What happens if the leads to the speaker are reversed??

[hasserl]

Originally Posted by VaughnC

AC theory says that single speaker polarity shouldn't make any difference. However, the electric guitar signal is a special case because of its high initial transient attack. A guitar signal actually acts like DC for an instant and, if a speaker initially moves forward, I hear/feel more presence than if a speaker initially moves backward. However, if you can't detect any difference either way, consider yourself lucky as it's one less thing to worry about . I'm just trying to explain why there's a difference between a steady sine wave and a real world guitar signal.

Ahh, but Vaughan, the theory isn't about the initial attack, it is about the effect on sustained and trailing notes of an overdriven amp; where the asymmetrical signal matches up with the asymmetrical efficiency of the speaker to produce a sound that sustains and rolls into feedback with enhanced coupling between guitar and speaker. And to be honest whether the first movement of the speaker is forward or backward is irrelevant. I do not believe for a millisecond that you or anyone can identify which direction the speaker moves with the initial attack of the note.

[John Phillips]

Originally Posted by hasserl

If this is true the effect only happens under conditions of an overdriven amp, when the asymmetry of the signal is exaggerated, and when the conditions exist that the asymmetry of the signal matches up with the asymmetry of the speaker.

I don't have a solid argument against it. Other than the vast number of ways the signal gets flipped, and the difficulty there would be in trying to maintain a perfect match in asymmetry.

The number of ways the signal gets flipped doesn't matter - it's only important at certain critical points, particularly between the amp and the speaker (assuming the amp is the largest cause of asymetry). The number of other reversals along the way don't matter.

FWIW, I do think you can hear which way the speaker moves in the initial attack, especially on a clean sound - the transient peak on one side of the waveform can easily be double the height of the next one on the other side, and you can see this difference if you look at the cone... so I don't think it's impossible that you can hear it too.

As to blind testing... IMO, this difference is one of those where you can call it if you have the opportunity to compare both. ie, if someone randomly flips the phase while you play, I think I can tell which is which. But if you had to call the phase of a sound where you can't compare - ie if you just have to listen to one sound and say whether it is "in phase" or "out of phase" - no, I don't think I could. (I can't speak for anyone else.) I don't think the difference is that 'absolute'.

[Swarty]

OK, now I'll tell you how I became a believer in high end instrument cables... I have a lefty strat that I do my Hendrix schtick with... I was using a 20ft Klotz cable with the big Neutrik plugs and this plug on the upside down strat was jabbing me right in the forearm so I plugged in a 15ft Monster cable w/ a 90 degree plug... Much more comfortable to play, but it sounded like someone threw a heavy blanket over my amp... I went back and forth and was astounded by the difference... and it was 25% shorter!

[hogy]

You guys are still missing the point. Reread Kimock's "flippant" post.

Reverse the polarity at the speaker and LISTEN. That's all there is to it. You don't need to understand a thing and it's not brain gymnastics.

If you can't hear a difference, good for you. One less thing to worry about.

If you DO hear a difference, go whichever way sounds best to you with this particular set up.

[hasserl]

I don't think we're missing anything. We just like to discuss the how's and why's of certain phenomenon. With all of the "snake oil" products and techniques found in this industry it's not a bad practice, trying to keep things honest. Besides, it's interesting stuff.

Besides, I did try this one evening with a Super Reverb, playing rather cleanly. It's pretty simple to flip the speaker wires on a SR. I did it enough times to see for myself that there was no difference either way. But in discussions with Scott Lerner the point was made that you're not going to notice it while playing clean and at relatively low volumes. Okay, fine.

And I've not bothered to try it under other conditions, I've had other things to occupy my free time. If someone else has the time and inclination to do it, God bless 'em.

BTW, at what point does flippant turn to arrogant? I'm just sayin.....

[vibroverbus]

Originally Posted by John Phillips

I know you're kidding, but for anyone else who is wondering...

heh heh... I knew you'd done the A/B on both counts as well... lessee now can we add another Great Topic of Audiophile Debate?

"speaker polarity really becomes evident when you are using vintage style oil-in-paper caps and carbon comp resistors..."

[Johnny Z]

Originally Posted by vibroverbus

heh heh... I knew you'd done the A/B on both counts as well... lessee now can we add another Great Topic of Audiophile Debate?

"speaker polarity really becomes evident when you are using vintage style oil-in-paper caps and carbon comp resistors..."

.....and if your using a $100 Monster cable and Mercury Magnets Tranny with a Cooling Fan Tone Kit.

[unklmickey]

Originally Posted by hogy

You guys are still missing the point. Reread Kimock's "flippant" post.

Reverse the polarity at the speaker and LISTEN. That's all there is to it. You don't need to understand a thing and it's not brain gymnastics.

If you can't hear a difference, good for you. One less thing to worry about.

If you DO hear a difference, go whichever way sounds best to you with this particular set up.

okay.....

Originally Posted by kimock

....Anyway, the goal is positive pulse at the input=positive pulse at the output. ...


...The guitar and amp are both sound sources, they're coupled acoustically.

They either sum, or they don't.
The speaker is hittin', or it's quittin'....

but what if that doesn't match with this?

(in some cases it will match. in others, they will be diametrically opposed.)

Originally Posted by John Phillips

...many amps don't distort symetrically either (especially those with mostly preamp distortion, where the stages are always run single-ended), consequently even the sustain portion of the note may make the speaker move asymetrically....

aw crap!

i forgot to ask how any of this would be affected by the orientation of the OT in the Earth's magnetic field! (coplanar or perpendicular)

now i guess we'll have to start all over again!

[kimock]

Originally Posted by unklmickey

hi Kimock,

your answer was a bit flippant, and i think you missed the point i was trying to make.



since you addressed this:



you HAVE said there IS a correct answer for question 1!

you simply stated that you are not capable of answering the question.




knowing the magnetic polarity of the pickup, without knowing the winding direction, and how it is connected is totally irrelevent.

the combination of magnetic polarity (north up or south up) and winding direction (clockwise or counterclockwise) and reference (start grounded or finish grounded), determines polarity of output relative to string displacement (moving toward or away from the pickup).






is this your way of saying: "if you can't dazzle them with brilliance, baffle them with bull$hit"?

Ouch, sorry... I was just trying to have some fun with this and I guess it came out a little upside down.
I thought the "devil's advocate" thing put you on the other side of the issue, and you were delibrately confusing phase and polarity at the input without accounting for speaker polarity, listening position, etc.
I thought they were trick questions! My bad...

There's a right answer in each case for the absolute polarity of the guitar/amp thing, just not enough info given to say what that is in any of the examples you offered. The "trick" part is that it's strictly a polarity issue, not an electronic phase issue.

The real question here is "why are some people able to hear this effect while other people can't?"

All waveform and driver asymmetries aside, the biggest asymmetry that needs to be accounted for is in our own perception of sound, and how the brain processes and interprets certain types of information.
That was the subjective constancy part....
Here's the visual analog to that idea.
http://www.michaelbach.de/ot/fcs_hollow-face/index.html

Subjective constancy in music is your ability to recognize the sound of an instrument as constant under changing conditions of pitch, loudness and timbre in different environments and with different players.
This would be analogous to facial recognition, visually, and the difficulty we have remembering names as compared to recognizing faces should give you some clue to the difference between conscious and unconscious grouping of info.

The clue we need to pick up from the rotating mask illusion is that a static shot of the stimulus from either polarity is going to be interpreted by the brain as identical. We need to be in motion, at an angle to catch the "flip".

What you don't want to do is stand in front of your Fender amp, play a couple of licks, set your guitar down, flip the speaker leads, pick up your guitar and play a couple of licks...
Your subjective constancy will be screaming at you "what? You don't recognize the sound of your own guitar??"

Here's the process. Make yourself a speaker cable with a pair of banana plugs that you can easily reach and flip from the top of your amp.

Doesn't matter which polarity you begin with.
Stand next to your amp, not in front of it, with one foot in front and one foot behind, your head right in the middle, looking down at the top of your amp.
With a quiet clean tone on a single coil pickup, just brush a chord across all six strings, shing, shing, shing, and listen.

Shift your listening position back and forth from the front of your amp to the back while you continue the shing, shing, shing routine.

After a couple of passes you're going to notice the high end change from
shing, shing, shing, to thwick, thwick thwick on one side or the other, and you should be able to hear that timbral shift clearly as your listening position crosses top dead center and moves closer to on axis.

When your satisfied that there are in fact two different sounds that you can hear on either side of the speaker, flip the banana plugs, and the shing/thwick effect will reverse as well.

What you're hearing on the "shing" side is the pick transient arriving at your listening position on the leading edge of a pressure wave.
The "thwick" effect is the inverse of that timbral prefix attenuated by the propagation of that wave in the rarefaction created by the initial cone movement away from your listening position.

Learning to hear the difference in the prefix is the key to hearing the absolute phase thing.
The attack has to show up at your listening position as a pressure wave.
You might not hear it right away, but once you do it's an unmistakeable signature, and yeah, it's learned.

I gotta go deal with my kids, more later if you want, and apologies again for my late night humor attempt, didn't mean to come off that way...

Peace SK

[Swarty]

I'm thinking a switch box would be the way to go... because as you state, the orientation between your ear and the source is critical. With a switch box your face does not move.

[kimock]

Originally Posted by Swarty

I'm thinking a switch box would be the way to go... because as you state, the orientation between your ear and the source is critical. With a switch box your face does not move.

I do the switch thing myself, but it's OK to move around.
Might be easier for some folks to catch the effect in transition, as a progression rather than a flip.
The big dumb "critical" part is having the speaker pointed at your listening position so that the attack arrives as a compression..
You'll hear it, good luck!

[scottl]

What's for dinner? Humble Pie maybe?? LOL

:BEER

Originally Posted by Johnny Z

You what I really don't care. I can play most of you under the table on top of the table in front of the table and behind the table. So whats for dinner? The speaker polarity dosen't matter much to me, food matters.

[scottl]

Hasserl,

I definately hear the initial transient. When in phase, the bass notes have a softer and more blooming attack. When reversed, the attack is a "thwack" for lack of better term.

My buddy Jim has Dumble #88 (back for upgrades to Alexander in '87) He also has an original Dumbletor and matching EVM12L Dumble cab. Dumble wired the speaker reverse phase in the cab since the rig had a Dumbleator and now had an odd number of flips.

Just sayin'

[billdurham]

Its not that the speaker cares... but in a cabinet that is designed for air to move from the front of it instead of the back.. thats what makes the difference. Changing the polarity made the speaker go out instead of in on a positive pulse from the amp, I would guess.

BD

[unklmickey]

Originally Posted by kimock

Ouch, sorry... I was just trying to have some fun with this and I guess it came out a little upside down.
I thought the "devil's advocate" thing put you on the other side of the issue, and you were delibrately confusing phase and polarity at the input without accounting for speaker polarity, listening position, etc.
I thought they were trick questions! My bad......

hey no worries. typing doesn't lend it self to inflection or gestures, so we all come out a little upside down at times.

interesting you should draw a distinction between phase and polarity.

i was trying to point out that the "polarity" could get flipped several times, but eventually it comes out "in agreement" or out.

although we can use the term phase to mean "in" (zero degrees) or "out" (180degrees) we can also use it to mean any number of degrees.

your methodology of standing astride the amp is interesting, but i think it might be minutia lost in the mud at any appreciable distance.

since sound travels at about 1000 feet/second, at a difference of 10 feet, the sound from the speaker will reach your ear 10 miliseconds later.

it is quite possible that the rarefaction, rather than leading edge of the pressure wave, would be a more appropriate reinforcement for the string movement at that time.

but i think "at volume" this becomes sort of moot anyway.

and who in the audience will hear any of the sound directly from the strings.


now we return to the issues John brought up regarding asymmetrical clipping.

depending on which stage is being most heavily overdriven, the clipping could in the direction where the speaker is moving outward.......or inward.

which direction more desireable, and does THAT happen to agree with the preferred direction we found in the "shing" test.

will this vary from one amp design to another? (yes)

so, if they happen to disagree, what then? which one is more important?



part of this discussion has been predicated on the assuption that a "transverse" picking motion always results in an detected impulse that is a singular "polarity" of intitiation.

since the direction of detection is "vertical" rather than transverse, i suspect the direction of impulse might actually be random.


i still haven't returned to the issue of the opposite polarity of the 2 channels on a Fender amp, but i think the waters are plenty muddy already.