Polarity Smolarity

[thebes]

My newest toy, a very minty Anthem Pre1 sounds very nice, happily improved with a little tube rolling but with a wide soundstage and detailed presentation it is still not quite as deep as I would like it. I'm wondering if it could in part to the polarity thing mentioned in the manual.

The manual says" Special Note: The Anthem Pre 1 line stage inverts polarity, but the phono stage is non-inverting. Therefore, you may want to reverse your speaker wiring polarity to ensure proper signal polarity alignment."

Now I have already done that by switching the positive and negative wires at each speaker. Then I tried it hooked up the regular way it doesn't sound that different but between warming up the pre, warming up the monoblocks, loading the player etc. it's really hard to tell them apart because too much time has passed.

Now is this polarity thing the same as phase inverting? Because when I try out my test cd and lp it shows both phono and cd in phase no matter which way the wires are hooked up. If there's no difference inphase what's going on here?

Also, any suggestions on a really simple switch I could attach to the speaker wires so I could go back and forth without having to turn everything off so I can do a proper a/b and see what one I like the best.

Inquiring Thebeses want to know.

[HarryO]

Marty,

Since it doesn't matter on the Klipsch about the polarity of the speaker wires as long as they are both the same I don't see how it could affect it at the amp. I may be thinking incorrectly but common sense tells me this.

Harry

[LarryC]

Limited understanding here...to me, inverting polarity means the speaker sucks in when it should be pooching out and vice versa. Some preamps invert polarity in the phono but not the line stages (I'm not sure there's a vice versa in that case). And then there's the Joule Electra pre which inverts the line but not the phono UNLESS you've switched in the MC gain. Or maybe it's the other way around.

Different inversions between line and phono are a pain, because you have to invert the phono cart leads (!) to get 'em the same, and then decide which way the speaker leads should be to get correct polarity all the way through. Double pain to keep it straight if you switch between an MC and an MM.

"In-phase" is different -- both speakers sucking in or pooching at the same time, or not if it's out of phase.

Somehow, I think you knew this. Oh, it seems to me that you can hook your speaker wire to a double-pole double throw switch:

[pauln]

As mentioned above, polarity is whether the electrically positive signal causes the speaker to move forward or backwards, and visa versa for the negative part of the signal. Phase is whether to two or more speakers are doing this alike or opposite each other. Some crossovers use a phase reversal on a component (like the midrange) to compensate for reversal of phase by some crossover elements.

But there is another "angle" to polarity...

Take a sine wave... the waveform is symmetrical around the zero level (upper positive part of the wave is the same amplitude and shape as the lower inverted negative part of the wave), so absolute polarity may be of no real consequence.

Take the same sine wave... and amplify it with a SET amp and things can be a little different. Because the amp is single ended, the upper and lower parts of the sine wave signal do not quite match each other in amplitude and/or shape. The positive upper part of the wave tends to round off smoothly with increased power while the lower negative part of the wave tends to extend somewhat lower and with a sharper curve. This is the signature of even 2nd harmonic distortion... so it may make a slight difference whether the speakers outward movement is the rounder upper part of the wave or the more extended sharper part of the wave... lots of pre amps (almost all tube pre amps, I think) are single ended...... see diagram:

[stereohermit]

Id use double banana plugs on speaker inputs, and by flipping both around, u can quickly invert absolute phase. If speaker uses barrier strips, fashion some adaptors using short section of cable.

[mas]

Phase and polarity are not the same thing.

Polarity describes the initial response of a system to a stimulus. So, in acoustsics, polarity refers to the motion of an acoustical system in response to a stimulus. Positive polarity results when the acoustic transducer generates a greater sound pressure level in response to a stimulus. A dynamic driver moves outward generating a positive sound wave when stimulated electronically. Negative polarity refers to a dynamic driver moving away from the listener resulting in a negative pressure level when stimulated.

This is most easily illustrated by an impulse response.

Phase describes the relationship in time between 2 signals, or a signal and some other point of reference. This is often illustrated in terms of position, but in fact it is actually a difference in time (i.e.: ms or degrees), Phase is simply a fancy name for time. Thus, two signals that are aligned in time, as said to be in phase. If one signal is ahead of another signal, it leads in phase. Likewise a signal that is behind another in time is said to lag in phase.

To complicate things a bit, there is absolute phase.and relative phase.

Absolute phase refers to comparing two signals to the instant of their inception. Thus, to use a race car analogy, absolute phase refers to the position of two cars as they start at the beginning of the race from the starting line.

Relative phase can be an expression of the relative position of the two cars to each other many laps into the race that does not reference their distance from the starting point. For instance, the one car may be one lap behind the other car, and thus they are positioned very differently in terms of absolute phase. But we may talk of them in relative phase terms as being separated, by say, a car length. This is the relative phase that describes their physical separation. But their absolute phase difference would have to take into consideration the total distance they have travelled from the start o the race, and thus the absolute difference in phase may be great indeed, even if their relative phase difference is relatively small.

The absolute phase difference is what is most critical, And this difference in time (phase) is the source of many destructive affects to intelligibility. The value of the use of relative phase is limited and most generally used for comparison of 2 signals in a more atomistic manner. Relative it holds little value except convenience in signal alignment.

Understanding the difference is important, as we encounter this
situation constantly in audio and it is a cause of MANY destructive artifacts.

[mas]

Attached is an article that goes into far too much detail for most

here, but it addresses many commonly encountered situations in the

pro-sound realm.

Polarity.pdf

[gaspr]

Good article...thanks. The article states that some reversals are

audible, some not. So would the polarity reversal that

thebes describes be audible?

[mas]

Let's make this simple. Within general parameters (without dealing with configurations such as the Bessel array,etc.), the absolute generalization is that you always want a positive polarity/ impulse response at the speaker.

[sputnik]

.......The absolute phase difference is what is most critical, And this difference in time (phase) is the source of many destructive affects to intelligibility. The value of the use of relative phase is limited and most generally used for comparison of 2 signals in a more atomistic manner. Relative it holds little value except convenience in signal alignment.

Understanding the difference is important, as we encounter this

situation constantly in audio and it is a cause of MANY destructive artifacts.

Is that why the soundstage might seem wider when the speakers are out of phase?

[mas]

.......The absolute phase difference is what is most critical, And this difference in time (phase) is the source of many destructive affects to intelligibility. The value of the use of relative phase is limited and most generally used for comparison of 2 signals in a more atomistic manner. Relative it holds little value except convenience in signal alignment.

Understanding the difference is important, as we encounter this

situation constantly in audio and it is a cause of MANY destructive artifacts.

Is that why the soundstage might seem wider when the speakers are out of phase?

I am unaware of any situation where resultant comb filtering and polar lobing anomalies are constructive to a soundstage.

[sputnik]

.......The absolute phase difference is what is most critical, And this difference in time (phase) is the source of many destructive affects to intelligibility. The value of the use of relative phase is limited and most generally used for comparison of 2 signals in a more atomistic manner. Relative it holds little value except convenience in signal alignment.

Understanding the difference is important, as we encounter this situation constantly in audio and it is a cause of MANY destructive artifacts.

Is that why the soundstage might seem wider when the speakers are out of phase?

I am unaware of any situation where resultant comb filtering and polar lobing anomalies are constructive to a soundstage.

I'm not sure of the correct audio terminology but when you mentioned destructive effects resulting from phase difference, it reminded me of a statement in my amp operation manual where they said that connecting speakers out of phase may result in a wider soundstage with some loss of bass (which is similar to what Thebes was describing in the original post.) Constructive interference (if that's even a correct term) outside of the speaker placement didn't seem to make sense but can the destructive interference (and loss) for direct sound propagation between the speakers seem to accentuate remaining side reflections and create and effect that is perceived as a wider soundstage.

[thebes]

Wow this is a lot more info then I was bargaining for. I guess I confused myself because my previous pre, a Conrad Johnson, had a phase correct linestage and phase inverting phono stage. I thought the situation with the Athem was much the same thing. I can understand the reasoning behind the phase methodology used in the CJ because it is one less circuit employed and theoretically it will produce a quieter signal.

I have no idea why Sonic Frontiers messed around with the polarity in this pre but it seems my search for a deeper soundstage must take another direction, perhaps toward some cap rolling etc.

By the way, tube rolling out the 12AX7's and 6DJ8's Russian supplied tubes for NOS tubes made a huge difference in overall sound. The Russian tubes were detailed and quiet but almost muted. Rolling really woke up the dynamics but soundstage was the same in both instances. Great phono on this thing also.

An interesting and informative discussion.

[Islander]

I'm not sure of the correct audio terminology but when you mentioned destructive effects resulting from phase difference, it reminded me of a statement in my amp operation manual where they said that connecting speakers out of phase may result in a wider soundstage with some loss of bass (which is similar to what Thebes was describing in the original post.) Constructive interference (if that's even a correct term) outside of the speaker placement didn't seem to make sense but can the destructive interference (and loss) for direct sound propagation between the speakers seem to accentuate remaining side reflections and create and effect that is perceived as a wider soundstage.

Constructive interference is definitely a correct term. It refers to what happens when two (or more) waves that are in phase or close to it meet and combine to create a larger wave. In the case of destructive interference, two (or more) waves that are out of phase meet and partially or completely cancel each other.

This can occur in a quite small area, so the reflections in a typical listening room can cause what might look like a patchwork quilt of peaks and dips (in 3-D, of course). If it sounds okay where you're sitting, good enough!

[Blvdre]

It's not that uncommon. I've owned both a CJ PV-10A and a PF1, and they both invert the line stage, phono non-inverting. Ditto with my Wright WPL11.

[pauln]

For phono listening it can even get more complicated... some folks have become a member of the OOPS (the Out Of Phase Society); they flip two wires on their phono headshell to
invert signal phase in one channel along the entire
replay/amplification chain and them turn it back to correct phase at the speaker connection. Both of the two leaking (cross-talking)
noise signals (from left towards right - in phase, and from right towards
left - out of phase) cancel out internally. This is similar to the balanced approach wherein the common ground shared by the two channels is replaced with two independent grounds, although the out of phase approach is not balanced.

Trying it is very easy... invert the phono pre-amplifiers
right input signal phase by swapping the right channels red and green
headshell wire connecting clips at the phono cartridge. I.e. the
cartridges right channel (+) output (marked red) now connects to the
green clip and the cartridges right channel () output (marked green)
gets the red clip. The left channel stays unchanged. Then
revert to correct signal phase in the right channel at the end of the
signal chain by swapping the right channel speaker
cables (+) and () connections, either at the speakers or at the power
amplifier outputs binding posts. That is all there is to it!

Of course, when listening from other non phono sources you have to change the
right channel speakers polarity back to normal by swapping its plugs... unless instead of making the initial phase inversion at the head shell you refabricate your ICs so that the phase inversion of one channel is an attribute of the interconnects' wiring themselves for all your sources.

[WMcD]

You can Google around to read about The Wood Effect.

Some years ago there was concern about more than just our playback systems and possible inversions. Rather, the concern was that we really can not be sure about anything in the process of microphones, mixing, and recording. So inversion could occur quite by accident before it gets to our living rooms. Fortunately this is one problem which can be easily solved with a simple switch. If you do have an inverted recording on your hands and inversion makes it sound bad, a simple switch will set things right and life will be grand.

It seems agreed that listeners can detect the inversion of an asymetric signal, e.g. a sine wave clipped on the top or bottom. However, it is probably fair to say that such asymetric signals seldom occur in music. I suppose there are instances of signals which similar to a step function or an impulse. Question: does a kick drum sound significantly different if you put the mike behind, or in front?

This appears to be a red herring and our ears don't detect inversion in the usual sources. The proponents argue that this lack of detection iin typical soureces is not really correct; rather we just don't have the correct conditions.

There is the theory that absolute polarity would be detected more widely, if only the phase information had not been so messed up by various mechanisms in the recording chain. I can see that point, in theory. But are the vast majority of recordings suffering from this?

The statements I see, by Googling, report only one or a few recordings where inversion makes things sound different, and better. But it is anecdotal and I'm not quite convinced.

It seems to me that experimentation here is very easy. A set of headphones can be easily wired for inversion with a simple DPDT switch. However, the headphone test reported used two sets rather than a simple instantious switch. I can only suppose such a switch would not show much of any change. If it did, it would be a staple of the Hi Fi world. It is not.

I seems that some use was made of a simple switch and nothing was found. The proponent who promised a startling result explained this away by claiming the inversion switch caused a problem arising from directionality in wires. Thus the benefits were negated. This directionality in wires theory is that speaker wire (and presumably every other wire) works better, or sounds better) when connected with a certain end at the source. =8^o

Some of the discussion is quite turbid. You can read for yourself.

Gil

[mas]

Folks, polarity and phase are still too often being used interchangeably as if they are equivalent.

They are not, and to the degree that this is being done, such use is totally incorrect.

Polarity is neither time nor frequency dependent.

Phase is the result of electrical, mechanical or acoustical offset of a signal in time.

Despite the fact that, for only a single fixed frequency, it is possible to delay a signal in time 180 degrees out of phase with the original waveform with the result being that the waveform appears virtually identical to a polarity reversal, they are in no way the same. A change in phase is by definition a function of time, and a change in phase alters the arrival time (but not the velocity!) of a signal.

Edit: Addendum:

Folks, sound is a pressure wave, NOT a traveling wave. Confusing electrical signal models with acoustical pressure waves without understanding the differences is asking for even more confusion (is that possible?)..

1. A classic example of this confusion is the phase of a reflection!

UNLIKE an electrical traveling wave reflection, when sound waves in air ( pressure waves) encounter a surface with a surface featuring a higher acoustical impedance than air (in other words, from low density to high density), there is no change in phase upon reflection.When the high pressure portion of the pressure wave impacts the wall, it is likewise reflected as a high pressure wave. It is not reflected with inverted phase which would imply its being reflected as a low pressure wave. Conversely, reflections from a lower acoustical impedance medium such as air (in other words, from high density to low density) will be reversed in phase, and a lower pressure region will be reflected.

2. And regarding polarity and phase, I will agree, within the audiophile community, it certainly seems that confusion reigns! In physics, the distinction is very clearly defined and understood.

[pauln]

I see sites that say."...absolute polarity (a. k. a. absolute phase)"... confusion reigns.

Directional wire... an audio signal goes through a wire in both directions, first one way, then the other. The degree of how strongly and when the direction changes are defined by the waveform of the signal. Any wire that did conduct differentially by direction would not be linear and not be appropriate for audio signals.

Maybe a good question would be: Does the ear hear a positive (relative compression of the air) differently than a negative (relative rarefication of air), and if so, does this detection translate to hearing a difference in music? The kick drum miked in front or behind is a good example... because there is a large initial forward movement of the drumhead (with lots of superimposed frequency energies distributed across it while it moves, both forward and back).

Wood Effect looks like the answer could be Yes: Discovered by Charles Wood at the Defense Research
Laboratory in 1957, it was first reported in 1962 in the Journal of the
Acoustical Society of America. "Wood used as a signal a sinusoid
partially clipped during half of each cycle. The resulting sound had a
different timbre when the flat-topped portion was presented to the ear
as a rarefaction, than it did when leads were reversed and the
flat-topped portion was presented as a compression."

Musical instruments generate different power spectrums of harmonics. This is a source for many to provide a non-symmetrical waves.

[gaspr]

Here

is a good article regarding the miking of drums etc. (edit)

After re-reading the article, it seems that the terms polarity and

phase, are sometimes used to mean the same thing in the pro sound world

as well....adding to the confusion.