autoformer and polarity

[Axz Hout]

x

[Marvel]

They both look the same using my iPad.

The EAW one loads with Greek characters on my pc. IE displays correctly, but FF does not. One might assume that Safari would show correctly, but I don't have it installed on my home PCs.

Bruce

[vindeville]

I appreciate the constructive input that some have offered. I would not ask a question unless I thought there was something to gain based on things I have heard or been told or read may be pertinant. I was just looking to understand this more and see if anyone had test results on tap selection to share. I think we all understand simple wire polarity at this level of audio enlightenment. I know that "by ear" impressions have merit but would like to see info or testing that quantifys this. Again I may have worded things poorly in my post and I am sorry if that caused issues for anyone. Inferring ignorance in ones reply is still not warranted regardless. Simple respectful replys are the ticket here so that we all can be a part of things regardless pf technical expertise. The only dumb questions are the ones never asked.

Edited April 13, 2014 by vindeville

[jcmusic]

I will post some measurement results later from today, I tried reversing the polarity in just the mid driver to see what changes it would produce...

[jcmusic]

Here are the measurements from earlier today, the first one is with the mid driver's polarity normal the second is with it reversed. All other parameters were the same just flipped the wires...

[Deang]

Actually Jay, the first plot is with the polarity inverted because the wiring is reversed on the network side. Anyways, the plots show what we should expect to see.

While examining the schematic for the CornScala-wall, I noticed that the polarity for the midrange was not inverted like it was on the Universal. Understand that the CornScala- wall and the Universal are the same design with the exception of the cap and coil combination which dictates the first transition. Here is my brief exchange with Al on the subject:

At 10:37 PM 8/2/2013, you wrote:

Al,

As with the Universal, polarity needs to be inverted for the squawker with this network. I noticed it wasn't, so I wanted to bring it to your attention.

Dean,

Driver polarity is a thorn in my side with all of these networks. In reality, every network / driver and speaker combination needs to be tested with instruments, individually to determine what the correct setting is. How do I do that? With the CSW network, who knows what speaker it's going to get used in!

______________________________________________

Is he right? All of the plots that I have access to, tell me that while he might be technically correct - in practical usage, that section of the filter should probably be inverted.

The new economy version of the Universal, like the CornScala-wall, does not invert polarity for the squawker.

If I owned this crossover and was running stock drivers, I would invert the wires for the squawker at the barrier strip. Looking at Jay's plot tells me that if I'm running that particular set-up, I would do the same for it.

All other iterations of the Universal have the squawker polarity inverted on the network side.

With other driver combinations, I would be inclined to try both ways. Conventional wisdom says the choice which sounds loudest is the correct setting. Personally, I would just flip the wires - the chances of a non-reversal don't seem very high to me.

Edited April 14, 2014 by DeanG

[jcmusic]

Ok Dean,

Here where things get tricky, my pre-amp inverts the output signal to my amp so to keep the polarity correct I have to flip the speaker wires on the amp.

This can get deep when adding subs taking the signal from the pre-amp, is it inverted or not?

[Deang]

The same but different

http://www.stereophile.com/content/seeking-advice-wiring-inverting-preamp

You are comparing the entire signal to a section of a filter that needs to play nice with the filter sections connected to it. In other words, flipping the speaker cables won't fix that notch-out in your frequency response (try it).

[Deang]

Caveat to my original post - the older JBL drivers that tell you the negative connection causes an outward movement of the diaphragm.

From Elliott's site:

"For reasons that remain totally obscure, for some time JBL reversed the polarity of their drivers. One expects that a positive voltage on the red (or + terminal) will cause the cone to move outwards, but JBL reversed this so positive on the black terminal causes the cone to move outwards. Incorrectly phased drivers - especially in the same physical enclosure - will be damaged very easily, because there is no loading on the cone. Newer drivers are phased correctly."

Edited April 15, 2014 by DeanG

[ClaudeJ1]

Polarity, polarity, polarity, NOT phase.

[Deang]

Lol, yes Claude, we know - it's covered in the document. We even have it in Greek, in the event that it might sound like Greek.

So, true or false: "180 out of phase" is the same as "a reversal in polarity"?

[Axz Hout]

x

[babadono]

The only dumb questions are the ones never asked.

:emotion-21:

[Deang]

If I'm building a crossover, each element introduces 90 degrees of phase shift. In a 1st order, we have 90 degrees, 2nd order, 180 degrees, 3rd order, 270 degrees, and fourth order, 360, or zero phase shift.

If the filter section is 2nd order, and has 180 degrees of phase shift - we invert polarity.

Phase and polarity may not be the same thing, but they are certainly related.

http://www.sweetwater.com/insync/out-of-phase/

Edited April 15, 2014 by DeanG

[jcmusic]

The same but different

http://www.stereophile.com/content/seeking-advice-wiring-inverting-preamp

You are comparing the entire signal to a section of a filter that needs to play nice with the filter sections connected to it. In other words, flipping the speaker cables won't fix that notch-out in your frequency response (try it).

I am not sure I follow you completely, anyway what I was saying is the my pre inverts the output signal so to keep the polarity proper or as it started I flip the cable at the amp. Now adding two subs that take the signal from the other set of pre outs which would be inverted does not get flipped. So are the subs and mains having the same polarity or not??? As for the plots I just wanted to show the OP what my curves looked like if I reversed the polarity on just the mid driver...

[Deang]

I've owned several preamps like that, I understand what you're saying. They say "phase inverting", but it's really polarity. That actually speaks to the point I was trying to make in my last post. Just do what the manual says - flip the wires to get the correct polarity. The subs are low level, and don't have speaker cables, but they should have a "phase switch" right? No matter, this part is complicated - because now it really is about phase, or "time", because of the distance of the subs from your mains and the overlapping wavelengths. This really is an exercise in frustration without some way to measure, which you apparently have.

[Marvel]

...and fourth order, 360, or zero phase shift.

Dean... a serious question.

If a signal is 360 degrees out of phase, does that meant at a given freq. it is one cycle behind? Wouldn't the component cause the delay/shift so that 360 wouldn't be the same as zero phase shift?

Bruce

[mark1101]

_{Good point Bruce.........I think that's all part of the "smear" of passive crossovers and non-time aligned systems. You can minimize it some by design but can't get rid of it.}

[ClaudeJ1]

So, true or false: "180 out of phase" is the same as "a reversal in polarity"?

Not always true. It's possible to have same polarity on 2 drivers with a 180 phase shift (no time alignment). It is also frequency dependent. But it's also entirely possible I have it all backwards. LOL.

Edited April 16, 2014 by ClaudeJ1

[mark1101]

I think Dean was referring to if a signal became out of phase with itself by 180 degrees (let's say by a switch on the preamp)..........is that the same as reverse polarity of the wires?