the other one. That could make some REALLY whacked-out stereo effects.

[Enzo]

Your ears can easily confuse you. SOmetime listen on headphones, plug your mic into a delay set for about 1 second, and send it to the phones. Now try to recite the alphabet.

[bob p]

But saying the ABCs never got me so light-headed that I went brain-dead and fell over face first ... unless you count those drinking games at the fraternity in college...

[kingjj]

i have felt it too. it was at a gig and i just thought it was anxiety because we sounded extra good. i blamed it on the lights but i guess really i got sucked in to the woosh of it somehow. i was still able to play but it was like i was drunk or disconected somehow.