Apologies in advance.........

[Wagner]

.........for asking a question that I know has been asked a 100 times here already.
BUT, I'm still unclear as to the answer.
Woofer polarity and proper wiring. On the L112 Century II schematic it shows the RED input terminal transitioning to the SOLID GREEN wire and attaching to the "+" terminal of the Low Frequency driver. There is no color indicated for "+", just "+".
So (you guessed it) does that mean to attach that SOLID GREEN wire, coming off the RED input terminal to the TRUE, electrically positive terminal of the 128H which would be the BLACK one, OR to attach it to the "RED" connector which folks generally assume and accept to means "positive".
Drives me nuts. Why on so many of these schematics do they abandon the color coding where the rubber actually meets the road, the driver itself? :biting:

And I ask as these woofers have been re-edged (before I got them), so I don't know if the wiring polarity is correct.

In brief: "+" mean red terminal on woofer, or "+" mean true electrical "positive" for forward cone movement?

Thank you for you patience! :)
Thomas

[DavidF]

.........for asking a question that I know has been asked a 100 times here already.
BUT, I'm still unclear as to the answer.
Woofer polarity and proper wiring. On the L112 Century II schematic it shows the RED input terminal transitioning to the SOLID GREEN wire and attaching to the "+" terminal of the Low Frequency driver. There is no color indicated for "+", just "+".
So (you guessed it) does that mean to attach that SOLID GREEN wire, coming off the RED input terminal to the TRUE, electrically positive terminal of the 128H which would be the BLACK one, OR to attach it to the "RED" connector which folks generally assume and accept to means "positive".
Drives me nuts. Why on so many of these schematics do they abandon the color coding where the rubber actually meets the road, the driver itself? :biting:

And I ask as these woofers have been re-edged (before I got them), so I don't know if the wiring polarity is correct.

In brief: "+" mean red terminal on woofer, or "+" mean true electrical "positive" for forward cone movement?

Thank you for you patience! :)
Thomas

Drivers with push buttons use the convention Red for the driver’s ‘hot’ lead (black for return).

Drivers with quick on terminals use the female terminal on the driver similarly.

The leads out of the crossover most often used a solid color for the hot lead, striped of same color or black for the return.

The designer and production engineers worked out the electrical flow so that the wiring harness was consistent to the assembly line staff and repair techs. The designer did not necessarily want the assembly line folks to have to interpret the correct connection, just go with the usual positioning. Green to woofer Red Terminal, striped green to Black; solid white to mid the positive terminal, white with black stripe to the negative, and so on.

Exceptions are likely out there but in the above sense it all worked under a logical and consistent formula.

What makes it difficult is only to the DIYs among us. JBL differed by having many drivers with positive-signal to red-terminal inverse from the usual and therefore the woofer cone or tweet dome moved inward. Then add the crossover where some legs are positive going and some negative to the driver’s positive terminals. Oy!

But that really makes no difference to the end user who buys the system and just leaves it alone. Never pulls it open, tries to tweak and “improve”. You know, there are one or two of these types out there.

[Wagner]

Drivers with push buttons use the convention Red for the driver’s ‘hot’ lead (black for return).

Drivers with quick on terminals use the female terminal on the driver similarly.

The leads out of the crossover most often used a solid color for the hot lead, striped of same color or black for the return.

The designer and production engineers worked out the electrical flow so that the wiring harness was consistent to the assembly line staff and repair techs. The designer did not necessarily want the assembly line folks to have to interpret the correct connection, just go with the usual positioning. Green to woofer Red Terminal, striped green to Black; solid white to mid the positive terminal, white with black stripe to the negative, and so on.

Exceptions are likely out there but in the above sense it all worked under a logical and consistent formula.

What makes it difficult is only to the DIYs among us. JBL differed by having many drivers with positive-signal to red-terminal inverse from the usual and therefore the woofer cone or tweet dome moved inward. Then add the crossover where some legs are positive going and some negative to the driver’s positive terminals. Oy!

But that really makes no difference to the end user who buys the system and just leaves it alone. Never pulls it open, tries to tweak and “improve”. You know, there are one or two of these types out there.


Hello David,
Thank you for the effort of so detailed a response. I own 7 pairs of JBL loudspeakers, and yes, with the exception of (1), the solid green wire from the RED amplifier input attaches at the push button connector on the woofer colored RED. I will just have to accept the fact that this is the way JBL chose to do things :D.........but I still don't understand it (WHY?) :o: I accept the assembly line explanation, but wouldn't that work the same if the little RED plastic button cap was on the actual "positive" terminal electrically speaking and the relative orientation of the input wires simply reversed? Red paint dot, whatever?
The exception I have is the late model L100A which uses the 123A-3 with the voice coil wound (or oriented, or simply the orientation of the little RED and BLACK plastic caps on the woofer's terminals?) in such a way that a low, positive DC current applied to the RED push button results in a FORWARD cone movement. The opposite being true with the 128H, LE14A etc.
Subsequently, it is in fact one exception, and the BLACK wire attaches at the RED push button. I am fine with that, it is what it is. The voice coils are wound in "reverse".
But are they wound in "reverse" or merely identified in reverse? I'm just too dense to grasp the logic of this practice when 99% of the industry (as far as I know) does it with RED resulting in FORWARD motion?
My confusion arises when I try to understand what the schematics are telling me (I am a dumb ass when it comes to this). I'll stick with the L112 example. It simply shows the GREEN and the GREEN/BLACK wires terminating at the woofer with no "ID" of the push connectors. The schematic says attach the GREEN wire to the "+" terminal of the woofer. Conventional thinking as far as I understand it is that the "+" terminal on a transducer is the one that results in a FORWARD cone movement REGARDLESS OF COLOR,
Hell, make it chartreuse.
So, if I were given the task to install a 128H woofer in an L112 cabinet equipped with only a screw driver and a schematic, I would first identity the terminals with a battery and attach the wire accordingly, the result being GREEN/BLACK to the woofer's RED push button and GREEN to the woofer's RED push button. This based solely on the polarity as indicated on the factory schematic with "+" and "-" signs.
And I would have installed it incorrectly as to intended design.
Also, if you look at the LX15 and the N100 schematics, they don't even indicate a "+" or a "-" when it comes to the woofers. And these GREEN wires are straight shots from the amp input terminals to the woofer's terminal with these two examples. I guess JBL assumed NO ONE would ever be doing this work except their people?
I just don't get it.
You can call me dumb ass. :bouncy:

Thomas

[Zilch]

Green wire goes to the red woofer terminal.

Another difficulty arises from all of this: in most cases the vintage JBL SYSYTEM is negative polarity. Use them in HT, for example, in combination with other speakers having industry standard polarity, and there's some sorting required.

I have no advice for stackers.... ;)

[Wagner]

Green wire goes to the red woofer terminal.

Another difficulty arises from all of this: in most cases the vintage JBL SYSYTEM is negative polarity. Use them in HT, for example, in combination with other speakers having industry standard polarity, and there's some sorting required.

I have no advice for stackers.... ;)

Hello and thanks.

Guess I'll just have to stop contemplating my navel and questioning authority; "it is what it is" ;)

Are there any other common, notable exceptions, like the late model L100 (123A-3) mentioned above?

Thomas

[DavidF]

Hello and thanks.

Guess I'll just have to stop contemplating my navel and questioning authority; "it is what it is" ;)

Are there any other common, notable exceptions, like the late model L100 (123A-3) mentioned above?

Thomas

This is been discussed before on this site. Just do some search on polarity, absolute phase, etc. JBL migrated more recently to DC to Red= outward. You can look to some Altec drivers and find they too were opposite 'convention'. Then again how many manufacturers of today were around in the thirties and forties to claim their convention was "industry standard" in contrast to Altec or JBL?

[boputnam]

Green wire goes to the red woofer terminal.Always the right answer. :)

[Wagner]

Always the right answer. :)


Unless you are working on late production L100s with 123A-3(s) that some joker pulled without making note, armed with only the "technical manual" schematic of the N100, 4/94 REV B. :(

Thank God for this place ;)

Thomas

[boputnam]

...that some joker pulled without making note...Yeah, Thomas - we've lamented the same thing here, many times.

If only "afficionados" would make notes of their well-intended work and tape it to the rear of the cabinet, so that future benefactors could more readily rectify things! :)