Black=positive

[carolus]

Do not use a battery to check polarity on a compression driver. Cones only say mids and woofers where you can see the movement.

Rob

Hi Rob,
FYI,
1) This is my home method: with battery (even 1,5Vdc) , long bristol-paper-rule (in a V-shape) and millimeter measuring rule ...
It's very easy to see the (+) or (-) 1/10mm diapragme deplacement .... So, my JBL2482 and 2441 are now with the correct polarity,
Second method,
2) And for a total check with drivers on horn (and blind woofers in casing) i use ... "phase-it", a fine pretty tool from Gato-Audio .... (final test with cabling between amp and driver ... no mistake)

Allez, salukes & the best,
Karel

[Earl K]

• Yes, holmimpusle for example will show you the thing immediatelyI was surprised when I installed some truextent diaphragm to see that they also follow the "old" reversed logic, whereas their doc tell the opposite!http://materion.com/~/media/Files/PD...nDiaphragm.pdfThe "+" on their diaphragm is in fact a "-", so the doc should read "positive voltage on - terminal moves diaphragms towards phase plug"...This is good for compatibility with older diaphragms that these are supposed to replace, but I wish their doc at least tell the truth, as I had to reinstall my diaphragms...

  When I installed the diaphragms I wanted to keep the original behavior of the JBL driver so I connected the black terminal to the + on the truextent to get a reverse polarity, but it was in phase...I know my test setup respects polarity so I am pretty sure about this (and also the fact that now that I reconnected the red terminal to the + the popularity is the same than my other JBL drivers)

  > Black ( on the driver ) to "+ on the TrueExtent" voice-coil gave you a positive displacement ( or "in-phase" as you mistaken call it ) just as TrueExtent says you should get ( assuming you connected a positive going pulse to the black terminal on the driver ) .
  
  > Maybe the problem here is that you think the " minus terminal ( for any type of polarity test ) " equates to the black terminal ( on the driver ) , when in fact ,"minus" (from say a tiny, tiny battery ) goes to the red terminal ( for a polarity test ).
  
  > This is for Legacy JBL stuff / also assuming you want to achieve a positive diaphragm displacement from a positive pulse ) .
  
  > Language can be a tricky thing , even for the natives .
  
  
  
  PS : BTW, I don't endorse the use of batteries for this type of test .

[Allanvh5150]

You can also do it by observing the wind direction of the coil and a compass.

Allan

[pos]

The doc states "positive voltage on the + terminal moves diaphragm towards phase plug", which is definitely not the case.
What else can I say

• 
  
  > Black ( on the driver ) to "+ on the TrueExtent" voice-coil gave you a positive displacement ( or "in-phase" as you mistaken call it ) just as TrueExtent says you should get ( assuming you connected a positive going pulse to the black terminal on the driver ) .
  
  > Maybe the problem here is that you think the " minus terminal ( for any type of polarity test ) " equates to the black terminal ( on the driver ) , when in fact ,"minus" (from say a tiny, tiny battery ) goes to the red terminal ( for a polarity test ).
  
  > This is for Legacy JBL stuff / also assuming you want to achieve a positive diaphragm displacement from a positive pulse ) .
  
  > Language can be a tricky thing , even for the natives .
  
  
  
  PS : BTW, I don't endorse the use of batteries for this type of test .

[Mr. Widget]

Semantics aside, I have contacted Truextent and with red faced embarrassment, they apologize for their error. Yes, in fact they have exactly duplicated JBL's diaphragm polarity convention and their spec sheet is incorrect.

Good call pos!


Widget

[grumpy]

in fact they have exactly duplicated JBL's diaphragm polarity convention

... as one would hope for a drop-in replacement. I actually just assumed that was the case, ignored the spec sheet in that regard entirely, and got lucky (in not spending time chasing down a response notch that should not have been there).

Nice to get this all nailed down though.

[Earl K]

,,,,and with red faced embarrassment, they apologize for their error. Yes, in fact they have exactly duplicated JBL's diaphragm polarity convention and,,,
their spec sheet is incorrect.

> Language can be a tricky thing , even for the natives .

Well,,, at least I got that part right . & Sorry for ever doubting you, pos .