Loud Speaker polarity ... again !

[j0k3335]

The problem I have with all of this is that it does change the sound with a single speaker. This tells me that as of yet we don't an explanation for it.
CW

so finally, I must line up with your position!

[pdf64]

…
So am I the victim of a placebo effect with this effect that I "think" I hear?!
…

To prove it to yourself, one way or the other, you could build a simple polarity flip pedal.
Maybe put an indicator led on a slide switch, switch it off, then you can stomp away without any preconception of which way it is, and which way should sound better.
Then when you’ve stomped on it for a while, identified the sound you prefer, turn the led on to check which way it is.
Repeat a few times to see if you get a consistent result.

I can’t hear a difference, but then my hearing is pretty shot.

[j0k3335]

To prove it to yourself, one way or the other, you could build a simple polarity flip pedal.
Maybe put an indicator led on a slide switch, switch it off, then you can stomp away without any preconception of which way it is, and which way should sound better.
Then when you’ve stomped on it for a while, identified the sound you prefer, turn the led on to check which way it is.
Repeat a few times to see if you get a consistent result.

I can’t hear a difference, but then my hearing is pretty shot.

as I have already explained, I have done a lot of tests and I hear this effect.
On the other hand, I may be in the ideal conditions:
. at my age, I always play at home in a home studio,
. the room, the position of the amp, the guitars used, ... all this is fixed, does not change,
. and I use very few pedals

So all is this is maybe favorable to what I hear this effect compared to others. ???

(PS : I don't have special hearing but it's true that I've always been careful (hearing protection during concerts, etc.) and that I'm used to paying great attention to sound, also loving Hi-FI
and that this have may be "trained" my hearing? )

who knows ???

[bepone]

…
in this example, rising peak has 1.4V amplitude, falling (second) has 0.8V amplitude. so in one speaker polarity TO YOU, in front, is coming the wave of 1.4V amplitude, and if you reverse polarity, to you in front is coming the second peak, falling , which is 0.8V. the first one 1.4V is now shot behind the speaker, in the cabinet, and it is considered like "waste wave".

That all seems a bit wonky to me
The rationale of the above seeming to be that we hear negative pressure fundamentally differently to positive pressure, even to the point that, to paraphrase, negative pressure is just waste, only positive pressure matters?

ma it is like it is we cannot change the physics. cone moves in one direction and after via suspension is moving in other direction with lover amplitude.
you cannot say that first wave == second wave , which is supended and attenuated and coming with delay of (delta)t after the first one.
and this is only on 1 positive impulse. what about permanent music then, is it better or worse?
i didnt make any tests by myself, i'm connecting minus pole of the speaker to 0 and + to + always but i will not be surprised if i will hear some difference

[pdf64]

…
as I have already explained, I have done a lot of tests and I hear this effect.
…

‘Some experiments’ were mentioned, but I didn’t notice any detail about how they were conducted?
The procedure I suggested should help to mitigate for unconscious bias affecting the findings.

[j0k3335]

‘Some experiments’ were mentioned, but I didn’t notice any detail about how they were conducted?
The procedure I suggested should help to mitigate for unconscious bias affecting the findings.

Exactly as you have mentionned: with a switch, keeping all the other parameters exactly the same .

[Max]

... in this example, rising peak has 1.4V amplitude, falling (second) has 0.8V amplitude. so in one speaker polarity TO YOU, in front, is coming the wave of 1.4V amplitude, and if you reverse polarity, to you in front is coming the second peak, falling , which is 0.8V. the first one 1.4V is now shot behind the speaker, in the cabinet, and it is considered like "waste wave".

...The rationale of the above seeming to be that we hear negative pressure fundamentally differently to positive pressure, even to the point that, to paraphrase, negative pressure is just waste, only positive pressure matters?

As I understand it, the task of a loudspeaker cone is to generate air pressure fluctuations in the air in front of the cone, which correspond to the voltage fluctuations present at the loudspeaker input.

When the cone moves backwards, an air pressure drop (acoustic wave trough by rarefaction of air molecules) occurs in the air in front of the cone, when the cone moves forward, an air pressure rise (acoustic wave crest by compression of air molecules) occurs in front of the cone. These air pressure fluctuations in front of the cone then propagate at the speed of sound until they reach the listener's eardrums.

The backward movement of the cone therefore does not produce a “waste wave”, but precisely the drop in air pressure in front of the cone, without which the acoustic waves, after reaching the eardrum, could only move it inwards (increase in air pressure), but not outwards (drop in air pressure).

If, for example, with a sinusoidal voltage fluctuating around 0 volts, the forward movement of some loudspeaker cone would result in an air pressure rise that is unequal to the air pressure drop generated during the backward movement, then such a loudspeaker would not, as I understand it, fulfill its purpose.

And from my understanding, such a defect could not be remedied by reversing the polarity.



Source: https://audiouniversityonline.com/audio ... und-works/

[j0k3335]

uncorrect ... sorry

[Max]

A speaker cone that - for whatever reason - is not able to convert a symmetrical voltage fluctuation into a corresponding symmetrical air pressure fluctuation will of course also not be able to do this with reversed polarity. As I understand it, a polarity reversal of a sinusoidal voltage fluctuation does not affect its symmetry.

If you - for whatever reason - want to find out whether you can tell when an acoustic wave front arrives at both eardrums at exactly the same moment (without time shift), whether both eardrums first move outwards towards the auditory canal, because a wave trough arrives first (drop in air pressure), or whether they first move in the direction of the inner ear, because a wave crest arrives first (increase in air pressure), then one could possibly contact the psychophysics department at a nearby university in this regard. AFAIK, subjects for psychophysical experiments are often in short supply and therefore usually welcome.

... cone moves in one direction and after via suspension is moving in other direction. ...

AFAIU, "moving in other direction" is not caused "via suspension":

"When the electrical current from an audio signal passes through its voice coil—a coil of wire capable of moving axially in a cylindrical gap containing a concentrated magnetic field produced by a permanent magnet—the coil is forced to move rapidly back and forth due to Faraday's law of induction; this attaches to a diaphragm or speaker cone (as it is usually conically shaped for sturdiness) in contact with air, thus creating sound waves. ... The suspension system keeps the coil centered in the gap and provides a restoring (centering) force that returns the cone to a neutral position after moving. https://en.wikipedia.org/wiki/Loudspeaker

[j0k3335]

AFAIK, subjects for psychophysical experiments are often in short supply and therefore usually welcome.

I have a little free time, of which it can be an idea. ...but need I mention this speakers polarity effect on Dumble-style amp ...
But can I be sure that I will not end up in the ... psychiatric department

just joking of course

[Max]

Alexander Dumble - Guitar Player Interview:

How does your philosophy on speaker enclosures contrast with other companies?

I think mine's different. I just don't believe in a baffle board with a couple of sides. Everything is designed to respond tonally. Even my open-back enclosures use air to the optimum. It's an ongoing process; I'm still finding out things that are useful.

There's a definite technique to developing enclosures. Instead of increasing the output all from the front by feeding more watts in, I designed a special series of open-back enclosures so that there's actually an air pole inversion process – I make the air respond in an in-phase relationship, both in front and in the rear of the enclosure. So, from the same amount of speakers, it's almost a doubling of sound. https://www.guitarplayer.com/gear/when- ... ew-in-full

[timrobertson100]

Just an idea - what if the input isn’t symmetrical? Is it reasonable to wonder if a speaker might behave differently to a distorted half of a wave in the forward motion to the backward motion?

[pompeiisneaks]

I have a general question here as well. There is, in an AC wave of any kind positive and negative signal direction. The speaker coil isn't going out only and then just 'releasing' but being withdrawn backwards by the attraction of the subsequent negative pull of the bottom half of the AC signal no? I.e. if I'm understanding the discussion it seems like some point is being made about the 'rebound being less than the force pushing it' but isn't it constantly being 'pulled' basically either postive or negative by the varying output signal from the amplifier, and therefore controlled more by a constantly changing magnetic field and not the 'rebound' of the cone? I'd think logically the only 'decelerating, weaker' kind of back response would be if the signal stopped at the exact moment the speaker reached it's maximum positive movement forward, and then it went silent, allowing the speaker to bounce backwards by the tension of the cone and not the magnetic action? Or did I miss something else being discussed in this magnum opus? I'd almost think the backwards motion would be easier for the negative pulses as the forwards motion creates tension in the speaker cone that it want's to inherently restore back to it's center position, and therefore snaps back quickly. Or is all the 'flex' happening in the softer rubber/foam ring that sits at the outside of the cone? Not sure their either.

Edit: spelling

~Phil

[romberg]

Just an idea - what if the input isn’t symmetrical? Is it reasonable to wonder if a speaker might behave differently to a distorted half of a wave in the forward motion to the backward motion?

This *might* do it. The ODS (and other amps) can produce very non-symmetric output. The preamp can clip one half of the wave and leave the other sunusoidal. There are some scope traces from my build showing this on this page:

https://ampgarage.com/forum/viewtopic.p ... 3a999384de

Now if (and this is a big IF) a speaker is very non-linear and is not matched as far as the pressure response in the push versus pull direction then I could easily see a non-symmetric overdrive tone being very noticeable over a sustained note when the polarity is flipped. One should be able to actually see this with test equipment. A speaker would have to have a balanced pressure response in the push and pull direction across the guitars whole frequency range. If it does not, then the polarity flip seems might more like a real thing.

Personally, I'm still in the camp that it (polarity) does not matter. But if I could see some evidence of measurable speaker non-symetric response I'd change my mind. I might even bust out my scope and a microphone and see if this can observe anything like this.

EDIT:
To try and clarify what I think has a possibility of happening. A speaker can be thought of as having two "springs". One pulls the cone towards it's rest position when the cone is pushed outward. The other spring works in the opposite direction. Now say that the two springs are not exactly matched. So, when the cone is moved outward a distance X there is less force pulling it to center than when it is pushe in the same distance X.

Now consider the 1/2 clipped wave. For simplicities sake say the wave goes up distance X and then oscillates at say 10 times the fundimental frequency then falls and is sinusoidal for the next 1/2 of the wave. The point is that there is high frequency content on the "clipped" 1/2 of the wave. Perhaps if the speaker has an imbanance in the push/pull "springs" this high frequeny content is attenuated if it is on one side? That might be something that could be heard.

But I have no idea how much guitar speakers act like this. They are not exactly hi fidelity. So, maybe....

Mike

[martin manning]

Here's a series of 15 notes, actually 15 copies of the same note, where some of them have been inverted. Can you hear any difference?