Transducer Polarity Listing - 18/04/2003
Here is a compilation of my testing results so-far. Luckily, I have a number of projects in process!
Tests were the 9-volt "click" test, applying the posts of a 9-volt to the corresponding posts on the transducers. Where needed, an alligator clamp bridge wire was used.
Negative = cone excursion "in" on positive voltage. Industry convention is "positive" (cone "out"), or reverse of convention JBL used on most - but not all - vintage components.
If you are pairing vintage JBL cabinets with more contemporary JBL, or ANY other brand of any age, the vintage JBL will be 180 degrees out of phase, resulting in complex frequency cancellations and poor imaging.
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The following are all NEGATIVE
Tweeters
LE20, LE25-4, LE26
Mid-range
LE5-2, LE5-9, LE5-12
Woofers
LE8T-2, LE8T-H, LE10A (both 8 and 16 ohm), LE10H, LE14A, LE15A
2213H
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The following tests POSITIVE
Woofer
123A-1
an archived reply from "Mr. Widget"
This was a recent very helpful reply posted on the temporary forum, with some replys to specific questions, too.
From "Mr. Widget" - 14/04/2003
Basically all JBL loudspeaker components and systems have been the reverse of the standard industry practice until the very latest models and systems. JBL has continued to produce components that will be used with it's previous systems like the 2235H woofers with the reversed polarity. As they come out with completely new systems they are being introduced with the industry standard cone moves forward with a positive DC voltage, but it is very confusing as in a complete system you may use newer speakers with one polarity and an older sub with the other polarity.
"3) Working on a pair of Flair 45's (S8), they instruct crossing the outputs from the LX5 going to the N7000 network - why is this? Is the LX5 different polarity than the (older?) N7000? In the S7 (sans the N7000) the horn is red-to-red from the LX5."
This is another animal altogether. This is a common practice in three way systems where to get the most accurate phase response you place the mid driver 180 degrees out of phase with the rest of the system.
"4) How do all of you JBL'ers deal with this - especially when mating a variety of components and maybe even paring cabinets side-by-side?"
It is a pain. I always check the woofers in my finished systems with a DC test to verify that I didn't accidentally cross a wire. With compression drivers, if it is JBL I assume it is reversed, if it is someone else's I assume it is standard.
and likewise from Tom Loizeaux
From "Tom Loizeaux" - 14/04/2003
When I wire up componants, I always check the woofer phase by touching a 9 volt battery to the leads. I then try to put my head between the woofer and compression driver to see if the sound comes from a spot between the componants. If in doubt, I switch the compression driver leads to see if it improves. Since I wanted the color-coded terminals and banana connectors to match, I've had to re-solder the leads inside my JBL cabinets to correct the factory phase.
I get all my speakers wired in phase so I can switch amps, wires and cabinets and never worry about phase problems.
A comment on "correcting" JBL polarity
If you are going to reverse the polarity of a JBL cabinet, it must be done AT EACH COMPONENT in the cabinet. You should not simply hook-up the cabinet red-to-black. That will not have the proper effect, because that will result in the signal being pathed through the transducer before the capacitor(s) - this is a DC circuit, and that is backwards. For the crossover network to work properly, the capacitor(s) must see the signal BEFORE the transducer, regardless of cabinet (and transducer) polarity.
To "correct" or re-phase a vintage JBL cabinet, you need to reverse-wire at each component. Simply alter the signal path AFTER the crossover and before the transducer, at each component binding posts.
As example, if your cabinet is out-of-phase (negative), and woofer is wired GRN-to-red post, switch the woofer to GRN/BLK-to-red post. Reverse the wiring for EACH component (this will ensure the mid-range stays 180-degrees out-of-phase in 3-way cabinets). The woofer - and cabinet - will then be positive, and industry standard.
It is handy - but not necessary - to review the network schematics, if you're so inclined, and yours is available:
Link: http://www.jblproservice.com/pdf/Network%20Schematics/
Galaxy Audio "Cricket" Polarity Tester
Humbly recommended by Mike Caldwell of VintageAudio.com (www.vintageaudiosales.com), this handy little device provides fool-proof verification of cabinet phasing. It's not cheap, but neither are JBL components and neither are the phasing questions trivial to resolve. The "Cricket" tests transducers already installed in the cabinet, more thoroughly than the 9-volt click test. It has other applications as well, to check the polarity of your entire system.
"Cricket" can be researched at: http://www.galaxyaudio.com/galaxy/Pr...l#TEST%20EQUIP - check with ElaineC there...
And, the folks at Northern Sound and Light (http://www.northernsound.net/Sales/t...o/cricket.html) gave the best pricing I could find. They drop-shipped it too - saved time.
I have no commercial relationship with either entity, and only recommend "cricket" as something that solved some questions I have, and looks to be VERY handy.
With it, I found the 066's are positive - they wouldn't test well any other way.