Speaker cables

[mhardy6647]

I met a stunning lady at a party about a decade ago, that was from Sacramento and close to some members of Cake.
It was like seeing a unicorn.

Hey -- I had an employee in a past life who went to High School with the CAKE guys (at least some of them) in Sacramento.
I have a good six degrees of Kevin Bacon story, too -- FWIW.

... but I digress.

 

[rwortman]

Two sine waves of opposite polarity:

Two sine waves 180 degrees (pi radians) out of phase

Recorded sounds of voices and instruments are not symmetrical. Some people in controlled conditions can hear polarity reversals.

 

[mhardy6647]

Recorded sounds of voices and instruments are not symmetrical. Some people in controlled conditions can hear polarity reversals.

Absolutely true IME -- I have a hifi colleague who (correctly, as it turns out) diagnosed, by ear, a polarity reversal on one driver in my own hifi back when it was in MA. Not sure what that has to do with polarity vs. phase, though.

Subsequently, I bought myself one of these, which comes in very handy for polarity troubleshooting.

CPTS Cricket Speaker Polarity & Continuity Tester - Galaxy Audio

CRICKET POLARITY TEST SET

www.galaxyaudio.com

 

[Holmz]

Absolutely true IME -- I have a hifi colleague who (correctly, as it turns out) diagnosed, by ear, a polarity reversal on one driver in my own hifi back when it was in MA. Not sure what that has to do with polarity vs. phase, though.
…

I think a lot to do with it.
or
A lot of people think of polarity as a phase shift at one frequency for a sine wave.

“out of phase”, and “reversed polarity” or “out of polarity” often seems to be describing the same stuff… but technically there must be correct phrase to use for it.

 

[Holmz]

I agree that a system should be linear "faithfully reproducing what is put in." That is the goal.

----

What I was getting at is that phase is changing in the recording and mixing process of the music that you are listening to, long before your system gets involved.

In using the kick drum as an example they almost never have a single mic (for most genres that is). I usually use 2 or more mics when I am recording a kick drum (not jazz ). If for example you have a mic on the beater (batter head) and another mic on the resonant head of the drum; those mic diaphragms will be moving in opposite directions with each strike of the beater. The engineer involved in said project is making a decision on which one they want to be "right." Said decision probably has more to do with how things feel (getting the mix where they want it) or playing well with other mics in the room than being accurate to the acoustic waveform.

Anytime a source has more than one microphone (audible) problems with phase are being introduced. Yet rarely do we have music in mono recorded with a single microphone.

---

Additionally when it comes to the mixing of music one of the main tools available is EQ. Any type of filter (EQ, Low-pass, High-pass etc) by their nature introduce changes in phase. Pass filters in a significant way. While linear phase EQ filters do exist in the digital realm they are able to achieve this at the cost of time (8+ ms usually); linear phase EQ does not exist in the analog world.

Bottom line: any album you listen to probably has a lot of significant changes occurring in phase before it gets to your system; especially records there were mixed and master with an all analog chain. I say sit back and enjoy the music, and trust the ears the created the album for you.

^All true^

I was thinking that the polarity would be always upright, But I have been told that recording engineers flip it Willy-nilly at will.

 

[egellings]

I would think that a driver out of phase in a multiway speaker would be audible.

 

[rwortman]

Phase shift is moving a signal in time. 180 phase shift may look identical to polarity reversal with a continuous symmetrical signal but it is not the same thing.

 

[rwortman]

I would think that a driver out of phase in a multiway speaker would be audible.

Audiophile magazines love high end Wilson speakers that go to great lengths to phase align the drivers. They also get giddy over Magico speakers that are not phase aligned. if you really meant incorrect polarity, that’s a different question.

 

[egellings]

For "out of phase" in my last comment, I meant wired backwards, not just out by a few 10's of degrees or so.

 

[mhardy6647]

Phase shift is moving a signal in time. 180 phase shift may look identical to polarity reversal with a continuous symmetrical signal but it is not the same thing.

We're saying the same thing, all righty.
We've just been out of phase.

 

[Ingenieur]

My basic approach, may be overkill
Use your amps 4 Ohm rating, max current
Mine is 220 W, V = sqrt(4 x 220) 30 V
I = 7.3 A

I use a max V drop of 2%, in this case 0.6 V
Z = 0.6/7.3 = 0.08 Ohm or less required

Assume length is 20' x 2 = 40' loop
NEC table lists values per 1000'
Z = 40/1000 x Z from table = 0.08
Or Z from table = 1000 / 40 x 0.08 = 2 Ohm
From the table using Z at 0.85 pf (30 deg)
Use PVC values
You need ~ 2 Ohm or less.
12 AWG 1.7 Ohm

Assume 35' rum 70'
Z required = 1000 / 70 x 0.08 = 1.15
You may want to upsize to 10 AWG at 1.1 Ohm

Power loss will be
If 10 W 8 Ohm, V = .9, I = 1.1
Ploss ~ 1.1^2 x 0.08 ~ 0.1 W or 1% or less

 

[Matthias McCready]

Maybe a better way to exemplify phase:

A signal can be:

1. Out of phase, but in time: Think of a sub being correctly delayed to your main speaker for your listening position, but because the sub and main are out of phase they cancel at the hand-off frequency.
2. In Phase, but out of time: If your sub-woofer is in phase with your main speaker, but is delayed 7 minutes behind your mains (a ludicrous example I know!).
3. In Phase, and in time: Time alignment is correct and the phase is aligned allowing for summation between the sub-woofer and mains at the listening position.

In example one; this would usually be corrected by flipping the polarity, as the timing is correct.

In example two, this would be corrected by utilizing delay. Which is usually just a few ms; unless you are working in a live sound environment.

----

As to us engineers flipping polarity "willy nilly"

There is usually a method to the madness. (usually... )

Going back to the kick drum example. For most live kick drum micing I utilize 2 mics, both placed inside the kick drum. One of them is respectively for the lower frequencies of the drum, and one is for the top-end attack. For the particular mic setup I use most often, and with how they are positioned I find that flipping the polarity on one of the pair sounds much better. When polarity is the same the sound of the drum is more midbass heavy; which is usually where I would make an EQ cut. Flipping polarity on one of the mics tightens up the low end, and causes the lower mids to be out of phase, causing cancellation; while leaving the top end fairly intact. Keep in mind that phase varies by frequency, which is due to the size of wavelengths. So in this example flipping the polarity of one of my mics gets me a lot closer to the sound I am looking for before utilizing any EQ.

In this sense audio engineers often use polarity (or degrees of it) as way to tonally shift things.

As another example if you have a bass guitar which has two sources: A miced amp and a DI, it is common that the phase of these two versions of the same source will not be the same. Well which one is "correct?" You don't know! Depending on how complex your DI or amp (and mic) is they might mess with things. So usually polarity will be flipped (or something such as a Little Labs IBP could be used) on one channel to see if that sound is preferred.

---

To the point if I am mixing a project and I wasn't there when it was recorded I probably won't know where mics were positioned relative to each other. I will be working off of what sounds best for the particular project.

---

Phase REALLY matters anytime you are listening to two instances of the same source. Flipping polarity on one of your instances will change the sound significantly. However I would maintain that if you polarity flip has no reference, it will not be noticeable.

For reading on the subject Bob McCarthy's textbook "Sound Systems: Design and Optimization: Modern Techniques and Tools for Sound System Design and Alignment," addresses phase near the beginning. While this book is fully geared towards live sound and systems engineering, he is quite thorough and does a great job explaining the science, and many of the inherent compromises involved with the propagation of sound.

 

[norcalscott]

Hey -- I had an employee in a past life who went to High School with the CAKE guys (at least some of them) in Sacramento.
I have a good six degrees of Kevin Bacon story, too -- FWIW.

... but I digress.

Sorry to digress further, but my son went to elementary school in a Sacramento suburb and his teacher was the aunt of one of the Cake guys and she used to bring in Cake merchandise and give to the students. My son (now senior in college) became a fan of the band because of that excellent marketing by the aunt.

To make this post relevant to the thread - I have been using this wire for my speakers and it works really well and having red and black makes the polarity issue moot.

 

[mhardy6647]

To make this post relevant to the thread - I have been using this wire for my speakers and it works really well and having red and black makes the polarity issue moot.

Well... yes and no.
Polarity can get a little fraught if one happens to be a devotee of vintage JBL & Altec drivers.
Not to mention that there are times that diaphragms in compression drivers have been replaced with more modern diaphragms that may not adhere to the original polarity convention for the driver in question, so it really becomes a trust but verify situation.


see, e.g.,

https://jblpro.com/en/site_elements/tech-note-polarity-conventions

288C Terminal Polarity

Greets all from Sydney... I have several 288C's, all of which have the older diaphragm in them. The driver terminals are marked 1 and 2. The actual di

www.hostboard.com

PS I like CAKE quite a bit.

 

[Chrispy]

Why is it that when people on another forum see an avatar of a speaker cable using lamp shade, they discredit the person posting?

I probably would have used something better, but I have been waiting ~5 months for the mogami to get in-stock and ship.
(and the speaker sound better with a lamp cord than with no cable… which I needed to do after replace it a monoblock with a stereo amp.)

It seems to be ire inducing.

View attachment 184613

Had to reread that a coupla times, while I've seen horrid lamp shades, be kinda hard to hook a speaker up with one Started reading answers and see you meant lamp cord. Those forums are full of idiots most likely, lamp cord is just fine of course as long as the gauge works for you.

 

[-Matt-]

... so it really becomes a trust but verify situation.

I remember reading on a car audio site the recommendation to use an AA battery to test wiring polarity...

You can watch the direction of cone excursion when you close the circuit with the battery (briefly tap the wire onto the battery). Ideally you want the cone pushing out for +ve.

 

[mhardy6647]

I remember reading on a car audio site the recommendation to use an AA battery to test wiring polarity...

You can watch the direction of cone excursion when you close the circuit with the battery (briefly tap the wire onto the battery). Ideally you want the cone pushing out for +ve.

That works great for a woofer or cone driver of moderate size.
Works less well for a tweeter or compression driver diaphragm, especially in situ. Careful digital (as in finger) touch can reveal the sense of the displacement, but it's tricky and nigh-on impossible with some drivers in my experience.

 

[dc655321]

That works great for a woofer or cone driver of moderate size.
Works less well for a tweeter or compression driver diaphragm, especially in situ. Careful digital (as in finger) touch can reveal the sense of the displacement, but it's tricky and nigh-on impossible with some drivers in my experience.

Easily determined with a microphone though.

 

[mhardy6647]

Easily determined with a microphone though.

Which is how the Cricket works. It uses a little asymmetric chirp tone and listens to it with an onboard mic. Foolproof (i.e., fool-tested, in my case ) and easy to use. Costs a hundred bucks (or, at least, it did when I bought one).

 

[rwortman]

Maybe a better way to exemplify phase:

A signal can be:

1. Out of phase, but in time: Think of a sub being correctly delayed to your main speaker for your listening position, but because the sub and main are out of phase they cancel at the hand-off frequency.
2. In Phase, but out of time: If your sub-woofer is in phase with your main speaker, but is delayed 7 minutes behind your mains (a ludicrious example I know!).
3. In Phase, and in time: Time alignment is correct and the phase is aligned allowing for summation between the sub-woofer and main.

In example one; this would usually be corrected by flipping the polarity, as the timing is correct.

In example two, this would be corrected by utilizing delay. Which is usually just a few ms; unless you are working in a live sound environment.

----

As to us engineers flipping phase "willy nilly"

There is usually a method to the madness. (usually... )

Going back to the kick drum example. For most live kick drum micing I utilize 2 mics, both placed inside the kick drum. One of them is respectively for the lower frequencies of the drum, and one is for the top-end attack. For the particular mic setup I use most often, and with how they are positioned I find that flipping the polarity on one of the pair sounds much better. When polarity is the same the sound of the drum is more midbass heavy; which is usually where I would make an EQ cut. Flipping polarity on one of the mics tightens up the low end, and causes the lower mids to be out of phase, causing cancellation; while leaving the top end fairly intact. Keep in mind that phase varies by frequency, which is due to the size of wavelengths. So in this example flipping the phase of one of my mics gets me a lot closer to the sound I am looking for before utilizing any EQ.

In this sense audio engineers often use polarity (or degrees of it) as way to tonally shift things.

As another example if you have a bass guitar which has two sources: A miced amp and a DI, it is common that the phase of these two versions of the same source will not be the same. Well which one is "correct?" You don't know! Depending on how complex your DI or amp (and mic) is they might mess with things. So usually polarity (or degrees of it) will be flipped on one channel to see if that sound is preferred.

---

To the point if I am mixing a project and I wasn't there when it was recorded I probably won't know where mics were positioned relative to each other. I will be working off of what sounds best for the particular project.

---

Phase REALLY matters anytime you are listening to two instances of the same source. Flipping polarity on one of your instances will change the sound significantly. However I would maintain that if you polarity flip has no reference, it will not be noticeable.

For reading on the subject Bob McCarthy's textbook "Sound Systems: Design and Optimization: Modern Techniques and Tools for Sound System Design and Alignment," addresses phase near the beginning. While this book is fully geared towards live sound and systems engineering, he is quite thorough and does a great job explaining the science, and many of the inherent compromises involved with the propagation of sound.

There is no such thing as degrees of polarity. Degrees refers to phase. You don’t “flip phase“, you flip polarity. Maybe you need to re-read that book.