Polarity Please!

[mrbluster]

Could someone please tell me the polarity of a 122a woofer ( Battery connected + to + ... - to - ) does the cone move up or down?
Thanks so much.

Mrbluster

[edgewound]

Positive voltage applied to the black terminal results in outward cone movement.

[E.T.]

Question: Is that a standard situation or just for this unit?

Tnx / E.T.

[Zilch]

Most JBL drivers are negative polarity like that.

There's a tech note about it in the JBL Pro website technical library.

Use "Search" on these forums to find numerous discussions of the subject here....

[edgewound]

The majority of vintage JBL drivers are + = Black. There are some exceptions. D123 is one of them. It's easy to check low frequency drivers with a 9 volt or flashlight battery by observing cone movement when voltage is applied to the terminals.


Here is a good reference:

http://www.jblpro.com/tech-library/JBL_TechNoteN1V12C_v5.pdf

[mrbluster]

Thanks for the help!

Mrbluster

[edgewound]

Thanks for the help!

Mrbluster

You're welcome:)

[boputnam]

Could someone please tell me the polarity of a 122a woofer ( Battery connected + to + ... - to - ) does the cone move up or down?
Yawn... You have awoken the Polarity Bear.

I'm curious - what is it you are doing...?

[Oldmics]

Bo quotes

"Yawn... You have awoken the Polarity Bear."

So if there are two-Are they referred to as the Bi-Polarity Bears?

Are they the bears on the Coke commercial?

Oldmics

[boputnam]

Dood! I can't be commenting on that from my ZIPcode!! Here, everyone goes both ways!! :rotfl:

[mrbluster]

Yawn... You have awoken the Polarity Bear.

I'm curious - what is it you are doing...?

I have a Driverless pair of L65 cabinets and was considering using something other than the original 122A woofer. Wanted to make sure I got the polarity correct. My potential substitute is an ME120HS which I believe has positive polarity, unlike the 122A.

Mrbluster

[boputnam]

Cool. Good answer, and, you are thinking about it quite correctly.

JBL, in their wisdom and knowing of the differing polarity of their components wanted things to go well on assembly so they colored the transducer leads such that the Red wire goes to Red terminal, etc. Therefore, the Red wire coming out from the crossover does not necessarily connect to the Red cabinet binding post. This works well so long as you stick with original components.

"Swapping" can introduce some unintended phase-shifts. While these are not themselves dangerous, the entire discussion of JBL Polarity can be quite maddening... :spin:

Oh, and on the 9v battery: While it's physical size is convenient because the battery poles are quite nicely spaced to touch both transducer terminals, it is an excessive drive for this test. If you use one, make it one not good for anything else, or use a 1.5v and just deal with getting the leads connected. :)

[edgewound]

Oh, and on the 9v battery: While it's physical size is convenient because the battery poles are quite nicely spaced to touch both transducer terminals, it is an excessive drive for this test. If you use one, make it one not good for anything else, or use a 1.5v and just deal with getting the leads connected. :)

Bo...maybe I should have qualified the 9 volt baterry should be a used one....that maybe puts out about 6 or so volts. That's very little power(watts)to put into a woofer or even a midrange...I've never blown a speaker with a 9 volt battery...and as you know...when testing a systems' polarity this way the crossover network capacitors will block any DC from mids and highs anyway. So...I dont see a problem. If that drive level damages the speaker, the speaker was already damaged.

[boputnam]

...and as you know...when testing a systems' polarity this way the crossover network capacitors will block any DC from mids and highs anyway. Ah, and in that, you are quite right.

I was thinking only of nekked, freightened little orphaned drivers laying desperately on the work bench... :eek: