• New Sponsor: ShipNerd, Ship Your Gear with Us... for less! Click Here.

Speaker polarity

sideman

Member
Messages
2,371
When you put signal on a speaker is the cone supposed to push out, or pull in, first? And with multi speaker amps, as long as the speakers are all going the same way, does it matter?
 

GCDEF

Silver Supporting Member
Messages
28,390
Some people will tell you it makes a difference. I don't believe them and I don't see how it could. With multiple speakers, they do need to be in phase.
 

scottl

Member
Messages
17,057
It matters. Easy to test if you feel/hear a difference. It is most noticeable at levels where you can get infinite sustain. The correct polarity for your system will be where you get the best feel on the bass strings and the easiest and longest sustain.

It is not dependent on your position. One way will almost always be preferable to the other.
 

Silent Sound

Member
Messages
5,601
It doesn't matter. Whether the speaker starts off one direction or the other won't matter. The sound wave is a displacement of air pressure created by the movement of the speaker cone. Whether you move in and out, or out and in, it's the same displacement of air. Now, it can matter if you have the same or a related sound coming out of a different speaker, such as a subwoofer or P.A. system. Then you have the potential for phase issues. At certain distances, however, it may sound better to intentionally place two speakers out of phase with each other so that the difference in phase correlates to the distance between the two speakers and aligns the peaks of certain desirable frequencies up to be in phase with each other to give a pleasing boost in and near those particular frequencies. But don't worry about that. As long as all of your guitar speakers are close together and in phase with each other, it'll sound the same no matter which way you have them wired.

Case in point. If a speaker out of phase actually sounded worse, then why do Fender amps have their reverb channels 180º out of phase?

Also, a sound wave can start off pulling a speaker in, just as easily as it can pushing the speaker out. If you record a guitar amp into a DAW and zoom into the wavefile, you can see that some sounds may start off above the axis (pushing the speaker out) and other sounds may start off below the axis (pulling the speaker in). You can't hear these differences, but you can see them. And who cares what you're amp's sound looks like. It only matters what your amp's sound sounds like.
 

GCDEF

Silver Supporting Member
Messages
28,390
It doesn't matter. Whether the speaker starts off one direction or the other won't matter. The sound wave is a displacement of air pressure created by the movement of the speaker cone. Whether you move in and out, or out and in, it's the same displacement of air. Now, it can matter if you have the same or a related sound coming out of a different speaker, such as a subwoofer or P.A. system. Then you have the potential for phase issues. At certain distances, however, it may sound better to intentionally place two speakers out of phase with each other so that the difference in phase correlates to the distance between the two speakers and aligns the peaks of certain desirable frequencies up to be in phase with each other to give a pleasing boost in and near those particular frequencies. But don't worry about that. As long as all of your guitar speakers are close together and in phase with each other, it'll sound the same no matter which way you have them wired.

Case in point. If a speaker out of phase actually sounded worse, then why do Fender amps have their reverb channels 180º out of phase?

Also, a sound wave can start off pulling a speaker in, just as easily as it can pushing the speaker out. If you record a guitar amp into a DAW and zoom into the wavefile, you can see that some sounds may start off above the axis (pushing the speaker out) and other sounds may start off below the axis (pulling the speaker in). You can't hear these differences, but you can see them. And who cares what you're amp's sound looks like. It only matters what your amp's sound sounds like.
The speaker's going in and out hundreds or even thousands of times a second. I don't see how it could possibly make any difference to your ear whether the first half of the first cycle is positive or negative.

The lowest note a guitar in standard tuning can produce is 83hz. The difference in timing between the speaker traveling forwards and the speaker traveling backwards is .006 seconds. There's no way you can hear that and there's no way it makes any difference. With higher notes, the difference is even smaller.
 

Structo

Member
Messages
9,555
I prefer the cone to push on the first attack.
You can easily check this by watching the cone and having the amp turned up loud.
Palm mute the strings and give it a hard strum while watching the cone.

If it pulls the cone in then reverse the wires on the speaker or make a speaker cable that has the wires so that the wire from the sleeve portion of the plug goes to the positive terminal on the speaker.

And of course if there are multiple speakers in the cab, make sure they are all the same polarity or you will get cancellation of some frequencies.

http://www.300guitars.com/articles/article-demystifying-the-phase-inverter/

My 2 cents.................YMMV
 

tonekingamps

Member
Messages
59
Up until about 10 years ago, I argued strongly that absolute phase could not possibly be heard, using much the same argument as GCDEF. From an engineering perspective, it just doesn't seem plausible. However, about 10 years ago I was struggling with comparing two speaker cabinet designs, each using the same speaker, and a very minor difference in the structure of the cabinet. I had been hooking them up to a footwitch that I used to quickly switch between them, and I connected them with alligator clips, ignoring speaker phase, since only one of them would be on at a time. For whatever reason, I had to disconnect them and reconnect them several times, again not paying attention to phase, and I noted that sometimes one cab would sound better, sometimes the other. Not seeing any other reason for the variation in judgement between the two, I tried experimenting with changing the absolute phase and found that it made a definite, easy-to-hear difference in the sound and feel (at least in a quiet room). If you have a junk 2-button footswitch and a soldering iron, it's easy enough to wire it up to reverse the phase of your speaker, so you can hear the difference without a time delay between the samples, and judge for yourself.

The problem is, when you consider absolute phase, you have to consider everything in the signal path, including your guitar pickups. There is no particular standard for the way pickups are wound, and amplifiers may invert the phase or not, depending on their design (effects devices too). So, if you are wiring up a speaker cabinet to be used with different amps and different guitars, you may as well ignore the phase, because you'll have it wrong 50% of the time regardless. You may want to just wire it so that it will be in phase with whatever other cabs you may be using it with in a multiple-cab setup.

Mark.
 
Last edited:

Tommy_G

Member
Messages
2,675
I understand the argument that if it's an AC signal, you shouldn't have a difference, unless the signal from the amp has different harmonics coming into play on the rise vs. the fall of the signal. But that palm muted attack thing rings true to me.

I'd love to do the A/B thing with the switch. In fact, have a Radial amp switcher pedal with the 180 deg. switch. Maybe I can rig it up through the effects loop.
 
Last edited:

sideman

Member
Messages
2,371
Thanks fellows. That thread, riffster, contained quite a discussion! But most of it is too technical for me.

It sounds like folks just disagree on whether the first signal to a speaker should push or pull the cone. Folks do seem to agree that when the speaker is hooked up "properly" (positive to positive), it pushes first.

The amp in question is a 2x12 Victoria Double Deluxe. I pulled one of the factory RI P12Qs this afternoon and swapped in a reconed P12N. The remaining P12Q and the P12N are in synch, both pulling on first signal. (This leads me to infer that either Victoria wired the amp to pull, or a prior owner messed with the speakers.)

My question is, should I leave the two speakers pulling together, or should I switch the wires on each so they both push together?

Some folks seem to say that, as a matter of physics, it doesn't matter, as long as the speakers are doing the same thing. Other folks say yes, it matters.
 

justnick

Member
Messages
3,671
I do wonder whether something else might be at play in the example Mark describes.

There are a number of ways one can see how wiring a speaker one way or another does not, in fact, create any kind of an "absolute polarity" relative to a source like an electric guitar.

1) If you switch between two pickups that are out of phase with each other the phase of the audio signal flips 180 degrees and therefore the relative polarity of the speaker inverts.

2) If you use the "Normal" channel of a blackface Fender amp instead of the "Vibrato" channel the phase of the audio signal flips 180 degrees and therefore the relative polarity of the speaker inverts.

3) If you play upstrokes instead of downstrokes (or play downstrokes on a guitar that's flipped over Hendrix style) the phase of the audio signal flips 180 degrees and therefore the relative polarity of speaker inverts.

You can easily see this if you record any of the above examples and have a look at the waveform in the DAW. For instance if you play a sharp down-stroke on the guitar the transient will begin with either a negative or positive peak (depending on the polarity of the pickup) and if you play a sharp upstroke it will begin with a peak in the opposite direction. This inevitably means that the speaker will initially move in the opposite direction in each case.

Again, this does not mean that something else might be happening when you change the polarity of the speaker connection and keep all other things the same, but it is very unlikely that what is happening is due to an absolute polarity relationship between the guitar and speaker.

And, as noted by many others, if you have multiple speakers you want them all wired with the same polarity so they are in phase, and you will most definitely hear all kinds of destructive interference (phase issues) if you don't.
 

riffmeister

Silver Supporting Member
Messages
16,670
When folks like Mark Bartel, Scott Lerner, and Steve Kimock say it makes a difference, I do believe them. A definitive explanation of the physics behind it, well that's another story.

I'm running a 2 amp rig, so for sure I make sure the two are in phase by reversing wires at one of the speakers. When they are not in phase, that makes a huge audible difference. Sometime I need to try reversing polarity on both speakers and see if I can hear the difference. I suspect it will be a small difference if I can hear it at all.
 

riffmeister

Silver Supporting Member
Messages
16,670
3) If you play upstrokes instead of downstrokes (or play downstrokes on a guitar that's flipped over Hendrix style) the phase of the audio signal flips 180 degrees and therefore the relative polarity of speaker inverts.
If I learned only one thing from the thread I quoted, it is that this is not true. It is the magnetic field in the plane perpendicular to the plane of the pickup that controls polarity of the signal. Up and down strokes produce the same motion in the plane perpendicular to the plane of the pickup. To reverse the polarity of the signal from a normally plucked string you have to pull the string up, away from the pickup, then release it.
 

Onioner

Member
Messages
2,860
If you have a junk 2-button footswitch and a soldering iron, it's easy enough to wire it up to reverse the phase of your speaker, so you can hear the difference without a time delay between the samples, and judge for yourself.
All you need is a consistent, and otherwise identical ability to swap phase, yah? Like, I could use the two outputs of Barber's Launch Pad, which are identical, except phase is swapped on one.

The problem is, when you consider absolute phase, you have to consider everything in the signal path, including your guitar pickups.
I know there are no guarantees, but it seems a reasonable assumption that if you are using pickups from one maker, especially a maker who isn't churning them out by the boatload, all of those pickups would be in phase with each other? So, if someone had a lot of Zhanguckers, the pickups at least could be taken out of the picture. If the signal path does not change, and only the amplifier and speaker are variables, then one could set one's speakers to be in phase with the chain with some given amp, then just learn when to swap phase when using a different amp. I'm assuming here single channel amps w/out multiple phase possibilities, though one could learn to take that into account...

For the record, I don't believe or disbelieve yet. I'm inclined to think that there aint no damned difference, but until I check that out for myself, I won't say it don't.
 

justnick

Member
Messages
3,671
If I learned only one thing from the thread I quoted, it is that this is not true. It is the magnetic field in the plane perpendicular to the plane of the pickup that controls polarity of the signal. Up and down strokes produce the same motion in the plane perpendicular to the plane of the pickup. To reverse the polarity of the signal from a normally plucked string you have to pull the string up, away from the pickup, then release it.
So why then, when I pluck up or down does the wave form begin with either a positive or negative peak respectively? This is very easy to demonstrate for yourself if you have a way of recording on your computer.

Though string motion is actually elliptical and shifts its orientation as the note decays, it's the sideways motion of the ferrous string that shifts the magnetic field back and forth so that it cuts perpendicularly across the coil of the pickup. That's what induces an alternating voltage in the coil. Same exact principle as you'll find in a generator. You can easily demonstrate which axis of movement induces the voltage with the elementary physics demonstration where you move a wire through a magnetic field. If you move parallel to the "lines of flux" (a way of visualizing the field) you won't induce a voltage. If you move perpendicular to them you will. At 45 degrees you'll get less voltage etc. The voltage varies as a sine wave, which is why the output of an AC generator is a sine wave, because the angle between the generator's armature (the rotating conductor) and the lines of flux of the magnetic field varies constantly from zero degrees (parallel) to 90 degrees, as it rotates.



n
 
Last edited:

justnick

Member
Messages
3,671
I suspect you could also easily demonstrate this by hooking a pickup up to a voltmeter and simply swiping a ferrous object across it. If you go in one direction you will induce a voltage with one polarity, in the other direction a voltage with reversed polarity.

Remember that the AC signal induced in a pickup is an analog of the string vibration--that's it makes a sound like the string vibrating when it drives a speaker. The primary axis of string vibration is not up/down, but parallel to the fretboard/pickups.

Keep in mind also that many amps (and pedals) flip the phase of the signal 180 degrees at one or another point in the signal path. In those cases also any "absolute polarity" relationship between guitar and speaker goes right out the window.
 

kimock

Member
Messages
12,520
There's no way you can hear that and there's no way it makes any difference. With higher notes, the difference is even smaller.

If you're willing to put your money where your mouth is, I'll take all your money.
 






Trending Topics

Top Bottom